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This chapter includes the following topics:
Analysis Framework for Determining High Availability Requirements
Any enterprise that is designing and implementing a high availability strategy must begin by performing a thorough analysis of the business drivers that require high availability. Implementing high availability may involve critical tasks such as:
Retiring legacy systems
Investment in more capable and robust systems and facilities
Redesign of the overall IT architecture and operations to adapt to this high availability model
Redesign of business processes
Hiring and training of personnel
An analysis of business requirements for high availability combined with an understanding of the level of investment required to implement different high availability solutions enables the development of a high availability architecture that will achieve both business and technical objectives. This chapter provides a simple framework that can be used effectively to evaluate the high availability requirements of a business.
The elements of this analysis framework are:
Total Cost of Ownership (TCO) and Return On Investment (ROI)
A rigorous business impact analysis identifies the critical business processes in an organization, calculates the quantifiable loss risk for unplanned and planned IT outages affecting each of these business processes, and outlines the effects of these outages. It takes into consideration essential business functions, people and system resources, government regulations, and internal and external business dependencies. This analysis is done using objective and subjective data gathered from interviews with knowledgeable and experienced personnel, reviewing business practice histories, financial reports, IT systems logs, and so on.
The business impact analysis categorizes the business processes based on the severity of the impact of IT-related outages. For example, consider a semiconductor manufacturer with chip fabrication plants located worldwide. Semiconductor manufacturing is an intensely competitive business requiring huge financial investment that is amortized over high production volumes. The human resource applications used by plant administration are unlikely to be considered as mission critical as the applications that control the manufacturing process in the plant. Failure of the applications supporting the fabrication process will affect production levels and have a direct impact on financial results of the company.
In a similar fashion, an internal knowledge management system is likely to be considered mission critical for a management consulting firm because the business of a client-focused company is based on internal research accessibility for its consultants and knowledge workers. The cost of downtime of such a system is extremely high for this business. This leads us to the next element in the high availability requirements framework: cost of downtime.
A complete business impact analysis provides the insight needed to quantify the costs of unplanned and planned downtime. Understanding this cost is essential because this helps prioritize your high availability investment and has a direct influence on the high availability technologies chosen to minimize the downtime risk.
Various reports have been published, documenting the costs of downtime across industry verticals. Examples include costs that range from millions of dollars for each hour of brokerage operations and credit card sales, to tens of thousands of dollars for each hour of package shipping services.
These numbers are staggering and the reasons are obvious. The Internet can connect the business directly to millions of customers. Application downtime can disrupt this connection, cutting off a business from its customers. In addition to lost revenue, downtime can have an equally negative effect on other critical and interdependent business issues such as customer relationships, competitive advantages, legal obligations, industry reputation, and shareholder confidence.
The business impact analysis will determine your recovery time objective (RTO). RTO is defined as the maximum amount of time that an IT-based business process can be down before the organization starts suffering unacceptable consequences (financial losses, impact to customer satisfaction, reputation, and so on). RTO indicates the downtime tolerance of a business process or an organization in general.
The RTO requirements are driven by the mission-critical nature of the business. Thus, for a system running a stock exchange, the RTO is zero or very near to zero.
An organization is likely to have varying RTO requirements across its various business processes. Thus, for a high volume e-commerce Web site, for which there is an expectation of rapid response times and for which customer switching costs are very low, the Web-based customer interaction system that drives e-commerce sales is likely to have an RTO close to zero. However, the RTO of the systems that support back-end operations, such as shipping and billing, can be higher. If these back-end systems are down, then the business may resort to manual operations temporarily without a significantly visible impact.
The business impact analysis also determines your recovery point objective (RPO). RPO is the maximum amount of data an IT-based business process may lose before causing detrimental harm to the organization. RPO indicates the data-loss tolerance of a business process or an organization in general. This data loss is often measured in terms of time, for example, 5 hours or 2 days worth of data loss.
A stock exchange where millions of dollars worth of transactions occur every minute cannot afford to lose any data. Thus, its RPO must be zero. Referring to the e-commerce example, the Web-based sales system does not strictly require an RPO of zero, although a low RPO is essential for customer satisfaction. However, its back-end merchandising and inventory update system may have a higher RPO; lost data in this case can be reentered.
A manageability goal is more subjective than either the RPO or the RTO. It results from an objective evaluation of the skill sets and management resources available in an organization, and the degree to which the organization can successfully manage all elements of a high availability architecture. In a fashion similar to how RPO and RTO measures an organization's tolerance toward downtime or data loss, your manageability goal measures the organization's tolerance to complexity in the IT environment. To the extent that less complexity is a requirement, simpler methods of achieving high availability are preferred over methods that may be more complex to manage, even if the latter could attain more aggressive RTO and RPO objectives. Having a good understanding of manageability goals helps organizations differentiate between what is possible and what is practical to implement.
Understanding TCO and ROI is essential to selecting an high availability architecture that also achieves the business goals of your organization. TCO includes all costs such as acquisition, implementation, systems, networks, facilities, staff, training, and support, over the useful life of the solution chosen. Likewise, the ROI calculation captures all of the financial benefits that accrue to a given high availability architecture.
For example, consider a high availability architecture in which IT systems/storage at a remote standby site remains idle and has no other business use that can be served by its standby systems. The only return on investment for the standby site is the cost of downtime avoided by its use in a failover scenario. Contrast this with a different high availability architecture that enables IT systems and storage at the standby site to be used productively while in the standby role (for example, for reports or for offloading the primary system of the overhead of end-user queries), that makes the standby system a production system in its own right. The return on investment of such an architecture includes both the cost of downtime avoided and the financial benefits that accrue to its use as a production system while in the standby database role.
Using the high availability analysis framework, a business can:
Complete a business impact analysis
Identify and categorize the critical business processes that have the high availability requirements
Formulate the cost of downtime
Establish utilization, RTO, and RPO goals for these various business processes.
Understand your goals for manageability, TCO, and ROI
This framework enables the business to define service level agreements (SLAs) in terms of high availability for critical aspects of its business. For example, it can categorize its business processes into several high availability tiers:
Tier 1 processes have maximum business impact. They have the most stringent high availability requirements, with RTO and RPO close to zero, and the systems supporting it need to be available on a continuous basis. For a business with a high-volume e-commerce presence, this may be the Web-based customer interaction system.
Tier 2 processes that have slightly relaxed high availability and RTO/RPO requirements. The second tier of an e-commerce business may be their supply chain and merchandising systems. For example, these systems do not need to maintain extremely high degrees of availability and may have nonzero RTO/RPO values. Thus, the high availability systems and technologies chosen to support these two tiers of businesses are likely to be different from those of the tier 1 processes.
Tier 3 processes may be related to internal development and quality assurance processes. Systems supporting these processes need not have the rigorous high availability requirements of the other tiers.
The next step for the business is to evaluate the capabilities of the various high availability systems and technologies, and choose the ones that meet its SLA requirements, within the guidelines as dictated by business performance issues, budgetary constraints, and anticipated business growth.
Figure 3-1 illustrates this process.
The following sections provide further details about this methodology:
A broad range of high availability and business continuity solutions exists today. As the sophistication and scope of these systems increase, they make more of the IT infrastructure, such as the data storage, server, network, applications, and facilities, highly available. They also reduce RTO and RPO from days to hours, or even to minutes and seconds. Increased availability often comes with an increased cost, and on some occasions, with an increased impact on systems performance. With Oracle Grid infrastructure, higher availability can equate to lower cost, greater scalability, and more complete utilization of system resources. The high availability approach to satisfying business requirements may differ for a legacy system.
Organizations need to carefully analyze the capabilities of these high availability systems and map their capabilities to the business requirements to ensure they have an optimal combination of high availability solutions to keep their business running. Consider the business with a significant e-commerce presence as an example.
For this business, the IT infrastructure supporting the system that customers encounter, the core e-commerce engine, must be highly available and disaster proof. The business may consider clustering for the Web servers, application servers and the database servers serving this e-commerce engine. With built-in redundancy, clustered solutions eliminate single points of failure. Also, modern clustering solutions are application transparent, provide scalability to accommodate future business growth, and provide load-balancing to handle heavy traffic. Thus, such clustering solutions are ideally suited for mission-critical high-transaction applications.
