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Chapter 7. Creating and managing topics	Chapter 7. Creating and managing topics Messages in Kafka are always sent to or received from a topic. This chapter describes how to create and manage Kafka topics. 7.1. Partitions and replicas A topic is always split into one or more partitions. Partitions act as shards. That means that every message sent by a producer is always written only into a single partition. Each partition can have one or more replicas, which will be stored on different brokers in the cluster. When creating a topic you can configure the number of replicas using the replication factor . Replication factor defines the number of copies which will be held within the cluster. One of the replicas for a given partition will be elected as a leader. The leader replica will be used by the producers to send new messages and by the consumers to consume messages. The other replicas will be follower replicas. The followers replicate the leader. If the leader fails, one of the in-sync followers will automatically become the new leader. Each server acts as a leader for some of its partitions and a follower for others so the load is well balanced within the cluster. Note The replication factor determines the number of replicas including the leader and the followers. For example, if you set the replication factor to 3 , then there will be one leader and two follower replicas. 7.2. Message retention The message retention policy defines how long the messages will be stored on the Kafka brokers. It can be defined based on time, partition size or both. For example, you can define that the messages should be kept: For 7 days Until the partition has 1GB of messages. Once the limit is reached, the oldest messages will be removed. For 7 days or until the 1GB limit has been reached. Whatever limit comes first will be used. Warning Kafka brokers store messages in log segments. The messages which are past their retention policy will be deleted only when a new log segment is created. New log segments are created when the log segment exceeds the configured log segment size. Additionally, users can request new segments to be created periodically. Kafka brokers support a compacting policy. For a topic with the compacted policy, the broker will always keep only the last message for each key. The older messages with the same key will be removed from the partition. Because compacting is a periodically executed action, it does not happen immediately when the new message with the same key is sent to the partition. Instead it might take some time until the older messages are removed. For more information about the message retention configuration options, see Section 7.5, "Topic configuration" . 7.3. Topic auto-creation By default, Kafka automatically creates a topic if a producer or consumer attempts to send or receive messages from a non-existent topic. This behavior is governed by the auto.create.topics.enable configuration property, which is set to true by default. For production environments, it is recommended to disable automatic topic creation. To do so, set auto.create.topics.enable to false in the Kafka configuration properties file: Disabling automatic topic creation 7.4. Topic deletion Kafka provides the option to prevent topic deletion, controlled by the delete.topic.enable property . By default, this property is set to true , allowing topics to be deleted. However, setting it to false in the Kafka configuration properties file will disable topic deletion. In this case, attempts to delete a topic will return a success status, but the topic itself will not be deleted. Disabling topic deletion 7.5. Topic configuration Auto-created topics will use the default topic configuration which can be specified in the broker properties file. However, when creating topics manually, their configuration can be specified at creation time. It is also possible to change a topic's configuration after it has been created. The main topic configuration options for manually created topics are: cleanup.policy Configures the retention policy to delete or compact . The delete policy will delete old records. The compact policy will enable log compaction. The default value is delete . For more information about log compaction, see Kafka website . compression.type Specifies the compression which is used for stored messages. Valid values are gzip , snappy , lz4 , uncompressed (no compression) and producer (retain the compression codec used by the producer). The default value is producer . max.message.bytes The maximum size of a batch of messages allowed by the Kafka broker, in bytes. The default value is 1000012 . min.insync.replicas The minimum number of replicas which must be in sync for a write to be considered successful. The default value is 1 . retention.ms Maximum number of milliseconds for which log segments will be retained. Log segments older than this value will be deleted. The default value is 604800000 (7 days). retention.bytes The maximum number of bytes a partition will retain. Once the partition size grows over this limit, the oldest log segments will be deleted. Value of -1 indicates no limit. The default value is -1 . segment.bytes The maximum file size of a single commit log segment file in bytes. When the segment reaches its size, a new segment will be started. The default value is 1073741824 bytes (1 gibibyte). The defaults for auto-created topics can be specified in the Kafka broker configuration using similar options: log.cleanup.policy See cleanup.policy above. compression.type See compression.type above. message.max.bytes See max.message.bytes above. min.insync.replicas See min.insync.replicas above. log.retention.ms See retention.ms above. log.retention.bytes See retention.bytes above. log.segment.bytes See segment.bytes above. default.replication.factor Default replication factor for automatically created topics. Default value is 1 . num.partitions Default number of partitions for automatically created topics. Default value is 1 . 7.6. Internal topics Internal topics are created and used internally by the Kafka brokers and clients. Kafka has several internal topics, two of which are used to store consumer offsets ( __consumer_offsets ) and transaction state ( __transaction_state ). __consumer_offsets and __transaction_state topics can be configured using dedicated Kafka broker configuration options starting with prefix offsets.topic. and transaction.state.log. . The most important configuration options are: offsets.topic.replication.factor Number of replicas for __consumer_offsets topic. The default value is 3 . offsets.topic.num.partitions Number of partitions for __consumer_offsets topic. The default value is 50 . transaction.state.log.replication.factor Number of replicas for __transaction_state topic. The default value is 3 . transaction.state.log.num.partitions Number of partitions for __transaction_state topic. The default value is 50 . transaction.state.log.min.isr Minimum number of replicas that must acknowledge a write to __transaction_state topic to be considered successful. If this minimum cannot be met, then the producer will fail with an exception. The default value is 2 . 7.7. Creating a topic Use the kafka-topics.sh tool to manage topics. kafka-topics.sh is part of the Streams for Apache Kafka distribution and is found in the bin directory. Prerequisites Streams for Apache Kafka is installed on each host , and the configuration files are available. Creating a topic Create a topic using the kafka-topics.sh utility and specify the following: Host and port of the Kafka broker in the --bootstrap-server option. The new topic to be created in the --create option. Topic name in the --topic option. The number of partitions in the --partitions option. Topic replication factor in the --replication-factor option. You can also override some of the default topic configuration options using the option --config . This option can be used multiple times to override different options. /opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_address> --create --topic <TopicName> --partitions <NumberOfPartitions> --replication-factor <ReplicationFactor> --config <Option1> = <Value1> --config <Option2> = <Value2> Example of the command to create a topic named mytopic /opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --create --topic mytopic --partitions 50 --replication-factor 3 --config cleanup.policy=compact --config min.insync.replicas=2 Verify that the topic exists using kafka-topics.sh . /opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_address> --describe --topic <TopicName> Example of the command to describe a topic named mytopic /opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --describe --topic mytopic 7.8. Listing and describing topics The kafka-topics.sh tool can be used to list and describe topics. kafka-topics.sh is part of the Streams for Apache Kafka distribution and can be found in the bin directory. Prerequisites Streams for Apache Kafka is installed on each host , and the configuration files are available. Describing a topic Describe a topic using the kafka-topics.sh utility and specify the following: Host and port of the Kafka broker in the --bootstrap-server option. Use the --describe option to specify that you want to describe a topic. Topic name must be specified in the --topic option. When the --topic option is omitted, it describes all available topics. /opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_host>:<port> --describe --topic <topic_name> Example of the command to describe a topic named mytopic /opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --describe --topic mytopic The command lists all partitions and replicas which belong to this topic. It also lists all topic configuration options. 7.9. Modifying a topic configuration The kafka-configs.sh tool can be used to modify topic configurations. kafka-configs.sh is part of the Streams for Apache Kafka distribution and can be found in the bin directory. Prerequisites Streams for Apache Kafka is installed on each host , and the configuration files are available. Modify topic configuration Use the kafka-configs.sh tool to get the current configuration. Specify the host and port of the Kafka broker in the --bootstrap-server option. Set the --entity-type as topic and --entity-name to the name of your topic. Use --describe option to get the current configuration. /opt/kafka/bin/kafka-configs.sh --bootstrap-server <broker_host>:<port> --entity-type topics --entity-name <topic_name> --describe Example of the command to get configuration of a topic named mytopic /opt/kafka/bin/kafka-configs.sh --bootstrap-server localhost:9092 --entity-type topics --entity-name mytopic --describe Use the kafka-configs.sh tool to change the configuration. Specify the host and port of the Kafka broker in the --bootstrap-server option. Set the --entity-type as topic and --entity-name to the name of your topic. Use --alter option to modify the current configuration. Specify the options you want to add or change in the option --add-config . /opt/kafka/bin/kafka-configs.sh --bootstrap-server <broker_host>:<port> --entity-type topics --entity-name <topic_name> --alter --add-config <option>=<value> Example of the command to change configuration of a topic named mytopic /opt/kafka/bin/kafka-configs.sh --bootstrap-server localhost:9092 --entity-type topics --entity-name mytopic --alter --add-config min.insync.replicas=1 Use the kafka-configs.sh tool to delete an existing configuration option. Specify the host and port of the Kafka broker in the --bootstrap-server option. Set the --entity-type as topic and --entity-name to the name of your topic. Use --delete-config option to remove existing configuration option. Specify the options you want to remove in the option --remove-config . /opt/kafka/bin/kafka-configs.sh --bootstrap-server <broker_host>:<port> --entity-type topics --entity-name <topic_name> --alter --delete-config <option> Example of the command to change configuration of a topic named mytopic /opt/kafka/bin/kafka-configs.sh --bootstrap-server localhost:9092 --entity-type topics --entity-name mytopic --alter --delete-config min.insync.replicas 7.10. Deleting a topic The kafka-topics.sh tool can be used to manage topics. kafka-topics.sh is part of the Streams for Apache Kafka distribution and can be found in the bin directory. Prerequisites Streams for Apache Kafka is installed on each host , and the configuration files are available. Deleting a topic Delete a topic using the kafka-topics.sh utility. Host and port of the Kafka broker in the --bootstrap-server option. Use the --delete option to specify that an existing topic should be deleted. Topic name must be specified in the --topic option. /opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_host>:<port> --delete --topic <topic_name> Example of the command to create a topic named mytopic /opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --delete --topic mytopic Verify that the topic was deleted using kafka-topics.sh . /opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_host>:<port> --list Example of the command to list all topics /opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --list	[ "auto.create.topics.enable=false", "delete.topic.enable=false", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_address> --create --topic <TopicName> --partitions <NumberOfPartitions> --replication-factor <ReplicationFactor> --config <Option1> = <Value1> --config <Option2> = <Value2>", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --create --topic mytopic --partitions 50 --replication-factor 3 --config cleanup.policy=compact --config min.insync.replicas=2", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_address> --describe --topic <TopicName>", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --describe --topic mytopic", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_host>:<port> --describe --topic <topic_name>", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --describe --topic mytopic", "/opt/kafka/bin/kafka-configs.sh --bootstrap-server <broker_host>:<port> --entity-type topics --entity-name <topic_name> --describe", "/opt/kafka/bin/kafka-configs.sh --bootstrap-server localhost:9092 --entity-type topics --entity-name mytopic --describe", "/opt/kafka/bin/kafka-configs.sh --bootstrap-server <broker_host>:<port> --entity-type topics --entity-name <topic_name> --alter --add-config <option>=<value>", "/opt/kafka/bin/kafka-configs.sh --bootstrap-server localhost:9092 --entity-type topics --entity-name mytopic --alter --add-config min.insync.replicas=1", "/opt/kafka/bin/kafka-configs.sh --bootstrap-server <broker_host>:<port> --entity-type topics --entity-name <topic_name> --alter --delete-config <option>", "/opt/kafka/bin/kafka-configs.sh --bootstrap-server localhost:9092 --entity-type topics --entity-name mytopic --alter --delete-config min.insync.replicas", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_host>:<port> --delete --topic <topic_name>", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --delete --topic mytopic", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server <broker_host>:<port> --list", "/opt/kafka/bin/kafka-topics.sh --bootstrap-server localhost:9092 --list" ]	https://docs.redhat.com/en/documentation/red_hat_streams_for_apache_kafka/2.7/html/using_streams_for_apache_kafka_on_rhel_with_zookeeper/topics-str
12.0 Release Notes	12.0 Release Notes Red Hat Developer Toolset 12 Release Notes for Red Hat Developer Toolset 12.0 Lenka Spackova Red Hat Customer Content Services [email protected] Jaromir Hradilek Red Hat Customer Content Services [email protected] Eliska Slobodova Red Hat Customer Content Services	null	https://docs.redhat.com/en/documentation/red_hat_developer_toolset/12/html/12.0_release_notes/index
4.4. Logical Volume Administration	4.4. Logical Volume Administration This section describes the commands that perform the various aspects of logical volume administration. 4.4.1. Creating Linear Logical Volumes To create a logical volume, use the lvcreate command. If you do not specify a name for the logical volume, the default name lvol # is used where # is the internal number of the logical volume. When you create a logical volume, the logical volume is carved from a volume group using the free extents on the physical volumes that make up the volume group. Normally logical volumes use up any space available on the underlying physical volumes on a -free basis. Modifying the logical volume frees and reallocates space in the physical volumes. The following command creates a logical volume 10 gigabytes in size in the volume group vg1 . The default unit for logical volume size is megabytes. The following command creates a 1500 megabyte linear logical volume named testlv in the volume group testvg , creating the block device /dev/testvg/testlv . The following command creates a 50 gigabyte logical volume named gfslv from the free extents in volume group vg0 . You can use the -l argument of the lvcreate command to specify the size of the logical volume in extents. You can also use this argument to specify the percentage of of the size of a related volume group, logical volume, or set of physical volumes. The suffix %VG denotes the total size of the volume group, the suffix %FREE the remaining free space in the volume group, and the suffix %PVS the free space in the specified physical volumes. For a snapshot, the size can be expressed as a percentage of the total size of the origin logical volume with the suffix %ORIGIN (100%ORIGIN provides space for the whole origin). When expressed as a percentage, the size defines an upper limit for the number of logical extents in the new logical volume. The precise number of logical extents in the new LV is not determined until the command has completed. The following command creates a logical volume called mylv that uses 60% of the total space in volume group testvg . The following command creates a logical volume called yourlv that uses all of the unallocated space in the volume group testvg . You can use -l argument of the lvcreate command to create a logical volume that uses the entire volume group. Another way to create a logical volume that uses the entire volume group is to use the vgdisplay command to find the "Total PE" size and to use those results as input to the lvcreate command. The following commands create a logical volume called mylv that fills the volume group named testvg . The underlying physical volumes used to create a logical volume can be important if the physical volume needs to be removed, so you may need to consider this possibility when you create the logical volume. For information on removing a physical volume from a volume group, see Section 4.3.7, "Removing Physical Volumes from a Volume Group" . To create a logical volume to be allocated from a specific physical volume in the volume group, specify the physical volume or volumes at the end at the lvcreate command line. The following command creates a logical volume named testlv in volume group testvg allocated from the physical volume /dev/sdg1 , You can specify which extents of a physical volume are to be used for a logical volume. The following example creates a linear logical volume out of extents 0 through 24 of physical volume /dev/sda1 and extents 50 through 124 of physical volume /dev/sdb1 in volume group testvg . The following example creates a linear logical volume out of extents 0 through 25 of physical volume /dev/sda1 and then continues laying out the logical volume at extent 100. The default policy for how the extents of a logical volume are allocated is inherit , which applies the same policy as for the volume group. These policies can be changed using the lvchange command. For information on allocation policies, see Section 4.3.1, "Creating Volume Groups" . 4.4.2. Creating Striped Volumes For large sequential reads and writes, creating a striped logical volume can improve the efficiency of the data I/O. For general information about striped volumes, see Section 2.3.2, "Striped Logical Volumes" . When you create a striped logical volume, you specify the number of stripes with the -i argument of the lvcreate command. This determines over how many physical volumes the logical volume will be striped. The number of stripes cannot be greater than the number of physical volumes in the volume group (unless the --alloc anywhere argument is used). If the underlying physical devices that make up a striped logical volume are different sizes, the maximum size of the striped volume is determined by the smallest underlying device. For example, in a two-legged stripe, the maximum size is twice the size of the smaller device. In a three-legged stripe, the maximum size is three times the size of the smallest device. The following command creates a striped logical volume across 2 physical volumes with a stripe of 64 kilobytes. The logical volume is 50 gigabytes in size, is named gfslv , and is carved out of volume group vg0 . As with linear volumes, you can specify the extents of the physical volume that you are using for the stripe. The following command creates a striped volume 100 extents in size that stripes across two physical volumes, is named stripelv and is in volume group testvg . The stripe will use sectors 0-49 of /dev/sda1 and sectors 50-99 of /dev/sdb1 . 4.4.3. RAID Logical Volumes LVM supports RAID0/1/4/5/6/10. Note RAID logical volumes are not cluster-aware. While RAID logical volumes can be created and activated exclusively on one machine, they cannot be activated simultaneously on more than one machine. If you require non-exclusive mirrored volumes, you must create the volumes with a mirror segment type, as described in Section 4.4.4, "Creating Mirrored Volumes" . To create a RAID logical volume, you specify a raid type as the --type argument of the lvcreate command. Table 4.1, "RAID Segment Types" describes the possible RAID segment types. Table 4.1. RAID Segment Types Segment type Description raid1 RAID1 mirroring. This is the default value for the --type argument of the lvcreate command when you specify the -m but you do not specify striping. raid4 RAID4 dedicated parity disk raid5 Same as raid5_ls raid5_la RAID5 left asymmetric. Rotating parity 0 with data continuation raid5_ra RAID5 right asymmetric. Rotating parity N with data continuation raid5_ls RAID5 left symmetric. Rotating parity 0 with data restart raid5_rs RAID5 right symmetric. Rotating parity N with data restart raid6 Same as raid6_zr raid6_zr RAID6 zero restart Rotating parity zero (left-to-right) with data restart raid6_nr RAID6 N restart Rotating parity N (left-to-right) with data restart raid6_nc RAID6 N continue Rotating parity N (left-to-right) with data continuation raid10 Striped mirrors. This is the default value for the --type argument of the lvcreate command if you specify the -m and you specify a number of stripes that is greater than 1. Striping of mirror sets raid0/raid0_meta (Red Hat Enterprise Linux 7.3 and later) Striping. RAID0 spreads logical volume data across multiple data subvolumes in units of stripe size. This is used to increase performance. Logical volume data will be lost if any of the data subvolumes fail. For information on creating RAID0 volumes, see Section 4.4.3.1, "Creating RAID0 Volumes (Red Hat Enterprise Linux 7.3 and Later)" . For most users, specifying one of the five available primary types ( raid1 , raid4 , raid5 , raid6 , raid10 ) should be sufficient. When you create a RAID logical volume, LVM creates a metadata subvolume that is one extent in size for every data or parity subvolume in the array. For example, creating a 2-way RAID1 array results in two metadata subvolumes ( lv_rmeta_0 and lv_rmeta_1 ) and two data subvolumes ( lv_rimage_0 and lv_rimage_1 ). Similarly, creating a 3-way stripe (plus 1 implicit parity device) RAID4 results in 4 metadata subvolumes ( lv_rmeta_0 , lv_rmeta_1 , lv_rmeta_2 , and lv_rmeta_3 ) and 4 data subvolumes ( lv_rimage_0 , lv_rimage_1 , lv_rimage_2 , and lv_rimage_3 ). The following command creates a 2-way RAID1 array named my_lv in the volume group my_vg that is one gigabyte in size. You can create RAID1 arrays with different numbers of copies according to the value you specify for the -m argument. Similarly, you specify the number of stripes for a RAID 4/5/6 logical volume with the -i argument . You can also specify the stripe size with the -I argument. The following command creates a RAID5 array (3 stripes + 1 implicit parity drive) named my_lv in the volume group my_vg that is one gigabyte in size. Note that you specify the number of stripes just as you do for an LVM striped volume; the correct number of parity drives is added automatically. The following command creates a RAID6 array (3 stripes + 2 implicit parity drives) named my_lv in the volume group my_vg that is one gigabyte in size. After you have created a RAID logical volume with LVM, you can activate, change, remove, display, and use the volume just as you would any other LVM logical volume. When you create RAID10 logical volumes, the background I/O required to initialize the logical volumes with a sync operation can crowd out other I/O operations to LVM devices, such as updates to volume group metadata, particularly when you are creating many RAID logical volumes. This can cause the other LVM operations to slow down. You can control the rate at which a RAID logical volume is initialized by implementing recovery throttling. You control the rate at which sync operations are performed by setting the minimum and maximum I/O rate for those operations with the --minrecoveryrate and --maxrecoveryrate options of the lvcreate command. You specify these options as follows. --maxrecoveryrate Rate [bBsSkKmMgG] Sets the maximum recovery rate for a RAID logical volume so that it will not crowd out nominal I/O operations. The Rate is specified as an amount per second for each device in the array. If no suffix is given, then kiB/sec/device is assumed. Setting the recovery rate to 0 means it will be unbounded. --minrecoveryrate Rate [bBsSkKmMgG] Sets the minimum recovery rate for a RAID logical volume to ensure that I/O for sync operations achieves a minimum throughput, even when heavy nominal I/O is present. The Rate is specified as an amount per second for each device in the array. If no suffix is given, then kiB/sec/device is assumed. The following command creates a 2-way RAID10 array with 3 stripes that is 10 gigabytes in size with a maximum recovery rate of 128 kiB/sec/device. The array is named my_lv and is in the volume group my_vg . You can also specify minimum and maximum recovery rates for a RAID scrubbing operation. For information on RAID scrubbing, see Section 4.4.3.11, "Scrubbing a RAID Logical Volume" . Note You can generate commands to create logical volumes on RAID storage with the LVM RAID Calculator application. This application uses the information you input about your current or planned storage to generate these commands. The LVM RAID Calculator application can be found at https://access.redhat.com/labs/lvmraidcalculator/ . The following sections describes the administrative tasks you can perform on LVM RAID devices: Section 4.4.3.1, "Creating RAID0 Volumes (Red Hat Enterprise Linux 7.3 and Later)" . Section 4.4.3.2, "Converting a Linear Device to a RAID Device" Section 4.4.3.3, "Converting an LVM RAID1 Logical Volume to an LVM Linear Logical Volume" Section 4.4.3.4, "Converting a Mirrored LVM Device to a RAID1 Device" Section 4.4.3.5, "Resizing a RAID Logical Volume" Section 4.4.3.6, "Changing the Number of Images in an Existing RAID1 Device" Section 4.4.3.7, "Splitting off a RAID Image as a Separate Logical Volume" Section 4.4.3.8, "Splitting and Merging a RAID Image" Section 4.4.3.9, "Setting a RAID fault policy" Section 4.4.3.10, "Replacing a RAID device" Section 4.4.3.11, "Scrubbing a RAID Logical Volume" Section 4.4.3.12, "RAID Takeover (Red Hat Enterprise Linux 7.4 and Later)" Section 4.4.3.13, "Reshaping a RAID Logical Volume (Red Hat Enterprise Linux 7.4 and Later)" Section 4.4.3.14, "Controlling I/O Operations on a RAID1 Logical Volume" Section 4.4.3.15, "Changing the region size on a RAID Logical Volume (Red Hat Enterprise Linux 7.4 and later)" 4.4.3.1. Creating RAID0 Volumes (Red Hat Enterprise Linux 7.3 and Later) The format for the command to create a RAID0 volume is as follows. Table 4.2. RAID0 Command Creation parameters Parameter Description --type raid0[_meta] Specifying raid0 creates a RAID0 volume without metadata volumes. Specifying raid0_meta creates a RAID0 volume with metadata volumes. Because RAID0 is non-resilient, it does not have to store any mirrored data blocks as RAID1/10 or calculate and store any parity blocks as RAID4/5/6 do. Hence, it does not need metadata volumes to keep state about resynchronization progress of mirrored or parity blocks. Metadata volumes become mandatory on a conversion from RAID0 to RAID4/5/6/10, however, and specifying raid0_meta preallocates those metadata volumes to prevent a respective allocation failure. --stripes Stripes Specifies the number of devices to spread the logical volume across. --stripesize StripeSize Specifies the size of each stripe in kilobytes. This is the amount of data that is written to one device before moving to the device. VolumeGroup Specifies the volume group to use. PhysicalVolumePath ... Specifies the devices to use. If this is not specified, LVM will choose the number of devices specified by the Stripes option, one for each stripe. 4.4.3.2. Converting a Linear Device to a RAID Device You can convert an existing linear logical volume to a RAID device by using the --type argument of the lvconvert command. The following command converts the linear logical volume my_lv in volume group my_vg to a 2-way RAID1 array. Since RAID logical volumes are composed of metadata and data subvolume pairs, when you convert a linear device to a RAID1 array, a new metadata subvolume is created and associated with the original logical volume on (one of) the same physical volumes that the linear volume is on. The additional images are added in metadata/data subvolume pairs. For example, if the original device is as follows: After conversion to a 2-way RAID1 array the device contains the following data and metadata subvolume pairs: If the metadata image that pairs with the original logical volume cannot be placed on the same physical volume, the lvconvert will fail. 4.4.3.3. Converting an LVM RAID1 Logical Volume to an LVM Linear Logical Volume You can convert an existing RAID1 LVM logical volume to an LVM linear logical volume with the lvconvert command by specifying the -m0 argument. This removes all the RAID data subvolumes and all the RAID metadata subvolumes that make up the RAID array, leaving the top-level RAID1 image as the linear logical volume. The following example displays an existing LVM RAID1 logical volume. The following command converts the LVM RAID1 logical volume my_vg/my_lv to an LVM linear device. When you convert an LVM RAID1 logical volume to an LVM linear volume, you can specify which physical volumes to remove. The following example shows the layout of an LVM RAID1 logical volume made up of two images: /dev/sda1 and /dev/sdb1 . In this example, the lvconvert command specifies that you want to remove /dev/sda1 , leaving /dev/sdb1 as the physical volume that makes up the linear device. 4.4.3.4. Converting a Mirrored LVM Device to a RAID1 Device You can convert an existing mirrored LVM device with a segment type of mirror to a RAID1 LVM device with the lvconvert command by specifying the --type raid1 argument. This renames the mirror subvolumes ( _mimage_ ) to RAID subvolumes ( _rimage_ ). In addition, the mirror log is removed and metadata subvolumes ( _rmeta_ ) are created for the data subvolumes on the same physical volumes as the corresponding data subvolumes. The following example shows the layout of a mirrored logical volume my_vg/my_lv . The following command converts the mirrored logical volume my_vg/my_lv to a RAID1 logical volume. 4.4.3.5. Resizing a RAID Logical Volume You can resize a RAID logical volume in the following ways; You can increase the size of a RAID logical volume of any type with the lvresize or lvextend command. This does not change the number of RAID images. For striped RAID logical volumes the same stripe rounding constraints apply as when you create a striped RAID logical volume. For more information on extending a RAID volume, see Section 4.4.18, "Extending a RAID Volume" . You can reduce the size of a RAID logical volume of any type with the lvresize or lvreduce command. This does not change the number of RAID images. As with the lvextend command, the same stripe rounding constraints apply as when you create a striped RAID logical volume. For an example of a command to reduce the size of a logical volume, see Section 4.4.16, "Shrinking Logical Volumes" . As of Red Hat Enterprise Linux 7.4, you can change the number of stripes on a striped RAID logical volume ( raid4/5/6/10 ) with the --stripes N parameter of the lvconvert command. This increases or reduces the size of the RAID logical volume by the capacity of the stripes added or removed. Note that raid10 volumes are capable only of adding stripes. This capability is part of the RAID reshaping feature that allows you to change attributes of a RAID logical volume while keeping the same RAID level. For information on RAID reshaping and examples of using the lvconvert command to reshape a RAID logical volume, see the lvmraid (7) man page. 4.4.3.6. Changing the Number of Images in an Existing RAID1 Device You can change the number of images in an existing RAID1 array just as you can change the number of images in the earlier implementation of LVM mirroring. Use the lvconvert command to specify the number of additional metadata/data subvolume pairs to add or remove. For information on changing the volume configuration in the earlier implementation of LVM mirroring, see Section 4.4.4.4, "Changing Mirrored Volume Configuration" . When you add images to a RAID1 device with the lvconvert command, you can specify the total number of images for the resulting device, or you can specify how many images to add to the device. You can also optionally specify on which physical volumes the new metadata/data image pairs will reside. Metadata subvolumes (named _rmeta_ ) always exist on the same physical devices as their data subvolume counterparts _rimage_ ). The metadata/data subvolume pairs will not be created on the same physical volumes as those from another metadata/data subvolume pair in the RAID array (unless you specify --alloc anywhere ). The format for the command to add images to a RAID1 volume is as follows: For example, the following command displays the LVM device my_vg/my_lv , which is a 2-way RAID1 array: The following command converts the 2-way RAID1 device my_vg/my_lv to a 3-way RAID1 device: When you add an image to a RAID1 array, you can specify which physical volumes to use for the image. The following command converts the 2-way RAID1 device my_vg/my_lv to a 3-way RAID1 device, specifying that the physical volume /dev/sdd1 be used for the array: To remove images from a RAID1 array, use the following command. When you remove images from a RAID1 device with the lvconvert command, you can specify the total number of images for the resulting device, or you can specify how many images to remove from the device. You can also optionally specify the physical volumes from which to remove the device. Additionally, when an image and its associated metadata subvolume volume are removed, any higher-numbered images will be shifted down to fill the slot. If you remove lv_rimage_1 from a 3-way RAID1 array that consists of lv_rimage_0 , lv_rimage_1 , and lv_rimage_2 , this results in a RAID1 array that consists of lv_rimage_0 and lv_rimage_1 . The subvolume lv_rimage_2 will be renamed and take over the empty slot, becoming lv_rimage_1 . The following example shows the layout of a 3-way RAID1 logical volume my_vg/my_lv . The following command converts the 3-way RAID1 logical volume into a 2-way RAID1 logical volume. The following command converts the 3-way RAID1 logical volume into a 2-way RAID1 logical volume, specifying the physical volume that contains the image to remove as /dev/sde1 . 