If unplanned and planned outages occur, the data that supports the high volume e-commerce transactions must be protected adequately and be available with minimal downtime. This data should not only be backed up at regular intervals at the local data centers, but should also be replicated to databases at a remote data center connected over a high-speed, redundant network. This remote data center should be equipped with secondary servers and databases readily available, and be synchronized with the primary servers and databases. This gives the business the capability to switch to these servers at a moment's notice with minimal downtime if there is an outage, instead of waiting for hours and days to rebuild servers and recover data from backed-up tapes. Factors to consider when planning a remote data center include the network bandwidth and latency (distance) between sites, and usage consideration (such as whether the sites are fully or partially staffed). These factors should be used to determine whether remote data centers are feasible and their location in relation to the primary data center.
Maintaining synchronized remote data centers is an example where redundancy is built along the entire system's infrastructure. This may be expensive; however, the mission-critical nature of the systems and the data it protects may warrant this expense. Considering another aspect of the business, the high availability requirements are less stringent for systems that gather clickstream data and perform data mining. The cost of downtime is low, and the RTO and RPO requirements for this system could be a few days, because even if this system is down and some data is lost, that does not have a detrimental effect on the business. While the business may need powerful computers to perform data mining, it does not need to mirror this data on a real-time basis. To obtain data protection, perform regularly scheduled backups, and archive the tapes for offsite storage.
For this e-commerce business, the back-end merchandising and inventory systems are expected to have higher high availability requirements than the data mining systems, and thus they may employ technologies such as local mirroring or local snapshots, in addition to scheduled backups and offsite archiving.
The business should employ a management infrastructure that performs overall systems management, administration and monitoring, and provides an executive dashboard. This management infrastructure should be highly available and fault tolerant.
Finally, the overall IT infrastructure for this e-commerce business should be extremely secure, to protect against malicious external and internal electronic attacks.
High availability solutions must also be based on business performance issues. For example, a business may use a zero-data-loss solution that synchronously mirrors every transaction on the primary database to a remote database. However, considering the speed-of-light limitations and the physical limitations associated with a network, there are round-trip-delays in the network transmission. These delays increase with distance and vary based on network bandwidth, traffic congestion, router latencies, and so on. Thus, this synchronous mirroring, if performed over large WAN distances, may impact the primary site performance. Online buyers may notice these system latencies and be frustrated with long system response times; consequently, they may go somewhere else for their purchases. This is an example where the business must make a trade-off between having a zero data loss solution and maximizing system performance. Conversely, if the business drivers justify the investment to avoid making this tradeoff, a multisite architecture can be implemented that places a synchronous zero data loss standby site in close proximity to the primary site and a second asynchronous standby site located up to thousands of miles away.
High availability solutions must also be based on financial considerations and future growth estimates. It is tempting to build redundancies throughout the IT infrastructure and claim that the infrastructure is completely failure proof. Although higher availability does not always equate higher cost, going to extremes with such solutions may lead to budget overruns or an unmanageable and unscalable combination of solutions that is extremely complex and expensive to integrate and maintain.
A high availability solution that has very impressive performance benchmark results may look good in theory. However, if an investment is made in such a solution without a careful analysis of how the technology capabilities match the business drivers, then a business may end up with a solution that:
Does not integrate well with the rest of the system infrastructure
Has annual integration and maintenance costs that easily exceed the up-front implementation costs
Forces a vendor lock-in
Cost-conscious and business-savvy decision makers must invest only in solutions that are well-integrated, standards-based, easy to implement, maintain and manage, and have a scalable architecture for accommodating future business growth.
Oracle Database offers an integrated suite of high availability solutions that increase availability and eliminate or minimize both planned and unplanned downtime. These solutions help enterprises maintain business continuity 24 hours a day, seven days a week. However, the Oracle high availability solutions go beyond reducing downtime by providing solutions to increase system utilization on the primary and secondary systems and to help improve overall performance, scalability, and manageability.
The chapter contains the following sections that outline the key impacts of the Oracle high availability features on businesses and applications:
Oracle High Availability Features and Solutions for Unplanned Downtime
Oracle High Availability Features and Solutions for Planned Downtime
Oracle provides the following features for high availability:
Also, the "Oracle High Availability Solutions and Recovery for Unplanned Downtime" section provides a summary of the key high availability solutions that address different types of unplanned downtime along with the recovery time for each solution.
See Also:
Oracle provides fast and predictable recovery from system faults and database failures. The Fast-Start Fault Recovery technology included in Oracle Database automatically bounds database recovery time at startup by using self-tuned checkpoint processing. This makes recovery time fast and predictable, and improves the ability to meet service-level objectives. The Oracle Fast-Start Fault Recovery feature can reduce recovery time on a heavily laden database from tens of minutes to a few seconds.
Fast-Start Fault Recovery features include:
Predictable, bounded recovery from instance, database, and computer failures
Database checkpointing that is self-tuning to maintain a desired recovery time objective
Oracle Real Application Clusters (Oracle RAC) and Oracle Clusterware allow the Oracle Database to run any packaged or custom application across a set of clustered servers. This capability provides the highest levels of availability and the most flexible scalability. If a clustered server fails, Oracle Database continues running on the surviving servers. When more processing power is needed, you can add another server without interrupting access to data.
Oracle RAC enables multiple instances that are linked by an interconnect to share access to an Oracle database. In an Oracle RAC environment, the Oracle Database runs on two or more systems in a cluster while concurrently accessing a single shared database. The result is a single database system that spans multiple hardware systems and enabling Oracle RAC to provide high availability and redundancy during failures in the cluster. Oracle RAC accommodates all system types, from read-only data warehouse (DSS) systems to update-intensive online transaction processing (OLTP) systems.
Oracle Clusterware is software that, when installed on servers running the same operating system, enables the servers to be bound together to operate as if they are one server and manages the availability of user applications and Oracle databases. Oracle Clusterware also provides all of the features required for cluster management, including node membership, group services, global resource management, and high availability functions:
For high availability, you can place Oracle databases (single-instance or Oracle RAC databases), and user applications (Oracle and non Oracle) under the management and protection of Oracle Clusterware so that the databases and applications restart when a process fails or so that a failover to another node occurs after a node failure.
For cluster management, Oracle Clusterware presents multiple independent servers as if they are a single-system image or one virtual server. This single virtual server is preserved across the cluster for all management operations, enabling administrators to perform installations, configurations, backups, upgrades, and monitoring functions once. Then, Oracle Clusterware automatically distributes the execution of these management functions to the appropriate nodes in the cluster.
Oracle Clusterware is a requirement for using Oracle RAC and it is the only clusterware that you need for most platforms on which Oracle RAC operates. Although the Oracle Database continues to support select third-party clusterware products on specified platforms, using Oracle Clusterware provides the benefit of dispensing with proprietary vendor clusterware and using an integrated software stack from Oracle that provides disk management with Oracle ASM to data management with the Oracle Database and Oracle RAC. In addition, Oracle Database features, such as Oracle Services, use the underlying Oracle Clusterware mechanisms to provide their capabilities.
Oracle Clusterware requires two clusterware components: a voting disk to record node membership information and the Oracle Cluster Registry (OCR) to record cluster configuration information. The voting disk and the OCR must reside on shared storage. The Oracle Clusterware requires that each node be connected to a private network over a private interconnect.
Together, Oracle RAC and Oracle Clusterware provide the following benefits:
Ability to tolerate and quickly recover from computer and instance failures
Ability to apply Oracle Clusterware upgrades, patch sets, and interim patches in a rolling fashion
For example, upgrading Oracle Clusterware from Oracle 10g to Oracle 11g, patching Oracle Clusterware from Oracle 10.2.0.3 to 10.2.0.4, and patching Oracle Clusterware from Oracle 10.2.0.2 Bundle 1 to Oracle 10.2.0.2 Bundle 2
Rolling upgrades for system and hardware changes
Rolling patch upgrades for some interim patches
Service relocation and, when you perform additional Fast Application Notification (FAN) and client configuration, distribution of FAN events so applications can react immediately to achieve fast, automatic, and intelligent connection and failover
Fast, automatic detection of connection failures and removal of terminated connections for any Java application using Oracle Universal Connection Pool (UCP), Fast Connection Failover, and FAN events
Work request balancing using Oracle UCP Runtime Connection Load Balancing
Runtime connection load balancing with Oracle UCP, OCI, and ODP.NET
Load balancing advisory
Flexibility to increase processing capacity using commodity hardware without downtime or changes to the application
Comprehensive manageability integrating database and cluster features
Scalability across database instances
Oracle Clusterware provides the following benefits
Automatically restarts failed Oracle processes
Automatically manages and fails over Oracle Virtual IP (VIP) on another node in the cluster on node failures
Automatically restarts resources from failed nodes on surviving nodes
For Oracle RAC databases, all Oracle processes are under the control of Oracle Clusterware by default; for Oracle single-instance databases, you can configure the Oracle processes into a resource group that is under the control of Oracle Clusterware
For Oracle and non Oracle applications, Oracle Clusterware provides an application programming interface (API) that enables you to control other Oracle processes with Oracle Clusterware, such as restart or react to failures and certain rules
Manages node membership and prevents split brain syndrome in which two or more instances attempt to control the database
Provides the ability to perform rolling release upgrades of Oracle Clusterware, with no downtime for applications
Oracle Data Guard ensures high availability, data protection, and disaster recovery for enterprise data. Oracle Data Guard provides a comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable Oracle databases to survive disasters and data corruptions. Oracle Data Guard maintains standby databases as transactionally consistent copies of the primary (production) database. Then, if the primary database becomes unavailable because of a planned or an unplanned outage, Oracle Data Guard can switch any standby database to the primary role, minimizing the downtime associated with the outage. Oracle Data Guard can be used with traditional backup, restoration, and cluster techniques to provide a high level of data protection and data availability.With Oracle Data Guard, administrators can optionally improve primary database performance by offloading resource-intensive backup and reporting operations to standby systems.
An Oracle Data Guard configuration consists of one primary database and one or more standby databases. Using a backup copy of the primary database, you can create up to nine standby databases and incorporate them in a Oracle Data Guard configuration. Once created, Oracle Data Guard automatically maintains each standby database by transmitting redo data from the primary database and then applying the redo to the standby database.
Similar to a primary database, a standby database can be either a single-instance Oracle database or an Oracle RAC database.
A standby database can be a physical standby database, a snapshot standby database, or a logical standby database, and a Oracle Data Guard configuration can include any combination of these types of standby databases:
A physical standby database provides a physically identical copy of the primary database, with data files that are identical to the primary database. The database schema, including indexes, are the same. A physical standby database is kept synchronized with the primary database, though Redo Apply, which recovers the redo data received from the primary database and applies the redo to the physical standby database.
You can use a physical standby database for business purposes other than disaster recovery. Starting in Oracle Database 11g Release 1, the physical standby database can be opened for read-only access while redo data is being applied to the standby database. This mode, referred to as the Oracle Active Data Guard optionFoot 1 , allows users to access an up-to-date physical standby database for queries at any time. See Section 220.127.116.11, "Oracle Active Data Guard Option for Physical Standby Databases" for more information.
Also, you can convert a physical standby database to:
A logical standby temporarily, called a transient logical standby database, to perform a rolling upgrade.
A snapshot standby database temporarily, to be used as a clone or a test database.
See Section 18.104.22.168, "Overview of Multiple Standby Database Architectures", for more information.
See Also:
A snapshot standby database is an updatable standby database that you create from a physical standby database. A snapshot standby database receives and archives redo data received from the primary database, but the snapshot standby database does not apply redo data from the primary database while the standby is open for read/write access. Thus, the snapshot standby typically diverges from the primary database over time. Moreover, local updates to the snapshot standby database cause additional divergence.
Redo data from the primary database is not applied until you convert the snapshot standby database back into a physical standby database, and after all local updates to the snapshot standby database are discarded. With a single command, you can revert a snapshot standby back to a physical standby database, at which time the changes made to the snapshot standby state are discarded, and Redo Apply automatically resynchronizes the physical standby database with the primary database using the redo data that was archived.
A logical standby database contains the same logical information as the primary database, although the physical organization and structure of the data can be different. The logical standby database is kept synchronized with the primary database though SQL Apply, which transforms the redo data received from the primary database into SQL statements and then executes the SQL statements on the standby database.
A key benefit of a logical standby database is that you can create significant auxiliary structures to optimize the reporting workload, including structures that could have a prohibitive effect on the transactional response time of the primary database. A logical standby database:
Can have its data physically reorganized into a different storage type with different partitioning having many different indexes, and having on-demand refresh materialized views created and maintained.
Can be used to drive the creation of data cubes and other OLAP data views.
Can be used for other business purposes in addition to satisfying disaster recovery requirements, allowing users to access a logical standby database for queries and reporting purposes at any time.
Can be used to upgrade Oracle Database software and patch sets with almost no downtime.
Thus, you can use a logical standby database concurrently for data protection, reporting, and database upgrades.
Oracle Data Guard provides the following benefits:
Maintenance of real-time, transactionally consistent database copies to provide protection against unplanned downtime and disaster.
Data protection and fast repair against computer failures, human errors, data corruption, lost writes, and site failures.
Automatic failover with flexible data protection levels to support all network configurations and business requirements.
Faster redo application, redo transport, and role transitions with various enhancements.
Reduction of planned downtime for system changes, some platform migrations, hardware and system upgrades, and Oracle patch set and database upgrades (see also Table 2-1, "Outage Types and Oracle High Availability Solutions for Unplanned Downtime").
Multiple levels of data protection and performance to balance data availability against system performance requirements.
Support for both physical standby databases (including the Active Data Guard option) and logical standby databases to provide more efficient use of system resources by diverting more querying and reporting functions from the primary database to standby databases (with the logical standby databases providing greater flexibility for any activity that requires access to a standby database that is open for read/write access). See also "Benefits of Physical Standby Databases" and "Benefits of Logical Standby Databases", and Section 18.104.22.168, "Oracle Active Data Guard Option for Physical Standby Databases".
Support for snapshot standby database for reporting or testing (cloning) purposes and automatic resynchronization with the primary database once reporting or testing has completed. See also "Benefits of Snapshot Standby Databases".
Managed and automatic role transition and application notification to minimize planned and unplanned downtime.
Automatic or automated resynchronization of a failed primary database following a failover.
Management of all systems as a single configuration for simplified administration.
Increased flexibility for Data Guard configurations where the primary and standby systems may have different CPU architectures, operating systems (for example, Windows and Linux), operating system binaries (32-bit and 64-bit), and Oracle database binaries (32-bit and 64-bit); this is subject to restrictions that are defined in support note 413484.1.
Benefits of Physical Standby Databases
Guarantees a physical, block-for-block copy of the primary database
Can be open for read-only queries while Redo Apply is active for real-time reporting (requires the Oracle Active Data Guard option that is described in Section 126.96.36.199, "Oracle Active Data Guard Option for Physical Standby Databases")
At role transition, offers assurance that the standby database is an exact replica of the old primary database
Can be used to offload backups from primary database
Very high performance, completely transparent to workload profile
Has no data type restrictions
Useful for minimizing downtime for many planned maintenance events
Benefits of Snapshot Standby Databases
Inherits all the attributes of a physical standby database
Can be open for read/write access and can process transactions independent of the primary database
Protects the primary database the entire time it is open for read-write I/O
Allows you to issue a single command to convert a Snapshot Standby back to a synchronized physical standby database
Provides an ideal test system, especially when combined with Oracle Real Application Testing
Benefits of Logical Standby Databases
Provides a logical, transaction-for-transaction copy of the primary database
Allows creation of additional objects, modification of objects
Provides the ability to skip apply on certain objects
Supports real-time reporting
Is open for read/write I/O (the data in tables that is maintained by SQL Apply cannot be changed)
Performance varies depending on the workload
Minimizes downtime for software upgrades
Oracle Streams is a very flexible and powerful database feature to implement fine-grained replication, multimaster replication, many-to-one replication, data transformation, hub and spoke replication, and message queuing.
Comparing Streams and Data Guard
Oracle Streams is designed for information sharing. It enables highly customized replication strategies to satisfy the many varied uses of data replicated to a target database. These same capabilities also make Oracle Streams a useful technology for addressing high availability and disaster recovery requirements and for minimizing planned downtime during upgrades to new database releases and patch sets.Oracle Data Guard is designed for simple, one-way replication of an entire database expressly for maintaining a synchronized copy that can assume the primary role in the event of a failure. Oracle Data Guard Redo Apply (physical standby) best exemplifies this notion of simplicity, as a disaster recovery solution that is both datatype and application agnostic, and able to scale to very high levels of performance. While Oracle Data Guard also provides capabilities that enable a standby database to offload from the primary database the overhead of performing backups, queries, and reports, these capabilities are ancillary to the primary mission of Oracle Data Guard, and are provided to increase your investments in high availability and disaster recovery. To get additional value from an Oracle Data Guard configuration, you can use Oracle Data Guard SQL Apply (logical standby database) to minimize planned downtime during upgrades to new database releases and patch sets.