4.4.3.7. Splitting off a RAID Image as a Separate Logical Volume You can split off an image of a RAID logical volume to form a new logical volume. The procedure for splitting off a RAID image is the same as the procedure for splitting off a redundant image of a mirrored logical volume, as described in Section 4.4.4.2, "Splitting Off a Redundant Image of a Mirrored Logical Volume" . The format of the command to split off a RAID image is as follows: Just as when you are removing a RAID image from an existing RAID1 logical volume (as described in Section 4.4.3.6, "Changing the Number of Images in an Existing RAID1 Device" ), when you remove a RAID data subvolume (and its associated metadata subvolume) from the middle of the device any higher numbered images will be shifted down to fill the slot. The index numbers on the logical volumes that make up a RAID array will thus be an unbroken sequence of integers. Note You cannot split off a RAID image if the RAID1 array is not yet in sync. The following example splits a 2-way RAID1 logical volume, my_lv , into two linear logical volumes, my_lv and new . The following example splits a 3-way RAID1 logical volume, my_lv , into a 2-way RAID1 logical volume, my_lv , and a linear logical volume, new 4.4.3.8. Splitting and Merging a RAID Image You can temporarily split off an image of a RAID1 array for read-only use while keeping track of any changes by using the --trackchanges argument in conjunction with the --splitmirrors argument of the lvconvert command. This allows you to merge the image back into the array at a later time while resyncing only those portions of the array that have changed since the image was split. The format for the lvconvert command to split off a RAID image is as follows. When you split off a RAID image with the --trackchanges argument, you can specify which image to split but you cannot change the name of the volume being split. In addition, the resulting volumes have the following constraints. The new volume you create is read-only. You cannot resize the new volume. You cannot rename the remaining array. You cannot resize the remaining array. You can activate the new volume and the remaining array independently. You can merge an image that was split off with the --trackchanges argument specified by executing a subsequent lvconvert command with the --merge argument. When you merge the image, only the portions of the array that have changed since the image was split are resynced. The format for the lvconvert command to merge a RAID image is as follows. The following example creates a RAID1 logical volume and then splits off an image from that volume while tracking changes to the remaining array. The following example splits off an image from a RAID1 volume while tracking changes to the remaining array, then merges the volume back into the array. Once you have split off an image from a RAID1 volume, you can make the split permanent by issuing a second lvconvert --splitmirrors command, repeating the initial lvconvert command that split the image without specifying the --trackchanges argument. This breaks the link that the --trackchanges argument created. After you have split an image with the --trackchanges argument, you cannot issue a subsequent lvconvert --splitmirrors command on that array unless your intent is to permanently split the image being tracked. The following sequence of commands splits an image and tracks the image and then permanently splits off the image being tracked. Note, however, that the following sequence of commands will fail. Similarly, the following sequence of commands will fail as well, since the split image is not the image being tracked. 4.4.3.9. Setting a RAID fault policy LVM RAID handles device failures in an automatic fashion based on the preferences defined by the raid_fault_policy field in the lvm.conf file. If the raid_fault_policy field is set to allocate , the system will attempt to replace the failed device with a spare device from the volume group. If there is no available spare device, this will be reported to the system log. If the raid_fault_policy field is set to warn , the system will produce a warning and the log will indicate that a device has failed. This allows the user to determine the course of action to take. As long as there are enough devices remaining to support usability, the RAID logical volume will continue to operate. 4.4.3.9.1. The allocate RAID Fault Policy In the following example, the raid_fault_policy field has been set to allocate in the lvm.conf file. The RAID logical volume is laid out as follows. If the /dev/sde device fails, the system log will display error messages. Since the raid_fault_policy field has been set to allocate , the failed device is replaced with a new device from the volume group. Note that even though the failed device has been replaced, the display still indicates that LVM could not find the failed device. This is because, although the failed device has been removed from the RAID logical volume, the failed device has not yet been removed from the volume group. To remove the failed device from the volume group, you can execute vgreduce --removemissing VG . If the raid_fault_policy has been set to allocate but there are no spare devices, the allocation will fail, leaving the logical volume as it is. If the allocation fails, you have the option of fixing the drive, then deactivating and activating the logical volume; this is described in Section 4.4.3.9.2, "The warn RAID Fault Policy" . Alternately, you can replace the failed device, as described in Section 4.4.3.10, "Replacing a RAID device" . 4.4.3.9.2. The warn RAID Fault Policy In the following example, the raid_fault_policy field has been set to warn in the lvm.conf file. The RAID logical volume is laid out as follows. If the /dev/sdh device fails, the system log will display error messages. In this case, however, LVM will not automatically attempt to repair the RAID device by replacing one of the images. Instead, if the device has failed you can replace the device with the --repair argument of the lvconvert command, as shown below. Note that even though the failed device has been replaced, the display still indicates that LVM could not find the failed device. This is because, although the failed device has been removed from the RAID logical volume, the failed device has not yet been removed from the volume group. To remove the failed device from the volume group, you can execute vgreduce --removemissing VG . If the device failure is a transient failure or you are able to repair the device that failed, you can initiate recovery of the failed device with the --refresh option of the lvchange command. Previously it was necessary to deactivate and then activate the logical volume. The following command refreshes a logical volume. 4.4.3.10. Replacing a RAID device RAID is not like traditional LVM mirroring. LVM mirroring required failed devices to be removed or the mirrored logical volume would hang. RAID arrays can keep on running with failed devices. In fact, for RAID types other than RAID1, removing a device would mean converting to a lower level RAID (for example, from RAID6 to RAID5, or from RAID4 or RAID5 to RAID0). Therefore, rather than removing a failed device unconditionally and potentially allocating a replacement, LVM allows you to replace a device in a RAID volume in a one-step solution by using the --replace argument of the lvconvert command. The format for the lvconvert --replace is as follows. The following example creates a RAID1 logical volume and then replaces a device in that volume. The following example creates a RAID1 logical volume and then replaces a device in that volume, specifying which physical volume to use for the replacement. You can replace more than one RAID device at a time by specifying multiple replace arguments, as in the following example. Note When you specify a replacement drive using the lvconvert --replace command, the replacement drives should never be allocated from extra space on drives already used in the array. For example, lv_rimage_0 and lv_rimage_1 should not be located on the same physical volume. 4.4.3.11. Scrubbing a RAID Logical Volume LVM provides scrubbing support for RAID logical volumes. RAID scrubbing is the process of reading all the data and parity blocks in an array and checking to see whether they are coherent. You initiate a RAID scrubbing operation with the --syncaction option of the lvchange command. You specify either a check or repair operation. A check operation goes over the array and records the number of discrepancies in the array but does not repair them. A repair operation corrects the discrepancies as it finds them. The format of the command to scrub a RAID logical volume is as follows: Note The lvchange --syncaction repair vg/raid_lv operation does not perform the same function as the lvconvert --repair vg/raid_lv operation. The lvchange --syncaction repair operation initiates a background synchronization operation on the array, while the lvconvert --repair operation is designed to repair/replace failed devices in a mirror or RAID logical volume. In support of the new RAID scrubbing operation, the lvs command now supports two new printable fields: raid_sync_action and raid_mismatch_count . These fields are not printed by default. To display these fields you specify them with the -o parameter of the lvs , as follows. The raid_sync_action field displays the current synchronization operation that the raid volume is performing. It can be one of the following values: idle : All sync operations complete (doing nothing) resync : Initializing an array or recovering after a machine failure recover : Replacing a device in the array check : Looking for array inconsistencies repair : Looking for and repairing inconsistencies The raid_mismatch_count field displays the number of discrepancies found during a check operation. The Cpy%Sync field of the lvs command now prints the progress of any of the raid_sync_action operations, including check and repair . The lv_attr field of the lvs command output now provides additional indicators in support of the RAID scrubbing operation. Bit 9 of this field displays the health of the logical volume, and it now supports the following indicators. ( m )ismatches indicates that there are discrepancies in a RAID logical volume. This character is shown after a scrubbing operation has detected that portions of the RAID are not coherent. ( r )efresh indicates that a device in a RAID array has suffered a failure and the kernel regards it as failed, even though LVM can read the device label and considers the device to be operational. The logical volume should be (r)efreshed to notify the kernel that the device is now available, or the device should be (r)eplaced if it is suspected of having failed. For information on the lvs command, see Section 4.8.2, "Object Display Fields" . When you perform a RAID scrubbing operation, the background I/O required by the sync operations can crowd out other I/O operations to LVM devices, such as updates to volume group metadata. This can cause the other LVM operations to slow down. You can control the rate at which the RAID logical volume is scrubbed by implementing recovery throttling. You control the rate at which sync operations are performed by setting the minimum and maximum I/O rate for those operations with the --minrecoveryrate and --maxrecoveryrate options of the lvchange command. You specify these options as follows. --maxrecoveryrate Rate [bBsSkKmMgG] Sets the maximum recovery rate for a RAID logical volume so that it will not crowd out nominal I/O operations. The Rate is specified as an amount per second for each device in the array. If no suffix is given, then kiB/sec/device is assumed. Setting the recovery rate to 0 means it will be unbounded. --minrecoveryrate Rate [bBsSkKmMgG] Sets the minimum recovery rate for a RAID logical volume to ensure that I/O for sync operations achieves a minimum throughput, even when heavy nominal I/O is present. The Rate is specified as an amount per second for each device in the array. If no suffix is given, then kiB/sec/device is assumed. 4.4.3.12. RAID Takeover (Red Hat Enterprise Linux 7.4 and Later) LVM supports Raid takeover , which means converting a RAID logical volume from one RAID level to another (such as from RAID 5 to RAID 6). Changing the RAID level is usually done to increase or decrease resilience to device failures or to restripe logical volumes. You use the lvconvert for RAID takeover. For information on RAID takeover and for examples of using the lvconvert to convert a RAID logical volume, see the lvmraid (7) man page. 4.4.3.13. Reshaping a RAID Logical Volume (Red Hat Enterprise Linux 7.4 and Later) RAID reshaping means changing attributes of a RAID logical volume while keeping the same RAID level. Some attributes you can change include RAID layout, stripe size, and number of stripes. For information on RAID reshaping and examples of using the lvconvert command to reshape a RAID logical volume, see the lvmraid (7) man page. 4.4.3.14. Controlling I/O Operations on a RAID1 Logical Volume You can control the I/O operations for a device in a RAID1 logical volume by using the --writemostly and --writebehind parameters of the lvchange command. The format for using these parameters is as follows. --[raid]writemostly PhysicalVolume [:{t\|y\|n}] Marks a device in a RAID1 logical volume as write-mostly . All reads to these drives will be avoided unless necessary. Setting this parameter keeps the number of I/O operations to the drive to a minimum. By default, the write-mostly attribute is set to yes for the specified physical volume in the logical volume. It is possible to remove the write-mostly flag by appending :n to the physical volume or to toggle the value by specifying :t . The --writemostly argument can be specified more than one time in a single command, making it possible to toggle the write-mostly attributes for all the physical volumes in a logical volume at once. --[raid]writebehind IOCount Specifies the maximum number of outstanding writes that are allowed to devices in a RAID1 logical volume that are marked as write-mostly . Once this value is exceeded, writes become synchronous, causing all writes to the constituent devices to complete before the array signals the write has completed. Setting the value to zero clears the preference and allows the system to choose the value arbitrarily. 4.4.3.15. Changing the region size on a RAID Logical Volume (Red Hat Enterprise Linux 7.4 and later) When you create a RAID logical volume, the region size for the logical volume will be the value of the raid_region_size parameter in the /etc/lvm/lvm.conf file. You can override this default value with the -R option of the lvcreate command. After you have created a RAID logical volume, you can change the region size of the volume with the -R option of the lvconvert command. The following example changes the region size of logical volume vg/raidlv to 4096K. The RAID volume must be synced in order to change the region size. 4.4.4. Creating Mirrored Volumes For the Red Hat Enterprise Linux 7.0 release, LVM supports RAID 1/4/5/6/10, as described in Section 4.4.3, "RAID Logical Volumes" . RAID logical volumes are not cluster-aware. While RAID logical volumes can be created and activated exclusively on one machine, they cannot be activated simultaneously on more than one machine. If you require non-exclusive mirrored volumes, you must create the volumes with a mirror segment type, as described in this section. Note For information on converting an existing LVM device with a segment type of mirror to a RAID1 LVM device, see Section 4.4.3.4, "Converting a Mirrored LVM Device to a RAID1 Device" . Note Creating a mirrored LVM logical volume in a cluster requires the same commands and procedures as creating a mirrored LVM logical volume with a segment type of mirror on a single node. However, in order to create a mirrored LVM volume in a cluster, the cluster and cluster mirror infrastructure must be running, the cluster must be quorate, and the locking type in the lvm.conf file must be set correctly to enable cluster locking. For an example of creating a mirrored volume in a cluster, see Section 5.5, "Creating a Mirrored LVM Logical Volume in a Cluster" . Attempting to run multiple LVM mirror creation and conversion commands in quick succession from multiple nodes in a cluster might cause a backlog of these commands. This might cause some of the requested operations to time out and, subsequently, fail. To avoid this issue, it is recommended that cluster mirror creation commands be executed from one node of the cluster. When you create a mirrored volume, you specify the number of copies of the data to make with the -m argument of the lvcreate command. Specifying -m1 creates one mirror, which yields two copies of the file system: a linear logical volume plus one copy. Similarly, specifying -m2 creates two mirrors, yielding three copies of the file system. The following command creates a mirrored logical volume with a single mirror. The volume is 50 gigabytes in size, is named mirrorlv , and is carved out of volume group vg0 : An LVM mirror divides the device being copied into regions that, by default, are 512KB in size. You can use the -R argument of the lvcreate command to specify the region size in megabytes. You can also change the default region size by editing the mirror_region_size setting in the lvm.conf file. Note Due to limitations in the cluster infrastructure, cluster mirrors greater than 1.5TB cannot be created with the default region size of 512KB. Users that require larger mirrors should increase the region size from its default to something larger. Failure to increase the region size will cause LVM creation to hang and may hang other LVM commands as well. As a general guideline for specifying the region size for mirrors that are larger than 1.5TB, you could take your mirror size in terabytes and round up that number to the power of 2, using that number as the -R argument to the lvcreate command. For example, if your mirror size is 1.5TB, you could specify -R 2 . If your mirror size is 3TB, you could specify -R 4 . For a mirror size of 5TB, you could specify -R 8 . The following command creates a mirrored logical volume with a region size of 2MB: When a mirror is created, the mirror regions are synchronized. For large mirror components, the sync process may take a long time. When you are creating a new mirror that does not need to be revived, you can specify the --nosync argument to indicate that an initial synchronization from the first device is not required. LVM maintains a small log which it uses to keep track of which regions are in sync with the mirror or mirrors. By default, this log is kept on disk, which keeps it persistent across reboots and ensures that the mirror does not need to be re-synced every time a machine reboots or crashes. You can specify instead that this log be kept in memory with the --mirrorlog core argument; this eliminates the need for an extra log device, but it requires that the entire mirror be resynchronized at every reboot. The following command creates a mirrored logical volume from the volume group bigvg . The logical volume is named ondiskmirvol and has a single mirror. The volume is 12MB in size and keeps the mirror log in memory. The mirror log is created on a separate device from the devices on which any of the mirror legs are created. It is possible, however, to create the mirror log on the same device as one of the mirror legs by using the --alloc anywhere argument of the vgcreate command. This may degrade performance, but it allows you to create a mirror even if you have only two underlying devices. The following command creates a mirrored logical volume with a single mirror for which the mirror log is on the same device as one of the mirror legs. In this example, the volume group vg0 consists of only two devices. This command creates a 500 MB volume named mirrorlv in the vg0 volume group. Note With clustered mirrors, the mirror log management is completely the responsibility of the cluster node with the currently lowest cluster ID. Therefore, when the device holding the cluster mirror log becomes unavailable on a subset of the cluster, the clustered mirror can continue operating without any impact, as long as the cluster node with lowest ID retains access to the mirror log. Since the mirror is undisturbed, no automatic corrective action (repair) is issued, either. When the lowest-ID cluster node loses access to the mirror log, however, automatic action will kick in (regardless of accessibility of the log from other nodes). To create a mirror log that is itself mirrored, you can specify the --mirrorlog mirrored argument. The following command creates a mirrored logical volume from the volume group bigvg . The logical volume is named twologvol and has a single mirror. The volume is 12MB in size and the mirror log is mirrored, with each log kept on a separate device. Just as with a standard mirror log, it is possible to create the redundant mirror logs on the same device as the mirror legs by using the --alloc anywhere argument of the vgcreate command. This may degrade performance, but it allows you to create a redundant mirror log even if you do not have sufficient underlying devices for each log to be kept on a separate device than the mirror legs. When a mirror is created, the mirror regions are synchronized. For large mirror components, the sync process may take a long time. When you are creating a new mirror that does not need to be revived, you can specify the --nosync argument to indicate that an initial synchronization from the first device is not required. You can specify which devices to use for the mirror legs and log, and which extents of the devices to use. To force the log onto a particular disk, specify exactly one extent on the disk on which it will be placed. LVM does not necessary respect the order in which devices are listed in the command line. If any physical volumes are listed that is the only space on which allocation will take place. Any physical extents included in the list that are already allocated will get ignored. The following command creates a mirrored logical volume with a single mirror and a single log that is not mirrored. The volume is 500 MB in size, it is named mirrorlv , and it is carved out of volume group vg0 . The first leg of the mirror is on device /dev/sda1 , the second leg of the mirror is on device /dev/sdb1 , and the mirror log is on /dev/sdc1 . The following command creates a mirrored logical volume with a single mirror. The volume is 500 MB in size, it is named mirrorlv , and it is carved out of volume group vg0 . The first leg of the mirror is on extents 0 through 499 of device /dev/sda1 , the second leg of the mirror is on extents 0 through 499 of device /dev/sdb1 , and the mirror log starts on extent 0 of device /dev/sdc1 . These are 1MB extents. If any of the specified extents have already been allocated, they will be ignored. Note You can combine striping and mirroring in a single logical volume. Creating a logical volume while simultaneously specifying the number of mirrors ( --mirrors X ) and the number of stripes ( --stripes Y ) results in a mirror device whose constituent devices are striped. 4.4.4.1. Mirrored Logical Volume Failure Policy You can define how a mirrored logical volume behaves in the event of a device failure with the mirror_image_fault_policy and mirror_log_fault_policy parameters in the activation section of the lvm.conf file. When these parameters are set to remove , the system attempts to remove the faulty device and run without it. When these parameters are set to allocate , the system attempts to remove the faulty device and tries to allocate space on a new device to be a replacement for the failed device. This policy acts like the remove policy if no suitable device and space can be allocated for the replacement. By default, the mirror_log_fault_policy parameter is set to allocate . Using this policy for the log is fast and maintains the ability to remember the sync state through crashes and reboots. If you set this policy to remove , when a log device fails the mirror converts to using an in-memory log; in this instance, the mirror will not remember its sync status across crashes and reboots and the entire mirror will be re-synced. By default, the mirror_image_fault_policy parameter is set to remove . With this policy, if a mirror image fails the mirror will convert to a non-mirrored device if there is only one remaining good copy. Setting this policy to allocate for a mirror device requires the mirror to resynchronize the devices; this is a slow process, but it preserves the mirror characteristic of the device. Note When an LVM mirror suffers a device failure, a two-stage recovery takes place. The first stage involves removing the failed devices. This can result in the mirror being reduced to a linear device. The second stage, if the mirror_log_fault_policy parameter is set to allocate , is to attempt to replace any of the failed devices. Note, however, that there is no guarantee that the second stage will choose devices previously in-use by the mirror that had not been part of the failure if others are available. For information on manually recovering from an LVM mirror failure, see Section 6.2, "Recovering from LVM Mirror Failure" . 4.4.4.2. Splitting Off a Redundant Image of a Mirrored Logical Volume You can split off a redundant image of a mirrored logical volume to form a new logical volume. To split off an image, use the --splitmirrors argument of the lvconvert command, specifying the number of redundant images to split off. You must use the --name argument of the command to specify a name for the newly-split-off logical volume. The following command splits off a new logical volume named copy from the mirrored logical volume vg/lv . The new logical volume contains two mirror legs. In this example, LVM selects which devices to split off. You can specify which devices to split off. The following command splits off a new logical volume named copy from the mirrored logical volume vg/lv . The new logical volume contains two mirror legs consisting of devices /dev/sdc1 and /dev/sde1 . 4.4.4.3. Repairing a Mirrored Logical Device You can use the lvconvert --repair command to repair a mirror after a disk failure. This brings the mirror back into a consistent state. The lvconvert --repair command is an interactive command that prompts you to indicate whether you want the system to attempt to replace any failed devices. To skip the prompts and replace all of the failed devices, specify the -y option on the command line. To skip the prompts and replace none of the failed devices, specify the -f option on the command line. To skip the prompts and still indicate different replacement policies for the mirror image and the mirror log, you can specify the --use-policies argument to use the device replacement policies specified by the mirror_log_fault_policy and mirror_device_fault_policy parameters in the lvm.conf file. 4.4.4.4. Changing Mirrored Volume Configuration You can increase or decrease the number of mirrors that a logical volume contains by using the lvconvert command. This allows you to convert a logical volume from a mirrored volume to a linear volume or from a linear volume to a mirrored volume. You can also use this command to reconfigure other mirror parameters of an existing logical volume, such as corelog . When you convert a linear volume to a mirrored volume, you are creating mirror legs for an existing volume. This means that your volume group must contain the devices and space for the mirror legs and for the mirror log. If you lose a leg of a mirror, LVM converts the volume to a linear volume so that you still have access to the volume, without the mirror redundancy. After you replace the leg, use the lvconvert command to restore the mirror. This procedure is provided in Section 6.2, "Recovering from LVM Mirror Failure" . The following command converts the linear logical volume vg00/lvol1 to a mirrored logical volume. The following command converts the mirrored logical volume vg00/lvol1 to a linear logical volume, removing the mirror leg. The following example adds an additional mirror leg to the existing logical volume vg00/lvol1 . This example shows the configuration of the volume before and after the lvconvert command changed the volume to a volume with two mirror legs. 4.4.5. Creating Thinly-Provisioned Logical Volumes Logical volumes can be thinly provisioned. This allows you to create logical volumes that are larger than the available extents. Using thin provisioning, you can manage a storage pool of free space, known as a thin pool, which can be allocated to an arbitrary number of devices when needed by applications. You can then create devices that can be bound to the thin pool for later allocation when an application actually writes to the logical volume. The thin pool can be expanded dynamically when needed for cost-effective allocation of storage space. Note This section provides an overview of the basic commands you use to create and grow thinly-provisioned logical volumes. For detailed information on LVM thin provisioning as well as information on using the LVM commands and utilities with thinly-provisioned logical volumes, see the lvmthin (7) man page. Note Thin volumes are not supported across the nodes in a cluster. The thin pool and all its thin volumes must be exclusively activated on only one cluster node. To create a thin volume, perform the following tasks: Create a volume group with the vgcreate command. Create a thin pool with the lvcreate command. Create a thin volume in the thin pool with the lvcreate command. You can use the -T (or --thin ) option of the lvcreate command to create either a thin pool or a thin volume. You can also use -T option of the lvcreate command to create both a thin pool and a thin volume in that pool at the same time with a single command. The following command uses the -T option of the lvcreate command to create a thin pool named mythinpool in the volume group vg001 and that is 100M in size. Note that since you are creating a pool of physical space, you must specify the size of the pool. The -T option of the lvcreate command does not take an argument; it deduces what type of device is to be created from the other options the command specifies. The following command uses the -T option of the lvcreate command to create a thin volume named thinvolume in the thin pool vg001/mythinpool . Note that in this case you are specifying virtual size, and that you are specifying a virtual size for the volume that is greater than the pool that contains it. The following command uses the -T option of the lvcreate command to create a thin pool and a thin volume in that pool by specifying both a size and a virtual size argument for the lvcreate command. This command creates a thin pool named mythinpool in the volume group vg001 and it also creates a thin volume named thinvolume in that pool. You can also create a thin pool by specifying the --thinpool parameter of the lvcreate command. Unlike the -T option, the --thinpool parameter requires an argument, which is the name of the thin pool logical volume that you are creating. The following example specifies the --thinpool parameter of the lvcreate command to create a thin pool named mythinpool in the volume group vg001 and that is 100M in size: Use the following criteria for using chunk size: Smaller chunk size requires more metadata and hinders the performance, but it provides better space utilization with snapshots. Huge chunk size requires less metadata manipulation but makes the snapshot less efficient. LVM2 calculates chunk size in the following manner: By default, LVM starts with a 64KiB chunk size and increases its value when the resulting size of the thin pool metadata device grows above 128MiB, so the metadata size remains compact. This may result in some big chunk size values, which is less efficient for snapshot usage. In this case, the smaller chunk size and bigger metadata size is a better option. If the volume data size is in the range of TiB, use ~15.8GiB metadata size, which is the maximum supported size, and use the chunk size as per your requirement. But it is not possible to increase the metadata size if you need to extend this volume data size and have a small chunk size. Warning Red Hat recommends to use at least the default chunk size. If the chunk size is too small and your volume runs out of space for metadata, the volume is unable to create data. Monitor your logical volumes to ensure that they are expanded or more storage created before metadata volumes become completely full. Ensure that you set up your thin pool with a large enough chunk size so that they do not run out of room for metadata. Striping is supported for pool creation. The following command creates a 100M thin pool named pool in volume group vg001 with two 64 kB stripes and a chunk size of 256 kB. It also creates a 1T thin volume, vg00/thin_lv . You can extend the size of a thin volume with the lvextend command. You cannot, however, reduce the size of a thin pool. The following command resizes an existing thin pool that is 100M in size by extending it another 100M. As with other types of logical volumes, you can rename the volume with the lvrename , you can remove the volume with the lvremove , and you can display information about the volume with the lvs and lvdisplay commands. By default, the lvcreate command sets the size of the thin pool's metadata logical volume according to the formula (Pool_LV_size / Pool_LV_chunk_size * 64). If you will have large numbers of snapshots or if you have small chunk sizes for your thin pool and thus expect significant growth of the size of the thin pool at a later time, you may need to increase the default value of the thin pool's metadata volume with the --poolmetadatasize parameter of the lvcreate command. The supported value for the thin pool's metadata logical volume is in the range between 2MiB and 16GiB. You can use the --thinpool parameter of the lvconvert command to convert an existing logical volume to a thin pool volume. When you convert an existing logical volume to a thin pool volume, you must use the --poolmetadata parameter in conjunction with the --thinpool parameter of the lvconvert to convert an existing logical volume to the thin pool volume's metadata volume. Note Converting a logical volume to a thin pool volume or a thin pool metadata volume destroys the content of the logical volume, since in this case the lvconvert does not preserve the content of the devices but instead overwrites the content. The following example converts the existing logical volume lv1 in volume group vg001 to a thin pool volume and converts the existing logical volume lv2 in volume group vg001 to the metadata volume for that thin pool volume. 