Streams Messaging and Information Flow
Oracle Streams enables information sharing. Using Oracle Streams, each unit of shared information is called a message, and you can share these messages in a stream. The stream can propagate information within a database or from one database to another.
For example, Figure 2-1 shows an Oracle Streams multimaster configuration where all sites are directly connected to all other sites participating in the replication environment. The multimaster configuration enables data to be replicated between all locations in a near realtime manner.
Another example is the Oracle Streams 1-N, or hub-and-spoke configuration in which changes made at the primary or hub location are propagated to the remote or spoke locations in a near real-time manner.
Although it is possible to configure a hub-and-spoke configuration for bidirectional replication, you may prefer to restrict updates to a single location, the hub, as shown in Figure 2-2. In query intensive environments, you can still balance the load between multiple locations, with fast local access, while updates are restricted to the hub. By offloading reporting to the spoke locations, you improve performance at the hub, or primary OLTP location. This type of configuration is easier to implement than multimaster replication because it is not necessary to establish connectivity between all locations in the replication environment and it is not necessary to implement a conflict resolution strategy.
The stream routes specific information to specific destinations. The result is a feature that provides greater functionality and flexibility than traditional solutions for capturing and managing messages, and sharing the messages with other databases and applications. Oracle Streams provides the capabilities needed to build and operate distributed enterprises and applications, data warehouses, and high availability solutions. You can use all of the capabilities of Oracle Streams at the same time. If your business requirements change, then you can implement a new capability of Oracle Streams without sacrificing existing capabilities.
As with any Oracle Streams configuration, there are three phases: capture, stage (propagate), and consume (apply). Using Oracle Streams, you control what information is put into a stream, how the stream flows or is routed from database to database, what happens to messages in the stream as they flow into each database, and how the stream terminates. By configuring specific capabilities of Oracle Streams, you can address specific requirements. Based on your specifications, Oracle Streams can capture, stage, and manage messages in the database automatically, including, but not limited to, data manipulation language (DML) changes and data definition language (DDL) changes. You can also put user-defined messages into a stream, and Streams can propagate the information to other databases or applications automatically. When messages reach a destination, Streams can consume them based on your specifications.
The following figure shows the Oracle Streams information flow.
With Oracle Streams, you can create a local or remote copy of a production database. In the event of human error or a catastrophe, you can use the copy to resume processing. You can use Oracle Streams to configure flexible high availability environments.You can use the features of Oracle Streams to achieve little or no database downtime during database upgrade and maintenance operations. Maintenance operations include migrating a database to a different platform, migrating a database to a different character set, modifying database schema objects to support upgr ��ades to user-created applications, and applying an Oracle software patch.
Figure 2-4 shows an application that explicitly enqueues and dequeues messages through Oracle Streams Advanced Queuing as a method of sharing information with business partners or customers with different messaging systems. Once enqueued, messages can be transformed and propagated as desired, before being dequeued to a business partner's application that is a nondatabase oriented messaging systems.
Benefits of Using Oracle Streams
Oracle Streams provides the following benefits:
Data protection by maintaining a full or partial remote copy of the database
Achieves little or no downtime during database upgrade or maintenance operations such as migrating a database to a different platform or character set, modifying database objects to support upgrades to applications, and applying an Oracle software patch
Data replication by capturing DML and DDL changes made to database objects and replicating these changes to one or more other databases; bidirectional replication environment, in which exactly two databases share the replicated database objects and data, is possible.
Event management and notification by enqueuing messages or capturing events, propagating the messages and events through queues, and dequeuing and applying or acting upon the message or event (as shown in Figure 2-4)
Supports heterogeneous platforms across databases in the configuration
Allows character sets to differ between replicas
Permits fine-grained control of data sharing
Note:Although Oracle Streams requires some initial implementation investment, it is well worth the effort because of the high flexibility you get with Streams.
Flashback technology provides a set of features to switch between views of the data as it existed at different points in time. Using Flashback features you can query past versions of schema objects and historical data. You can also perform change analysis and self-service repair to recover from logical corruption while the database is online.
Flashback technology provides a SQL interface to quickly analyze and repair human errors. Flashback technology provides fine-grained analysis and repair for localized damage such as deleting the wrong customer order. Flashback technology also enables correction of more widespread damage, yet does it quickly to avoid long downtime. Flashback technology is unique to Oracle Database and supports recovery at all levels including row, transaction, table, tablespace, and database.
Most of the flashback features use undo data while other features, such as Flashback Database and Block Media Recovery, use flashback logs:
Undo tablespace—A dedicated tablespace that stores only undo information when the database is run in automatic undo management mode.
Flashback data archive—An archive that is stored in a tablespace and contains transactional changes to every record in a table for the duration of the record's lifetime. The archived data can be retained for much longer duration than the retention period offered by an undo tablespace.
Flashback logs—Oracle-generated logs used to perform flashback operations. The database can only write flashback logs to the flash recovery area. Flashback logs are written sequentially and are not archived. They cannot be backed up to disk.
The following list describes the Flashback features:
Oracle Flashback Query provides the ability to view the data as it existed in the past by using the Automatic Undo Management system to obtain metadata and historical data for transactions. Undo data is persistent and survives a database malfunction or shutdown. The unique features of Flashback Query not only provide the ability to query previous versions of tables, they also provide a powerful mechanism to recover from erroneous operations.
Uses of Flashback Query include:
Recovering lost data or undoing incorrect, committed changes. For example, rows that have been deleted or updated can be immediately repaired even after they have been committed.
Comparing current data with the corresponding data at some time in the past. For example, using a daily report that shows the changes in data from yesterday, it is possible to compare individual rows of table data, or find intersections or unions of sets of rows.
Checking the state of transactional data at a particular time, such as verifying the account balance on a certain day.
Simplifying application design by removing the need to store certain types of temporal data. Using a Flashback Query, it is possible to retrieve past data directly from the database.
Applying packaged applications, such as report generation tools, to past data.
Providing self-service error correction for an application, enabling users to undo and correct their errors.
Oracle Flashback Versions Query
Oracle Flashback Versions Query is an extension to SQL that you can use to retrieve the versions of rows in a given table that existed in a specific time interval. Oracle Flashback Versions Query returns a row for each version of the row that existed in the specified time interval. For any given table, a new row version is created each time the
COMMIT statement is executed.
Flashback Versions Query is a powerful tool for the DBA to run analysis to determine the sources of problems. Additionally, application developers can use Flashback Versions Query to build customized applications for auditing purposes.
Oracle Flashback Transaction
Oracle Flashback Transaction is a new feature in Oracle Database 11g Release 1 that can easily back out a transaction and its dependent transactions. The
DBMS_FLASHBACK.TRANSACTION_BACKOUT() procedure rolls back a transaction and its dependent transactions while the database remains online. This recovery operation uses undo data to create and execute the compensating transactions that return the affected data to its original state. You can query the
DBA_FLASHBACK_TRANSACTION_STATE view to see the current state of a transaction with respect to whether the transaction has been backed out using dependency rules or forced out by either:
Backing out nonconflicting rows
Applying undo SQL
Oracle Flashback Transaction increases availability during logical recovery by easily and quickly backing out a specific transaction or set of transactions and their dependent transactions, with one command while the database remains online.
Oracle Flashback Transaction Query
Oracle Flashback Transaction Query provides a mechanism to view all changes made to the database at the transaction level. When used in conjunction with Flashback Versions Query, it offers a fast and efficient means to recover from a human or application error. Flashback Transaction Query increases the ability to perform online diagnosis of problems in the database by returning the database user that changed the row, and performs analysis and audits on transactions.
Oracle Flashback Table
Oracle Flashback Table recovers a table to a previous point in time. It provides a fast, online solution for recovering a table or set of tables that has been modified by a human or application error. In most cases, Flashback Table alleviates the need for administrators to perform more complicated point-in-time recovery operations. Even after a flashing back a table, the data in the original table is not lost; it can later be reverted back to the original state.