4.4.6. Creating Snapshot Volumes Note LVM supports thinly-provisioned snapshots. For information on creating thinly-provisioned snapshot volumes, see Section 4.4.7, "Creating Thinly-Provisioned Snapshot Volumes" . Use the -s argument of the lvcreate command to create a snapshot volume. A snapshot volume is writable. Note LVM snapshots are not supported across the nodes in a cluster. You cannot create a snapshot volume in a clustered volume group. However, if you need to create a consistent backup of data on a clustered logical volume you can activate the volume exclusively and then create the snapshot. For information on activating logical volumes exclusively on one node, see Section 4.7, "Activating Logical Volumes on Individual Nodes in a Cluster" . Note LVM snapshots are supported for mirrored logical volumes. Snapshots are supported for RAID logical volumes. For information on creating RAID logical volumes, see Section 4.4.3, "RAID Logical Volumes" . LVM does not allow you to create a snapshot volume that is larger than the size of the origin volume plus needed metadata for the volume. If you specify a snapshot volume that is larger than this, the system will create a snapshot volume that is only as large as will be needed for the size of the origin. By default, a snapshot volume is skipped during normal activation commands. For information on controlling the activation of a snapshot volume, see Section 4.4.20, "Controlling Logical Volume Activation" . The following command creates a snapshot logical volume that is 100 MB in size named /dev/vg00/snap . This creates a snapshot of the origin logical volume named /dev/vg00/lvol1 . If the original logical volume contains a file system, you can mount the snapshot logical volume on an arbitrary directory in order to access the contents of the file system to run a backup while the original file system continues to get updated. After you create a snapshot logical volume, specifying the origin volume on the lvdisplay command yields output that includes a list of all snapshot logical volumes and their status (active or inactive). The following example shows the status of the logical volume /dev/new_vg/lvol0 , for which a snapshot volume /dev/new_vg/newvgsnap has been created. The lvs command, by default, displays the origin volume and the current percentage of the snapshot volume being used. The following example shows the default output for the lvs command for a system that includes the logical volume /dev/new_vg/lvol0 , for which a snapshot volume /dev/new_vg/newvgsnap has been created. Warning Because the snapshot increases in size as the origin volume changes, it is important to monitor the percentage of the snapshot volume regularly with the lvs command to be sure it does not fill. A snapshot that is 100% full is lost completely, as a write to unchanged parts of the origin would be unable to succeed without corrupting the snapshot. In addition to the snapshot itself being invalidated when full, any mounted file systems on that snapshot device are forcibly unmounted, avoiding the inevitable file system errors upon access to the mount point. In addition, you can specify the snapshot_autoextend_threshold option in the lvm.conf file. This option allows automatic extension of a snapshot whenever the remaining snapshot space drops below the threshold you set. This feature requires that there be unallocated space in the volume group. LVM does not allow you to create a snapshot volume that is larger than the size of the origin volume plus needed metadata for the volume. Similarly, automatic extension of a snapshot will not increase the size of a snapshot volume beyond the maximum calculated size that is necessary for the snapshot. Once a snapshot has grown large enough to cover the origin, it is no longer monitored for automatic extension. Information on setting snapshot_autoextend_threshold and snapshot_autoextend_percent is provided in the lvm.conf file itself. For information about the lvm.conf file, see Appendix B, The LVM Configuration Files . 4.4.7. Creating Thinly-Provisioned Snapshot Volumes Red Hat Enterprise Linux provides support for thinly-provisioned snapshot volumes. For information on the benefits and limitations of thin snapshot volumes, see Section 2.3.6, "Thinly-Provisioned Snapshot Volumes" . Note This section provides an overview of the basic commands you use to create and grow thinly-provisioned snapshot volumes. For detailed information on LVM thin provisioning as well as information on using the LVM commands and utilities with thinly-provisioned logical volumes, see the lvmthin (7) man page. Important When creating a thin snapshot volume, you do not specify the size of the volume. If you specify a size parameter, the snapshot that will be created will not be a thin snapshot volume and will not use the thin pool for storing data. For example, the command lvcreate -s vg/thinvolume -L10M will not create a thin snapshot, even though the origin volume is a thin volume. Thin snapshots can be created for thinly-provisioned origin volumes, or for origin volumes that are not thinly-provisioned. You can specify a name for the snapshot volume with the --name option of the lvcreate command. The following command creates a thinly-provisioned snapshot volume of the thinly-provisioned logical volume vg001/thinvolume that is named mysnapshot1 . Note When using thin provisioning, it is important that the storage administrator monitor the storage pool and add more capacity if it starts to become full. For information on extending the size of a thin volume, see Section 4.4.5, "Creating Thinly-Provisioned Logical Volumes" A thin snapshot volume has the same characteristics as any other thin volume. You can independently activate the volume, extend the volume, rename the volume, remove the volume, and even snapshot the volume. By default, a snapshot volume is skipped during normal activation commands. For information on controlling the activation of a snapshot volume, see Section 4.4.20, "Controlling Logical Volume Activation" . You can also create a thinly-provisioned snapshot of a non-thinly-provisioned logical volume. Since the non-thinly-provisioned logical volume is not contained within a thin pool, it is referred to as an external origin . External origin volumes can be used and shared by many thinly-provisioned snapshot volumes, even from different thin pools. The external origin must be inactive and read-only at the time the thinly-provisioned snapshot is created. To create a thinly-provisioned snapshot of an external origin, you must specify the --thinpool option. The following command creates a thin snapshot volume of the read-only inactive volume origin_volume . The thin snapshot volume is named mythinsnap . The logical volume origin_volume then becomes the thin external origin for the thin snapshot volume mythinsnap in volume group vg001 that will use the existing thin pool vg001/pool . Because the origin volume must be in the same volume group as the snapshot volume, you do not need to specify the volume group when specifying the origin logical volume. You can create a second thinly-provisioned snapshot volume of the first snapshot volume, as in the following command. As of Red Hat Enterprise Linux 7.2, you can display a list of all ancestors and descendants of a thin snapshot logical volume by specifying the lv_ancestors and lv_descendants reporting fields of the lvs command. In the following example: stack1 is an origin volume in volume group vg001 . stack2 is a snapshot of stack1 stack3 is a snapshot of stack2 stack4 is a snapshot of stack3 Additionally: stack5 is also a snapshot of stack2 stack6 is a snapshot of stack5 Note The lv_ancestors and lv_descendants fields display existing dependencies but do not track removed entries which can break a dependency chain if the entry was removed from the middle of the chain. For example, if you remove the logical volume stack3 from this sample configuration, the display is as follows. As of Red Hat Enterprise Linux 7.3, however, you can configure your system to track and display logical volumes that have been removed, and you can display the full dependency chain that includes those volumes by specifying the lv_ancestors_full and lv_descendants_full fields. For information on tracking, displaying, and removing historical logical volumes, see Section 4.4.21, "Tracking and Displaying Historical Logical Volumes (Red Hat Enterprise Linux 7.3 and Later)" . 4.4.8. Creating LVM Cache Logical Volumes As of the Red Hat Enterprise Linux 7.1 release, LVM provides full support for LVM cache logical volumes. A cache logical volume uses a small logical volume consisting of fast block devices (such as SSD drives) to improve the performance of a larger and slower logical volume by storing the frequently used blocks on the smaller, faster logical volume. LVM caching uses the following LVM logical volume types. All of these associated logical volumes must be in the same volume group. Origin logical volume - the large, slow logical volume Cache pool logical volume - the small, fast logical volume, which is composed of two devices: the cache data logical volume, and the cache metadata logical volume Cache data logical volume - the logical volume containing the data blocks for the cache pool logical volume Cache metadata logical volume - the logical volume containing the metadata for the cache pool logical volume, which holds the accounting information that specifies where data blocks are stored (for example, on the origin logical volume or the cache data logical volume). Cache logical volume - the logical volume containing the origin logical volume and the cache pool logical volume. This is the resultant usable device which encapsulates the various cache volume components. The following procedure creates an LVM cache logical volume. Create a volume group that contains a slow physical volume and a fast physical volume. In this example. /dev/sde1 is a slow device and /dev/sdf1 is a fast device and both devices are contained in volume group VG . Create the origin volume. This example creates an origin volume named lv that is ten gigabytes in size and that consists of /dev/sde1 , the slow physical volume. Create the cache pool logical volume. This example creates the cache pool logical volume named cpool on the fast device /dev/sdf1 , which is part of the volume group VG . The cache pool logical volume this command creates consists of the hidden cache data logical volume cpool_cdata and the hidden cache metadata logical volume cpool_cmeta . For more complicated configurations you may need to create the cache data and the cache metadata logical volumes individually and then combine the volumes into a cache pool logical volume. For information on this procedure, see the lvmcache (7) man page. Create the cache logical volume by linking the cache pool logical volume to the origin logical volume. The resulting user-accessible cache logical volume takes the name of the origin logical volume. The origin logical volume becomes a hidden logical volume with _corig appended to the original name. Note that this conversion can be done live, although you must ensure you have performed a backup first. Optionally, as of Red Hat Enterprise Linux release 7.2, you can convert the cached logical volume to a thin pool logical volume. Note that any thin logical volumes created from the pool will share the cache. The following command uses the fast device, /dev/sdf1 , for allocating the thin pool metadata ( lv_tmeta ). This is the same device that is used by the cache pool volume, which means that the thin pool metadata volume shares that device with both the cache data logical volume cpool_cdata and the cache metadata logical volume cpool_cmeta . For further information on LVM cache volumes, including additional administrative examples, see the lvmcache (7) man page. For information on creating thinly-provisioned logical volumes, see Section 4.4.5, "Creating Thinly-Provisioned Logical Volumes" . 4.4.9. Merging Snapshot Volumes You can use the --merge option of the lvconvert command to merge a snapshot into its origin volume. If both the origin and snapshot volume are not open, the merge will start immediately. Otherwise, the merge will start the first time either the origin or snapshot are activated and both are closed. Merging a snapshot into an origin that cannot be closed, for example a root file system, is deferred until the time the origin volume is activated. When merging starts, the resulting logical volume will have the origin's name, minor number and UUID. While the merge is in progress, reads or writes to the origin appear as they were directed to the snapshot being merged. When the merge finishes, the merged snapshot is removed. The following command merges snapshot volume vg00/lvol1_snap into its origin. You can specify multiple snapshots on the command line, or you can use LVM object tags to specify that multiple snapshots be merged to their respective origins. In the following example, logical volumes vg00/lvol1 , vg00/lvol2 , and vg00/lvol3 are all tagged with the tag @some_tag . The following command merges the snapshot logical volumes for all three volumes serially: vg00/lvol1 , then vg00/lvol2 , then vg00/lvol3 . If the --background option were used, all snapshot logical volume merges would start in parallel. For information on tagging LVM objects, see Appendix D, LVM Object Tags . For further information on the lvconvert --merge command, see the lvconvert (8) man page. 4.4.10. Persistent Device Numbers Major and minor device numbers are allocated dynamically at module load. Some applications work best if the block device is always activated with the same device (major and minor) number. You can specify these with the lvcreate and the lvchange commands by using the following arguments: Use a large minor number to be sure that it has not already been allocated to another device dynamically. If you are exporting a file system using NFS, specifying the fsid parameter in the exports file may avoid the need to set a persistent device number within LVM. 4.4.11. Changing the Parameters of a Logical Volume Group To change the parameters of a logical volume, use the lvchange command. For a listing of the parameters you can change, see the lvchange (8) man page. You can use the lvchange command to activate and deactivate logical volumes. To activate and deactivate all the logical volumes in a volume group at the same time, use the vgchange command, as described in Section 4.3.9, "Changing the Parameters of a Volume Group" . The following command changes the permission on volume lvol1 in volume group vg00 to be read-only. 4.4.12. Renaming Logical Volumes To rename an existing logical volume, use the lvrename command. Either of the following commands renames logical volume lvold in volume group vg02 to lvnew . Renaming the root logical volume requires additional reconfiguration. For information on renaming a root volume, see How to rename root volume group or logical volume in Red Hat Enterprise Linux . For more information on activating logical volumes on individual nodes in a cluster, see Section 4.7, "Activating Logical Volumes on Individual Nodes in a Cluster" . 4.4.13. Removing Logical Volumes To remove an inactive logical volume, use the lvremove command. If the logical volume is currently mounted, unmount the volume before removing it. In addition, in a clustered environment you must deactivate a logical volume before it can be removed. The following command removes the logical volume /dev/testvg/testlv from the volume group testvg . Note that in this case the logical volume has not been deactivated. You could explicitly deactivate the logical volume before removing it with the lvchange -an command, in which case you would not see the prompt verifying whether you want to remove an active logical volume. 4.4.14. Displaying Logical Volumes There are three commands you can use to display properties of LVM logical volumes: lvs , lvdisplay , and lvscan . The lvs command provides logical volume information in a configurable form, displaying one line per logical volume. The lvs command provides a great deal of format control, and is useful for scripting. For information on using the lvs command to customize your output, see Section 4.8, "Customized Reporting for LVM" . The lvdisplay command displays logical volume properties (such as size, layout, and mapping) in a fixed format. The following command shows the attributes of lvol2 in vg00 . If snapshot logical volumes have been created for this original logical volume, this command shows a list of all snapshot logical volumes and their status (active or inactive) as well. The lvscan command scans for all logical volumes in the system and lists them, as in the following example. 4.4.15. Growing Logical Volumes To increase the size of a logical volume, use the lvextend command. When you extend the logical volume, you can indicate how much you want to extend the volume, or how large you want it to be after you extend it. The following command extends the logical volume /dev/myvg/homevol to 12 gigabytes. The following command adds another gigabyte to the logical volume /dev/myvg/homevol . As with the lvcreate command, you can use the -l argument of the lvextend command to specify the number of extents by which to increase the size of the logical volume. You can also use this argument to specify a percentage of the volume group, or a percentage of the remaining free space in the volume group. The following command extends the logical volume called testlv to fill all of the unallocated space in the volume group myvg . After you have extended the logical volume it is necessary to increase the file system size to match. By default, most file system resizing tools will increase the size of the file system to be the size of the underlying logical volume so you do not need to worry about specifying the same size for each of the two commands. 4.4.16. Shrinking Logical Volumes You can reduce the size of a logical volume with the lvreduce command. Note Shrinking is not supported on a GFS2 or XFS file system, so you cannot reduce the size of a logical volume that contains a GFS2 or XFS file system. If the logical volume you are reducing contains a file system, to prevent data loss you must ensure that the file system is not using the space in the logical volume that is being reduced. For this reason, it is recommended that you use the --resizefs option of the lvreduce command when the logical volume contains a file system. When you use this option, the lvreduce command attempts to reduce the file system before shrinking the logical volume. If shrinking the file system fails, as can occur if the file system is full or the file system does not support shrinking, then the lvreduce command will fail and not attempt to shrink the logical volume. Warning In most cases, the lvreduce command warns about possible data loss and asks for a confirmation. However, you should not rely on these confirmation prompts to prevent data loss because in some cases you will not see these prompts, such as when the logical volume is inactive or the --resizefs option is not used. Note that using the --test option of the lvreduce command does not indicate where the operation is safe, as this option does not check the file system or test the file system resize. The following command shrinks the logical volume lvol1 in volume group vg00 to be 64 megabytes. In this example, lvol1 contains a file system, which this command resizes together with the logical volume. This example shows the output to the command. Specifying the - sign before the resize value indicates that the value will be subtracted from the logical volume's actual size. The following example shows the command you would use if, instead of shrinking a logical volume to an absolute size of 64 megabytes, you wanted to shrink the volume by a value 64 megabytes. 4.4.17. Extending a Striped Volume In order to increase the size of a striped logical volume, there must be enough free space on the underlying physical volumes that make up the volume group to support the stripe. For example, if you have a two-way stripe that that uses up an entire volume group, adding a single physical volume to the volume group will not enable you to extend the stripe. Instead, you must add at least two physical volumes to the volume group. For example, consider a volume group vg that consists of two underlying physical volumes, as displayed with the following vgs command. You can create a stripe using the entire amount of space in the volume group. Note that the volume group now has no more free space. The following command adds another physical volume to the volume group, which then has 135 gigabytes of additional space. At this point you cannot extend the striped logical volume to the full size of the volume group, because two underlying devices are needed in order to stripe the data. To extend the striped logical volume, add another physical volume and then extend the logical volume. In this example, having added two physical volumes to the volume group we can extend the logical volume to the full size of the volume group. If you do not have enough underlying physical devices to extend the striped logical volume, it is possible to extend the volume anyway if it does not matter that the extension is not striped, which may result in uneven performance. When adding space to the logical volume, the default operation is to use the same striping parameters of the last segment of the existing logical volume, but you can override those parameters. The following example extends the existing striped logical volume to use the remaining free space after the initial lvextend command fails. 4.4.18. Extending a RAID Volume You can grow RAID logical volumes with the lvextend command without performing a synchronization of the new RAID regions. If you specify the --nosync option when you create a RAID logical volume with the lvcreate command, the RAID regions are not synchronized when the logical volume is created. If you later extend a RAID logical volume that you have created with the --nosync option, the RAID extensions are not synchronized at that time, either. You can determine whether an existing logical volume was created with the --nosync option by using the lvs command to display the volume's attributes. A logical volume will show "R" as the first character in the attribute field if it is a RAID volume that was created without an initial synchronization, and it will show "r" if it was created with initial synchronization. The following command displays the attributes of a RAID logical volume named lv that was created without initial synchronization, showing "R" as the first character in the attribute field. The seventh character in the attribute field is "r", indicating a target type of RAID. For information on the meaning of the attribute field, see Table 4.5, "lvs Display Fields" . If you grow this logical volume with the lvextend command, the RAID extension will not be resynchronized. If you created a RAID logical volume without specifying the --nosync option of the lvcreate command, you can grow the logical volume without resynchronizing the mirror by specifying the --nosync option of the lvextend command. The following example extends a RAID logical volume that was created without the --nosync option, indicated that the RAID volume was synchronized when it was created. This example, however, specifies that the volume not be synchronized when the volume is extended. Note that the volume has an attribute of "r", but after executing the lvextend command with the --nosync option the volume has an attribute of "R". If a RAID volume is inactive, it will not automatically skip synchronization when you extend the volume, even if you create the volume with the --nosync option specified. Instead, you will be prompted whether to do a full resync of the extended portion of the logical volume. Note If a RAID volume is performing recovery, you cannot extend the logical volume if you created or extended the volume with the --nosync option specified. If you did not specify the --nosync option, however, you can extend the RAID volume while it is recovering. 4.4.19. Extending a Logical Volume with the cling Allocation Policy When extending an LVM volume, you can use the --alloc cling option of the lvextend command to specify the cling allocation policy. This policy will choose space on the same physical volumes as the last segment of the existing logical volume. If there is insufficient space on the physical volumes and a list of tags is defined in the lvm.conf file, LVM will check whether any of the tags are attached to the physical volumes and seek to match those physical volume tags between existing extents and new extents. For example, if you have logical volumes that are mirrored between two sites within a single volume group, you can tag the physical volumes according to where they are situated by tagging the physical volumes with @site1 and @site2 tags. You can then specify the following line in the lvm.conf file: For information on tagging physical volumes, see Appendix D, LVM Object Tags . In the following example, the lvm.conf file has been modified to contain the following line: Also in this example, a volume group taft has been created that consists of the physical volumes /dev/sdb1 , /dev/sdc1 , /dev/sdd1 , /dev/sde1 , /dev/sdf1 , /dev/sdg1 , and /dev/sdh1 . These physical volumes have been tagged with tags A , B , and C . The example does not use the C tag, but this will show that LVM uses the tags to select which physical volumes to use for the mirror legs. The following command creates a 10 gigabyte mirrored volume from the volume group taft . The following command shows which devices are used for the mirror legs and RAID metadata subvolumes. The following command extends the size of the mirrored volume, using the cling allocation policy to indicate that the mirror legs should be extended using physical volumes with the same tag. The following display command shows that the mirror legs have been extended using physical volumes with the same tag as the leg. Note that the physical volumes with a tag of C were ignored. 4.4.20. Controlling Logical Volume Activation You can flag a logical volume to be skipped during normal activation commands with the -k or --setactivationskip {y\|n} option of the lvcreate or lvchange command. This flag is not applied during deactivation. You can determine whether this flag is set for a logical volume with the lvs command, which displays the k attribute as in the following example. By default, thin snapshot volumes are flagged for activation skip. You can activate a logical volume with the k attribute set by using the -K or --ignoreactivationskip option in addition to the standard -ay or --activate y option. The following command activates a thin snapshot logical volume. The persistent "activation skip" flag can be turned off when the logical volume is created by specifying the -kn or --setactivationskip n option of the lvcreate command. You can turn the flag off for an existing logical volume by specifying the -kn or --setactivationskip n option of the lvchange command. You can turn the flag on again with the -ky or --setactivationskip y option. The following command creates a snapshot logical volume without the activation skip flag The following command removes the activation skip flag from a snapshot logical volume. You can control the default activation skip setting with the auto_set_activation_skip setting in the /etc/lvm/lvm.conf file. 4.4.21. Tracking and Displaying Historical Logical Volumes (Red Hat Enterprise Linux 7.3 and Later) As of Red Hat Enterprise Linux 7.3, you can configure your system to track thin snapshot and thin logical volumes that have been removed by enabling the record_lvs_history metadata option in the lvm.conf configuration file. This allows you to display a full thin snapshot dependency chain that includes logical volumes that have been removed from the original dependency chain and have become historical logical volumes. You can configure your system to retain historical volumes for a defined period of time by specifying the retention time, in seconds, with the lvs_history_retention_time metadata option in the lvm.conf configuration file. A historical logical volume retains a simplified representation of the logical volume that has been removed, including the following reporting fields for the volume: lv_time_removed : the removal time of the logical volume lv_time : the creation time of the logical volume lv_name : the name of the logical volume lv_uuid : the UUID of the logical volume vg_name : the volume group that contains the logical volume. When a volume is removed, the historical logical volume name acquires a hypen as a prefix. For example, when you remove the logical volume lvol1 , the name of the historical volume is -lvol1 . A historical logical volume cannot be reactivated. Even when the record_lvs_history metadata option enabled, you can prevent the retention of historical logical volumes on an individual basis when you remove a logical volume by specifying the --nohistory option of the lvremove command. To include historical logical volumes in volume display, you specify the -H\|--history option of an LVM display command. You can display a full thin snapshot dependency chain that includes historical volumes by specifying the lv_full_ancestors and lv_full_descendants reporting fields along with the -H option. The following series of commands provides examples of how you can display and manage historical logical volumes. Ensure that historical logical volumes are retained by setting record_lvs_history=1 in the lvm.conf file. This metadata option is not enabled by default. Enter the following command to display a thin provisioned snapshot chain. In this example: lvol1 is an origin volume, the first volume in the chain. lvol2 is a snapshot of lvol1 . lvol3 is a snapshot of lvol2 . lvol4 is a snapshot of lvol3 . lvol5 is also a snapshot of lvol3 . Note that even though the example lvs display command includes the -H option, no thin snapshot volume has yet been removed and there are no historical logical volumes to display. Remove logical volume lvol3 from the snapshot chain, then run the following lvs command again to see how historical logical volumes are displayed, along with their ancestors and descendants. You can use the lv_time_removed reporting field to display the time a historical volume was removed. You can reference historical logical volumes individually in a display command by specifying the vgname/lvname format, as in the following example. Note that the fifth bit in the lv_attr field is set to h to indicate the volume is a historical volume. LVM does not keep historical logical volumes if the volume has no live descendant. This means that if you remove a logical volume at the end of a snapshot chain, the logical volume is not retained as a historical logical volume. Run the following commands to remove the volume lvol1 and lvol2 and to see how the lvs command displays the volumes once they have been removed. To remove a historical logical volume completely, you can run the lvremove command again, specifying the name of the historical volume that now includes the hyphen, as in the following example. A historical logical volumes is retained as long as there is a chain that includes live volumes in its descendants. This means that removing a historical logical volume also removes all of the logical volumes in the chain if no existing descendant is linked to them, as shown in the following example.	[ "lvcreate -L 10G vg1", "lvcreate -L 1500 -n testlv testvg", "lvcreate -L 50G -n gfslv vg0", "lvcreate -l 60%VG -n mylv testvg", "lvcreate -l 100%FREE -n yourlv testvg", "vgdisplay testvg \| grep \"Total PE\" Total PE 10230 lvcreate -l 10230 -n mylv testvg", "lvcreate -L 1500 -n testlv testvg /dev/sdg1", "lvcreate -l 100 -n testlv testvg /dev/sda1:0-24 /dev/sdb1:50-124", "lvcreate -l 100 -n testlv testvg /dev/sda1:0-25:100-", "lvcreate -L 50G -i 2 -I 64 -n gfslv vg0", "lvcreate -l 100 -i 2 -n stripelv testvg /dev/sda1:0-49 /dev/sdb1:50-99 Using default stripesize 64.00 KB Logical volume \"stripelv\" created", "lvcreate --type raid1 -m 1 -L 1G -n my_lv my_vg", "lvcreate --type raid5 -i 3 -L 1G -n my_lv my_vg", "lvcreate --type raid6 -i 3 -L 1G -n my_lv my_vg", "lvcreate --type raid10 -i 2 -m 1 -L 10G --maxrecoveryrate 128 -n my_lv my_vg", "lvcreate --type raid0[_meta] --stripes Stripes --stripesize StripeSize VolumeGroup [ PhysicalVolumePath ...]", "lvconvert --type raid1 -m 1 my_vg/my_lv", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv /dev/sde1(0)", "lvconvert --type raid1 -m 1 my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 6.25 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sde1(0) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rmeta_0] /dev/sde1(256) [my_lv_rmeta_1] /dev/sdf1(0)", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sde1(1) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rmeta_0] /dev/sde1(0) [my_lv_rmeta_1] /dev/sdf1(0)", "lvconvert -m0 my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv /dev/sde1(1)", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sda1(1) [my_lv_rimage_1] /dev/sdb1(1) [my_lv_rmeta_0] /dev/sda1(0) [my_lv_rmeta_1] /dev/sdb1(0) lvconvert -m0 my_vg/my_lv /dev/sda1 lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv /dev/sdb1(1)", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 15.20 my_lv_mimage_0(0),my_lv_mimage_1(0) [my_lv_mimage_0] /dev/sde1(0) [my_lv_mimage_1] /dev/sdf1(0) [my_lv_mlog] /dev/sdd1(0)", "lvconvert --type raid1 my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sde1(0) [my_lv_rimage_1] /dev/sdf1(0) [my_lv_rmeta_0] /dev/sde1(125) [my_lv_rmeta_1] /dev/sdf1(125)", "lvconvert -m new_absolute_count vg/lv [ removable_PVs ] lvconvert -m + num_additional_images vg/lv [ removable_PVs ]", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 6.25 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sde1(0) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rmeta_0] /dev/sde1(256) [my_lv_rmeta_1] /dev/sdf1(0)", "lvconvert -m 2 my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 6.25 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sde1(0) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rimage_2] /dev/sdg1(1) [my_lv_rmeta_0] /dev/sde1(256) [my_lv_rmeta_1] /dev/sdf1(0) [my_lv_rmeta_2] /dev/sdg1(0)", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 56.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sda1(1) [my_lv_rimage_1] /dev/sdb1(1) [my_lv_rmeta_0] /dev/sda1(0) [my_lv_rmeta_1] /dev/sdb1(0) lvconvert -m 2 my_vg/my_lv /dev/sdd1 lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 28.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sda1(1) [my_lv_rimage_1] /dev/sdb1(1) [my_lv_rimage_2] /dev/sdd1(1) [my_lv_rmeta_0] /dev/sda1(0) [my_lv_rmeta_1] /dev/sdb1(0) [my_lv_rmeta_2] /dev/sdd1(0)", "lvconvert -m new_absolute_count vg/lv [ removable_PVs ] lvconvert -m - num_fewer_images vg/lv [ removable_PVs ]", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sde1(1) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rimage_2] /dev/sdg1(1) [my_lv_rmeta_0] /dev/sde1(0) [my_lv_rmeta_1] /dev/sdf1(0) [my_lv_rmeta_2] /dev/sdg1(0)", "lvconvert -m1 my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sde1(1) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rmeta_0] /dev/sde1(0) [my_lv_rmeta_1] /dev/sdf1(0)", "lvconvert -m1 my_vg/my_lv /dev/sde1 lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sdf1(1) [my_lv_rimage_1] /dev/sdg1(1) [my_lv_rmeta_0] /dev/sdf1(0) [my_lv_rmeta_1] /dev/sdg1(0)", "lvconvert --splitmirrors count -n splitname vg/lv [ removable_PVs ]", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 12.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sde1(1) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rmeta_0] /dev/sde1(0) [my_lv_rmeta_1] /dev/sdf1(0) lvconvert --splitmirror 1 -n new my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv /dev/sde1(1) new /dev/sdf1(1)", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sde1(1) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rimage_2] /dev/sdg1(1) [my_lv_rmeta_0] /dev/sde1(0) [my_lv_rmeta_1] /dev/sdf1(0) [my_lv_rmeta_2] /dev/sdg1(0) lvconvert --splitmirror 1 -n new my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sde1(1) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rmeta_0] /dev/sde1(0) [my_lv_rmeta_1] /dev/sdf1(0) new /dev/sdg1(1)", "lvconvert --splitmirrors count --trackchanges vg/lv [ removable_PVs ]", "lvconvert --merge raid_image", "lvcreate --type raid1 -m 2 -L 1G -n my_lv .vg Logical volume \"my_lv\" created lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sdb1(1) [my_lv_rimage_1] /dev/sdc1(1) [my_lv_rimage_2] /dev/sdd1(1) [my_lv_rmeta_0] /dev/sdb1(0) [my_lv_rmeta_1] /dev/sdc1(0) [my_lv_rmeta_2] /dev/sdd1(0) lvconvert --splitmirrors 1 --trackchanges my_vg/my_lv my_lv_rimage_2 split from my_lv for read-only purposes. Use 'lvconvert --merge my_vg/my_lv_rimage_2' to merge back into my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sdb1(1) [my_lv_rimage_1] /dev/sdc1(1) my_lv_rimage_2 /dev/sdd1(1) [my_lv_rmeta_0] /dev/sdb1(0) [my_lv_rmeta_1] /dev/sdc1(0) [my_lv_rmeta_2] /dev/sdd1(0)", "lvconvert --splitmirrors 1 --trackchanges my_vg/my_lv lv_rimage_1 split from my_lv for read-only purposes. Use 'lvconvert --merge my_vg/my_lv_rimage_1' to merge back into my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sdc1(1) my_lv_rimage_1 /dev/sdd1(1) [my_lv_rmeta_0] /dev/sdc1(0) [my_lv_rmeta_1] /dev/sdd1(0) lvconvert --merge my_vg/my_lv_rimage_1 my_vg/my_lv_rimage_1 successfully merged back into my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sdc1(1) [my_lv_rimage_1] /dev/sdd1(1) [my_lv_rmeta_0] /dev/sdc1(0) [my_lv_rmeta_1] /dev/sdd1(0)", "lvconvert --splitmirrors 1 --trackchanges my_vg/my_lv my_lv_rimage_1 split from my_lv for read-only purposes. Use 'lvconvert --merge my_vg/my_lv_rimage_1' to merge back into my_lv lvconvert --splitmirrors 1 -n new my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv /dev/sdc1(1) new /dev/sdd1(1)", "lvconvert --splitmirrors 1 --trackchanges my_vg/my_lv my_lv_rimage_1 split from my_lv for read-only purposes. Use 'lvconvert --merge my_vg/my_lv_rimage_1' to merge back into my_lv lvconvert --splitmirrors 1 --trackchanges my_vg/my_lv Cannot track more than one split image at a time", "lvconvert --splitmirrors 1 --trackchanges my_vg/my_lv my_lv_rimage_1 split from my_lv for read-only purposes. Use 'lvconvert --merge my_vg/my_lv_rimage_1' to merge back into my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sdc1(1) my_lv_rimage_1 /dev/sdd1(1) [my_lv_rmeta_0] /dev/sdc1(0) [my_lv_rmeta_1] /dev/sdd1(0) lvconvert --splitmirrors 1 -n new my_vg/my_lv /dev/sdc1 Unable to split additional image from my_lv while tracking changes for my_lv_rimage_1", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sde1(1) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rimage_2] /dev/sdg1(1) [my_lv_rmeta_0] /dev/sde1(0) [my_lv_rmeta_1] /dev/sdf1(0) [my_lv_rmeta_2] /dev/sdg1(0)", "grep lvm /var/log/messages Jan 17 15:57:18 bp-01 lvm[8599]: Device #0 of raid1 array, my_vg-my_lv, has failed. Jan 17 15:57:18 bp-01 lvm[8599]: /dev/sde1: read failed after 0 of 2048 at 250994294784: Input/output error Jan 17 15:57:18 bp-01 lvm[8599]: /dev/sde1: read failed after 0 of 2048 at 250994376704: Input/output error Jan 17 15:57:18 bp-01 lvm[8599]: /dev/sde1: read failed after 0 of 2048 at 0: Input/output error Jan 17 15:57:18 bp-01 lvm[8599]: /dev/sde1: read failed after 0 of 2048 at 4096: Input/output error Jan 17 15:57:19 bp-01 lvm[8599]: Couldn't find device with uuid 3lugiV-3eSP-AFAR-sdrP-H20O-wM2M-qdMANy. Jan 17 15:57:27 bp-01 lvm[8599]: raid1 array, my_vg-my_lv, is not in-sync. Jan 17 15:57:36 bp-01 lvm[8599]: raid1 array, my_vg-my_lv, is now in-sync.", "lvs -a -o name,copy_percent,devices vg Couldn't find device with uuid 3lugiV-3eSP-AFAR-sdrP-H20O-wM2M-qdMANy. LV Copy% Devices lv 100.00 lv_rimage_0(0),lv_rimage_1(0),lv_rimage_2(0) [lv_rimage_0] /dev/sdh1(1) [lv_rimage_1] /dev/sdf1(1) [lv_rimage_2] /dev/sdg1(1) [lv_rmeta_0] /dev/sdh1(0) [lv_rmeta_1] /dev/sdf1(0) [lv_rmeta_2] /dev/sdg1(0)", "lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sdh1(1) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rimage_2] /dev/sdg1(1) [my_lv_rmeta_0] /dev/sdh1(0) [my_lv_rmeta_1] /dev/sdf1(0) [my_lv_rmeta_2] /dev/sdg1(0)", "lvconvert --repair my_vg/my_lv /dev/sdh1: read failed after 0 of 2048 at 250994294784: Input/output error /dev/sdh1: read failed after 0 of 2048 at 250994376704: Input/output error /dev/sdh1: read failed after 0 of 2048 at 0: Input/output error /dev/sdh1: read failed after 0 of 2048 at 4096: Input/output error Couldn't find device with uuid fbI0YO-GX7x-firU-Vy5o-vzwx-vAKZ-feRxfF. Attempt to replace failed RAID images (requires full device resync)? [y/n]: y lvs -a -o name,copy_percent,devices my_vg Couldn't find device with uuid fbI0YO-GX7x-firU-Vy5o-vzwx-vAKZ-feRxfF. LV Copy% Devices my_lv 64.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sde1(1) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rimage_2] /dev/sdg1(1) [my_lv_rmeta_0] /dev/sde1(0) [my_lv_rmeta_1] /dev/sdf1(0) [my_lv_rmeta_2] /dev/sdg1(0)", "lvchange --refresh my_vg/my_lv", "lvconvert --replace dev_to_remove vg/lv [ possible_replacements ]", "lvcreate --type raid1 -m 2 -L 1G -n my_lv my_vg Logical volume \"my_lv\" created lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sdb1(1) [my_lv_rimage_1] /dev/sdb2(1) [my_lv_rimage_2] /dev/sdc1(1) [my_lv_rmeta_0] /dev/sdb1(0) [my_lv_rmeta_1] /dev/sdb2(0) [my_lv_rmeta_2] /dev/sdc1(0) lvconvert --replace /dev/sdb2 my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 37.50 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sdb1(1) [my_lv_rimage_1] /dev/sdc2(1) [my_lv_rimage_2] /dev/sdc1(1) [my_lv_rmeta_0] /dev/sdb1(0) [my_lv_rmeta_1] /dev/sdc2(0) [my_lv_rmeta_2] /dev/sdc1(0)", "lvcreate --type raid1 -m 1 -L 100 -n my_lv my_vg Logical volume \"my_lv\" created lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sda1(1) [my_lv_rimage_1] /dev/sdb1(1) [my_lv_rmeta_0] /dev/sda1(0) [my_lv_rmeta_1] /dev/sdb1(0) pvs PV VG Fmt Attr PSize PFree /dev/sda1 my_vg lvm2 a-- 1020.00m 916.00m /dev/sdb1 my_vg lvm2 a-- 1020.00m 916.00m /dev/sdc1 my_vg lvm2 a-- 1020.00m 1020.00m /dev/sdd1 my_vg lvm2 a-- 1020.00m 1020.00m lvconvert --replace /dev/sdb1 my_vg/my_lv /dev/sdd1 lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 28.00 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sda1(1) [my_lv_rimage_1] /dev/sdd1(1) [my_lv_rmeta_0] /dev/sda1(0) [my_lv_rmeta_1] /dev/sdd1(0)", "lvcreate --type raid1 -m 2 -L 100 -n my_lv my_vg Logical volume \"my_lv\" created lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sda1(1) [my_lv_rimage_1] /dev/sdb1(1) [my_lv_rimage_2] /dev/sdc1(1) [my_lv_rmeta_0] /dev/sda1(0) [my_lv_rmeta_1] /dev/sdb1(0) [my_lv_rmeta_2] /dev/sdc1(0) lvconvert --replace /dev/sdb1 --replace /dev/sdc1 my_vg/my_lv lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 60.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sda1(1) [my_lv_rimage_1] /dev/sdd1(1) [my_lv_rimage_2] /dev/sde1(1) [my_lv_rmeta_0] /dev/sda1(0) [my_lv_rmeta_1] /dev/sdd1(0) [my_lv_rmeta_2] /dev/sde1(0)", "lvchange --syncaction {check\|repair} vg/raid_lv", "lvs -o +raid_sync_action,raid_mismatch_count vg/lv", "lvconvert -R 4096K vg/raid1 Do you really want to change the region_size 512.00 KiB of LV vg/raid1 to 4.00 MiB? [y/n]: y Changed region size on RAID LV vg/raid1 to 4.00 MiB.", "lvcreate --type mirror -L 50G -m 1 -n mirrorlv vg0", "lvcreate --type mirror -m 1 -L 2T -R 2 -n mirror vol_group", "lvcreate --type mirror -L 12MB -m 1 --mirrorlog core -n ondiskmirvol bigvg Logical volume \"ondiskmirvol\" created", "lvcreate --type mirror -L 500M -m 1 -n mirrorlv -alloc anywhere vg0", "lvcreate --type mirror -L 12MB -m 1 --mirrorlog mirrored -n twologvol bigvg Logical volume \"twologvol\" created", "lvcreate --type mirror -L 500M -m 1 -n mirrorlv vg0 /dev/sda1 /dev/sdb1 /dev/sdc1", "lvcreate --type mirror -L 500M -m 1 -n mirrorlv vg0 /dev/sda1:0-499 /dev/sdb1:0-499 /dev/sdc1:0", "lvconvert --splitmirrors 2 --name copy vg/lv", "lvconvert --splitmirrors 2 --name copy vg/lv /dev/sd[ce]1", "lvconvert -m1 vg00/lvol1", "lvconvert -m0 vg00/lvol1", "lvs -a -o name,copy_percent,devices vg00 LV Copy% Devices lvol1 100.00 lvol1_mimage_0(0),lvol1_mimage_1(0) [lvol1_mimage_0] /dev/sda1(0) [lvol1_mimage_1] /dev/sdb1(0) [lvol1_mlog] /dev/sdd1(0) lvconvert -m 2 vg00/lvol1 vg00/lvol1: Converted: 13.0% vg00/lvol1: Converted: 100.0% Logical volume lvol1 converted. lvs -a -o name,copy_percent,devices vg00 LV Copy% Devices lvol1 100.00 lvol1_mimage_0(0),lvol1_mimage_1(0),lvol1_mimage_2(0) [lvol1_mimage_0] /dev/sda1(0) [lvol1_mimage_1] /dev/sdb1(0) [lvol1_mimage_2] /dev/sdc1(0) [lvol1_mlog] /dev/sdd1(0)", "lvcreate -L 100M -T vg001/mythinpool Rounding up size to full physical extent 4.00 MiB Logical volume \"mythinpool\" created lvs LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert my mythinpool vg001 twi-a-tz 100.00m 0.00", "lvcreate -V 1G -T vg001/mythinpool -n thinvolume Logical volume \"thinvolume\" created lvs LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert mythinpool vg001 twi-a-tz 100.00m 0.00 thinvolume vg001 Vwi-a-tz 1.00g mythinpool 0.00", "lvcreate -L 100M -T vg001/mythinpool -V 1G -n thinvolume Rounding up size to full physical extent 4.00 MiB Logical volume \"thinvolume\" created lvs LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert mythinpool vg001 twi-a-tz 100.00m 0.00 thinvolume vg001 Vwi-a-tz 1.00g mythinpool 0.00", "lvcreate -L 100M --thinpool mythinpool vg001 Rounding up size to full physical extent 4.00 MiB Logical volume \"mythinpool\" created lvs LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert mythinpool vg001 twi-a-tz 100.00m 0.00", "lvcreate -i 2 -I 64 -c 256 -L 100M -T vg00/pool -V 1T --name thin_lv", "lvextend -L+100M vg001/mythinpool Extending logical volume mythinpool to 200.00 MiB Logical volume mythinpool successfully resized lvs LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert mythinpool vg001 twi-a-tz 200.00m 0.00 thinvolume vg001 Vwi-a-tz 1.00g mythinpool 0.00", "lvconvert --thinpool vg001/lv1 --poolmetadata vg001/lv2 Converted vg001/lv1 to thin pool.", "lvcreate --size 100M --snapshot --name snap /dev/vg00/lvol1", "lvdisplay /dev/new_vg/lvol0 --- Logical volume --- LV Name /dev/new_vg/lvol0 VG Name new_vg LV UUID LBy1Tz-sr23-OjsI-LT03-nHLC-y8XW-EhCl78 LV Write Access read/write LV snapshot status source of /dev/new_vg/newvgsnap1 [active] LV Status available # open 0 LV Size 52.00 MB Current LE 13 Segments 1 Allocation inherit Read ahead sectors 0 Block device 253:2", "lvs LV VG Attr LSize Origin Snap% Move Log Copy% lvol0 new_vg owi-a- 52.00M newvgsnap1 new_vg swi-a- 8.00M lvol0 0.20", "lvcreate -s --name mysnapshot1 vg001/thinvolume Logical volume \"mysnapshot1\" created lvs LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert mysnapshot1 vg001 Vwi-a-tz 1.00g mythinpool thinvolume 0.00 mythinpool vg001 twi-a-tz 100.00m 0.00 thinvolume vg001 Vwi-a-tz 1.00g mythinpool 0.00", "lvcreate -s --thinpool vg001/pool origin_volume --name mythinsnap", "lvcreate -s vg001/mythinsnap --name my2ndthinsnap", "lvs -o name,lv_ancestors,lv_descendants vg001 LV Ancestors Descendants stack1 stack2,stack3,stack4,stack5,stack6 stack2 stack1 stack3,stack4,stack5,stack6 stack3 stack2,stack1 stack4 stack4 stack3,stack2,stack1 stack5 stack2,stack1 stack6 stack6 stack5,stack2,stack1 pool", "lvs -o name,lv_ancestors,lv_descendants vg001 LV Ancestors Descendants stack1 stack2,stack5,stack6 stack2 stack1 stack5,stack6 stack4 stack5 stack2,stack1 stack6 stack6 stack5,stack2,stack1 pool", "pvcreate /dev/sde1 pvcreate /dev/sdf1 vgcreate VG /dev/sde1 /dev/sdf1", "lvcreate -L 10G -n lv VG /dev/sde1", "lvcreate --type cache-pool -L 5G -n cpool VG /dev/sdf1 Using default stripesize 64.00 KiB. Logical volume \"cpool\" created. lvs -a -o name,size,attr,devices VG LV LSize Attr Devices [cpool] 5.00g Cwi---C--- cpool_cdata(0) [cpool_cdata] 5.00g Cwi-ao---- /dev/sdf1(4) [cpool_cmeta] 8.00m ewi-ao---- /dev/sdf1(2)", "lvconvert --type cache --cachepool cpool VG/lv Logical volume cpool is now cached. lvs -a -o name,size,attr,devices vg LV LSize Attr Devices [cpool] 5.00g Cwi---C--- cpool_cdata(0) [cpool_cdata] 5.00g Cwi-ao---- /dev/sdf1(4) [cpool_cmeta] 8.00m ewi-ao---- /dev/sdf1(2) lv 10.00g Cwi-a-C--- lv_corig(0) [lv_corig] 10.00g owi-aoC--- /dev/sde1(0) [lvol0_pmspare] 8.00m ewi------- /dev/sdf1(0)", "lvconvert --type thin-pool VG/lv /dev/sdf1 WARNING: Converting logical volume VG/lv to thin pool's data volume with metadata wiping. THIS WILL DESTROY CONTENT OF LOGICAL VOLUME (filesystem etc.) Do you really want to convert VG/lv? [y/n]: y Converted VG/lv to thin pool. lvs -a -o name,size,attr,devices vg LV LSize Attr Devices [cpool] 5.00g Cwi---C--- cpool_cdata(0) [cpool_cdata] 5.00g Cwi-ao---- /dev/sdf1(4) [cpool_cmeta] 8.00m ewi-ao---- /dev/sdf1(2) lv 10.00g twi-a-tz-- lv_tdata(0) [lv_tdata] 10.00g Cwi-aoC--- lv_tdata_corig(0) [lv_tdata_corig] 10.00g owi-aoC--- /dev/sde1(0) [lv_tmeta] 12.00m ewi-ao---- /dev/sdf1(1284) [lvol0_pmspare] 12.00m ewi------- /dev/sdf1(0) [lvol0_pmspare] 12.00m ewi------- /dev/sdf1(1287)", "lvconvert --merge vg00/lvol1_snap", "lvconvert --merge @some_tag", "--persistent y --major major --minor minor", "lvchange -pr vg00/lvol1", "lvrename /dev/vg02/lvold /dev/vg02/lvnew", "lvrename vg02 lvold lvnew", "lvremove /dev/testvg/testlv Do you really want to remove active logical volume \"testlv\"? [y/n]: y Logical volume \"testlv\" successfully removed", "lvdisplay -v /dev/vg00/lvol2", "lvscan ACTIVE '/dev/vg0/gfslv' [1.46 GB] inherit", "lvextend -L12G /dev/myvg/homevol lvextend -- extending logical volume \"/dev/myvg/homevol\" to 12 GB lvextend -- doing automatic backup of volume group \"myvg\" lvextend -- logical volume \"/dev/myvg/homevol\" successfully extended", "lvextend -L+1G /dev/myvg/homevol lvextend -- extending logical volume \"/dev/myvg/homevol\" to 13 GB lvextend -- doing automatic backup of volume group \"myvg\" lvextend -- logical volume \"/dev/myvg/homevol\" successfully extended", "lvextend -l +100%FREE /dev/myvg/testlv Extending logical volume testlv to 68.59 GB Logical volume testlv successfully resized", "lvreduce --resizefs -L 64M vg00/lvol1 fsck from util-linux 2.23.2 /dev/mapper/vg00-lvol1: clean, 11/25688 files, 8896/102400 blocks resize2fs 1.42.9 (28-Dec-2013) Resizing the filesystem on /dev/mapper/vg00-lvol1 to 65536 (1k) blocks. The filesystem on /dev/mapper/vg00-lvol1 is now 65536 blocks long. Size of logical volume vg00/lvol1 changed from 100.00 MiB (25 extents) to 64.00 MiB (16 extents). Logical volume vg00/lvol1 successfully resized.", "lvreduce --resizefs -L -64M vg00/lvol1", "vgs VG #PV #LV #SN Attr VSize VFree vg 2 0 0 wz--n- 271.31G 271.31G", "lvcreate -n stripe1 -L 271.31G -i 2 vg Using default stripesize 64.00 KB Rounding up size to full physical extent 271.31 GB Logical volume \"stripe1\" created lvs -a -o +devices LV VG Attr LSize Origin Snap% Move Log Copy% Devices stripe1 vg -wi-a- 271.31G /dev/sda1(0),/dev/sdb1(0)", "vgs VG #PV #LV #SN Attr VSize VFree vg 2 1 0 wz--n- 271.31G 0", "vgextend vg /dev/sdc1 Volume group \"vg\" successfully extended vgs VG #PV #LV #SN Attr VSize VFree vg 3 1 0 wz--n- 406.97G 135.66G", "lvextend vg/stripe1 -L 406G Using stripesize of last segment 64.00 KB Extending logical volume stripe1 to 406.00 GB Insufficient suitable allocatable extents for logical volume stripe1: 34480 more required", "vgextend vg /dev/sdd1 Volume group \"vg\" successfully extended vgs VG #PV #LV #SN Attr VSize VFree vg 4 1 0 wz--n- 542.62G 271.31G lvextend vg/stripe1 -L 542G Using stripesize of last segment 64.00 KB Extending logical volume stripe1 to 542.00 GB Logical volume stripe1 successfully resized", "lvextend vg/stripe1 -L 406G Using stripesize of last segment 64.00 KB Extending logical volume stripe1 to 406.00 GB Insufficient suitable allocatable extents for logical volume stripe1: 34480 more required lvextend -i1 -l+100%FREE vg/stripe1", "lvs vg LV VG Attr LSize Pool Origin Snap% Move Log Cpy%Sync Convert lv vg Rwi-a-r- 5.00g 100.00", "lvs vg LV VG Attr LSize Pool Origin Snap% Move Log Cpy%Sync Convert lv vg rwi-a-r- 20.00m 100.00 lvextend -L +5G vg/lv --nosync Extending 2 mirror images. Extending logical volume lv to 5.02 GiB Logical volume lv successfully resized lvs vg LV VG Attr LSize Pool Origin Snap% Move Log Cpy%Sync Convert lv vg Rwi-a-r- 5.02g 100.00", "cling_tag_list = [ \"@site1\", \"@site2\" ]", "cling_tag_list = [ \"@A\", \"@B\" ]", "pvs -a -o +pv_tags /dev/sd[bcdefgh] PV VG Fmt Attr PSize PFree PV Tags /dev/sdb1 taft lvm2 a-- 15.00g 15.00g A /dev/sdc1 taft lvm2 a-- 15.00g 15.00g B /dev/sdd1 taft lvm2 a-- 15.00g 15.00g B /dev/sde1 taft lvm2 a-- 15.00g 15.00g C /dev/sdf1 taft lvm2 a-- 15.00g 15.00g C /dev/sdg1 taft lvm2 a-- 15.00g 15.00g A /dev/sdh1 taft lvm2 a-- 15.00g 15.00g A", "lvcreate --type raid1 -m 1 -n mirror --nosync -L 10G taft WARNING: New raid1 won't be synchronised. Don't read what you didn't write! Logical volume \"mirror\" created", "lvs -a -o +devices LV VG Attr LSize Log Cpy%Sync Devices mirror taft Rwi-a-r--- 10.00g 100.00 mirror_rimage_0(0),mirror_rimage_1(0) [mirror_rimage_0] taft iwi-aor--- 10.00g /dev/sdb1(1) [mirror_rimage_1] taft iwi-aor--- 10.00g /dev/sdc1(1) [mirror_rmeta_0] taft ewi-aor--- 4.00m /dev/sdb1(0) [mirror_rmeta_1] taft ewi-aor--- 4.00m /dev/sdc1(0)", "lvextend --alloc cling -L +10G taft/mirror Extending 2 mirror images. Extending logical volume mirror to 20.00 GiB Logical volume mirror successfully resized", "lvs -a -o +devices LV VG Attr LSize Log Cpy%Sync Devices mirror taft Rwi-a-r--- 20.00g 100.00 mirror_rimage_0(0),mirror_rimage_1(0) [mirror_rimage_0] taft iwi-aor--- 20.00g /dev/sdb1(1) [mirror_rimage_0] taft iwi-aor--- 20.00g /dev/sdg1(0) [mirror_rimage_1] taft iwi-aor--- 20.00g /dev/sdc1(1) [mirror_rimage_1] taft iwi-aor--- 20.00g /dev/sdd1(0) [mirror_rmeta_0] taft ewi-aor--- 4.00m /dev/sdb1(0) [mirror_rmeta_1] taft ewi-aor--- 4.00m /dev/sdc1(0)", "lvs vg/thin1s1 LV VG Attr LSize Pool Origin thin1s1 vg Vwi---tz-k 1.00t pool0 thin1", "lvchange -ay -K VG/SnapLV", "lvcreate --type thin -n SnapLV -kn -s ThinLV --thinpool VG/ThinPoolLV", "lvchange -kn VG/SnapLV", "lvs -H -o name,full_ancestors,full_descendants LV FAncestors FDescendants lvol1 lvol2,lvol3,lvol4,lvol5 lvol2 lvol1 lvol3,lvol4,lvol5 lvol3 lvol2,lvol1 lvol4,lvol5 lvol4 lvol3,lvol2,lvol1 lvol5 lvol3,lvol2,lvol1 pool", "lvremove -f vg/lvol3 Logical volume \"lvol3\" successfully removed lvs -H -o name,full_ancestors,full_descendants LV FAncestors FDescendants lvol1 lvol2,-lvol3,lvol4,lvol5 lvol2 lvol1 -lvol3,lvol4,lvol5 -lvol3 lvol2,lvol1 lvol4,lvol5 lvol4 -lvol3,lvol2,lvol1 lvol5 -lvol3,lvol2,lvol1 pool", "lvs -H -o name,full_ancestors,full_descendants,time_removed LV FAncestors FDescendants RTime lvol1 lvol2,-lvol3,lvol4,lvol5 lvol2 lvol1 -lvol3,lvol4,lvol5 -lvol3 lvol2,lvol1 lvol4,lvol5 2016-03-14 14:14:32 +0100 lvol4 -lvol3,lvol2,lvol1 lvol5 -lvol3,lvol2,lvol1 pool", "lvs -H vg/-lvol3 LV VG Attr LSize -lvol3 vg ----h----- 0", "lvremove -f vg/lvol5 Automatically removing historical logical volume vg/-lvol5. Logical volume \"lvol5\" successfully removed lvs -H -o name,full_ancestors,full_descendants LV FAncestors FDescendants lvol1 lvol2,-lvol3,lvol4 lvol2 lvol1 -lvol3,lvol4 -lvol3 lvol2,lvol1 lvol4 lvol4 -lvol3,lvol2,lvol1 pool", "lvremove -f vg/lvol1 vg/lvol2 Logical volume \"lvol1\" successfully removed Logical volume \"lvol2\" successfully removed lvs -H -o name,full_ancestors,full_descendants LV FAncestors FDescendants -lvol1 -lvol2,-lvol3,lvol4 -lvol2 -lvol1 -lvol3,lvol4 -lvol3 -lvol2,-lvol1 lvol4 lvol4 -lvol3,-lvol2,-lvol1 pool", "lvremove -f vg/-lvol3 Historical logical volume \"lvol3\" successfully removed lvs -H -o name,full_ancestors,full_descendants LV FAncestors FDescendants -lvol1 -lvol2,lvol4 -lvol2 -lvol1 lvol4 lvol4 -lvol2,-lvol1 pool", "lvremove -f vg/lvol4 Automatically removing historical logical volume vg/-lvol1. Automatically removing historical logical volume vg/-lvol2. Automatically removing historical logical volume vg/-lvol4. Logical volume \"lvol4\" successfully removed" ]	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/logical_volume_manager_administration/lv?extIdCarryOver=true&sc_cid=701f2000001Css5AAC
Chapter 3. Distribution of content in RHEL 8	Chapter 3. Distribution of content in RHEL 8 3.1. Installation Red Hat Enterprise Linux 8 is installed using ISO images. Two types of ISO image are available for the AMD64, Intel 64-bit, 64-bit ARM, IBM Power Systems, and IBM Z architectures: Binary DVD ISO: A full installation image that contains the BaseOS and AppStream repositories and allows you to complete the installation without additional repositories. Note The Binary DVD ISO image is larger than 4.7 GB, and as a result, it might not fit on a single-layer DVD. A dual-layer DVD or USB key is recommended when using the Binary DVD ISO image to create bootable installation media. You can also use the Image Builder tool to create customized RHEL images. For more information about Image Builder, see the Composing a customized RHEL system image document. Boot ISO: A minimal boot ISO image that is used to boot into the installation program. This option requires access to the BaseOS and AppStream repositories to install software packages. The repositories are part of the Binary DVD ISO image. See the Interactively installing RHEL from installation media document for instructions on downloading ISO images, creating installation media, and completing a RHEL installation. For automated Kickstart installations and other advanced topics, see the Automatically installing RHEL document. 3.2. Repositories Red Hat Enterprise Linux 8 is distributed through two main repositories: BaseOS AppStream Both repositories are required for a basic RHEL installation, and are available with all RHEL subscriptions. Content in the BaseOS repository is intended to provide the core set of the underlying OS functionality that provides the foundation for all installations. This content is available in the RPM format and is subject to support terms similar to those in releases of RHEL. For a list of packages distributed through BaseOS, see the Package manifest . Content in the Application Stream repository includes additional user space applications, runtime languages, and databases in support of the varied workloads and use cases. Application Streams are available in the familiar RPM format, as an extension to the RPM format called modules , or as Software Collections. For a list of packages available in AppStream, see the Package manifest . In addition, the CodeReady Linux Builder repository is available with all RHEL subscriptions. It provides additional packages for use by developers. Packages included in the CodeReady Linux Builder repository are unsupported. For more information about RHEL 8 repositories, see the Package manifest . 3.3. Application Streams Red Hat Enterprise Linux 8 introduces the concept of Application Streams. Multiple versions of user space components are now delivered and updated more frequently than the core operating system packages. This provides greater flexibility to customize Red Hat Enterprise Linux without impacting the underlying stability of the platform or specific deployments. Components made available as Application Streams can be packaged as modules or RPM packages and are delivered through the AppStream repository in RHEL 8. Each Application Stream component has a given life cycle, either the same as RHEL 8 or shorter. For details, see Red Hat Enterprise Linux Life Cycle . Modules are collections of packages representing a logical unit: an application, a language stack, a database, or a set of tools. These packages are built, tested, and released together. Module streams represent versions of the Application Stream components. For example, several streams (versions) of the PostgreSQL database server are available in the postgresql module with the default postgresql:10 stream. Only one module stream can be installed on the system. Different versions can be used in separate containers. Detailed module commands are described in the Installing, managing, and removing user-space components document. For a list of modules available in AppStream, see the Package manifest . 3.4. Package management with YUM/DNF On Red Hat Enterprise Linux 8, installing software is ensured by the YUM tool, which is based on the DNF technology. We deliberately adhere to usage of the yum term for consistency with major versions of RHEL. However, if you type dnf instead of yum , the command works as expected because yum is an alias to dnf for compatibility. For more details, see the following documentation: Installing, managing, and removing user-space components Considerations in adopting RHEL 8	null	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/html/8.2_release_notes/distribution-of-content-in-rhel-8
9.4. Security Technical Implementation Guide	9.4. Security Technical Implementation Guide A Security Technical Implementation Guide (STIG) is a methodology for standardized secure installation and maintenance of computer software and hardware. See the following URL for more information on STIG: https://public.cyber.mil/stigs/ .	null	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/security_guide/sec-security_technical_implementation_guide
Chapter 24. Automatically discovering bare metal nodes	Chapter 24. Automatically discovering bare metal nodes You can use auto-discovery to register overcloud nodes and generate their metadata, without the need to create an instackenv.json file. This improvement can help to reduce the time it takes to collect information about a node. For example, if you use auto-discovery, you do not to collate the IPMI IP addresses and subsequently create the instackenv.json . 24.1. Enabling auto-discovery Enable and configure Bare Metal auto-discovery to automatically discover and import nodes that join your provisioning network when booting with PXE. Procedure Enable Bare Metal auto-discovery in the undercloud.conf file: enable_node_discovery - When enabled, any node that boots the introspection ramdisk using PXE is enrolled in the Bare Metal service (ironic) automatically. discovery_default_driver - Sets the driver to use for discovered nodes. For example, ipmi . Add your IPMI credentials to ironic: Add your IPMI credentials to a file named ipmi-credentials.json . Replace the SampleUsername , RedactedSecurePassword , and bmc_address values in this example to suit your environment: Import the IPMI credentials file into ironic: 24.2. Testing auto-discovery PXE boot a node that is connected to your provisioning network to test the Bare Metal auto-discovery feature. Procedure Power on the required nodes. Run the openstack baremetal node list command. You should see the new nodes listed in an enrolled state: Set the resource class for each node: Configure the kernel and ramdisk for each node: Set all nodes to available: 24.3. Using rules to discover different vendor hardware If you have a heterogeneous hardware environment, you can use introspection rules to assign credentials and remote management credentials. For example, you might want a separate discovery rule to handle your Dell nodes that use DRAC. Procedure Create a file named dell-drac-rules.json with the following contents: Replace the user name and password values in this example to suit your environment: Import the rule into ironic:	[ "enable_node_discovery = True discovery_default_driver = ipmi", "[ { \"description\": \"Set default IPMI credentials\", \"conditions\": [ {\"op\": \"eq\", \"field\": \"data://auto_discovered\", \"value\": true} ], \"actions\": [ {\"action\": \"set-attribute\", \"path\": \"driver_info/ipmi_username\", \"value\": \"SampleUsername\"}, {\"action\": \"set-attribute\", \"path\": \"driver_info/ipmi_password\", \"value\": \"RedactedSecurePassword\"}, {\"action\": \"set-attribute\", \"path\": \"driver_info/ipmi_address\", \"value\": \"{data[inventory][bmc_address]}\"} ] } ]", "openstack baremetal introspection rule import ipmi-credentials.json", "openstack baremetal node list +--------------------------------------+------+---------------+-------------+--------------------+-------------+ \| UUID \| Name \| Instance UUID \| Power State \| Provisioning State \| Maintenance \| +--------------------------------------+------+---------------+-------------+--------------------+-------------+ \| c6e63aec-e5ba-4d63-8d37-bd57628258e8 \| None \| None \| power off \| enroll \| False \| \| 0362b7b2-5b9c-4113-92e1-0b34a2535d9b \| None \| None \| power off \| enroll \| False \| +--------------------------------------+------+---------------+-------------+--------------------+-------------+", "for NODE in `openstack baremetal node list -c UUID -f value` ; do openstack baremetal node set USDNODE --resource-class baremetal ; done", "for NODE in `openstack baremetal node list -c UUID -f value` ; do openstack baremetal node manage USDNODE ; done openstack overcloud node configure --all-manageable", "for NODE in `openstack baremetal node list -c UUID -f value` ; do openstack baremetal node provide USDNODE ; done", "[ { \"description\": \"Set default IPMI credentials\", \"conditions\": [ {\"op\": \"eq\", \"field\": \"data://auto_discovered\", \"value\": true}, {\"op\": \"ne\", \"field\": \"data://inventory.system_vendor.manufacturer\", \"value\": \"Dell Inc.\"} ], \"actions\": [ {\"action\": \"set-attribute\", \"path\": \"driver_info/ipmi_username\", \"value\": \"SampleUsername\"}, {\"action\": \"set-attribute\", \"path\": \"driver_info/ipmi_password\", \"value\": \"RedactedSecurePassword\"}, {\"action\": \"set-attribute\", \"path\": \"driver_info/ipmi_address\", \"value\": \"{data[inventory][bmc_address]}\"} ] }, { \"description\": \"Set the vendor driver for Dell hardware\", \"conditions\": [ {\"op\": \"eq\", \"field\": \"data://auto_discovered\", \"value\": true}, {\"op\": \"eq\", \"field\": \"data://inventory.system_vendor.manufacturer\", \"value\": \"Dell Inc.\"} ], \"actions\": [ {\"action\": \"set-attribute\", \"path\": \"driver\", \"value\": \"idrac\"}, {\"action\": \"set-attribute\", \"path\": \"driver_info/drac_username\", \"value\": \"SampleUsername\"}, {\"action\": \"set-attribute\", \"path\": \"driver_info/drac_password\", \"value\": \"RedactedSecurePassword\"}, {\"action\": \"set-attribute\", \"path\": \"driver_info/drac_address\", \"value\": \"{data[inventory][bmc_address]}\"} ] } ]", "openstack baremetal introspection rule import dell-drac-rules.json" ]	https://docs.redhat.com/en/documentation/red_hat_openstack_platform/17.0/html/director_installation_and_usage/assembly_automatically-discovering-bare-metal-nodes
4.14. Using Shared System Certificates	4.14. Using Shared System Certificates The Shared System Certificates storage allows NSS, GnuTLS, OpenSSL, and Java to share a default source for retrieving system certificate anchors and black list information. By default, the trust store contains the Mozilla CA list, including positive and negative trust. The system allows updating of the core Mozilla CA list or choosing another certificate list. 4.14.1. Using a System-wide Trust Store In Red Hat Enterprise Linux 7, the consolidated system-wide trust store is located in the /etc/pki/ca-trust/ and /usr/share/pki/ca-trust-source/ directories. The trust settings in /usr/share/pki/ca-trust-source/ are processed with lower priority than settings in /etc/pki/ca-trust/ . Certificate files are treated depending on the subdirectory they are installed to: /usr/share/pki/ca-trust-source/anchors/ or /etc/pki/ca-trust/source/anchors/ - for trust anchors. See Section 4.5.6, "Understanding Trust Anchors" . /usr/share/pki/ca-trust-source/blacklist/ or /etc/pki/ca-trust/source/blacklist/ - for distrusted certificates. /usr/share/pki/ca-trust-source/ or /etc/pki/ca-trust/source/ - for certificates in the extended BEGIN TRUSTED file format. 4.14.2. Adding New Certificates To add a certificate in the simple PEM or DER file formats to the list of CAs trusted on the system, copy the certificate file to the /usr/share/pki/ca-trust-source/anchors/ or /etc/pki/ca-trust/source/anchors/ directory. To update the system-wide trust store configuration, use the update-ca-trust command, for example: Note While the Firefox browser is able to use an added certificate without executing update-ca-trust , it is recommended to run update-ca-trust after a CA change. Also note that browsers, such as Firefox, Epiphany, or Chromium, cache files, and you might need to clear the browser's cache or restart your browser to load the current system certificates configuration. 4.14.3. Managing Trusted System Certificates To list, extract, add, remove, or change trust anchors, use the trust command. To see the built-in help for this command, enter it without any arguments or with the --help directive: To list all system trust anchors and certificates, use the trust list command: All sub-commands of the trust commands offer a detailed built-in help, for example: To store a trust anchor into the system-wide trust store, use the trust anchor sub-command and specify a path.to a certificate, for example: To remove a certificate, use either a path.to a certificate or an ID of a certificate: 4.14.4. Additional Resources For more information, see the following man pages: update-ca-trust(8) trust(1)	[ "cp ~/certificate-trust-examples/Cert-trust-test-ca.pem /usr/share/pki/ca-trust-source/anchors/ update-ca-trust", "trust usage: trust command <args> Common trust commands are: list List trust or certificates extract Extract certificates and trust extract-compat Extract trust compatibility bundles anchor Add, remove, change trust anchors dump Dump trust objects in internal format See 'trust <command> --help' for more information", "trust list pkcs11:id=%d2%87%b4%e3%df%37%27%93%55%f6%56%ea%81%e5%36%cc%8c%1e%3f%bd;type=cert type: certificate label: ACCVRAIZ1 trust: anchor category: authority pkcs11:id=%a6%b3%e1%2b%2b%49%b6%d7%73%a1%aa%94%f5%01%e7%73%65%4c%ac%50;type=cert type: certificate label: ACEDICOM Root trust: anchor category: authority [output has been truncated]", "trust list --help usage: trust list --filter=<what> --filter=<what> filter of what to export ca-anchors certificate anchors blacklist blacklisted certificates trust-policy anchors and blacklist (default) certificates all certificates pkcs11:object=xx a PKCS#11 URI --purpose=<usage> limit to certificates usable for the purpose server-auth for authenticating servers client-auth for authenticating clients email for email protection code-signing for authenticating signed code 1.2.3.4.5... an arbitrary object id -v, --verbose show verbose debug output -q, --quiet suppress command output", "trust anchor path.to/certificate.crt", "trust anchor --remove path.to/certificate.crt trust anchor --remove \"pkcs11:id=%AA%BB%CC%DD%EE;type=cert\"" ]	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/security_guide/sec-shared-system-certificates