Oracle Flashback Drop
Dropping objects by accident is a problem for database users and database administrators alike. While there is no easy way to recover dropped tables, indexes, constraints, or triggers, Oracle Flashback Drop provides a safety net when dropping objects. When you drop a table, Oracle automatically places it into the Recycle Bin. The Recycle Bin is a virtual container where all dropped objects reside. You can continue to query data in a dropped table.
Oracle Flashback Restore Points
When an Oracle Flashback recovery operation is performed on the database, the DBA must determine the point in time—identified by the System Change Number (SCN) or timestamp—to which the data can later be flashed back. Oracle Flashback restore points are labels you can define that can be substituted for the SCN or transaction time used in Flashback Database, Flashback Table, and Recovery Manager (RMAN) operations. Furthermore, a database can be flashed back through a previous database recovery and open resetlogs by using guaranteed restore points. Guaranteed restore points allow major database changes—such as database batch jobs, upgrade, or patch—to be quickly undone by ensuring that the undo required to rewind the database is retained.
Using the Oracle Flashback Restore Points feature provides the following benefits:
Provides the ability to quickly restore to a consistent state, to a point in time that was before a planned operation that has gone awry (for example, a failed batch job, an Oracle software upgrade, or an application upgrade.
Allows the snapshot standby to be resynchronized with the production database.
Allows for a quick mechanism to restore a test or cloned database back to its original state.
Oracle Flashback Database
Oracle Flashback Database provides a more efficient alternative to database point-in-time recovery. With Oracle Flashback Database, current data files can be reverted to their contents at a past time. The result is much like restoring data from data file backups and executing point-in-time database recovery. However, Flashback Database skips the data file restoration and most of the application of redo data.
Enabling Oracle Flashback Database provides the following benefits:
Eliminates the time to restore a backup when fixing human error that has a database-wide impact.
Because human errors can be quickly undone, it allows standby databases to use real-time apply to synchronize with the primary database.
Allows quick standby database reinstantiation after a database failover.
Block Recovery Using Flashback Logs
Starting with Oracle Database release 11.1, block recovery can optionally retrieve a more recent copy of a data block from the flashback logs to reduce recovery time. Furthermore, a corrupted block encountered during instance recovery does not result in instance recovery failing. The block is automatically marked as corrupt and added to the RMAN corruption list in the
V$DATABASE_BLOCK_CORRUPTION table. You can subsequently issue the RMAN
RECOVER BLOCK command to fix the associated block.
An archive that is stored in a tablespace and contains transactional changes to every record in a table for the duration of the record's lifetime. The archived data can be retained for a much longer duration than the retention period offered by an undo tablespace.
Automatic Storage Management (ASM) provides a vertically integrated file system and volume manager directly in the Oracle kernel, resulting in:
Significantly less work to provision database storage
Higher level of availability
Elimination of the expense, installation, and maintenance of specialized storage products
Unique capabilities for database applications
For optimal performance, ASM spreads files across all available storage. To protect against data loss, ASM extends the concept of SAME (stripe and mirror everything) and adds more flexibility in that it can mirror at the database file level rather than the entire disk level.
More importantly, ASM simplifies the processes of setting up mirroring, adding disks, and removing disks. Instead of managing hundreds and possibly thousands of files (as in a large data warehouse), DBAs using ASM create and administer a larger-grained object called a disk group. The disk group identifies the set of disks that are managed as a logical unit. Automation of file naming and placement of the underlying database files save administrators time and ensure adherence to standard best practices.
The ASM native mirroring mechanism (2-way or 3-way) is an option that protects against storage failures. With ASM mirroring, you can provide an additional level of data protection with the use of failure groups. A failure group is a set of disks sharing a common resource (disk controller or an entire disk array) whose failure can be tolerated. Once defined, an ASM failure group intelligently places redundant copies of the data in separate failure groups. This ensures that the data is available and transparently protected against the failure of any component in the storage subsystem.
ASM provides the following benefits:
Provides the ability to mirror and stripe across drives and storage arrays
Automatically re-mirrors from a failed drive to remaining drives
Automatically rebalances stored data when disks are added or removed while the database remains online
Allows for operational simplicity in managing database storage
Provides local read capability, which gives better performance in an extended cluster
Supports very large databases
Supports ASM rolling upgrades
Supports finer granularity in tuning and security
ASM Fast Mirror Resync, which provides fast repair after a temporary disk failure
Recovery Manager (RMAN) is an Oracle utility to manage database backup and, more importantly, the recovery of the database. RMAN eliminates operational complexity while providing superior performance and availability of the database.
RMAN determines the most efficient method of executing the requested backup, restoration, or recovery operation and then submits these operations to the Oracle Database server for processing. RMAN and the server automatically identify modifications to the structure of the database and dynamically adjust the required operation to adapt to the changes.
RMAN provides the following benefits:
Automatic channel failover on backup and restore operations
Automatic failover to a previous backup when the restore operation discovers a missing or corrupt backup
Automatic creation of new database and temporary files during recovery
Automatic recovery through a previous point-in-time recovery—recovery through resetlogs
Block media recovery enables the data file to remain online while fixing the block corruption
Fast incremental backups using block change tracking
Fast backup and restore operations with intrafile and interfile parallelism
Enhanced security with Virtual Private Catalog
Lower space consumption when creating a database over the network by eliminating staging areas
Merge incremental backups into image copies in the background providing up-to-date recoverability
Optimized backup and restore of required files only
Retention policy ensures that relevant backups are retained
Ability to resume backup and restore of previously failed operations
Automatic backup of the control file and the server parameter file ensuring that backup metadata is available in times of database structural changes and media failure and disasters
Online backup does not require the database to be placed into hot backup mode
Oracle Secure Backup is a centralized tape backup management solution providing performant, heterogeneous data protection in distributed UNIX, Linux, Windows, and Network Attached Storage (NAS) environments. By protecting file system and Oracle database data, Oracle Secure Backup provides a complete tape backup solution for your IT environment.
Oracle Secure Backup is tightly integrated with RMAN to provide the media management layer for RMAN, supporting releases since Oracle9i. With optimized integration points, Oracle Secure Backup and RMAN provide the fastest and most efficient tape backup capability for the Oracle database.
You can backup distributed servers to local and remote tape devices from a central Oracle Secure Backup administrative server using backup policies, calendar-based scheduling for lights out operations, or on-demand backup for immediate requirements. With its highly scalable client/server architecture, Oracle Secure Backup provides local and remote data protection, leveraging SSL for secure intradomain communication and two-way server authentication.
The following list describes the key benefits of Oracle Secure Backup:
Optimized tape backup for the Oracle database by backing up only the currently used blocks and increasing backup performance by 10% to 25%.
Policy-based management allows backup administrators to exercise precise control over the backup domain.
Dynamic drive sharing for increased tape resource use.
Heterogeneous storage area network (SAN) support allowing NAS, UNIX, Windows, and Linux to share tape drives and media.
File system backup at the file, directory, file system or raw partition level with full, incremental and offsite backup scheduling.
Integrated with Oracle Enterprise Manager, providing an intuitive, familiar interface.
Backup encryption to tape.
Broad tape-device support for new and legacy tape devices in SAN and SCSI environments.
Network Data Management Protocol (NDMP) support for highly efficient backup of NAS filers.
Scalable, low-cost licensing model reduces IT costs and operational considerations.
Data Recovery Advisor is a new feature in Oracle Database 11g that automatically diagnoses persistent (on disk) data failures, presents appropriate repair options, and runs repair operations at your request.
Note:The initial release of Data Recovery Advisor does not support Oracle RAC. In addition, while you can use Data Recovery Advisor when managing a primary database in a Data Guard configuration, you cannot use Data Recovery Advisor to troubleshoot a physical standby database. Data Recovery Advisor only takes the presence of a standby database into account when recommending repair strategies if you are using Enterprise Manager 11g Grid Control.
Data Recovery Advisor includes the following functionality:
Failure Diagnosis
The first symptoms of database failure are usually error messages, alarms, trace files and dumps, and failed health checks. Assessing these symptoms can be complicated, error-prone and time-consuming. Data Recovery Advisor automatically diagnoses data failures and informs you about them.