4.10. Configuring Fencing Levels	4.10. Configuring Fencing Levels Pacemaker supports fencing nodes with multiple devices through a feature called fencing topologies. To implement topologies, create the individual devices as you normally would and then define one or more fencing levels in the fencing-topology section in the configuration. Each level is attempted in ascending numeric order, starting at 1. If a device fails, processing terminates for the current level. No further devices in that level are exercised and the level is attempted instead. If all devices are successfully fenced, then that level has succeeded and no other levels are tried. The operation is finished when a level has passed (success), or all levels have been attempted (failed). Use the following command to add a fencing level to a node. The devices are given as a comma-separated list of stonith ids, which are attempted for the node at that level. The following command lists all of the fencing levels that are currently configured. In the following example, there are two fence devices configured for node rh7-2 : an ilo fence device called my_ilo and an apc fence device called my_apc . These commands sets up fence levels so that if the device my_ilo fails and is unable to fence the node, then Pacemaker will attempt to use the device my_apc . This example also shows the output of the pcs stonith level command after the levels are configured. The following command removes the fence level for the specified node and devices. If no nodes or devices are specified then the fence level you specify is removed from all nodes. The following command clears the fence levels on the specified node or stonith id. If you do not specify a node or stonith id, all fence levels are cleared. If you specify more than one stonith id, they must be separated by a comma and no spaces, as in the following example. The following command verifies that all fence devices and nodes specified in fence levels exist.	[ "pcs stonith level add level node devices", "pcs stonith level", "pcs stonith level add 1 rh7-2 my_ilo pcs stonith level add 2 rh7-2 my_apc pcs stonith level Node: rh7-2 Level 1 - my_ilo Level 2 - my_apc", "pcs stonith level remove level [ node_id ] [ stonith_id ] ... [ stonith_id ]", "pcs stonith level clear [ node \| stonith_id (s)]", "pcs stonith level clear dev_a,dev_b", "pcs stonith level verify" ]	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/6/html/configuring_the_red_hat_high_availability_add-on_with_pacemaker/s1-fencelevels-haar
Chapter 17. Installing a three-node cluster on AWS	Chapter 17. Installing a three-node cluster on AWS In OpenShift Container Platform version 4.15, you can install a three-node cluster on Amazon Web Services (AWS). A three-node cluster consists of three control plane machines, which also act as compute machines. This type of cluster provides a smaller, more resource efficient cluster, for cluster administrators and developers to use for testing, development, and production. You can install a three-node cluster using either installer-provisioned or user-provisioned infrastructure. Note Deploying a three-node cluster using an AWS Marketplace image is not supported. 17.1. Configuring a three-node cluster You configure a three-node cluster by setting the number of worker nodes to 0 in the install-config.yaml file before deploying the cluster. Setting the number of worker nodes to 0 ensures that the control plane machines are schedulable. This allows application workloads to be scheduled to run from the control plane nodes. Note Because application workloads run from control plane nodes, additional subscriptions are required, as the control plane nodes are considered to be compute nodes. Prerequisites You have an existing install-config.yaml file. Procedure Set the number of compute replicas to 0 in your install-config.yaml file, as shown in the following compute stanza: Example install-config.yaml file for a three-node cluster apiVersion: v1 baseDomain: example.com compute: - name: worker platform: {} replicas: 0 # ... If you are deploying a cluster with user-provisioned infrastructure: After you create the Kubernetes manifest files, make sure that the spec.mastersSchedulable parameter is set to true in cluster-scheduler-02-config.yml file. You can locate this file in <installation_directory>/manifests . For more information, see "Creating the Kubernetes manifest and Ignition config files" in "Installing a cluster on user-provisioned infrastructure in AWS by using CloudFormation templates". Do not create additional worker nodes. Example cluster-scheduler-02-config.yml file for a three-node cluster apiVersion: config.openshift.io/v1 kind: Scheduler metadata: creationTimestamp: null name: cluster spec: mastersSchedulable: true policy: name: "" status: {} 17.2. steps Installing a cluster on AWS with customizations Installing a cluster on user-provisioned infrastructure in AWS by using CloudFormation templates	[ "apiVersion: v1 baseDomain: example.com compute: - name: worker platform: {} replicas: 0", "apiVersion: config.openshift.io/v1 kind: Scheduler metadata: creationTimestamp: null name: cluster spec: mastersSchedulable: true policy: name: \"\" status: {}" ]	https://docs.redhat.com/en/documentation/openshift_container_platform_installation/4.15/html/installing_on_aws/installing-aws-three-node
Chapter 2. Upgrading to Red Hat Ansible Automation Platform 2.4	Chapter 2. Upgrading to Red Hat Ansible Automation Platform 2.4 To upgrade your Red Hat Ansible Automation Platform, start by reviewing planning information to ensure a successful upgrade. You can then download the desired version of the Ansible Automation Platform installer, configure the inventory file in the installation bundle to reflect your environment, and then run the installer. 2.1. Ansible Automation Platform upgrade planning Before you begin the upgrade process, review the following considerations to plan and prepare your Ansible Automation Platform deployment: Automation controller Even if you have a valid license from a version, you must provide your credentials or a subscriptions manifest upon upgrading to the latest version of automation controller. If you need to upgrade Red Hat Enterprise Linux and automation controller, you must first backup and restore your automation controller data. Clustered upgrades require special attention to instance and instance groups before upgrading. Additional resources Importing a subscription Backup and restore Clustering Automation hub When upgrading to Ansible Automation Platform 2.4, you can either add an existing automation hub API token or generate a new one and invalidate any existing tokens. Existing container images are removed when upgrading Ansible Automation Platform. This is because, when upgrading Ansible Automation Platform with setup.sh script, podman system reset -f is executed. This removes all container images on your Ansible Automation Platform nodes then pushes the new execution environment image that is bundled with installer. See Running the Red Hat Ansible Automation Platform installer setup script . Additional resources Setting up the inventory file Event-Driven Ansible controller If you are currently running Event-Driven Ansible controller and plan to deploy it when you upgrade to Ansible Automation Platform 2.4, it is recommended that you disable all Event-Driven Ansible activations before upgrading to ensure that only new activations run after the upgrade process has completed. This prevents possibilities of orphaned containers running activations from the version. 2.2. Choosing and obtaining a Red Hat Ansible Automation Platform installer Choose the Red Hat Ansible Automation Platform installer you need based on your Red Hat Enterprise Linux environment internet connectivity. Review the following scenarios and decide on which Red Hat Ansible Automation Platform installer meets your needs. Note A valid Red Hat customer account is required to access Red Hat Ansible Automation Platform installer downloads on the Red Hat Customer Portal. Installing with internet access Choose the Red Hat Ansible Automation Platform installer if your Red Hat Enterprise Linux environment is connected to the internet. Installing with internet access retrieves the latest required repositories, packages, and dependencies. Choose one of the following ways to set up your Ansible Automation Platform installer. Tarball install Navigate to the Red Hat Ansible Automation Platform download page. Click Download Now for the Ansible Automation Platform <latest-version> Setup . Extract the files: USD tar xvzf ansible-automation-platform-setup-<latest-version>.tar.gz RPM install Install Ansible Automation Platform Installer Package v.2.4 for RHEL 8 for x86_64 USD sudo dnf install --enablerepo=ansible-automation-platform-2.4-for-rhel-8-x86_64-rpms ansible-automation-platform-installer v.2.4 for RHEL 9 for x86-64 USD sudo dnf install --enablerepo=ansible-automation-platform-2.4-for-rhel-9-x86_64-rpms ansible-automation-platform-installer Note dnf install enables the repo as the repo is disabled by default. When you use the RPM installer, the files are placed under the /opt/ansible-automation-platform/installer directory. Installing without internet access Use the Red Hat Ansible Automation Platform Bundle installer if you are unable to access the internet, or would prefer not to install separate components and dependencies from online repositories. Access to Red Hat Enterprise Linux repositories is still needed. All other dependencies are included in the tar archive. Navigate to the Red Hat Ansible Automation Platform download page. Click Download Now for the Ansible Automation Platform <latest-version> Setup Bundle . Extract the files: USD tar xvzf ansible-automation-platform-setup-bundle-<latest-version>.tar.gz 2.3. Setting up the inventory file Before upgrading your Red Hat Ansible Automation Platform installation, edit the inventory file so that it matches your desired configuration. You can keep the same parameters from your existing Ansible Automation Platform deployment or you can modify the parameters to match any changes to your environment. Procedure Navigate to the installation program directory. Bundled installer USD cd ansible-automation-platform-setup-bundle-2.4-1-x86_64 Online installer USD cd ansible-automation-platform-setup-2.4-1 Open the inventory file for editing. Modify the inventory file to provision new nodes, deprovision nodes or groups, and import or generate automation hub API tokens. You can use the same inventory file from an existing Ansible Automation Platform 2.1 installation if there are no changes to the environment. Note Provide a reachable IP address or fully qualified domain name (FQDN) for the [automationhub] and [automationcontroller] hosts to ensure that users can synchronize and install content from Ansible automation hub from a different node. Do not use localhost . If localhost is used, the upgrade will be stopped as part of preflight checks. Provisioning new nodes in a cluster Add new nodes alongside existing nodes in the inventory file as follows: [controller] clusternode1.example.com clusternode2.example.com clusternode3.example.com [all:vars] admin_password='password' pg_host='' pg_port='' pg_database='<database_name>' pg_username='<your_username>' pg_password='<your_password>' Deprovisioning nodes or groups in a cluster Append node_state-deprovision to the node or group within the inventory file. Importing and generating API tokens When upgrading from Red Hat Ansible Automation Platform 2.0 or earlier to Red Hat Ansible Automation Platform 2.1 or later, you can use your existing automation hub API token or generate a new token. In the inventory file, edit one of the following fields before running the Red Hat Ansible Automation Platform installer setup script setup.sh : Import an existing API token with the automationhub_api_token flag as follows: automationhub_api_token= <api_token> Generate a new API token, and invalidate any existing tokens, with the generate_automationhub_token flag as follows: generate_automationhub_token=True Additional resources Red Hat Ansible Automation Platform Installation Guide Deprovisioning individual nodes or instance groups 2.4. Running the Red Hat Ansible Automation Platform installer setup script You can run the setup script once you have finished updating the inventory file. Procedure Run the setup.sh script USD ./setup.sh The installation will begin.	[ "tar xvzf ansible-automation-platform-setup-<latest-version>.tar.gz", "sudo dnf install --enablerepo=ansible-automation-platform-2.4-for-rhel-8-x86_64-rpms ansible-automation-platform-installer", "sudo dnf install --enablerepo=ansible-automation-platform-2.4-for-rhel-9-x86_64-rpms ansible-automation-platform-installer", "tar xvzf ansible-automation-platform-setup-bundle-<latest-version>.tar.gz", "cd ansible-automation-platform-setup-bundle-2.4-1-x86_64", "cd ansible-automation-platform-setup-2.4-1", "[controller] clusternode1.example.com clusternode2.example.com clusternode3.example.com [all:vars] admin_password='password' pg_host='' pg_port='' pg_database='<database_name>' pg_username='<your_username>' pg_password='<your_password>'", "automationhub_api_token= <api_token>", "generate_automationhub_token=True", "./setup.sh" ]	https://docs.redhat.com/en/documentation/red_hat_ansible_automation_platform/2.4/html/red_hat_ansible_automation_platform_upgrade_and_migration_guide/aap-upgrading-platform
Preface	Preface You can install Red Hat Developer Hub on Microsoft Azure Kubernetes Service (AKS) using one of the following methods: The Red Hat Developer Hub Operator The Red Hat Developer Hub Helm chart	null	https://docs.redhat.com/en/documentation/red_hat_developer_hub/1.4/html/installing_red_hat_developer_hub_on_microsoft_azure_kubernetes_service/pr01
Chapter 7. Managing DNS records in IdM	Chapter 7. Managing DNS records in IdM This chapter describes how to manage DNS records in Identity Management (IdM). As an IdM administrator, you can add, modify and delete DNS records in IdM. The chapter contains the following sections: DNS records in IdM Adding DNS resource records from the IdM Web UI Adding DNS resource records from the IdM CLI Common ipa dnsrecord-add options Deleting DNS records in the IdM Web UI Deleting an entire DNS record in the IdM Web UI Deleting DNS records in the IdM CLI Prerequisites Your IdM deployment contains an integrated DNS server. For information how to install IdM with integrated DNS, see one of the following links: Installing an IdM server: With integrated DNS, with an integrated CA as the root CA . Installing an IdM server: With integrated DNS, with an external CA as the root CA . 7.1. DNS records in IdM Identity Management (IdM) supports many different DNS record types. The following four are used most frequently: A This is a basic map for a host name and an IPv4 address. The record name of an A record is a host name, such as www . The IP Address value of an A record is an IPv4 address, such as 192.0.2.1 . For more information about A records, see RFC 1035 . AAAA This is a basic map for a host name and an IPv6 address. The record name of an AAAA record is a host name, such as www . The IP Address value is an IPv6 address, such as 2001:DB8::1111 . For more information about AAAA records, see RFC 3596 . SRV Service (SRV) resource records map service names to the DNS name of the server that is providing that particular service. For example, this record type can map a service like an LDAP directory to the server which manages it. The record name of an SRV record has the format _service . _protocol , such as _ldap._tcp . The configuration options for SRV records include priority, weight, port number, and host name for the target service. For more information about SRV records, see RFC 2782 . PTR A pointer record (PTR) adds a reverse DNS record, which maps an IP address to a domain name. Note All reverse DNS lookups for IPv4 addresses use reverse entries that are defined in the in-addr.arpa. domain. The reverse address, in human-readable form, is the exact reverse of the regular IP address, with the in-addr.arpa. domain appended to it. For example, for the network address 192.0.2.0/24 , the reverse zone is 2.0.192.in-addr.arpa . The record name of a PTR must be in the standard format specified in RFC 1035 , extended in RFC 2317 , and RFC 3596 . The host name value must be a canonical host name of the host for which you want to create the record. Note Reverse zones can also be configured for IPv6 addresses, with zones in the .ip6.arpa. domain. For more information about IPv6 reverse zones, see RFC 3596 . When adding DNS resource records, note that many of the records require different data. For example, a CNAME record requires a host name, while an A record requires an IP address. In the IdM Web UI, the fields in the form for adding a new record are updated automatically to reflect what data is required for the currently selected type of record. 7.2. Adding DNS resource records in the IdM Web UI Follow this procedure to add DNS resource records in the Identity Management (IdM) Web UI. Prerequisites The DNS zone to which you want to add a DNS record exists and is managed by IdM. For more information about creating a DNS zone in IdM DNS, see Managing DNS zones in IdM . You are logged in as IdM administrator. Procedure In the IdM Web UI, click Network Services DNS DNS Zones . Click the DNS zone to which you want to add a DNS record. In the DNS Resource Records section, click Add to add a new record. Figure 7.1. Adding a New DNS Resource Record Select the type of record to create and fill out the other fields as required. Figure 7.2. Defining a New DNS Resource Record Click Add to confirm the new record. 7.3. Adding DNS resource records from the IdM CLI Follow this procedure to add a DNS resource record of any type from the command line interface (CLI). Prerequisites The DNS zone to which you want to add a DNS records exists. For more information about creating a DNS zone in IdM DNS, see Managing DNS zones in IdM . You are logged in as IdM administrator. Procedure To add a DNS resource record, use the ipa dnsrecord-add command. The command follows this syntax: In the command above: The zone_name is the name of the DNS zone to which the record is being added. The record_name is an identifier for the new DNS resource record. For example, to add an A type DNS record of host1 to the idm.example.com zone, enter: 7.4. Common ipa dnsrecord-* options You can use the following options when adding, modifying and deleting the most common DNS resource record types in Identity Management (IdM): A (IPv4) AAAA (IPv6) SRV PTR In Bash , you can define multiple entries by listing the values in a comma-separated list inside curly braces, such as --option={val1,val2,val3} . Table 7.1. General Record Options Option Description --ttl = number Sets the time to live for the record. --structured Parses the raw DNS records and returns them in a structured format. Table 7.2. "A" record options Option Description Examples --a-rec = ARECORD Passes a single A record or a list of A records. ipa dnsrecord-add idm.example.com host1 --a-rec=192.168.122.123 Can create a wildcard A record with a given IP address. ipa dnsrecord-add idm.example.com "*" --a-rec=192.168.122.123 [a] --a-ip-address = string Gives the IP address for the record. When creating a record, the option to specify the A record value is --a-rec . However, when modifying an A record, the --a-rec option is used to specify the current value for the A record. The new value is set with the --a-ip-address option. ipa dnsrecord-mod idm.example.com --a-rec 192.168.122.123 --a-ip-address 192.168.122.124 [a] The example creates a wildcard A record with the IP address of 192.0.2.123. Table 7.3. "AAAA" record options Option Description Example --aaaa-rec = AAAARECORD Passes a single AAAA (IPv6) record or a list of AAAA records. ipa dnsrecord-add idm.example.com www --aaaa-rec 2001:db8::1231:5675 --aaaa-ip-address = string Gives the IPv6 address for the record. When creating a record, the option to specify the A record value is --aaaa-rec . However, when modifying an A record, the --aaaa-rec option is used to specify the current value for the A record. The new value is set with the --a-ip-address option. ipa dnsrecord-mod idm.example.com --aaaa-rec 2001:db8::1231:5675 --aaaa-ip-address 2001:db8::1231:5676 Table 7.4. "PTR" record options Option Description Example --ptr-rec = PTRRECORD Passes a single PTR record or a list of PTR records. When adding the reverse DNS record, the zone name used with the ipa dnsrecord-add command is reversed, compared to the usage for adding other DNS records. Typically, the host IP address is the last octet of the IP address in a given network. The first example on the right adds a PTR record for server4.idm.example.com with IPv4 address 192.168.122.4. The second example adds a reverse DNS entry to the 0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa. IPv6 reverse zone for the host server2.example.com with the IP address 2001:DB8::1111 . ipa dnsrecord-add 122.168.192.in-addr.arpa 4 --ptr-rec server4.idm.example.com. USD ipa dnsrecord-add 0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa. 1.1.1.0.0.0.0.0.0.0.0.0.0.0.0 --ptr-rec server2.idm.example.com. --ptr-hostname = string Gives the host name for the record. Table 7.5. "SRV" Record Options Option Description Example --srv-rec = SRVRECORD Passes a single SRV record or a list of SRV records. In the examples on the right, _ldap._tcp defines the service type and the connection protocol for the SRV record. The --srv-rec option defines the priority, weight, port, and target values. The weight values of 51 and 49 in the examples add up to 100 and represent the probability, in percentages, that a particular record is used. # ipa dnsrecord-add idm.example.com _ldap._tcp --srv-rec="0 51 389 server1.idm.example.com." # ipa dnsrecord-add server.idm.example.com _ldap._tcp --srv-rec="1 49 389 server2.idm.example.com." --srv-priority = number Sets the priority of the record. There can be multiple SRV records for a service type. The priority (0 - 65535) sets the rank of the record; the lower the number, the higher the priority. A service has to use the record with the highest priority first. # ipa dnsrecord-mod server.idm.example.com _ldap._tcp --srv-rec="1 49 389 server2.idm.example.com." --srv-priority=0 --srv-weight = number Sets the weight of the record. This helps determine the order of SRV records with the same priority. The set weights should add up to 100, representing the probability (in percentages) that a particular record is used. # ipa dnsrecord-mod server.idm.example.com _ldap._tcp --srv-rec="0 49 389 server2.idm.example.com." --srv-weight=60 --srv-port = number Gives the port for the service on the target host. # ipa dnsrecord-mod server.idm.example.com _ldap._tcp --srv-rec="0 60 389 server2.idm.example.com." --srv-port=636 --srv-target = string Gives the domain name of the target host. This can be a single period (.) if the service is not available in the domain. Additional resources Run ipa dnsrecord-add --help . 7.5. Deleting DNS records in the IdM Web UI Follow this procedure to delete DNS records in Identity Management (IdM) using the IdM Web UI. Prerequisites You are logged in as IdM administrator. Procedure In the IdM Web UI, click Network Services DNS DNS Zones . Click the zone from which you want to delete a DNS record, for example example.com. . In the DNS Resource Records section, click the name of the resource record. Figure 7.3. Selecting a DNS Resource Record Select the check box by the name of the record type to delete. Click Delete . Figure 7.4. Deleting a DNS Resource Record The selected record type is now deleted. The other configuration of the resource record is left intact. Additional resources See Deleting an entire DNS record in the IdM Web UI . 7.6. Deleting an entire DNS record in the IdM Web UI Follow this procedure to delete all the records for a particular resource in a zone using the Identity Management (IdM) Web UI. Prerequisites You are logged in as IdM administrator. Procedure In the IdM Web UI, click Network Services DNS DNS Zones . Click the zone from which you want to delete a DNS record, for example zone.example.com. . In the DNS Resource Records section, select the check box of the resource record to delete. Click Delete . Figure 7.5. Deleting an Entire Resource Record The entire resource record is now deleted. 7.7. Deleting DNS records in the IdM CLI Follow this procedure to remove DNS records from a zone managed by the Identity Management (IdM) DNS. Prerequisites You are logged in as IdM administrator. Procedure To remove records from a zone, use the ipa dnsrecord-del command and add the -- recordType -rec option together with the record value. For example, to remove an A type record: If you run ipa dnsrecord-del without any options, the command prompts for information about the record to delete. Note that passing the --del-all option with the command removes all associated records for the zone. Additional resources Run the ipa dnsrecord-del --help command. 7.8. Additional resources See Using Ansible to manage DNS records in IdM .	[ "ipa dnsrecord-add zone_name record_name -- record_type_option=data", "ipa dnsrecord-add idm.example.com host1 --a-rec=192.168.122.123", "ipa dnsrecord-del example.com www --a-rec 192.0.2.1" ]	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/8/html/working_with_dns_in_identity_management/managing-dns-records-in-idm_working-with-dns-in-identity-management
8.38. evolution	8.38. evolution 8.38.1. RHSA-2013:1540 - Low: evolution security, bug fix, and enhancement update Updated evolution packages that fix one security issue, several bugs, and add various enhancements are now available for Red Hat Enterprise Linux 6. The Red Hat Security Response Team has rated this update as having low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, are available for each vulnerability from the CVE links associated with each description below. Evolution is the integrated collection of email, calendaring, contact management, communications, and personal information management (PIM) tools for the GNOME desktop environment. Security Fix CVE-2013-4166 A flaw was found in the way Evolution selected GnuPG public keys when encrypting emails. This could result in emails being encrypted with public keys other than the one belonging to the intended recipient. Note The Evolution packages have been upgraded to upstream version 2.32.3, which provides a number of bug fixes and enhancements over the version. These changes include implementation of Gnome XDG Config Folders, and support for Exchange Web Services (EWS) protocol to connect to Microsoft Exchange servers. EWS support has been added as a part of the evolution-exchange packages. (BZ# 883010 , BZ# 883014 , BZ# 883015 , BZ# 883017 , BZ# 524917 , BZ# 524921 , BZ# 883044 ) The gtkhtml3 packages have been upgraded to upstream version 2.32.2, which provides a number of bug fixes and enhancements over the version. (BZ# 883019 ) The libgdata packages have been upgraded to upstream version 0.6.4, which provides a number of bug fixes and enhancements over the version. (BZ# 883032 ) Bug Fix BZ# 665967 The Exchange Calendar could not fetch the "Free" and "Busy" information for meeting attendees when using Microsoft Exchange 2010 servers, and this information thus could not be displayed. This happened because Microsoft Exchange 2010 servers use more strict rules for "Free" and "Busy" information fetching. With this update, the respective code in the openchange packages has been modified so the "Free" and "Busy" information fetching now complies with the fetching rules on Microsoft Exchange 2010 servers. The "Free" and "Busy" information can now be displayed as expected in the Exchange Calendar. All Evolution users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add these enhancements. All running instances of Evolution must be restarted for this update to take effect.	null	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/6/html/6.5_technical_notes/evolution
Chapter 1. Connecting RHEL systems directly to AD using SSSD	Chapter 1. Connecting RHEL systems directly to AD using SSSD To connect a RHEL system to Active Directory (AD), use: System Security Services Daemon (SSSD) for identity and authentication realmd to detect available domains and configure the underlying RHEL system services. 1.1. Overview of direct integration using SSSD You use SSSD to access a user directory for authentication and authorization through a common framework with user caching to permit offline logins. SSSD is highly configurable; it provides Pluggable Authentication Modules (PAM) and Name Switch Service (NSS) integration and a database to store local users as well as extended user data retrieved from a central server. SSSD is the recommended component to connect a RHEL system with one of the following types of identity server: Active Directory Identity Management (IdM) in RHEL Any generic LDAP or Kerberos server Note Direct integration with SSSD works only within a single AD forest by default. The most convenient way to configure SSSD to directly integrate a Linux system with AD is to use the realmd service. It allows callers to configure network authentication and domain membership in a standard way. The realmd service automatically discovers information about accessible domains and realms and does not require advanced configuration to join a domain or realm. You can use SSSD for both direct and indirect integration with AD and it allows you to switch from one integration approach to another. Direct integration is a simple way to introduce RHEL systems to an AD environment. However, as the share of RHEL systems grows, your deployments usually need a better centralized management of the identity-related policies such as host-based access control, sudo, or SELinux user mappings. Initially, you can maintain the configuration of these aspects of the RHEL systems in local configuration files. However, with a growing number of systems, distribution and management of the configuration files is easier with a provisioning system such as Red Hat Satellite. When direct integration does not scale anymore, you should consider indirect integration. For more information about moving from direct integration (RHEL clients are in the AD domain) to indirect integration (IdM with trust to AD), see Moving RHEL clients from AD domain to IdM Server. Important If IdM is in FIPS mode, the IdM-AD integration does not work due to AD only supporting the use of RC4 or AES HMAC-SHA1 encryptions, while RHEL 9 in FIPS mode allows only AES HMAC-SHA2 by default. For more information, see the Red Hat Knowledgebase solution AD Domain Users unable to login in to the FIPS-compliant environment . IdM does not support the more restrictive FIPS:OSPP crypto policy, which should only be used on Common Criteria evaluated systems. Additional resources realm(8) , sssd-ad(5) , and sssd(8) man pages on your system Deciding between indirect and direct integration 1.2. Supported Windows platforms for direct integration You can directly integrate your RHEL system with Active Directory forests that use the following forest and domain functional levels: Forest functional level range: Windows Server 2008 - Windows Server 2016 Domain functional level range: Windows Server 2008 - Windows Server 2016 Direct integration has been tested on the following supported operating systems: Windows Server 2022 (RHEL 9.1 or later) Windows Server 2019 Windows Server 2016 Windows Server 2012 R2 Note Windows Server 2019 and Windows Server 2022 do not introduce a new functional level. The highest functional level Windows Server 2019 and Windows Server 2022 use is Windows Server 2016. 1.3. Connecting directly to AD The System Security Services Daemon (SSSD) is the recommended component to connect a Red Hat Enterprise Linux (RHEL) system with Active Directory (AD). You can integrate directly with AD by using either POSIX ID mapping, which is the default for SSSD, or by using POSIX attributes defined in AD. Important Before joining your system to AD, ensure you configured your system correctly by following the procedure in the Red Hat Knowledgebase solution Basic Prechecks Steps: RHEL Join With Active Directory using 'adcli', 'realm' and 'net' commands . 1.3.1. Options for integrating with AD: using POSIX ID mapping or POSIX attributes Linux and Windows systems use different identifiers for users and groups: Linux uses user IDs (UID) and group IDs (GID). See Introduction to managing user and group accounts in Configuring Basic System Settings . Linux UIDs and GIDs are compliant with the POSIX standard. Windows use security IDs (SID). Important After connecting a RHEL system to AD, you can authenticate with your AD username and password. Do not create a Linux user with the same name as a Windows user, as duplicate names might cause a conflict and interrupt the authentication process. To authenticate to a RHEL system as an AD user, you must have a UID and GID assigned. SSSD provides the option to integrate with AD either using POSIX ID mapping or POSIX attributes in AD. The default is to use POSIX ID mapping. 1.3.2. Connecting to AD using POSIX ID mapping SSSD uses the SID of an AD user to algorithmically generate POSIX IDs in a process called POSIX ID mapping. POSIX ID mapping creates an association between SIDs in AD and IDs on Linux. When SSSD detects a new AD domain, it assigns a range of available IDs to the new domain. When an AD user logs in to an SSSD client machine for the first time, SSSD creates an entry for the user in the SSSD cache, including a UID based on the user's SID and the ID range for that domain. Because the IDs for an AD user are generated in a consistent way from the same SID, the user has the same UID and GID when logging in to any RHEL system. Note When all client systems use SSSD to map SIDs to Linux IDs, the mapping is consistent. If some clients use different software, choose one of the following: Ensure that the same mapping algorithm is used on all clients. Use explicit POSIX attributes defined in AD. For more information, see the section on ID mapping in the sssd-ad man page. 1.3.2.1. Discovering and joining an AD Domain using SSSD Follow this procedure to discover an AD domain and connect a RHEL system to that domain using SSSD. Prerequisites Ensure that the required ports are open: Ports required for direct integration of RHEL systems into AD using SSSD Ensure that you are using the AD domain controller server for DNS. Verify that the system time on both systems is synchronized. This ensures that Kerberos is able to work correctly. Procedure Install the following packages: To display information for a specific domain, run realm discover and add the name of the domain you want to discover: The realmd system uses DNS SRV lookups to find the domain controllers in this domain automatically. Note The realmd system can discover both Active Directory and Identity Management domains. If both domains exist in your environment, you can limit the discovery results to a specific type of server using the --server-software=active-directory option. Configure the local RHEL system with the realm join command. The realmd suite edits all required configuration files automatically. For example, for a domain named ad.example.com : Verification Display an AD user details, such as the administrator user: Additional resources realm(8) and nmcli(1) man pages on your system 1.3.3. Connecting to AD using POSIX attributes defined in Active Directory AD can create and store POSIX attributes, such as uidNumber , gidNumber , unixHomeDirectory , or loginShell . When using POSIX ID mapping, SSSD creates new UIDs and GIDs, which overrides the values defined in AD. To keep the AD-defined values, you must disable POSIX ID mapping in SSSD. For best performance, publish the POSIX attributes to the AD global catalog. If POSIX attributes are not present in the global catalog, SSSD connects to the individual domain controllers directly on the LDAP port. Prerequisites Ensure that the required ports are open: Ports required for direct integration of RHEL systems into AD using SSSD Ensure that you are using the AD domain controller server for DNS. Verify that the system time on both systems is synchronized. This ensures that Kerberos is able to work correctly. Procedure Install the following packages: Configure the local RHEL system with POSIX ID mapping disabled using the realm join command with the --automatic-id-mapping=no option. The realmd suite edits all required configuration files automatically. For example, for a domain named ad.example.com : If you already joined a domain, you can manually disable POSIX ID Mapping in SSSD: Open the /etc/sssd/sssd.conf file. In the AD domain section, add the ldap_id_mapping = false setting. Remove the SSSD caches: Restart SSSD: SSSD now uses POSIX attributes from AD, instead of creating them locally. Note You must have the relevant POSIX attributes ( uidNumber , gidNumber , unixHomeDirectory , and loginShell ) configured for the users in AD. Verification Display an AD user details, such as the administrator user: Additional resources sssd-ldap(8) man page on your system 1.3.4. Connecting to multiple domains in different AD forests with SSSD You can use an Active Directory (AD) Managed Service Account (MSA) to access AD domains from different forests where there is no trust between them. See Accessing AD with a Managed Service Account . 1.4. How the AD provider handles dynamic DNS updates Active Directory (AD) actively maintains its DNS records by timing out ( aging ) and removing ( scavenging ) inactive records. By default, the SSSD service refreshes a RHEL client's DNS record at the following intervals: Every time the identity provider comes online. Every time the RHEL system reboots. At the interval specified by the dyndns_refresh_interval option in the /etc/sssd/sssd.conf configuration file. The default value is 86400 seconds (24 hours). Note If you set the dyndns_refresh_interval option to the same interval as the DHCP lease, you can update the DNS record after the IP lease is renewed. SSSD sends dynamic DNS updates to the AD server using Kerberos/GSSAPI for DNS (GSS-TSIG). This means that you only need to enable secure connections to AD. Additional resources sssd-ad(5) man page on your system 1.5. Modifying dynamic DNS settings for the AD provider The System Security Services Daemon (SSSD) service refreshes the DNS record of a Red Hat Enterprise Linux (RHEL) client joined to an AD environment at default intervals. The following procedure adjusts these intervals. Prerequisites You have joined a RHEL host to an Active Directory environment with the SSSD service. You need root permissions to edit the /etc/sssd/sssd.conf configuration file. Procedure Open the /etc/sssd/sssd.conf configuration file in a text editor. Add the following options to the [domain] section for your AD domain to set the DNS record refresh interval to 12 hours, disable updating PTR records, and set the DNS record Time To Live (TTL) to 1 hour. Save and close the /etc/sssd/sssd.conf configuration file. Restart the SSSD service to load the configuration changes. Note You can disable dynamic DNS updates by setting the dyndns_update option in the sssd.conf file to false : Additional resources How the AD provider handles dynamic DNS updates sssd-ad(5) man page on your system 1.6. How the AD provider handles trusted domains If you set the id_provider = ad option in the /etc/sssd/sssd.conf configuration file, SSSD handles trusted domains as follows: SSSD only supports domains in a single AD forest. If SSSD requires access to multiple domains from multiple forests, consider using IPA with trusts (preferred) or the winbindd service instead of SSSD. By default, SSSD discovers all domains in the forest and, if a request for an object in a trusted domain arrives, SSSD tries to resolve it. If the trusted domains are not reachable or geographically distant, which makes them slow, you can set the ad_enabled_domains parameter in /etc/sssd/sssd.conf to limit from which trusted domains SSSD resolves objects. By default, you must use fully-qualified user names to resolve users from trusted domains. Additional resources sssd.conf(5) man page on your system 1.7. Overriding Active Directory site autodiscovery with SSSD Active Directory (AD) forests can be very large, with numerous different domain controllers, domains, child domains and physical sites. AD uses the concept of sites to identify the physical location for its domain controllers. This enables clients to connect to the domain controller that is geographically closest, which increases client performance. This section describes how SSSD uses autodiscovery to find an AD site to connect to, and how you can override autodiscovery and specify a site manually. 1.7.1. How SSSD handles AD site autodiscovery By default, SSSD clients use autodiscovery to find its AD site and connect to the closest domain controller. The process consists of these steps: SSSD performs an SRV query to find Domain Controllers (DCs) in the domain. SSSD reads the discovery domain from the dns_discovery_domain or the ad_domain options in the SSSD configuration file. SSSD performs Connection-Less LDAP (CLDAP) pings to these DCs in 3 batches to avoid pinging too many DCs and avoid timeouts from unreachable DCs. If SSSD receives site and forest information during any of these batches, it skips the rest of the batches. SSSD creates and saves a list of site-specific and backup servers. 1.7.2. Overriding AD site autodiscovery To override the autodiscovery process, specify the AD site to which you want the client to connect by adding the ad_site option to the [domain] section of the /etc/sssd/sssd.conf file. This example configures the client to connect to the ExampleSite AD site. Prerequisites You have joined a RHEL host to an Active Directory environment using the SSSD service. You can authenticate as the root user so you can edit the /etc/sssd/sssd.conf configuration file. Procedure Open the /etc/sssd/sssd.conf file in a text editor. Add the ad_site option to the [domain] section for your AD domain: Save and close the /etc/sssd/sssd.conf configuration file. Restart the SSSD service to load the configuration changes: 1.8. realm commands The realmd system has two major task areas: Managing system enrollment in a domain. Controlling which domain users are allowed to access local system resources. In realmd use the command line tool realm to run commands. Most realm commands require the user to specify the action that the utility should perform, and the entity, such as a domain or user account, for which to perform the action. Table 1.1. realmd commands Command Description Realm Commands discover Run a discovery scan for domains on the network. join Add the system to the specified domain. leave Remove the system from the specified domain. list List all configured domains for the system or all discovered and configured domains. Login Commands permit Enable access for specific users or for all users within a configured domain to access the local system. deny Restrict access for specific users or for all users within a configured domain to access the local system. Additional resources realm(8) man page on your system 1.9. Ports required for direct integration of RHEL systems into AD using SSSD The following ports must be open and accessible to the AD domain controllers and the RHEL host. Table 1.2. Ports Required for Direct Integration of Linux Systems into AD Using SSSD Service Port Protocol Notes DNS 53 UDP and TCP LDAP 389 UDP and TCP LDAPS 636 TCP Optional Samba 445 UDP and TCP For AD Group Policy Objects (GPOs) Kerberos 88 UDP and TCP Kerberos 464 UDP and TCP Used by kadmin for setting and changing a password LDAP Global Catalog 3268 TCP If the id_provider = ad option is being used LDAPS Global Catalog 3269 TCP Optional NTP 123 UDP Optional NTP 323 UDP Optional	[ "dnf install samba-common-tools realmd oddjob oddjob-mkhomedir sssd adcli krb5-workstation", "realm discover ad.example.com ad.example.com type: kerberos realm-name: AD.EXAMPLE.COM domain-name: ad.example.com configured: no server-software: active-directory client-software: sssd required-package: oddjob required-package: oddjob-mkhomedir required-package: sssd required-package: adcli required-package: samba-common", "realm join ad.example.com", "getent passwd [email protected] [email protected]::1450400500:1450400513:Administrator:/home/[email protected]:/bin/bash", "dnf install realmd oddjob oddjob-mkhomedir sssd adcli krb5-workstation", "realm join --automatic-id-mapping=no ad.example.com", "rm -f /var/lib/sss/db/", "systemctl restart sssd", "getent passwd [email protected] [email protected]:*:10000:10000:Administrator:/home/Administrator:/bin/bash", "[domain/ ad.example.com ] id_provider = ad dyndns_refresh_interval = 43200 dyndns_update_ptr = false dyndns_ttl = 3600", "systemctl restart sssd", "[domain/ ad.example.com ] id_provider = ad dyndns_update = false", "[domain/ad.example.com] id_provider = ad ad_site = ExampleSite", "systemctl restart sssd" ]	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/integrating_rhel_systems_directly_with_windows_active_directory/connecting-rhel-systems-directly-to-ad-using-sssd_integrating-rhel-systems-directly-with-active-directory
Chapter 29. Delegating permissions to user groups to manage users using IdM CLI	Chapter 29. Delegating permissions to user groups to manage users using IdM CLI Delegation is one of the access control methods in IdM, along with self-service rules and role-based access control (RBAC). You can use delegation to assign permissions to one group of users to manage entries for another group of users. This section covers the following topics: Delegation rules Creating a delegation rule using IdM CLI Viewing existing delegation rules using IdM CLI Modifying a delegation rule using IdM CLI Deleting a delegation rule using IdM CLI 29.1. Delegation rules You can delegate permissions to user groups to manage users by creating delegation rules . Delegation rules allow a specific user group to perform write (edit) operations on specific attributes for users in another user group. This form of access control rule is limited to editing the values of a subset of attributes you specify in a delegation rule; it does not grant the ability to add or remove whole entries or control over unspecified attributes. Delegation rules grant permissions to existing user groups in IdM. You can use delegation to, for example, allow the managers user group to manage selected attributes of users in the employees user group. 29.2. Creating a delegation rule using IdM CLI Follow this procedure to create a delegation rule using the IdM CLI. Prerequisites You are logged in as a member of the admins group. Procedure Enter the ipa delegation-add command. Specify the following options: --group : the group who is being granted permissions to the entries of users in the user group. --membergroup : the group whose entries can be edited by members of the delegation group. --permissions : whether users will have the right to view the given attributes ( read ) and add or change the given attributes ( write ). If you do not specify permissions, only the write permission will be added. --attrs : the attributes which users in the member group are allowed to view or edit. For example: 29.3. Viewing existing delegation rules using IdM CLI Follow this procedure to view existing delegation rules using the IdM CLI. Prerequisites You are logged in as a member of the admins group. Procedure Enter the ipa delegation-find command: 29.4. Modifying a delegation rule using IdM CLI Follow this procedure to modify an existing delegation rule using the IdM CLI. Important The --attrs option overwrites whatever the list of supported attributes was, so always include the complete list of attributes along with any new attributes. This also applies to the --permissions option. Prerequisites You are logged in as a member of the admins group. Procedure Enter the ipa delegation-mod command with the desired changes. For example, to add the displayname attribute to the basic manager attributes example rule: 29.5. Deleting a delegation rule using IdM CLI Follow this procedure to delete an existing delegation rule using the IdM CLI. Prerequisites You are logged in as a member of the admins group. Procedure Enter the ipa delegation-del command. When prompted, enter the name of the delegation rule you want to delete:	[ "ipa delegation-add \"basic manager attributes\" --permissions=read --permissions=write --attrs=businesscategory --attrs=departmentnumber --attrs=employeetype --attrs=employeenumber --group=managers --membergroup=employees ------------------------------------------- Added delegation \"basic manager attributes\" ------------------------------------------- Delegation name: basic manager attributes Permissions: read, write Attributes: businesscategory, departmentnumber, employeetype, employeenumber Member user group: employees User group: managers", "ipa delegation-find -------------------- 1 delegation matched -------------------- Delegation name: basic manager attributes Permissions: read, write Attributes: businesscategory, departmentnumber, employeenumber, employeetype Member user group: employees User group: managers ---------------------------- Number of entries returned 1 ----------------------------", "ipa delegation-mod \"basic manager attributes\" --attrs=businesscategory --attrs=departmentnumber --attrs=employeetype --attrs=employeenumber --attrs=displayname ---------------------------------------------- Modified delegation \"basic manager attributes\" ---------------------------------------------- Delegation name: basic manager attributes Permissions: read, write Attributes: businesscategory, departmentnumber, employeetype, employeenumber, displayname Member user group: employees User group: managers", "ipa delegation-del Delegation name: basic manager attributes --------------------------------------------- Deleted delegation \"basic manager attributes\" ---------------------------------------------" ]	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/managing_idm_users_groups_hosts_and_access_control_rules/delegating-permissions-to-user-groups-to-manage-users-using-idm-cli_managing-users-groups-hosts
Chapter 4. Technology previews	Chapter 4. Technology previews This section describes technology preview features introduced in Red Hat OpenShift Data Foundation 4.9 under Technology Preview support limitations. Important Technology Preview features are provided with a limited support scope, as detailed on the Customer Portal: Technology Preview Features Support Scope . PV encryption - service account per namespace As of Openshift Data Foundation 4.9, you can use service accounts to authenticate a tenant with Vault as a technology preview. For more information, see Persistent volume encryption . Alerts to control overprovision With this release, you can get alerts for the overprovision. This enables you to define a quota on the amount of persistent volume claims (PVCs) consumed from a storage cluster based on the specific application namespace. For more information, see Overprovision level policy control .	null	https://docs.redhat.com/en/documentation/red_hat_openshift_data_foundation/4.9/html/4.9_release_notes/technology_previews
1.7. Listing Enabled Software Collections	1.7. Listing Enabled Software Collections To get a list of Software Collections that are enabled in the current session, print the USDX_SCLS environment variable by running the following command: echo USDX_SCLS	null	https://docs.redhat.com/en/documentation/red_hat_software_collections/3/html/packaging_guide/sect-listing_enabled_software_collections
Chapter 5. Installing a three-node cluster on Nutanix	Chapter 5. Installing a three-node cluster on Nutanix In OpenShift Container Platform version 4.16, you can install a three-node cluster on Nutanix. A three-node cluster consists of three control plane machines, which also act as compute machines. This type of cluster provides a smaller, more resource efficient cluster, for cluster administrators and developers to use for testing, development, and production. 5.1. Configuring a three-node cluster You configure a three-node cluster by setting the number of worker nodes to 0 in the install-config.yaml file before deploying the cluster. Setting the number of worker nodes to 0 ensures that the control plane machines are schedulable. This allows application workloads to be scheduled to run from the control plane nodes. Note Because application workloads run from control plane nodes, additional subscriptions are required, as the control plane nodes are considered to be compute nodes. Prerequisites You have an existing install-config.yaml file. Procedure Set the number of compute replicas to 0 in your install-config.yaml file, as shown in the following compute stanza: Example install-config.yaml file for a three-node cluster apiVersion: v1 baseDomain: example.com compute: - name: worker platform: {} replicas: 0 # ... 5.2. steps Installing a cluster on Nutanix	[ "apiVersion: v1 baseDomain: example.com compute: - name: worker platform: {} replicas: 0" ]	https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html/installing_on_nutanix/installing-nutanix-three-node
Preface	Preface Open Java Development Kit (OpenJDK) is a free and open source implementation of the Java Platform, Standard Edition (Java SE). The Red Hat build of OpenJDK is available in three versions: 8u, 11u, and 17u. Packages for the Red Hat build of OpenJDK are made available on Red Hat Enterprise Linux and Microsoft Windows and shipped as a JDK and JRE in the Red Hat Ecosystem Catalog.	null	https://docs.redhat.com/en/documentation/red_hat_build_of_openjdk/17/html/release_notes_for_red_hat_build_of_openjdk_17.0.6/pr01
Chapter 305. SIP Component	Chapter 305. SIP Component Available as of Camel version 2.5 The sip component in Camel is a communication component, based on the Jain SIP implementation (available under the JCP license). Session Initiation Protocol (SIP) is an IETF-defined signaling protocol, widely used for controlling multimedia communication sessions such as voice and video calls over Internet Protocol (IP).The SIP protocol is an Application Layer protocol designed to be independent of the underlying transport layer; it can run on Transmission Control Protocol (TCP), User Datagram Protocol (UDP) or Stream Control Transmission Protocol (SCTP). The Jain SIP implementation supports TCP and UDP only. The Camel SIP component only supports the SIP Publish and Subscribe capability as described in the RFC3903 - Session Initiation Protocol (SIP) Extension for Event This camel component supports both producer and consumer endpoints. Camel SIP Producers (Event Publishers) and SIP Consumers (Event Subscribers) communicate event & state information to each other using an intermediary entity called a SIP Presence Agent (a stateful brokering entity). For SIP based communication, a SIP Stack with a listener must be instantiated on both the SIP Producer and Consumer (using separate ports if using localhost). This is necessary in order to support the handshakes & acknowledgements exchanged between the SIP Stacks during communication. Maven users will need to add the following dependency to their pom.xml for this component: <dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-sip</artifactId> <version>x.x.x</version> <!-- use the same version as your Camel core version --> </dependency> 305.1. URI format The URI scheme for a sip endpoint is as follows: sip://johndoe@localhost:99999[?options] sips://johndoe@localhost:99999/[?options] This component supports producer and consumer endpoints for both TCP and UDP. You can append query options to the URI in the following format, ?option=value&option=value&... 305.2. Options The SIP Component offers an extensive set of configuration options & capability to create custom stateful headers needed to propagate state via the SIP protocol. The SIP component has no options. The SIP endpoint is configured using URI syntax: with the following path and query parameters: 305.2.1. Path Parameters (1 parameters): Name Description Default Type uri Required URI of the SIP server to connect to (the username and password can be included such as: john:secretmyserver:9999) URI 305.2.2. Query Parameters (44 parameters): Name Description Default Type cacheConnections (common) Should connections be cached by the SipStack to reduce cost of connection creation. This is useful if the connection is used for long running conversations. false boolean contentSubType (common) Setting for contentSubType can be set to any valid MimeSubType. plain String contentType (common) Setting for contentType can be set to any valid MimeType. text String eventHeaderName (common) Setting for a String based event type. String eventId (common) Setting for a String based event Id. Mandatory setting unless a registry based FromHeader is specified String fromHost (common) Hostname of the message originator. Mandatory setting unless a registry based FromHeader is specified String fromPort (common) Port of the message originator. Mandatory setting unless a registry based FromHeader is specified int fromUser (common) Username of the message originator. Mandatory setting unless a registry based custom FromHeader is specified. String msgExpiration (common) The amount of time a message received at an endpoint is considered valid 3600 int receiveTimeoutMillis (common) Setting for specifying amount of time to wait for a Response and/or Acknowledgement can be received from another SIP stack 10000 long stackName (common) Name of the SIP Stack instance associated with an SIP Endpoint. NAME_NOT_SET String toHost (common) Hostname of the message receiver. Mandatory setting unless a registry based ToHeader is specified String toPort (common) Portname of the message receiver. Mandatory setting unless a registry based ToHeader is specified int toUser (common) Username of the message receiver. Mandatory setting unless a registry based custom ToHeader is specified. String transport (common) Setting for choice of transport protocol. Valid choices are tcp or udp. tcp String bridgeErrorHandler (consumer) Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored. false boolean consumer (consumer) This setting is used to determine whether the kind of header (FromHeader,ToHeader etc) that needs to be created for this endpoint false boolean presenceAgent (consumer) This setting is used to distinguish between a Presence Agent & a consumer. This is due to the fact that the SIP Camel component ships with a basic Presence Agent (for testing purposes only). Consumers have to set this flag to true. false boolean exceptionHandler (consumer) To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored. ExceptionHandler exchangePattern (consumer) Sets the exchange pattern when the consumer creates an exchange. ExchangePattern addressFactory (advanced) To use a custom AddressFactory AddressFactory callIdHeader (advanced) A custom Header object containing call details. Must implement the type javax.sip.header.CallIdHeader CallIdHeader contactHeader (advanced) An optional custom Header object containing verbose contact details (email, phone number etc). Must implement the type javax.sip.header.ContactHeader ContactHeader contentTypeHeader (advanced) A custom Header object containing message content details. Must implement the type javax.sip.header.ContentTypeHeader ContentTypeHeader eventHeader (advanced) A custom Header object containing event details. Must implement the type javax.sip.header.EventHeader EventHeader expiresHeader (advanced) A custom Header object containing message expiration details. Must implement the type javax.sip.header.ExpiresHeader ExpiresHeader extensionHeader (advanced) A custom Header object containing user/application specific details. Must implement the type javax.sip.header.ExtensionHeader ExtensionHeader fromHeader (advanced) A custom Header object containing message originator settings. Must implement the type javax.sip.header.FromHeader FromHeader headerFactory (advanced) To use a custom HeaderFactory HeaderFactory listeningPoint (advanced) To use a custom ListeningPoint implementation ListeningPoint maxForwardsHeader (advanced) A custom Header object containing details on maximum proxy forwards. This header places a limit on the viaHeaders possible. Must implement the type javax.sip.header.MaxForwardsHeader MaxForwardsHeader maxMessageSize (advanced) Setting for maximum allowed Message size in bytes. 1048576 int messageFactory (advanced) To use a custom MessageFactory MessageFactory sipFactory (advanced) To use a custom SipFactory to create the SipStack to be used SipFactory sipStack (advanced) To use a custom SipStack SipStack sipUri (advanced) To use a custom SipURI. If none configured, then the SipUri fallback to use the options toUser toHost:toPort SipURI synchronous (advanced) Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported). false boolean toHeader (advanced) A custom Header object containing message receiver settings. Must implement the type javax.sip.header.ToHeader ToHeader viaHeaders (advanced) List of custom Header objects of the type javax.sip.header.ViaHeader. Each ViaHeader containing a proxy address for request forwarding. (Note this header is automatically updated by each proxy when the request arrives at its listener) List implementationDebugLogFile (logging) Name of client debug log file to use for logging String implementationServerLogFile (logging) Name of server log file to use for logging String implementationTraceLevel (logging) Logging level for tracing 0 String maxForwards (proxy) Number of maximum proxy forwards int useRouterForAllUris (proxy) This setting is used when requests are sent to the Presence Agent via a proxy. false boolean 305.3. Spring Boot Auto-Configuration The component supports 2 options, which are listed below. Name Description Default Type camel.component.sip.enabled Enable sip component true Boolean camel.component.sip.resolve-property-placeholders Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders. true Boolean 305.4. Sending Messages to/from a SIP endpoint 305.4.1. Creating a Camel SIP Publisher In the example below, a SIP Publisher is created to send SIP Event publications to a user "agent@localhost:5152". This is the address of the SIP Presence Agent which acts as a broker between the SIP Publisher and Subscriber using a SIP Stack named client using a registry based eventHeader called evtHdrName using a registry based eventId called evtId from a SIP Stack with Listener set up as user2@localhost:3534 The Event being published is EVENT_A A Mandatory Header called REQUEST_METHOD is set to Request.Publish thereby setting up the endpoint as a Event publisher" producerTemplate.sendBodyAndHeader( "sip://agent@localhost:5152?stackName=client&eventHeaderName=evtHdrName&eventId=evtid&fromUser=user2&fromHost=localhost&fromPort=3534", "EVENT_A", "REQUEST_METHOD", Request.PUBLISH); 305.4.2. Creating a Camel SIP Subscriber In the example below, a SIP Subscriber is created to receive SIP Event publications sent to a user "johndoe@localhost:5154" using a SIP Stack named Subscriber registering with a Presence Agent user called agent@localhost:5152 using a registry based eventHeader called evtHdrName. The evtHdrName contains the Event which is se to "Event_A" using a registry based eventId called evtId @Override protected RouteBuilder createRouteBuilder() throws Exception { return new RouteBuilder() { @Override public void configure() throws Exception { // Create PresenceAgent from("sip://agent@localhost:5152?stackName=PresenceAgent&presenceAgent=true&eventHeaderName=evtHdrName&eventId=evtid") .to("mock:neverland"); // Create Sip Consumer(Event Subscriber) from("sip://johndoe@localhost:5154?stackName=Subscriber&toUser=agent&toHost=localhost&toPort=5152&eventHeaderName=evtHdrName&eventId=evtid") .to("log:ReceivedEvent?level=DEBUG") .to("mock:notification"); } }; } The Camel SIP component also ships with a Presence Agent that is meant to be used for Testing and Demo purposes only. An example of instantiating a Presence Agent is given above. Note that the Presence Agent is set up as a user agent@localhost:5152 and is capable of communicating with both Publisher as well as Subscriber. It has a separate SIP stackName distinct from Publisher as well as Subscriber. While it is set up as a Camel Consumer, it does not actually send any messages along the route to the endpoint "mock:neverland".	[ "<dependency> <groupId>org.apache.camel</groupId> <artifactId>camel-sip</artifactId> <version>x.x.x</version> <!-- use the same version as your Camel core version --> </dependency>", "sip://johndoe@localhost:99999[?options] sips://johndoe@localhost:99999/[?options]", "sip:uri", "producerTemplate.sendBodyAndHeader( \"sip://agent@localhost:5152?stackName=client&eventHeaderName=evtHdrName&eventId=evtid&fromUser=user2&fromHost=localhost&fromPort=3534\", \"EVENT_A\", \"REQUEST_METHOD\", Request.PUBLISH);", "@Override protected RouteBuilder createRouteBuilder() throws Exception { return new RouteBuilder() { @Override public void configure() throws Exception { // Create PresenceAgent from(\"sip://agent@localhost:5152?stackName=PresenceAgent&presenceAgent=true&eventHeaderName=evtHdrName&eventId=evtid\") .to(\"mock:neverland\"); // Create Sip Consumer(Event Subscriber) from(\"sip://johndoe@localhost:5154?stackName=Subscriber&toUser=agent&toHost=localhost&toPort=5152&eventHeaderName=evtHdrName&eventId=evtid\") .to(\"log:ReceivedEvent?level=DEBUG\") .to(\"mock:notification\"); } }; }" ]	https://docs.redhat.com/en/documentation/red_hat_fuse/7.13/html/apache_camel_component_reference/sip-component
Chapter 6. Deploying Event-Driven Ansible controller with Red Hat Ansible Automation Platform Operator on Red Hat OpenShift Container Platform	Chapter 6. Deploying Event-Driven Ansible controller with Red Hat Ansible Automation Platform Operator on Red Hat OpenShift Container Platform Event-Driven Ansible controller is the interface for event-driven automation and introduces automated resolution of IT requests. This component helps you connect to sources of events and acts on those events using rulebooks. When you deploy Event-Driven Ansible controller, you can automate decision making, use numerous event sources, implement event-driven automation within and across multiple IT use cases, and achieve more efficient service delivery. Use the following instructions to install Event-Driven Ansible with your Ansible Automation Platform Operator on OpenShift Container Platform. Prerequisites You have installed Ansible Automation Platform Operator on OpenShift Container Platform. You have installed and configured automation controller. Procedure Select Operators Installed Operators . Locate and select your installation of Ansible Automation Platform. Under the Details tab, locate the EDA modal and click Create instance . Click Form view , and in the Name field, enter the name you want for your new Event-Driven Ansible controller deployment. Important If you have installed other Ansible Automation Platform components in your current OpenShift Container Platform namespace, ensure that you provide a unique name for your Event-Driven Ansible controller when you create your Event-Driven Ansible custom resource. Otherwise, naming conflicts can occur and impact Event-Driven Ansible controller deployment. Specify your controller URL in the Automation Server URL field. If you deployed automation controller in Openshift as well, you can find the URL in the navigation panel under Networking Routes . Note This is the only required customization, but you can customize other options using the UI form or directly in the YAML configuration tab, if desired. Important To ensure that you can run concurrent Event-Driven Ansible activations efficiently, you must set your maximum number of activations in proportion to the resources available on your cluster. You can do this by adjusting your Event-Driven Ansible settings in the YAML view. When you activate an Event-Driven Ansible rulebook under standard conditions, it uses approximately 250 MB of memory. However, the actual memory consumption can vary significantly based on the complexity of your rules and the volume and size of the events processed. In scenarios where a large number of events are anticipated or the rulebook complexity is high, conduct a preliminary assessment of resource usage in a staging environment. This ensures that your maximum number of activations is based on the capacity of your resources. Click YAML view to update your YAML key values. Copy and paste the following string at the end of the spec key value section: extra_settings: - setting: EDA_MAX_RUNNING_ACTIVATIONS value: '12' database: resource_requirements: requests: cpu: 200m memory: 512Mi storage_requirements: requests: storage: 100Gi Click Create . This deploys Event-Driven Ansible controller in the namespace you specified. After a couple minutes when the installation is marked as Successful , you can find the URL for the Event-Driven Ansible UI on the Routes page in the OpenShift UI. From the navigation panel, select Networking Routes to find the new Route URL that has been created for you. Routes are listed according to the name of your custom resource. Click the new URL under the Location column to navigate to Event-Driven Ansible in the browser. From the navigation panel, select Workloads Secrets and locate the Admin Password k8s secret that was created for you, unless you specified a custom one. Secrets are listed according to the name of your custom resource and appended with -admin-password. Note You can use the password value in the secret to log in to the Event-Driven Ansible controller UI. The default user is admin .	[ "extra_settings: - setting: EDA_MAX_RUNNING_ACTIVATIONS value: '12' database: resource_requirements: requests: cpu: 200m memory: 512Mi storage_requirements: requests: storage: 100Gi" ]	https://docs.redhat.com/en/documentation/red_hat_ansible_automation_platform/2.4/html/deploying_the_red_hat_ansible_automation_platform_operator_on_openshift_container_platform/deploy-eda-controller-on-aap-operator-ocp