Failure Impact Assessment
After a failure is diagnosed, you must understand its extent and assess its impact on applications before devising a repair strategy. Data Recovery Advisor automatically assesses the impact of a failure and displays it in a easily understood format.
Repair Generation
Typically, Data Recovery Advisor presents several repair options, offering trade-offs in recovery time and potential data loss. If there are multiple failures present, you must also determine the best sequence of repair steps. In some situations it can be advantageous to consolidate repairs. Data Recovery Advisor does all this for you, automatically determining the best repair options.
Repair Feasibility Checks
Before presenting repair options, Data Recovery Advisor validates them with respect to the specific environment and availability of media components required to complete the proposed repair. The feasibility check is fast and validates if the required backups are available. The actual contents of these backups will be validated during repair.
Repair Automation
If you accept the suggested repair option, Data Recovery Advisor automatically performs the repairs, verifies that the repair was successful, and closes the appropriate failures.
Validation of Data Consistency and Database Recoverability
Data Recovery Advisor can validate the consistency of your data, and backups and redo stream, whenever you choose.
Early Detection of Corruption
Through Health Monitor, you can schedule periodic runs of Data Recovery Advisor diagnostic checks to detect, analyze, and repair data failures before a database process executing a transaction discovers the corruption and signals an error. Early warnings can limit the damage caused by corruption.
Integration of Data Validation and Repair
Data Recovery Advisor is a single tool for data validation and repair.
See Also:"Diagnosing and Repairing Failures with the Data Recovery Advisor" in Oracle Database Backup and Recovery User's Guide
The flash recovery area is a unified storage location for all recovery-related files and activities in Oracle Database. After this feature is enabled, all RMAN backups, archived redo logs, control file autobackup ��s, and data file copies are automatically written to a specified file system or automatic storage management disk group, and the management of this disk space is handled by RMAN and the database server.
Performing a backup to disk is faster because using the flash recovery area eliminates the bottleneck of writing to tape. More importantly, if database media recovery is required, then data file backups are readily available. Restoration and recovery time is reduced because you do not need to find a tape and a free tape device to restore the needed data files and archived redo logs.
The flash recovery area provides the following benefits:
Unified storage location of related recovery files
Management of the disk space allocated for recovery files, which simplifies database administration tasks
Fast, reliable disk-based backup and restoration
Ability to backup and restore the entire flash recovery area
Ability to tolerate failures to the flash recovery area
The best protection against human errors is to prevent their occurrence. The best way to prevent human errors is to restrict user access to only those data and services truly needed to perform business functions. Oracle provides a wide range of security tools to control access to application data by authenticating database users and then enabling administrators to grant them only those privileges required to perform their duties.
In addition, the Oracle Database security model provides the ability to restrict data access at a row level using Virtual Private Database, thereby further isolating database users from data that they do not need to access.
Oracle security features include the following benefits:
Authentication control to validate the identities of entities using networks, databases, and applications. Network sessions between databases, such as redo transport sessions, are also authenticated.
Authorization control to provide limits to access and actions linked by database user identities and roles.
Access control to objects, providing protection regardless of the entity seeking to access or alter them.
Auditing control to monitor and gather data about specific database activities, investigate suspicious activity, deter users (or others) from inappropriate activities, and detect problems with authorization or access control implementation.
Security policy management using profiles.
Encryption of data residing in the database and backups, or transferred to and from databases.
Oracle log files contain useful information about the activities and history of the Oracle database. Log files contain all data necessary to perform database recovery, and also record all changes made to the data and metadata in the database.
LogMiner is a fully relational tool that allows redo log files to be read, analyzed, and interpreted using SQL. Using LogMiner, you can analyze log files to:
Track or audit changes to data
Provide supplemental information for tuning and capacity planning
Retrieve critical information for debugging complex applications
Recover deleted data
Provide additional browser-based simplification to help troubleshoot and resolve logical failures
LogMiner features include:
Pinpointing when a logical corruption to the database—such as errors made at the application level—may have occurred
Determining the necessary actions to perform fine-grained recovery at the transaction level
Providing performance tuning and capacity planning through trend analysis
Performing post auditing
See Also:Oracle Database Utilities
The Hardware Assisted Resilient Data (HARD) Initiative is an initiative between Oracle and hardware vendors to prevent data corruptions from being written out to disk. Data corruption is very rare, but when it happens, it can have a catastrophic effect on a database, and therefore a business.
Under the HARD Initiative, Oracle works with selected system and storage vendors to build operating system and storage components that can detect corruption early and prevent corrupted data from being written to disk. The key approach is block checking where the storage subsystem validates the Oracle block contents.
Any data files and log files located on HARD-compliant storage is protected. You must also enable the HARD validation feature on the storage, using the vendor-provided interface. When Oracle writes data to the storage, the storage system validates the data. If the data appears to be corrupted, then the write is either rejected with an error, or it is accepted with an error logged by the storage in the internal logs.
Storage vendors may choose to implement some or all of the checks in their implementation. Also, each vendor's implementation is unique and their control interfaces may have different features.
See Also:The HARD initiative page for the latest vendor and implementation information at
Before Oracle Database 11g, block corruptions detected by RMAN were recorded in
V$DATABASE_BLOCK_CORRUPTION. In Oracle Database 11g, several database components and utilities in addition to RMAN can detect a corrupt block and record it in that view. Oracle Database automatically updates this view when block corruptions are detected or repaired (for example, using block media recovery or data file recovery). The benefit is that the time it takes to discover block corruptions is shortened.
In addition, you can use the
DB_ULTRA_SAFE initialization parameter to automatically configure the appropriate data protection block checking level in the database. The performance impact may vary depending on the application and available system resources, but the effect can vary from 1% to 10%.
DB_ULTRA_SAFE initialization parameter:
Controls the setting of other related initialization parameters, including
DB_BLOCK_CHECKSUM, and
Controls other data protection behavior in the Oracle Database, such as requiring ASM to perform sequential mirror writes
By making it possible to detect data corruptions in a timely manner, these features provide critical high availability benefits for the Oracle database.
See Also:Oracle Database Reference for more information about these views and initialization parameters
Oracle provides high availability solutions to prevent, tolerate and reduce downtime for all types of unplanned failures.
Table 2-1 describes the various Oracle high availability solutions for unplanned downtime along with the recovery time that can be attained with each solution. The table shows how the features discussed in Section 2.1.1 through Section 2.1.14 can be used to address various causes of unplanned downtime. Also, see Table 4-4 for a summary of the attainable recovery times for all types of unplanned downtime for each Oracle high availability architecture.
Table 2-1 Outage Types and Oracle High Availability Solutions for Unplanned Downtime
|Outage Scope
|Oracle Solution
Site Failures
Site Failures
Site Failures
Computer Failures
Oracle Real Application Clusters and Oracle Clusterware
Computer Failures
Computer Failures
Computer Failures
Storage Failures
Storage Failures
Storage Failures
Storage Failures
Data Corruption
Hardware Assisted Resilient Data (HARD) Initiative
Data Corruption
Data Block Corruption Prevention and Detection Parameters
Database initialization settings such as
Data Corruption
Data Recovery Advisor and Recovery Manager with Flash Recovery Area
Data Corruption
Data Corruption
Human Errors
Human Errors
Human Errors
Lost writes
Oracle Data Guard, Recovery Manager, and the
Also, setting
Lost writes
Hardware Assisted Resilient Data (HARD) Initiative
Hangs or slow down
Oracle Database and Oracle Enterprise Manager
Planned downtime can be just as disruptive to operations as unplanned downtime. This holds especially true for global enterprises that need to support users in multiple time zones, or for those that need to provide Internet access to customers 24 hours a day, seven days a week.
In the past, planned downtime became necessary when performing periodic maintenance or when migrating to new deployments. Periodic maintenance—such as patching or reconfiguring the system—may be necessary to update the database, application, operating system, middleware, or network. New deployments include major upgrades or new rollouts of the hardware, database, application, operating system, middleware, or network.