Chapter 2. Conclusion	Chapter 2. Conclusion Using the procedure you can: Create groups with permissions to curate namespaces and upload collections to it. Add information and resources to the namespace that helps end users of the collection in their automation tasks. Upload a collection to the namespace. Review the namespace import logs to determine the success or failure of uploading the collection and its current approval status.	null	https://docs.redhat.com/en/documentation/red_hat_ansible_automation_platform/2.3/html/curating_collections_using_namespaces_in_automation_hub/conclusion
Chapter 1. Installing and Configuring Data Warehouse	Chapter 1. Installing and Configuring Data Warehouse 1.1. Overview of Configuring Data Warehouse You can install and configure Data Warehouse on the same machine as the Manager, or on a separate machine with access to the Manager: Install and configure Data Warehouse on the Manager machine This configuration requires only a single registered machine, and is the simplest to configure, but it increases the demand on the Manager machine. Users who require access to the Data Warehouse service require access to the Manager machine itself. See Configuring the Red Hat Virtualization Manager in Installing Red Hat Virtualization as a standalone Manager with local databases . Install and configure Data Warehouse on a separate machine This configuration requires two registered machines. It reduces the load on the Manager machine and avoids potential CPU and memory-sharing conflicts on that machine. Administrators can also allow user access to the Data Warehouse machine, without the need to grant access to the Manager machine. See Installing and Configuring Data Warehouse on a Separate Machine for more information on this configuration. Important It is recommended that you set the system time zone for all machines in your Data Warehouse deployment to UTC. This ensures that data collection is not interrupted by variations in your local time zone: for example, a change from summer time to winter time. To calculate an estimate of the space and resources the ovirt_engine_history database will use, use the RHV Manager History Database Size Calculator tool. The estimate is based on the number of entities and the length of time you have chosen to retain the history records. Important The following behavior is expected in engine-setup : Install the Data Warehouse package, run engine-setup , and answer No to configuring Data Warehouse: Configure Data Warehouse on this host (Yes, No) [Yes]: No Run engine-setup again; setup no longer presents the option to configure Data Warehouse. To force engine-setup to present the option again, run engine-setup --reconfigure-optional-components . To configure only the currently installed Data Warehouse packages, and prevent setup from applying package updates found in enabled repositories, add the --offline option .	[ "Configure Data Warehouse on this host (Yes, No) [Yes]: No" ]	https://docs.redhat.com/en/documentation/red_hat_virtualization/4.4/html/data_warehouse_guide/chap-installing_and_configuring_data_warehouse
Chapter 2. Learn more about OpenShift Container Platform	Chapter 2. Learn more about OpenShift Container Platform Use the following sections to find content to help you learn about and use OpenShift Container Platform. 2.1. Architect Learn about OpenShift Container Platform Plan an OpenShift Container Platform deployment Additional resources Enterprise Kubernetes with OpenShift Tested platforms OpenShift blog Architecture Security and compliance What's new in OpenShift Container Platform Networking OpenShift Container Platform life cycle Backup and restore 2.2. Cluster Administrator Learn about OpenShift Container Platform Deploy OpenShift Container Platform Manage OpenShift Container Platform Additional resources Enterprise Kubernetes with OpenShift Installing OpenShift Container Platform Using Insights to identify issues with your cluster Getting Support Architecture Post installation configuration Logging OpenShift Knowledgebase articles OpenShift Interactive Learning Portal Networking Monitoring overview OpenShift Container Platform Life Cycle Storage Backup and restore Updating a cluster 2.3. Application Site Reliability Engineer (App SRE) Learn about OpenShift Container Platform Deploy and manage applications Additional resources OpenShift Interactive Learning Portal Projects Getting Support Architecture Operators OpenShift Knowledgebase articles Logging OpenShift Container Platform Life Cycle Blogs about logging Monitoring 2.4. Developer Learn about application development in OpenShift Container Platform Deploy applications Getting started with OpenShift for developers (interactive tutorial) Creating applications Red Hat Developers site Builds Red Hat CodeReady Workspaces Operators Images Developer-focused CLI	null	https://docs.redhat.com/en/documentation/openshift_container_platform/4.10/html/about/learn_more_about_openshift
Installation and Configuration Guide	Installation and Configuration Guide Red Hat Enterprise Linux Atomic Host 7 Installation and Configuration Guide Red Hat Atomic Host Documentation Team [email protected]	null	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux_atomic_host/7/html/installation_and_configuration_guide/index
Release Notes for Connectivity Link 1.0	Release Notes for Connectivity Link 1.0 Red Hat Connectivity Link 1.0 What's new in Red Hat Connectivity Link Red Hat Connectivity Link documentation team	null	https://docs.redhat.com/en/documentation/red_hat_connectivity_link/1.0/html/release_notes_for_connectivity_link_1.0/index
22.16.8. Adding a Manycast Server Address	22.16.8. Adding a Manycast Server Address To add a manycast server address, that is to say, to configure an address to allow the clients to discover the server by multicasting NTP packets, make use of the manycastserver command in the ntp.conf file. The manycastserver command takes the following form: manycastserver address Enables the sending of multicast messages. Where address is the address to multicast to. This should be used together with authentication to prevent service disruption. This command configures a system to act as an NTP server. Systems can be both client and server at the same time.	null	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/6/html/deployment_guide/s2_adding_a_manycastserver_address
10.5.13. ExtendedStatus	10.5.13. ExtendedStatus The ExtendedStatus directive controls whether Apache generates basic ( off ) or detailed server status information ( on ), when the server-status handler is called. The server-status handler is called using Location tags. More information on calling server-status is included in Section 10.5.60, " Location " .	null	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/4/html/reference_guide/s2-apache-extendedstatus
Chapter 2. Integrating with CI systems	Chapter 2. Integrating with CI systems Red Hat Advanced Cluster Security for Kubernetes (RHACS) integrates with a variety of continuous integration (CI) products. Before you deploy images, you can use RHACS to apply build-time and deploy-time security rules to your images. After images are built and pushed to a registry, RHACS integrates into CI pipelines. Pushing the image first allows developers to continue testing their artifacts while dealing with any policy violations alongside any other CI test failures, linter violations, or other problems. If possible, configure the version control system to block pull or merge requests from being merged if the build stage, which includes RHACS checks, fails. The integration with your CI product functions by contacting your RHACS installation to check whether the image complies with build-time policies you have configured. If there are policy violations, a detailed message is displayed on the console log, including the policy description, rationale, and remediation instructions. Each policy includes an optional enforcement setting. If you mark a policy for build-time enforcement, failure of that policy causes the client to exit with a nonzero error code. To integrate Red Hat Advanced Cluster Security for Kubernetes with your CI system, follow these steps: Configure build policies . Configure a registry integration . Configure access to your RHACS instance. Integrate with your CI pipeline . 2.1. Configuring build policies You can check RHACS policies during builds. Procedure Configure policies that apply to the build time of the container lifecycle. Integrate with the registry that images are pushed to during the build. Additional resources Integrating with image registries 2.1.1. Checking existing build-time policies Use the RHACS portal to check any existing build-time policies that you have configured in Red Hat Advanced Cluster Security for Kubernetes. Procedure In the RHACS portal, go to Platform Configuration Policy Management . Use global search to search for Lifecycle Stage:Build . 2.1.2. Creating a new system policy In addition to using the default policies, you can also create custom policies in Red Hat Advanced Cluster Security for Kubernetes. Procedure In the RHACS portal, go to Platform Configuration Policy Management . Click + New Policy . Enter the Name for the policy. Select a Severity level for the policy: Critical, High, Medium, or Low. Choose the Lifecycle Stages for which the policy is applicable, from Build , Deploy , or Runtime . You can select more than one stage. Note If you create a new policy for integrating with a CI system, select Build as the lifecycle stage. Build-time policies apply to image fields such as CVEs and Dockerfile instructions. Deploy-time policies can include all build-time policy criteria. They can also have data from your cluster configurations, such as running in privileged mode or mounting the Docker daemon socket. Runtime policies can include all build-time and deploy-time policy criteria, and data about process executions during runtime. Enter information about the policy in the Description , Rationale , and Remediation fields. When CI validates the build, the data from these fields is displayed. Therefore, include all information explaining the policy. Select a category from the Categories drop-down menu. Select a notifier from the Notifications drop-down menu that receives alert notifications when a violation occurs for this policy. Note You must integrate RHACS with your notification providers, such as webhooks, Jira, or PagerDuty, to receive alert notifications. Notifiers only show up if you have integrated any notification providers with RHACS. Use Restrict to Scope to enable this policy only for a specific cluster, namespace, or label. You can add multiple scopes and also use regular expressions in RE2 Syntax for namespaces and labels. Use Exclude by Scope to exclude deployments, clusters, namespaces, and labels. This field indicates that the policy will not apply to the entities that you specify. You can add multiple scopes and also use regular expressions in RE2 Syntax for namespaces and labels. However, you cannot use regular expressions for selecting deployments. For Excluded Images (Build Lifecycle only) , select all the images from the list for which you do not want to trigger a violation for the policy. Note The Excluded Images (Build Lifecycle only) setting only applies when you check images in a continuous integration system (the Build lifecycle stage). It does not have any effect if you use this policy to check running deployments (the Deploy lifecycle stage) or runtime activities (the Runtime lifecycle stage). In the Policy Criteria section, configure the attributes that will trigger the policy. Select on the panel header. The new policy panel shows a preview of the violations that are triggered if you enable the policy. Select on the panel header. Choose the enforcement behavior for the policy. Enforcement settings are only available for the stages that you selected for the Lifecycle Stages option. Select ON to enforce policy and report a violation. Select OFF to only report a violation. Note The enforcement behavior is different for each lifecycle stage. For the Build stage, RHACS fails your CI builds when images match the conditions of the policy. For the Deploy stage, RHACS blocks the creation and update of deployments that match the conditions of the policy if the RHACS admission controller is configured and running. In clusters with admission controller enforcement, the Kubernetes or OpenShift Container Platform API server blocks all noncompliant deployments. In other clusters, RHACS edits noncompliant deployments to prevent pods from being scheduled. For existing deployments, policy changes only result in enforcement at the detection of the criteria, when a Kubernetes event occurs. For more information about enforcement, see "Security policy enforcement for the deploy stage". For the Runtime stage, RHACS stops all pods that match the conditions of the policy. Warning Policy enforcement can impact running applications or development processes. Before you enable enforcement options, inform all stakeholders and plan how to respond to the automated enforcement actions. 2.1.2.1. Security policy enforcement for the deploy stage Red Hat Advanced Cluster Security for Kubernetes supports two forms of security policy enforcement for deploy-time policies: hard enforcement through the admission controller and soft enforcement by RHACS Sensor. The admission controller blocks creation or updating of deployments that violate policy. If the admission controller is disabled or unavailable, Sensor can perform enforcement by scaling down replicas for deployments that violate policy to 0 . Warning Policy enforcement can impact running applications or development processes. Before you enable enforcement options, inform all stakeholders and plan how to respond to the automated enforcement actions. 2.1.2.1.1. Hard enforcement Hard enforcement is performed by the RHACS admission controller. In clusters with admission controller enforcement, the Kubernetes or OpenShift Container Platform API server blocks all noncompliant deployments. The admission controller blocks CREATE and UPDATE operations. Any pod create or update request that satisfies a policy configured with deploy-time enforcement enabled will fail. Note Kubernetes admission webhooks support only CREATE , UPDATE , DELETE , or CONNECT operations. The RHACS admission controller supports only CREATE and UPDATE operations. Operations such as kubectl patch , kubectl set , and kubectl scale are PATCH operations, not UPDATE operations. Because PATCH operations are not supported in Kubernetes, RHACS cannot perform enforcement on PATCH operations. For blocking enforcement, you must enable the following settings for the cluster in RHACS: Enforce on Object Creates : This toggle in the Dynamic Configuration section controls the behavior of the admission control service. You must have the Configure Admission Controller Webhook to listen on Object Creates toggle in the Static Configuration section turned on for this to work. Enforce on Object Updates : This toggle in the Dynamic Configuration section controls the behavior of the admission control service. You must have the Configure Admission Controller Webhook to listen on Object Updates toggle in the Static Configuration section turned on for this to work. If you make changes to settings in the Static Configuration setting, you must redeploy the secured cluster for those changes to take effect. 2.1.2.1.2. Soft enforcement Soft enforcement is performed by RHACS Sensor. This enforcement prevents an operation from being initiated. With soft enforcement, Sensor scales the replicas to 0, and prevents pods from being scheduled. In this enforcement, a non-ready deployment is available in the cluster. If soft enforcement is configured, and Sensor is down, then RHACS cannot perform enforcement. 2.1.2.1.3. Namespace exclusions By default, RHACS excludes certain administrative namespaces, such as the stackrox , kube-system , and istio-system namespaces, from enforcement blocking. The reason for this is that some items in these namespaces must be deployed for RHACS to work correctly. 2.1.2.1.4. Enforcement on existing deployments For existing deployments, policy changes only result in enforcement at the detection of the criteria, when a Kubernetes event occurs. If you make changes to a policy, you must reassess policies by selecting Policy Management and clicking Reassess All . This action applies deploy policies on all existing deployments regardless of whether there are any new incoming Kubernetes events. If a policy is violated, then RHACS performs enforcement. Additional resources Using admission controller enforcement 2.2. Configuring registry integration To scan images, you must provide Red Hat Advanced Cluster Security for Kubernetes with access to the image registry you are using in your build pipeline. 2.2.1. Checking for existing registry integration You can use the RHACS portal to check if you have already integrated with a registry. Procedure In the RHACS portal, go to Platform Configuration Integrations . Under the Image Integration section, look for highlighted Registry tiles. The tiles also list the number of items already configured for that tile. If none of the Registry tiles are highlighted, you must first integrate with an image registry. 2.2.1.1. Additional resources Integrating with image registries 2.3. Configuring access RHACS provides the roxctl command-line interface (CLI) to make it easy to integrate RHACS policies into your build pipeline. The roxctl CLI prints detailed information about problems and how to fix them so that developers can maintain high standards in the early phases of the container lifecycle. To securely authenticate to the Red Hat Advanced Cluster Security for Kubernetes API server, you must create an API token. 2.3.1. Exporting and saving the API token Procedure After you have generated the authentication token, export it as the ROX_API_TOKEN variable by entering the following command: USD export ROX_API_TOKEN=<api_token> (Optional): You can also save the token in a file and use it with the --token-file option by entering the following command: USD roxctl central debug dump --token-file <token_file> Note the following guidelines: You cannot use both the -password ( -p ) and the --token-file options simultaneously. If you have already set the ROX_API_TOKEN variable, and specify the --token-file option, the roxctl CLI uses the specified token file for authentication. If you have already set the ROX_API_TOKEN variable, and specify the --password option, the roxctl CLI uses the specified password for authentication. 2.3.2. Installing the roxctl CLI by downloading the binary You can install the roxctl CLI to interact with Red Hat Advanced Cluster Security for Kubernetes from a command-line interface. You can install roxctl on Linux, Windows, or macOS. 2.3.2.1. Installing the roxctl CLI on Linux You can install the roxctl CLI binary on Linux by using the following procedure. Note roxctl CLI for Linux is available for amd64 , arm64 , ppc64le , and s390x architectures. Procedure Determine the roxctl architecture for the target operating system: USD arch="USD(uname -m \| sed "s/x86_64//")"; arch="USD{arch:+-USDarch}" Download the roxctl CLI: USD curl -L -f -o roxctl "https://mirror.openshift.com/pub/rhacs/assets/4.6.3/bin/Linux/roxctlUSD{arch}" Make the roxctl binary executable: USD chmod +x roxctl Place the roxctl binary in a directory that is on your PATH : To check your PATH , execute the following command: USD echo USDPATH Verification Verify the roxctl version you have installed: USD roxctl version 2.3.2.2. Installing the roxctl CLI on macOS You can install the roxctl CLI binary on macOS by using the following procedure. Note roxctl CLI for macOS is available for amd64 and arm64 architectures. Procedure Determine the roxctl architecture for the target operating system: USD arch="USD(uname -m \| sed "s/x86_64//")"; arch="USD{arch:+-USDarch}" Download the roxctl CLI: USD curl -L -f -o roxctl "https://mirror.openshift.com/pub/rhacs/assets/4.6.3/bin/Darwin/roxctlUSD{arch}" Remove all extended attributes from the binary: USD xattr -c roxctl Make the roxctl binary executable: USD chmod +x roxctl Place the roxctl binary in a directory that is on your PATH : To check your PATH , execute the following command: USD echo USDPATH Verification Verify the roxctl version you have installed: USD roxctl version 2.3.2.3. Installing the roxctl CLI on Windows You can install the roxctl CLI binary on Windows by using the following procedure. Note roxctl CLI for Windows is available for the amd64 architecture. Procedure Download the roxctl CLI: USD curl -f -O https://mirror.openshift.com/pub/rhacs/assets/4.6.3/bin/Windows/roxctl.exe Verification Verify the roxctl version you have installed: USD roxctl version 2.3.3. Running the roxctl CLI from a container The roxctl client is the default entry point in the RHACS roxctl image. To run the roxctl client in a container image: Prerequisites You must first generate an authentication token from the RHACS portal. Procedure Log in to the registry.redhat.io registry. USD docker login registry.redhat.io Pull the latest container image for the roxctl CLI. USD docker pull registry.redhat.io/advanced-cluster-security/rhacs-roxctl-rhel8:4.6.3 After you install the CLI, you can run it by using the following command: USD docker run -e ROX_API_TOKEN=USDROX_API_TOKEN \ -it registry.redhat.io/advanced-cluster-security/rhacs-roxctl-rhel8:4.6.3 \ -e USDROX_CENTRAL_ADDRESS <command> Note In Red Hat Advanced Cluster Security Cloud Service (RHACS Cloud Service), when using roxctl commands that require the Central address, use the Central instance address as displayed in the Instance Details section of the Red Hat Hybrid Cloud Console. For example, use acs-ABCD12345.acs.rhcloud.com instead of acs-data-ABCD12345.acs.rhcloud.com . Verification Verify the roxctl version you have installed. USD docker run -it registry.redhat.io/advanced-cluster-security/rhacs-roxctl-rhel8:4.6.3 version 2.4. Integrating with your CI pipeline After you have finished these procedures, the step is to integrate with your CI pipeline. Each CI system might require a slightly different configuration. 2.4.1. Using Jenkins Use the StackRox Container Image Scanner Jenkins plugin for integrating with Jenkins. You can use this plugin in both Jenkins freestyle projects and pipelines. 2.4.2. Using CircleCI You can integrate Red Hat Advanced Cluster Security for Kubernetes with CircleCI. Prerequisites You have a token with read and write permissions for the Image resource. You have a username and password for your Docker Hub account. Procedure Log in to CircleCI and open an existing project or create a new project. Click Project Settings . Click Environment variables . Click Add variable and create the following three environment variables: Name : STACKROX_CENTRAL_HOST - The DNS name or IP address of Central. Name : ROX_API_TOKEN - The API token to access Red Hat Advanced Cluster Security for Kubernetes. Name : DOCKERHUB_PASSWORD - The password for your Docker Hub account. Name : DOCKERHUB_USER - The username for your Docker Hub account. Create a directory called .circleci in the root directory of your local code repository for your selected project, if you do not already have a CircleCI configuration file. Create a config.yml configuration file with the following lines in the .circleci directory: version: 2 jobs: check-policy-compliance: docker: - image: 'circleci/node:latest' auth: username: USDDOCKERHUB_USER password: USDDOCKERHUB_PASSWORD steps: - checkout - run: name: Install roxctl command: \| curl -H "Authorization: Bearer USDROX_API_TOKEN" https://USDSTACKROX_CENTRAL_HOST:443/api/cli/download/roxctl-linux -o roxctl && chmod +x ./roxctl - run: name: Scan images for policy deviations and vulnerabilities command: \| ./roxctl image check --endpoint "USDSTACKROX_CENTRAL_HOST:443" --image "<your_registry/repo/image_name>" 1 - run: name: Scan deployment files for policy deviations command: \| ./roxctl image check --endpoint "USDSTACKROX_CENTRAL_HOST:443" --image "<your_deployment_file>" 2 # Important note: This step assumes the YAML file you'd like to test is located in the project. workflows: version: 2 build_and_test: jobs: - check-policy-compliance 1 Replace <your_registry/repo/image_name> with your registry and image path. 2 Replace <your_deployment_file> with the path to your deployment file. Note If you already have a config.yml file for CircleCI in your repository, add a new jobs section with the specified details in your existing configuration file. After you commit the configuration file to your repository, go to the Jobs queue in your CircleCI dashboard to verify the build policy enforcement.	[ "export ROX_API_TOKEN=<api_token>", "roxctl central debug dump --token-file <token_file>", "arch=\"USD(uname -m \| sed \"s/x86_64//\")\"; arch=\"USD{arch:+-USDarch}\"", "curl -L -f -o roxctl \"https://mirror.openshift.com/pub/rhacs/assets/4.6.3/bin/Linux/roxctlUSD{arch}\"", "chmod +x roxctl", "echo USDPATH", "roxctl version", "arch=\"USD(uname -m \| sed \"s/x86_64//\")\"; arch=\"USD{arch:+-USDarch}\"", "curl -L -f -o roxctl \"https://mirror.openshift.com/pub/rhacs/assets/4.6.3/bin/Darwin/roxctlUSD{arch}\"", "xattr -c roxctl", "chmod +x roxctl", "echo USDPATH", "roxctl version", "curl -f -O https://mirror.openshift.com/pub/rhacs/assets/4.6.3/bin/Windows/roxctl.exe", "roxctl version", "docker login registry.redhat.io", "docker pull registry.redhat.io/advanced-cluster-security/rhacs-roxctl-rhel8:4.6.3", "docker run -e ROX_API_TOKEN=USDROX_API_TOKEN -it registry.redhat.io/advanced-cluster-security/rhacs-roxctl-rhel8:4.6.3 -e USDROX_CENTRAL_ADDRESS <command>", "docker run -it registry.redhat.io/advanced-cluster-security/rhacs-roxctl-rhel8:4.6.3 version", "version: 2 jobs: check-policy-compliance: docker: - image: 'circleci/node:latest' auth: username: USDDOCKERHUB_USER password: USDDOCKERHUB_PASSWORD steps: - checkout - run: name: Install roxctl command: \| curl -H \"Authorization: Bearer USDROX_API_TOKEN\" https://USDSTACKROX_CENTRAL_HOST:443/api/cli/download/roxctl-linux -o roxctl && chmod +x ./roxctl - run: name: Scan images for policy deviations and vulnerabilities command: \| ./roxctl image check --endpoint \"USDSTACKROX_CENTRAL_HOST:443\" --image \"<your_registry/repo/image_name>\" 1 - run: name: Scan deployment files for policy deviations command: \| ./roxctl image check --endpoint \"USDSTACKROX_CENTRAL_HOST:443\" --image \"<your_deployment_file>\" 2 # Important note: This step assumes the YAML file you'd like to test is located in the project. workflows: version: 2 build_and_test: jobs: - check-policy-compliance" ]	https://docs.redhat.com/en/documentation/red_hat_advanced_cluster_security_for_kubernetes/4.6/html/integrating/integrate-with-ci-systems
Chapter 7. Managing alerts on the Ceph dashboard	Chapter 7. Managing alerts on the Ceph dashboard As a storage administrator, you can see the details of alerts and create silences for them on the Red Hat Ceph Storage dashboard. This includes the following pre-defined alerts: CephadmDaemonFailed CephadmPaused CephadmUpgradeFailed CephDaemonCrash CephDeviceFailurePredicted CephDeviceFailurePredictionTooHigh CephDeviceFailureRelocationIncomplete CephFilesystemDamaged CephFilesystemDegraded CephFilesystemFailureNoStandby CephFilesystemInsufficientStandby CephFilesystemMDSRanksLow CephFilesystemOffline CephFilesystemReadOnly CephHealthError CephHealthWarning CephMgrModuleCrash CephMgrPrometheusModuleInactive CephMonClockSkew CephMonDiskspaceCritical CephMonDiskspaceLow CephMonDown CephMonDownQuorumAtRisk CephNodeDiskspaceWarning CephNodeInconsistentMTU CephNodeNetworkPacketDrops CephNodeNetworkPacketErrors CephNodeRootFilesystemFull CephObjectMissing CephOSDBackfillFull CephOSDDown CephOSDDownHigh CephOSDFlapping CephOSDFull CephOSDHostDown CephOSDInternalDiskSizeMismatch CephOSDNearFull CephOSDReadErrors CephOSDTimeoutsClusterNetwork CephOSDTimeoutsPublicNetwork CephOSDTooManyRepairs CephPGBackfillAtRisk CephPGImbalance CephPGNotDeepScrubbed CephPGNotScrubbed CephPGRecoveryAtRisk CephPGsDamaged CephPGsHighPerOSD CephPGsInactive CephPGsUnclean CephPGUnavilableBlockingIO CephPoolBackfillFull CephPoolFull CephPoolGrowthWarning CephPoolNearFull CephSlowOps PrometheusJobMissing Figure 7.1. Pre-defined alerts You can also monitor alerts using simple network management protocol (SNMP) traps. 7.1. Enabling monitoring stack You can manually enable the monitoring stack of the Red Hat Ceph Storage cluster, such as Prometheus, Alertmanager, and Grafana, using the command-line interface. You can use the Prometheus and Alertmanager API to manage alerts and silences. Prerequisite A running Red Hat Ceph Storage cluster. root-level access to all the hosts. Procedure Log into the cephadm shell: Example Set the APIs for the monitoring stack: Specify the host and port of the Alertmanager server: Syntax Example To see the configured alerts, configure the URL to the Prometheus API. Using this API, the Ceph Dashboard UI verifies that a new silence matches a corresponding alert. Syntax Example After setting up the hosts, refresh your browser's dashboard window. Specify the host and port of the Grafana server: Syntax Example Get the Prometheus, Alertmanager, and Grafana API host details: Example Optional: If you are using a self-signed certificate in your Prometheus, Alertmanager, or Grafana setup, disable the certificate verification in the dashboard This avoids refused connections caused by certificates signed by an unknown Certificate Authority (CA) or that do not match the hostname. For Prometheus: Example For Alertmanager: Example For Grafana: Example Get the details of the self-signed certificate verification setting for Prometheus, Alertmanager, and Grafana: Example Optional: If the dashboard does not reflect the changes, you have to disable and then enable the dashboard: Example Additional Resources See the Bootstrap command options section in the Red Hat Ceph Storage Installation Guide . See the Red Hat Ceph Storage installation chapter in the Red Hat Ceph Storage Installation Guide . See the Deploying the monitoring stack using the Ceph Orchestrator section in the Red Hat Ceph Storage Operations Guide . 7.2. Configuring Grafana certificate The cephadm deploys Grafana using the certificate defined in the ceph key/value store. If a certificate is not specified, cephadm generates a self-signed certificate during the deployment of the Grafana service. You can configure a custom certificate with the ceph config-key set command. Prerequisite A running Red Hat Ceph Storage cluster. Procedure Log into the cephadm shell: Example Configure the custom certificate for Grafana: Example If Grafana is already deployed, then run reconfig to update the configuration: Example Every time a new certificate is added, follow the below steps: Make a new directory Example Generate the key: Example View the key: Example Make a request: Example Review the request prior to sending it for signature: Example As the CA sign: Example Check the signed certificate: Example Additional Resources See the Using shared system certificates for more details. 7.3. Adding Alertmanager webhooks You can add new webhooks to an existing Alertmanager configuration to receive real-time alerts about the health of the storage cluster. You have to enable incoming webhooks to allow asynchronous messages into third-party applications. For example, if an OSD is down in a Red Hat Ceph Storage cluster, you can configure the Alertmanager to send notification on Google chat. Prerequisite A running Red Hat Ceph Storage cluster with monitoring stack components enabled. Incoming webhooks configured on the receiving third-party application. Procedure Log into the cephadm shell: Example Configure the Alertmanager to use the webhook for notification: Syntax The default_webhook_urls is a list of additional URLs that are added to the default receivers' webhook_configs configuration. Example Update Alertmanager configuration: Example Verification An example notification from Alertmanager to Gchat: Example 7.4. Viewing alerts on the Ceph dashboard After an alert has fired, you can view it on the Red Hat Ceph Storage Dashboard. You can edit the Manager module settings to trigger a mail when an alert is fired. Prerequisite A running Red Hat Ceph Storage cluster. Dashboard is installed. A running simple mail transfer protocol (SMTP) configured. An alert emitted. Procedure From the dashboard navigation, go to Observability->Alerts . View active Prometheus alerts from the Active Alerts tab. View all alerts from the Alerts tab. To view alert details, expand the alert row. To view the source of an alert, click on its row, and then click Source . Additional resources See the Using the Ceph Manager alerts module for more details to configure SMTP. 7.5. Creating a silence on the Ceph dashboard You can create a silence for an alert for a specified amount of time on the Red Hat Ceph Storage Dashboard. Prerequisite A running Red Hat Ceph Storage cluster. Dashboard is installed. An alert fired. Procedure From the dashboard navigation, go to Observability->Alerts . On the Silences tab, click Create . In the Create Silence form, fill in the required fields. Use the Add matcher to add silence requirements. Figure 7.2. Creating a silence Click Create Silence . A notification displays that the silence was created successfully and the Alerts Silenced updates in the Silences table. 7.6. Recreating a silence on the Ceph dashboard You can recreate a silence from an expired silence on the Red Hat Ceph Storage Dashboard. Prerequisite A running Red Hat Ceph Storage cluster. Dashboard is installed. An alert fired. A silence created for the alert. Procedure From the dashboard navigation, go to Observability->Alerts . On the Silences tab, select the row with the alert that you want to recreate, and click Recreate from the action drop-down. Edit any needed details, and click Recreate Silence button. A notification displays indicating that the silence was edited successfully and the status of the silence is now active . 7.7. Editing a silence on the Ceph dashboard You can edit an active silence, for example, to extend the time it is active on the Red Hat Ceph Storage Dashboard. If the silence has expired, you can either recreate a silence or create a new silence for the alert. Prerequisite A running Red Hat Ceph Storage cluster. Dashboard is installed. An alert fired. A silence created for the alert. Procedure Log in to the Dashboard. On the navigation menu, click Cluster . Select Monitoring from the drop-down menu. Click the Silences tab. To edit the silence, click it's row. In the Edit drop-down menu, select Edit . In the Edit Silence window, update the details and click Edit Silence . Figure 7.3. Edit silence You get a notification that the silence was updated successfully. 7.8. Expiring a silence on the Ceph dashboard You can expire a silence so any matched alerts will not be suppressed on the Red Hat Ceph Storage Dashboard. Prerequisite A running Red Hat Ceph Storage cluster. Dashboard is installed. An alert fired. A silence created for the alert. Procedure From the dashboard navigation, go to Observability->Alerts . On the Silences tab, select the row with the alert that you want to expire, and click Expire from the action drop-down. In the Expire Silence notification, select Yes, I am sure and click Expire Silence . A notification displays indicating that the silence was expired successfully and the Status of the alert is expired , in the Silences table. Additional Resources For more information, see the Red Hat Ceph StorageTroubleshooting Guide .	[ "cephadm shell", "ceph dashboard set-alertmanager-api-host ALERTMANAGER_API_HOST : PORT", "ceph dashboard set-alertmanager-api-host http://10.0.0.101:9093 Option ALERTMANAGER_API_HOST updated", "ceph dashboard set-prometheus-api-host PROMETHEUS_API_HOST : PORT", "ceph dashboard set-prometheus-api-host http://10.0.0.101:9095 Option PROMETHEUS_API_HOST updated", "ceph dashboard set-grafana-api-url GRAFANA_API_URL : PORT", "ceph dashboard set-grafana-api-url https://10.0.0.101:3000 Option GRAFANA_API_URL updated", "ceph dashboard get-alertmanager-api-host http://10.0.0.101:9093 ceph dashboard get-prometheus-api-host http://10.0.0.101:9095 ceph dashboard get-grafana-api-url http://10.0.0.101:3000", "ceph dashboard set-prometheus-api-ssl-verify False", "ceph dashboard set-alertmanager-api-ssl-verify False", "ceph dashboard set-grafana-api-ssl-verify False", "ceph dashboard get-prometheus-api-ssl-verify ceph dashboard get-alertmanager-api-ssl-verify ceph dashboard get-grafana-api-ssl-verify", "ceph mgr module disable dashboard ceph mgr module enable dashboard", "cephadm shell", "ceph config-key set mgr/cephadm/grafana_key -i USDPWD/key.pem ceph config-key set mgr/cephadm/grafana_crt -i USDPWD/certificate.pem", "ceph orch reconfig grafana", "mkdir /root/internalca cd /root/internalca", "openssl ecparam -genkey -name secp384r1 -out USD(date +%F).key", "openssl ec -text -in USD(date +%F).key \| less", "umask 077; openssl req -config openssl-san.cnf -new -sha256 -key USD(date +%F).key -out USD(date +%F).csr", "openssl req -text -in USD(date +%F).csr \| less", "openssl ca -extensions v3_req -in USD(date +%F).csr -out USD(date +%F).crt -extfile openssl-san.cnf", "openssl x509 -text -in USD(date +%F).crt -noout \| less", "cephadm shell", "service_type: alertmanager spec: user_data: default_webhook_urls: - \"_URLS_\"", "service_type: alertmanager spec: user_data: webhook_configs: - url: 'http:127.0.0.10:8080'", "ceph orch reconfig alertmanager", "using: https://chat.googleapis.com/v1/spaces/(xx- space identifyer -xx)/messages posting: {'status': 'resolved', 'labels': {'alertname': 'PrometheusTargetMissing', 'instance': 'postgres-exporter.host03.chest response: 200 response: { \"name\": \"spaces/(xx- space identifyer -xx)/messages/3PYDBOsIofE.3PYDBOsIofE\", \"sender\": { \"name\": \"users/114022495153014004089\", \"displayName\": \"monitoring\", \"avatarUrl\": \"\", \"email\": \"\", \"domainId\": \"\", \"type\": \"BOT\", \"isAnonymous\": false, \"caaEnabled\": false }, \"text\": \"Prometheus target missing (instance postgres-exporter.cluster.local:9187)\\n\\nA Prometheus target has disappeared. An e \"cards\": [], \"annotations\": [], \"thread\": { \"name\": \"spaces/(xx- space identifyer -xx)/threads/3PYDBOsIofE\" }, \"space\": { \"name\": \"spaces/(xx- space identifyer -xx)\", \"type\": \"ROOM\", \"singleUserBotDm\": false, \"threaded\": false, \"displayName\": \"_privmon\", \"legacyGroupChat\": false }, \"fallbackText\": \"\", \"argumentText\": \"Prometheus target missing (instance postgres-exporter.cluster.local:9187)\\n\\nA Prometheus target has disappea \"attachment\": [], \"createTime\": \"2022-06-06T06:17:33.805375Z\", \"lastUpdateTime\": \"2022-06-06T06:17:33.805375Z\"" ]	https://docs.redhat.com/en/documentation/red_hat_ceph_storage/7/html/dashboard_guide/management-of-alerts-on-the-ceph-dashboard