Oracle provides the following high availability solutions to eliminate or reduce planned downtime for system and database changes, data changes, and application changes:
For system and database changes, see Dynamic Resource Provisioning
For data changes, see Online Reorganization and Redefinition
For application changes, see Online Application Maintenance and Upgrades
This section describes dynamic resource provisioning under the following topics:
Automated Distribution of Data files, Control Files, and Log Files
Oracle continues to broaden support for dynamic reconfiguration of the database, enabling it to adapt to changes in hardware demands without any service interruptions. Oracle Database dynamically accommodates various changes to hardware and database configurations:
Add and remove processors from an SMP server
Add and remove nodes and instances in an Oracle RAC environment
Dynamically grow and shrink its shared memory allocation and automatically tune memory online using Automatic Shared Memory Management
Add and remove database disks online without disturbing database activities using Automatic Storage Management (ASM)
Add and remove storage arrays online without disturbing database activities using ASM
Automatically rebalance the I/O load across the database storage using ASM
Move data files online when adding or dropping disks using ASM, which automatically rebalances database storage whenever the storage configuration is changed
Change almost all initialization parameters without shutting down the instance by using the SQL*Plus
ALTER SESSION statement to change the value of a parameter during a session, or the
ALTER SYSTEM statement to change the value of a parameter in all sessions of an instance for the duration of the instance
These capabilities provide no-cost system changes and capacity on-demand provisioning, both of which are fundamental requirements of enterprise Grid computing.
Beginning with Oracle Database 11g two memory management initialization parameters,
MEMORY_TARGET and
MEMORY_MAX_TARGET enable automatic management of the system global area (SGA), program global area (PGA), and other memory required to run Oracle Database.
MEMORY_MAX_TARGET is the value up to which
MEMORY_TARGET can grow dynamically. If these initialization parameters are left at their default values (
0), then Oracle Database does not autotune memory. If one parameter is set to a nonzero value and other is not set, then Oracle Database internally sets both parameters to the nonzero value.
Oracle Database uses a noncentralized policy to free and acquire memory in each subcomponent of the SGA and the PGA. Oracle Database autotunes memory by prompting the operating system to transfer granules of memory from less needy to more needy components. The granularity of the memory transfer is dependent on the current free memory and the amount of memory the operating system requires to maintain a basic level of service.
Note:Automatic memory management with the
MEMORY_TARGET and
MEMORY_MAX_TARGET initialization parameters is supported on Linux, Windows, Solaris, HP-UX, and AIX. See the Oracle Database Concepts and Oracle Database Administrator's Guide for more information about all supported platforms.
ASM automates and simplifies the layout of data files, control files, and log files. Database files are automatically distributed across all available disks. Database storage is rebalanced whenever the storage configuration changes, including adding and removing disks or storage arrays. ASM provides redundancy through the mirroring of database files, and provides optimal performance by automatically striping database files across available disks.


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Expect high temperatures this afternoon in the low 60s with a 30 percent chance of afternoon thunderstorms. Saturday will be warmer, but there is still a chance for our typical afternoon spring storm. Sunday is shaping up nicely, mostly dry with temperatures in the 80s.
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text: The New Era Introducing 2011 gallery tour recently kicked off at Shoreditch Underground in the heart of East London. The private launch celebrated, among others, the work of Linda Al Amoudi, the creative mind behind this year's winning entry. The tour will continue to make its way across Europe, the Middle East and Africa, offering attendees the chance to view the elaborate displays in person.


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There is but one therapeutic agency in the treatment of tuberculosis that has stood the test of all time, and that is rest. For many years the technic of rest has been studied and notable contributions to it have come into general use. A few are in the developmental stage and deserve study and trial in well selected cases. The five methods in addition to rest in bed which have been proposed for producing relative immobilization of all or part of one side of the lungs are: (1) (a) Postural rest, lying twenty-three and one-half hours a day on the affected side in one-sided cases, advocated by Webb. (b) Sand bags on the affected part (Sewell), giving, to less degree, the same result. (2) Section of the phrenic nerve in the neck on the affected side, causing paralysis of one half of the diaphragm
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Where do I get a Budget Revision Form?
Budget Revision Forms may be downloaded to your computer or complete the form on-line and print for signature (See Forms).
When do I need to use a Budget Revision Form?
Budget Revision Forms should be used (1) to temporarily change this year's budget to reflect current needs or (2) to make a permanent change to this year's base budget.
What are the Budget Revision time lines?
Departmental budget dollars may be moved between account codes within an index anytime during the fiscal year until June 30. Departments have complete control of how funds are budgeted within their index except for funds in benefits (account code 62000) and longevity (account codes 61120, 61220, 61620, and 61320). Benefits and longevity are budgeted centrally and can not be used by departments to cover other types of expenses. Funds may be moved between accounts anytime during the year with one exception. After March 31st each year the Spring Estimated Budget is finalized and educational and general functional totals are frozen according to Tennessee Board of Regents Policy 4:01:00:00.
Official Budget documents are submitted to the Tennessee Board of Regents in July and October of each year. The July submission contains both the Proposed Budget for the upcoming fiscal year and the final Estimated Budget for the current fiscal year.
Why are Functional Totals frozen?
Each spring the final current year budget is submitted along with the proposed budget for the next fiscal year. It contains the education and general control totals against which final year-end amounts are compared. After this submission, education and general functional totals are frozen. Tennessee Board of Regents Policy 4:01:00:00 states that "once approved the institution may not exceed those functional control limits established by the Board without prior approval of the Chancellor". During the year end closing process, functional expenditure totals are analyzed for adherence to the approved control levels. The financial information is examined for compliance with all budget guidelines and/or Board policies in effect for the fiscal year just completed. The Chancellor reports any institutional and school deficiencies or non-compliance with budget controls and guidelines to the Board.
How do I obtain a new account number?
New indexes must be obtained from and set up by Accounting Services. Please contact their office @2940 for further information. The Budget Office does not issue new indexes. Budget entries can only be made to active indexes.
How do I obtain a new position number?
Position numbers, except for Grants, may be obtained by sending an e-mail to firstname.lastname@example.com with the following information:
Positions may also be obtained by calling the Budget Office at ext. 5790. However, please review "What type of position do I need?" before contacting the office. Positions for Grant Accounts should still be requested through the Sponsored Programs office. New full time positions must still be approved through the budget process before they can be advertised and filled.
What type of position do I need?
There are several considerations to determine the type of position number required for a particular employee(s). All of the following must be determined before a position number can be set up:
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Only a few days remain before his company, Lustig Dance Theatre, presents the premiere of "Jangala;" and the director wants to make sure everything is in order.
The list seems unusual for a dance concert, but then, so is the cast. The props include four trampolines for the monkeys in the disco scene. Check. And the dancers require helmets for the buffalo stampede. Check.
The monkeys and the buffalo have special needs, but they aren't the only animals in "Jangala," an elaborate dance production inspired by Rudyard Kipling's famous stories in "The Jungle Book." A pack of wolves also is essential. They're the ones who adopt the man-cub, Mowgli, when the child is lost. Then there's Shere-Khan, the villainous Bengal tiger who does everything he can to kill Mowgli and eat him. Shere-Khan comes to a bad end, trampled underfoot by the buffalo—but not before the whole cast strikes a pose and sways to the seductive rhythms of an Indian raga.
Lustig says his version of the story isn't as syrupy as the Disney film. In "Jangala," the whole story is told through dance. Children ages 7 and older are still the target audience, however. Coincidentally, Lustig says he was about 7 years old when he first became immersed in "Jungle Book" lore. As a Cub Scout in his native England, he learned how to tie knots, light a fire and help old ladies cross the street. Meanwhile, the Scout leaders and den mothers all took their names from Kipling's characters.
As an adult, the choreographer's perspective grew more sophisticated. Creating "Jangala," he decided to transpose the action of "The Jungle Book" from its original setting to a modern city, with its discos, construction sites and junk yards inhabited by feral dogs. This urban jungle can be a dangerous place, he says. "In our society, there are still those that are hunted and those that are the hunters."
To acknowledge the story's Indian roots, Lustig has teamed up with Renuka Srinivasan, who teaches classical Indian Bharata Natyam at her Tala Shruti school in Fords. Srinivasan introduced Lustig and his company to a sacred dance vocabulary that is thousands of years old—intricately coordinated hand gestures and facial expressions, accompanied by rhythmic stamping. "It is so exquisite," Lustig says, adding, "We're learning to dance with our eyes."
The choreographer fused these elements with his own contemporary inventions, and with Bhangra, the Punjabi folk dance that became a pop sensation. Srinivasan has lent the company one of her star pupils, Shobana Natarajan, a guest artist who will play Mowgli's human mother, Messua. Natarajan's dancing gives the production "an aura of authenticity," Lustig says.