Appendix G. Kafka Streams configuration parameters	Appendix G. Kafka Streams configuration parameters application.id Type: string Importance: high An identifier for the stream processing application. Must be unique within the Kafka cluster. It is used as 1) the default client-id prefix, 2) the group-id for membership management, 3) the changelog topic prefix. bootstrap.servers Type: list Importance: high A list of host/port pairs to use for establishing the initial connection to the Kafka cluster. The client will make use of all servers irrespective of which servers are specified here for bootstrapping-this list only impacts the initial hosts used to discover the full set of servers. This list should be in the form host1:port1,host2:port2,... . Since these servers are just used for the initial connection to discover the full cluster membership (which may change dynamically), this list need not contain the full set of servers (you may want more than one, though, in case a server is down). replication.factor Type: int Default: 1 Importance: high The replication factor for change log topics and repartition topics created by the stream processing application. If your broker cluster is on version 2.4 or newer, you can set -1 to use the broker default replication factor. state.dir Type: string Default: /tmp/kafka-streams Importance: high Directory location for state store. This path must be unique for each streams instance sharing the same underlying filesystem. acceptable.recovery.lag Type: long Default: 10000 Valid Values: [0,... ] Importance: medium The maximum acceptable lag (number of offsets to catch up) for a client to be considered caught-up for an active task.Should correspond to a recovery time of well under a minute for a given workload. Must be at least 0. cache.max.bytes.buffering Type: long Default: 10485760 Valid Values: [0,... ] Importance: medium Maximum number of memory bytes to be used for buffering across all threads. client.id Type: string Default: "" Importance: medium An ID prefix string used for the client IDs of internal consumer, producer and restore-consumer, with pattern '<client.id>-StreamThread-<threadSequenceNumber>-<consumer\|producer\|restore-consumer>'. default.deserialization.exception.handler Type: class Default: org.apache.kafka.streams.errors.LogAndFailExceptionHandler Importance: medium Exception handling class that implements the org.apache.kafka.streams.errors.DeserializationExceptionHandler interface. default.key.serde Type: class Default: org.apache.kafka.common.serialization.SerdesUSDByteArraySerde Importance: medium Default serializer / deserializer class for key that implements the org.apache.kafka.common.serialization.Serde interface. Note when windowed serde class is used, one needs to set the inner serde class that implements the org.apache.kafka.common.serialization.Serde interface via 'default.windowed.key.serde.inner' or 'default.windowed.value.serde.inner' as well. default.production.exception.handler Type: class Default: org.apache.kafka.streams.errors.DefaultProductionExceptionHandler Importance: medium Exception handling class that implements the org.apache.kafka.streams.errors.ProductionExceptionHandler interface. default.timestamp.extractor Type: class Default: org.apache.kafka.streams.processor.FailOnInvalidTimestamp Importance: medium Default timestamp extractor class that implements the org.apache.kafka.streams.processor.TimestampExtractor interface. default.value.serde Type: class Default: org.apache.kafka.common.serialization.SerdesUSDByteArraySerde Importance: medium Default serializer / deserializer class for value that implements the org.apache.kafka.common.serialization.Serde interface. Note when windowed serde class is used, one needs to set the inner serde class that implements the org.apache.kafka.common.serialization.Serde interface via 'default.windowed.key.serde.inner' or 'default.windowed.value.serde.inner' as well. default.windowed.key.serde.inner Type: class Default: null Importance: medium Default serializer / deserializer for the inner class of a windowed key. Must implement the org.apache.kafka.common.serialization.Serde interface. default.windowed.value.serde.inner Type: class Default: null Importance: medium Default serializer / deserializer for the inner class of a windowed value. Must implement the org.apache.kafka.common.serialization.Serde interface. max.task.idle.ms Type: long Default: 0 Importance: medium Maximum amount of time in milliseconds a stream task will stay idle when not all of its partition buffers contain records, to avoid potential out-of-order record processing across multiple input streams. max.warmup.replicas Type: int Default: 2 Valid Values: [1,... ] Importance: medium The maximum number of warmup replicas (extra standbys beyond the configured num.standbys) that can be assigned at once for the purpose of keeping the task available on one instance while it is warming up on another instance it has been reassigned to. Used to throttle how much extra broker traffic and cluster state can be used for high availability. Must be at least 1. num.standby.replicas Type: int Default: 0 Importance: medium The number of standby replicas for each task. num.stream.threads Type: int Default: 1 Importance: medium The number of threads to execute stream processing. processing.guarantee Type: string Default: at_least_once Valid Values: [at_least_once, exactly_once, exactly_once_beta] Importance: medium The processing guarantee that should be used. Possible values are at_least_once (default), exactly_once (requires brokers version 0.11.0 or higher), and exactly_once_beta (requires brokers version 2.5 or higher). Note that exactly-once processing requires a cluster of at least three brokers by default what is the recommended setting for production; for development you can change this, by adjusting broker setting transaction.state.log.replication.factor and transaction.state.log.min.isr . security.protocol Type: string Default: PLAINTEXT Importance: medium Protocol used to communicate with brokers. Valid values are: PLAINTEXT, SSL, SASL_PLAINTEXT, SASL_SSL. task.timeout.ms Type: long Default: 300000 (5 minutes) Valid Values: [0,... ] Importance: medium The maximum amount of time in milliseconds a task might stall due to internal errors and retries until an error is raised. For a timeout of 0ms, a task would raise an error for the first internal error. For any timeout larger than 0ms, a task will retry at least once before an error is raised. topology.optimization Type: string Default: none Valid Values: [none, all] Importance: medium A configuration telling Kafka Streams if it should optimize the topology, disabled by default. application.server Type: string Default: "" Importance: low A host:port pair pointing to a user-defined endpoint that can be used for state store discovery and interactive queries on this KafkaStreams instance. buffered.records.per.partition Type: int Default: 1000 Importance: low Maximum number of records to buffer per partition. built.in.metrics.version Type: string Default: latest Valid Values: [0.10.0-2.4, latest] Importance: low Version of the built-in metrics to use. commit.interval.ms Type: long Default: 30000 (30 seconds) Valid Values: [0,... ] Importance: low The frequency in milliseconds with which to save the position of the processor. (Note, if processing.guarantee is set to exactly_once , the default value is 100 , otherwise the default value is 30000 . connections.max.idle.ms Type: long Default: 540000 (9 minutes) Importance: low Close idle connections after the number of milliseconds specified by this config. metadata.max.age.ms Type: long Default: 300000 (5 minutes) Valid Values: [0,... ] Importance: low The period of time in milliseconds after which we force a refresh of metadata even if we haven't seen any partition leadership changes to proactively discover any new brokers or partitions. metric.reporters Type: list Default: "" Importance: low A list of classes to use as metrics reporters. Implementing the org.apache.kafka.common.metrics.MetricsReporter interface allows plugging in classes that will be notified of new metric creation. The JmxReporter is always included to register JMX statistics. metrics.num.samples Type: int Default: 2 Valid Values: [1,... ] Importance: low The number of samples maintained to compute metrics. metrics.recording.level Type: string Default: INFO Valid Values: [INFO, DEBUG, TRACE] Importance: low The highest recording level for metrics. metrics.sample.window.ms Type: long Default: 30000 (30 seconds) Valid Values: [0,... ] Importance: low The window of time a metrics sample is computed over. partition.grouper Type: class Default: org.apache.kafka.streams.processor.DefaultPartitionGrouper Importance: low Partition grouper class that implements the org.apache.kafka.streams.processor.PartitionGrouper interface. WARNING: This config is deprecated and will be removed in 3.0.0 release. poll.ms Type: long Default: 100 Importance: low The amount of time in milliseconds to block waiting for input. probing.rebalance.interval.ms Type: long Default: 600000 (10 minutes) Valid Values: [60000,... ] Importance: low The maximum time in milliseconds to wait before triggering a rebalance to probe for warmup replicas that have finished warming up and are ready to become active. Probing rebalances will continue to be triggered until the assignment is balanced. Must be at least 1 minute. receive.buffer.bytes Type: int Default: 32768 (32 kibibytes) Valid Values: [-1,... ] Importance: low The size of the TCP receive buffer (SO_RCVBUF) to use when reading data. If the value is -1, the OS default will be used. reconnect.backoff.max.ms Type: long Default: 1000 (1 second) Valid Values: [0,... ] Importance: low The maximum amount of time in milliseconds to wait when reconnecting to a broker that has repeatedly failed to connect. If provided, the backoff per host will increase exponentially for each consecutive connection failure, up to this maximum. After calculating the backoff increase, 20% random jitter is added to avoid connection storms. reconnect.backoff.ms Type: long Default: 50 Valid Values: [0,... ] Importance: low The base amount of time to wait before attempting to reconnect to a given host. This avoids repeatedly connecting to a host in a tight loop. This backoff applies to all connection attempts by the client to a broker. request.timeout.ms Type: int Default: 40000 (40 seconds) Valid Values: [0,... ] Importance: low The configuration controls the maximum amount of time the client will wait for the response of a request. If the response is not received before the timeout elapses the client will resend the request if necessary or fail the request if retries are exhausted. retries Type: int Default: 0 Valid Values: [0,... ,2147483647] Importance: low Setting a value greater than zero will cause the client to resend any request that fails with a potentially transient error. It is recommended to set the value to either zero or MAX_VALUE and use corresponding timeout parameters to control how long a client should retry a request. retry.backoff.ms Type: long Default: 100 Valid Values: [0,... ] Importance: low The amount of time to wait before attempting to retry a failed request to a given topic partition. This avoids repeatedly sending requests in a tight loop under some failure scenarios. rocksdb.config.setter Type: class Default: null Importance: low A Rocks DB config setter class or class name that implements the org.apache.kafka.streams.state.RocksDBConfigSetter interface. send.buffer.bytes Type: int Default: 131072 (128 kibibytes) Valid Values: [-1,... ] Importance: low The size of the TCP send buffer (SO_SNDBUF) to use when sending data. If the value is -1, the OS default will be used. state.cleanup.delay.ms Type: long Default: 600000 (10 minutes) Importance: low The amount of time in milliseconds to wait before deleting state when a partition has migrated. Only state directories that have not been modified for at least state.cleanup.delay.ms will be removed. upgrade.from Type: string Default: null Valid Values: [null, 0.10.0, 0.10.1, 0.10.2, 0.11.0, 1.0, 1.1, 2.0, 2.1, 2.2, 2.3] Importance: low Allows upgrading in a backward compatible way. This is needed when upgrading from [0.10.0, 1.1] to 2.0+, or when upgrading from [2.0, 2.3] to 2.4+. When upgrading from 2.4 to a newer version it is not required to specify this config. Default is null . Accepted values are "0.10.0", "0.10.1", "0.10.2", "0.11.0", "1.0", "1.1", "2.0", "2.1", "2.2", "2.3" (for upgrading from the corresponding old version). window.size.ms Type: long Default: null Importance: low Sets window size for the deserializer in order to calculate window end times. windowstore.changelog.additional.retention.ms Type: long Default: 86400000 (1 day) Importance: low Added to a windows maintainMs to ensure data is not deleted from the log prematurely. Allows for clock drift. Default is 1 day.	null	https://docs.redhat.com/en/documentation/red_hat_amq/2021.q3/html/using_amq_streams_on_rhel/kafka-streams-configuration-parameters-str
Chapter 36. Setting the priority for a process with the chrt utility	Chapter 36. Setting the priority for a process with the chrt utility You can set the priority for a process using the chrt utility. Prerequisites You have administrator privileges. 36.1. Setting the process priority using the chrt utility The chrt utility checks and adjusts scheduler policies and priorities. It can start new processes with the desired properties, or change the properties of a running process. Procedure To set the scheduling policy of a process, run the chrt command with the appropriate command options and parameters. In the following example, the process ID affected by the command is 1000 , and the priority ( -p ) is 50 . To start an application with a specified scheduling policy and priority, add the name of the application, and the path to it, if necessary, along with the attributes. For more information about the chrt utility options, see The chrt utility options . 36.2. The chrt utility options The chrt utility options include command options and parameters specifying the process and priority for the command. Policy options -f Sets the scheduler policy to SCHED_FIFO . -o Sets the scheduler policy to SCHED_OTHER . -r Sets the scheduler policy to SCHED_RR (round robin). -d Sets the scheduler policy to SCHED_DEADLINE . -p n Sets the priority of the process to n . When setting a process to SCHED_DEADLINE, you must specify the runtime , deadline , and period parameters. For example: where --sched-runtime 5000000 is the run time in nanoseconds. --sched-deadline 10000000 is the relative deadline in nanoseconds. --sched-period 16666666 is the period in nanoseconds. 0 is a placeholder for unused priority required by the chrt command. 36.3. Additional resources chrt(1) man page on your system	[ "chrt -f -p 50 1000", "chrt -r -p 50 /bin/my-app", "chrt -d --sched-runtime 5000000 --sched-deadline 10000000 --sched-period 16666666 0 video_processing_tool" ]	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux_for_real_time/9/html/optimizing_rhel_9_for_real_time_for_low_latency_operation/assembly_setting-the-priority-for-a-process-with-the-chrt-utility_optimizing-RHEL9-for-real-time-for-low-latency-operation
Network Observability	Network Observability OpenShift Container Platform 4.17 Configuring and using the Network Observability Operator in OpenShift Container Platform Red Hat OpenShift Documentation Team	null	https://docs.redhat.com/en/documentation/openshift_container_platform/4.17/html/network_observability/index
3.8. Considerations for NetworkManager	3.8. Considerations for NetworkManager The use of NetworkManager is not supported on cluster nodes. If you have installed NetworkManager on your cluster nodes, you should either remove it or disable it. Note The cman service will not start if NetworkManager is either running or has been configured to run with the chkconfig command.	null	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/6/html/cluster_administration/s1-networkmanager-ca
Chapter 8. Important links	Chapter 8. Important links Red Hat AMQ 7 Supported Configurations Red Hat AMQ 7 Component Details Revised on 2021-12-14 20:09:39 UTC	null	https://docs.redhat.com/en/documentation/red_hat_amq/2021.q3/html/release_notes_for_amq_streams_1.8_on_rhel/important-links-str
Chapter 20. Workload partitioning	Chapter 20. Workload partitioning In resource-constrained environments, you can use workload partitioning to isolate OpenShift Container Platform services, cluster management workloads, and infrastructure pods to run on a reserved set of CPUs. The minimum number of reserved CPUs required for the cluster management is four CPU Hyper-Threads (HTs). With workload partitioning, you annotate the set of cluster management pods and a set of typical add-on Operators for inclusion in the cluster management workload partition. These pods operate normally within the minimum size CPU configuration. Additional Operators or workloads outside of the set of minimum cluster management pods require additional CPUs to be added to the workload partition. Workload partitioning isolates user workloads from platform workloads using standard Kubernetes scheduling capabilities. The following changes are required for workload partitioning: In the install-config.yaml file, add the additional field: cpuPartitioningMode . apiVersion: v1 baseDomain: devcluster.openshift.com cpuPartitioningMode: AllNodes 1 compute: - architecture: amd64 hyperthreading: Enabled name: worker platform: {} replicas: 3 controlPlane: architecture: amd64 hyperthreading: Enabled name: master platform: {} replicas: 3 1 Sets up a cluster for CPU partitioning at install time. The default value is None . Note Workload partitioning can only be enabled during cluster installation. You cannot disable workload partitioning postinstallation. In the performance profile, specify the isolated and reserved CPUs. Recommended performance profile configuration apiVersion: performance.openshift.io/v2 kind: PerformanceProfile metadata: # if you change this name make sure the 'include' line in TunedPerformancePatch.yaml # matches this name: include=openshift-node-performance-USD{PerformanceProfile.metadata.name} # Also in file 'validatorCRs/informDuValidator.yaml': # name: 50-performance-USD{PerformanceProfile.metadata.name} name: openshift-node-performance-profile annotations: ran.openshift.io/reference-configuration: "ran-du.redhat.com" spec: additionalKernelArgs: - "rcupdate.rcu_normal_after_boot=0" - "efi=runtime" - "vfio_pci.enable_sriov=1" - "vfio_pci.disable_idle_d3=1" - "module_blacklist=irdma" cpu: isolated: USDisolated reserved: USDreserved hugepages: defaultHugepagesSize: USDdefaultHugepagesSize pages: - size: USDsize count: USDcount node: USDnode machineConfigPoolSelector: pools.operator.machineconfiguration.openshift.io/USDmcp: "" nodeSelector: node-role.kubernetes.io/USDmcp: "" numa: topologyPolicy: "restricted" # To use the standard (non-realtime) kernel, set enabled to false realTimeKernel: enabled: true workloadHints: # WorkloadHints defines the set of upper level flags for different type of workloads. # See https://github.com/openshift/cluster-node-tuning-operator/blob/master/docs/performanceprofile/performance_profile.md#workloadhints # for detailed descriptions of each item. # The configuration below is set for a low latency, performance mode. realTime: true highPowerConsumption: false perPodPowerManagement: false Table 20.1. PerformanceProfile CR options for single-node OpenShift clusters PerformanceProfile CR field Description metadata.name Ensure that name matches the following fields set in related GitOps ZTP custom resources (CRs): include=openshift-node-performance-USD{PerformanceProfile.metadata.name} in TunedPerformancePatch.yaml name: 50-performance-USD{PerformanceProfile.metadata.name} in validatorCRs/informDuValidator.yaml spec.additionalKernelArgs "efi=runtime" Configures UEFI secure boot for the cluster host. spec.cpu.isolated Set the isolated CPUs. Ensure all of the Hyper-Threading pairs match. Important The reserved and isolated CPU pools must not overlap and together must span all available cores. CPU cores that are not accounted for cause an undefined behaviour in the system. spec.cpu.reserved Set the reserved CPUs. When workload partitioning is enabled, system processes, kernel threads, and system container threads are restricted to these CPUs. All CPUs that are not isolated should be reserved. spec.hugepages.pages Set the number of huge pages ( count ) Set the huge pages size ( size ). Set node to the NUMA node where the hugepages are allocated ( node ) spec.realTimeKernel Set enabled to true to use the realtime kernel. spec.workloadHints Use workloadHints to define the set of top level flags for different type of workloads. The example configuration configures the cluster for low latency and high performance. Workload partitioning introduces an extended management.workload.openshift.io/cores resource type for platform pods. kubelet advertises the resources and CPU requests by pods allocated to the pool within the corresponding resource. When workload partitioning is enabled, the management.workload.openshift.io/cores resource allows the scheduler to correctly assign pods based on the cpushares capacity of the host, not just the default cpuset . Additional resources For the recommended workload partitioning configuration for single-node OpenShift clusters, see Workload partitioning .	[ "apiVersion: v1 baseDomain: devcluster.openshift.com cpuPartitioningMode: AllNodes 1 compute: - architecture: amd64 hyperthreading: Enabled name: worker platform: {} replicas: 3 controlPlane: architecture: amd64 hyperthreading: Enabled name: master platform: {} replicas: 3", "apiVersion: performance.openshift.io/v2 kind: PerformanceProfile metadata: # if you change this name make sure the 'include' line in TunedPerformancePatch.yaml # matches this name: include=openshift-node-performance-USD{PerformanceProfile.metadata.name} # Also in file 'validatorCRs/informDuValidator.yaml': # name: 50-performance-USD{PerformanceProfile.metadata.name} name: openshift-node-performance-profile annotations: ran.openshift.io/reference-configuration: \"ran-du.redhat.com\" spec: additionalKernelArgs: - \"rcupdate.rcu_normal_after_boot=0\" - \"efi=runtime\" - \"vfio_pci.enable_sriov=1\" - \"vfio_pci.disable_idle_d3=1\" - \"module_blacklist=irdma\" cpu: isolated: USDisolated reserved: USDreserved hugepages: defaultHugepagesSize: USDdefaultHugepagesSize pages: - size: USDsize count: USDcount node: USDnode machineConfigPoolSelector: pools.operator.machineconfiguration.openshift.io/USDmcp: \"\" nodeSelector: node-role.kubernetes.io/USDmcp: \"\" numa: topologyPolicy: \"restricted\" # To use the standard (non-realtime) kernel, set enabled to false realTimeKernel: enabled: true workloadHints: # WorkloadHints defines the set of upper level flags for different type of workloads. # See https://github.com/openshift/cluster-node-tuning-operator/blob/master/docs/performanceprofile/performance_profile.md#workloadhints # for detailed descriptions of each item. # The configuration below is set for a low latency, performance mode. realTime: true highPowerConsumption: false perPodPowerManagement: false" ]	https://docs.redhat.com/en/documentation/openshift_container_platform/4.14/html/scalability_and_performance/enabling-workload-partitioning
23.16. Timer Element Attributes	23.16. Timer Element Attributes The name element contains the name of the time source to be used. It can have any of the following values: Table 23.12. Name attribute values Value Description pit Programmable Interval Timer - a timer with periodic interrupts. When using this attribute, the tickpolicy delay becomes the default setting. rtc Real Time Clock - a continuously running timer with periodic interrupts. This attribute supports the tickpolicy catchup sub-element. kvmclock KVM clock - the recommended clock source for KVM guest virtual machines. KVM pvclock, or kvm-clock allows guest virtual machines to read the host physical machine's wall clock time. The track attribute specifies what is tracked by the timer, and is only valid for a name value of rtc . Table 23.13. track attribute values Value Description boot Corresponds to old host physical machine option, this is an unsupported tracking option. guest RTC always tracks the guest virtual machine time. wall RTC always tracks the host time. The tickpolicy attribute and the values dictate the policy that is used to pass ticks on to the guest virtual machine. Table 23.14. tickpolicy attribute values Value Description delay Continue to deliver at normal rate (ticks are delayed). catchup Deliver at a higher rate to catch up. merge Ticks merged into one single tick. discard All missed ticks are discarded. The present attribute is used to override the default set of timers visible to the guest virtual machine. The present attribute can take the following values: Table 23.15. present attribute values Value Description yes Force this timer to be visible to the guest virtual machine. no Force this timer to not be visible to the guest virtual machine.	null	https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/7/html/virtualization_deployment_and_administration_guide/sect-manipulating_the_domain_xml-timer_element_attributes
Data Grid Security Guide	Data Grid Security Guide Red Hat Data Grid 8.4 Enable and configure Data Grid security Red Hat Customer Content Services	null	https://docs.redhat.com/en/documentation/red_hat_data_grid/8.4/html/data_grid_security_guide/index
Chapter 6. Connecting clients to the router network	Chapter 6. Connecting clients to the router network After creating a router network, you can connect clients (messaging applications) to it so that they can begin sending and receiving messages. By default, the Red Hat Integration - AMQ Interconnect Operator creates a Service for the router deployment and configures the following ports for client access: 5672 for plain AMQP traffic without authentication 5671 for AMQP traffic secured with TLS authentication To connect clients to the router network, you can do the following: If any clients are outside of the OpenShift cluster, expose the ports so that they can connect to the router network. Configure your clients to connect to the router network. 6.1. Exposing ports for clients outside of OpenShift Container Platform You expose ports to enable clients outside of the OpenShift Container Platform cluster to connect to the router network. Procedure Start editing the Interconnect Custom Resource YAML file that describes the router deployment for which you want to expose ports. In the spec.listeners section, expose each port that you want clients outside of the cluster to be able to access. In this example, port 5671 is exposed. This enables clients outside of the cluster to authenticate with and connect to the router network. Sample router-mesh.yaml file apiVersion: interconnectedcloud.github.io/v1alpha1 kind: Interconnect metadata: name: router-mesh spec: ... listeners: - port: 5672 - authenticatePeer: true expose: true http: true port: 8080 - port: 5671 sslProfile: default expose: true ... The Red Hat Integration - AMQ Interconnect Operator creates a Route, which clients from outside the cluster can use to connect to the router network. 6.2. Authentication for client connections When you create a router deployment, the Red Hat Integration - AMQ Interconnect Operator uses the Red Hat Integration - AMQ Certificate Manager Operator to create default SSL/TLS certificates for client authentication, and configures port 5671 for SSL encryption. 6.3. Configuring clients to connect to the router network You can connect messaging clients running in the same OpenShift cluster as the router network, a different cluster, or outside of OpenShift altogether so that they can exchange messages. Prerequisites If the client is outside of the OpenShift Container Platform cluster, a connecting port must be exposed. For more information, see Section 6.1, "Exposing ports for clients outside of OpenShift Container Platform" . Procedure To connect a client to the router network, use the following connection URL format: <scheme> Use one of the following: amqp - unencrypted TCP from within the same OpenShift cluster amqps - for secure connections using SSL/TLS authentication amqpws - AMQP over WebSockets for unencrypted connections from outside the OpenShift cluster <username> If you deployed the router mesh with user name/password authentication, provide the client's user name. <host> If the client is in the same OpenShift cluster as the router network, use the OpenShift Service host name. Otherwise, use the host name of the Route. <port> If you are connecting to a Route, you must specify the port. To connect on an unsecured connection, use port 80 . Otherwise, to connect on a secured connection, use port 443 . Note To connect on an unsecured connection (port 80 ), the client must use AMQP over WebSockets ( amqpws ). The following table shows some example connection URLs. URL Description amqp://admin@router-mesh:5672 The client and router network are both in the same OpenShift cluster, so the Service host name is used for the connection URL. In this case, user name/password authentication is implemented, which requires the user name ( admin ) to be provided. amqps://router-mesh-myproject.mycluster.com:443 The client is outside of OpenShift, so the Route host name is used for the connection URL. In this case, SSL/TLS authentication is implemented, which requires the amqps scheme and port 443 . amqpws://router-mesh-myproject.mycluster.com:80 The client is outside of OpenShift, so the Route host name is used for the connection URL. In this case, no authentication is implemented, which means the client must use the amqpws scheme and port 80 .	[ "oc edit -f router-mesh.yaml", "apiVersion: interconnectedcloud.github.io/v1alpha1 kind: Interconnect metadata: name: router-mesh spec: listeners: - port: 5672 - authenticatePeer: true expose: true http: true port: 8080 - port: 5671 sslProfile: default expose: true", "< scheme >://[< username >@]< host >[:< port >]" ]	https://docs.redhat.com/en/documentation/red_hat_amq/2021.q1/html/deploying_amq_interconnect_on_openshift/connecting-clients-router-network-router-ocp
11.10. Additional Resources	11.10. Additional Resources Installed Documentation udev(7) man page - Describes the Linux dynamic device management daemon, udevd . systemd(1) man page - Describes systemd system and service manager. biosdevname(1) man page - Describes the utility for obtaining the BIOS-given name of a device. Online Documentation The IBM Knowledge Center Publication SC34-2710-00 Device Drivers, Features, and Commands on Red Hat Enterprise Linux 7 includes information on " Predictable network device names " for IBM System z devices and attachments.	null	https://docs.redhat.com/en/documentation/Red_Hat_Enterprise_Linux/7/html/networking_guide/sec-consistent_network_device_naming-additional_resources