"Jangala" (the word means "jungle" in Hindi) is also Lustig's latest attempt to expand the audience for his work, following overtures to the Latino community with a dance called "Luna Mexicana," and to the Irish, with "Invisible Fields."
"I am so totally hoping to embrace the Indian community," he says.
Robert Johnson: email@example.com


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Southeastern workers looking to improve their economic outlook may have been disheartened by a recently released Harvard study.
The report from the Equality of Opportunity Project received a good deal of attention for its data and its interactive maps and graphics at the project website www.equality-of-opportunity.org, as well as an interactive map on the New York Times website. The fairly stark imagery shows that it's difficult to move too far up the economic ladder in much of the country.
Of course, there's more to the data than meets the eye, said Von Bakanic associate professor of sociology at the College of Charleston.
In terms of social mobility, it's much easier to go up one or two steps than to make a move from the bottom to the very top of the economic ladder, she said. And if you live someplace where the median income is very low, it doesn't take much to move up.
"It's a different scale from the bottom to the top in the Dakotas than it is in New York or California," she said.
A difficult road
Among the 50 biggest cities, none in the Southeast rank among the top 10 for mobility, but Southeastern cities appear four times on the list of the bottom 10.
In other words, people in Atlanta, Raleigh, Charlotte, or Jacksonville, Fla., have a slimmer chance of moving from the bottom fifth to the top fifth of the economic ladder than their counterparts in Seattle, Pittsburgh or Boston.
Bakanic says yes, we've had more poverty in the American Southeast than in other parts of the country, but you can move out of poverty, if the right job structure is in place.
The recent fast-food worker strikes have drawn renewed attention to the problems of minimum wage employment.
"We're not really paying the lowest rung on our employment ladder enough to support them and their families," Bakanic said. What that leads to, in effect, is government subsidization of those workers through food stamps and publicly funded health care, she added. So finding a way to increase the minimum wage should be of interest to folks on all parts of the political spectrum.
Well-paid jobs
"It would be better for the economy if we had well-paid working class jobs," by which she means things like production, maintenance and transportation of goods.
Which highlights the importance of BMW in Greenville and the port and Boeing in the Charleston region, because they provide those kinds of jobs and corresponding wages.
That's the key. It's not just job creation, it's creation of more jobs at a higher level of pay, she said.
Even Friday's jobless report held a few bright spots, such as the increase in college enrollment among those who have left the workforce or who have yet to enter. That will lead to a better educated workforce that's better prepared to fill those better-paying jobs that can lead to more social mobility and a better way of life.
Go to postandcourier.com for the study summary and a link to the interactive graphics.


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"Martin Bailey"
wrote on 04 loka 2004:
> My T3 screen has suddenly, and for no apparent reason, become
> darker than it was. It's just a month old and although still easy
> to see, it has changed and I have not changed any settings.
> Any ideas why this may have changed?
My T2 started doing this a couple months back -- as if the backlight
just died. Occasionally it comes back just by shaking the T2 a little.
Probably some kind of connector trouble inside, maybe in the power
feed to backlight or something.
Samy Merchi | firstname.lastname@example.com | http://www.iki.fi/samy | #152235689
Reader of superhero comic books, writer of superhero fanfiction


text:
Six area businesses are encouraging people to come out from 10 a.m. to 2 p.m. Saturday to shop in the event dubbed the first annual Tiffin Shop Hop.
Those who want to partake can pick up a card at the following participating shops: Neumeister's Candy Shop, Threads, Mercy Tiffin Hospital Gift Shop, Maurices, Angie's Boutique or Scrap Happy.
Customers are to try to get a card stamped at each store for a chance to enter into a drawing for the grand prize of $150 in combined store products. The drawing is 11 a.m. Monday at Angie's Boutique, 40 Fair Lane.
"We started talking about it a year ago with Angie's Boutique," Threads owner Kelli Dariano said. "I think the stores appeal to the same customer base."
Threads, Scrap Happy and Neumeister's are located at Wolf Creek Plaza, 2449 W. Market Street and Maurices is at the Tiffin Mall, 870 W. Market St.
"It will be a nice time before the kids go back (to school)," Neumeister's owner Diana Hoover said. "Why not spend four hours and do something fun."
Neumeister's moved to Tiffin last fall.
"We had a nice customer base in Tiffin so we decided to move here," Hoover said. "We are even telling our Upper (Sandusky) customers about it."
Hoover, who has owned the Upper Sandusky store for more than a dozen years, said this is her first time being in this type of event.
"We strongly encourage activities like this when people get together and do collaborative marketing," Seneca Regional Chamber of Commerce and Visitor Services CEO and President John Detwiler said. "It's an opportunity for people to go in and see what they have to offer."
Stores also are offering discounts Saturday.


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The graduate students of the American Studies, African American Studies and History Departments at Yale University invite submissions for the upcoming conference- Pathways: A Graduate Conference on American Indian Studies to be held April 23-25, 2004. The purposes of this conference are: to provide a comfortable forum for graduate students working within some aspect of American Indian Studies (AIS) to share their work with one another, to foster student-to-student and student-to-professional relationships by encouraging networking and community-building for those working within AIS, to educate graduate students working in AIS about the process of professionalization through traditional and alternate career paths at colleges, universities, libraries, museums, tribal/national institutions, and non-profit organizations, to collaborate with undergraduates and members of local communities on issues pertinent to American Indian people and AIS, and to discuss, assess, and actively shape the future of AIS as a field. We are very pleased to announce that Devon Mihesuah (Choctaw), noted historian and professor of Applied Indigenous Studies at Northern Arizona University, will be our keynote speaker. Professor Mihesuah is the editor of American Indian Quarterly, and has authored and edited numerous books, including Cultivating the Rosebuds: The Education of Women at the Cherokee Female Seminary, 1851-1909 (1993), Natives and Academics: Researching and Writing about American Indians (1998), Indigenous North American Women: Decolonization, Empowerment, Activism
(2003), and Indigenizing the Academy: Native Scholars and Scholarship
on Natives (forthcoming sequel to Natives and Academics).
Graduate student papers are invited on any topic within American Indian Studies from any disciplinary approach. Preference will be given to explicitly interdisciplinary work. We are especially desirous of papers that demonstrate and discuss emergent approaches in AIS, and/or those that demonstrate an active involvement with American Indian communities. In order to foster a regionally diverse community of graduate student presenters, travel expenses will be paid for students whose papers are selected.
Abstracts of 500 words should be mailed by October 15, 2003 to the address below. E-mail by attachment or in the body of the message to the address below.
Pathways is sponsored by The Beinecke Rare Book and Manuscript Library- Western Americana Collection, The Howard R. Lamar Center for the Study of Frontiers and Borders at Yale University, The Graduate School of Arts and Sciences, and The Association of Native Americans at Yale.


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Also, respect to the Pro Patria fans who applauded him off the pitch and condemned the racist minority.
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- Donald Trump's home near Washington, DC has security cameras inside and out, monitored from New York, insiders say.
- The hair vitamins promoted by the Kardashians make "largely inaccurate" nutrient claims, according to lab tests.
- Donald Trump accused former Miss Universe Alicia Machado of being in a sex tape, calling her "disgusting." He's appeared in a softcore porn.


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Mr. and Mrs. Robert Klotz, Linden, observed their 25th wedding anniversary Feb. 14, 2012.
They were married by the Rev. George Dippel at the Church of Jesus Christ of Latter-Day Saints, Bloomsburg.
Mrs. Klotz, the former Pamela Joan Wells, is a native of Williamsport. She is the daughter of Joan and Melvin Wells, South Williamsport. She graduated from South Williamsport Area High School in 1973. She also graduated from St. Vincent School of Nursing, Erie, in 1983 and Pennsylvania College of Technology in 2006. She is employed by the State Department of Health as a registered nurse.
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Mr. Klotz, a native of Williamsport, is the son of the late Rosella and Herbert Klotz. He graduated from South Williamsport Area High School and retired from Kaverner Willfab in 2007. They are the parents of four sons, Bryan, Montoursville; Mark Milford, Erie; Matthew Milford, Indiana; and Michael Milford, Pittsburgh; and a daughter, Wendy Ashton, South Williamsport.
There are eight grandchildren.
In honor of their anniversary, a cruise to the Virgin Islands is being planned for March.