2.3. Configuring Cluster Components
2.3. Configuring Cluster Components To configure the components and attributes of a cluster, click on the name of the cluster displayed on the Manage Clusters screen. This brings up the Nodes page, as described in Section 2.3.1, "Cluster Nodes" . This page displays a menu along the top of the page, as shown in Figure 2.3, "Cluster Components Menu" , with the following entries: Nodes , as described in Section 2.3.1, "Cluster Nodes" Resources , as described in Section 2.3.2, "Cluster Resources" Fence Devices , as described in Section 2.3.3, "Fence Devices" ACLs , as described in Section 2.3.4, "Configuring ACLs" Cluster Properties , as described in Section 2.3.5, "Cluster Properties" Figure 2.3. Cluster Components Menu 2.3.1. Cluster Nodes Selecting the Nodes option from the menu along the top of the cluster management page displays the currently configured nodes and the status of the currently selected node, including which resources are running on the node and the resource location preferences. This is the default page that displays when you select a cluster from the Manage Clusters screen. You can add or remove nodes from this page, and you can start, stop, restart, or put a node in standby mode. For information on standby mode, see Section 4.4.5, "Standby Mode" . You can also configure fence devices directly from this page, as described in Section 2.3.3, "Fence Devices" . by selecting Configure Fencing . 2.3.2. Cluster Resources Selecting the Resources option from the menu along the top of the cluster management page displays the currently configured resources for the cluster, organized according to resource groups. Selecting a group or a resource displays the attributes of that group or resource. From this screen, you can add or remove resources, you can edit the configuration of existing resources, and you can create a resource group. To add a new resource to the cluster, click Add . The brings up the Add Resource screen. When you select a resource type from the dropdown Type menu, the arguments you must specify for that resource appear in the menu. You can click Optional Arguments to display additional arguments you can specify for the resource you are defining. After entering the parameters for the resource you are creating, click Create Resource . When configuring the arguments for a resource, a brief description of the argument appears in the menu. If you move the cursor to the field, a longer help description of that argument is displayed. You can define as resource as a cloned resource, or as a master/slave resource. For information on these resource types, see Chapter 9, Advanced Configuration . Once you have created at least one resource, you can create a resource group. For information on resource groups, see Section 6.5, "Resource Groups" . To create a resource group, select a resource that will be part of the group from the Resources screen, then click Create Group . This displays the Create Group screen. Enter a group name and click Create Group . This returns you to the Resources screen, which now displays the group name for the resource. After you have created a resource group, you can indicate that group name as a resource parameter when you create or modify additional resources. 2.3.3. Fence Devices Selecting the Fence Devices option from the menu along the top of the cluster management page displays Fence Devices screen, showing the currently configured fence devices. To add a new fence device to the cluster, click Add . The brings up the Add Fence Device screen. When you select a fence device type from the drop-down Type menu, the arguments you must specify for that fence device appear in the menu. You can click on Optional Arguments to display additional arguments you can specify for the fence device you are defining. After entering the parameters for the new fence device, click Create Fence Instance . For information on configuring fence devices with Pacemaker, see Chapter 5, Fencing: Configuring STONITH . 2.3.4. Configuring ACLs Selecting the ACLS option from the menu along the top of the cluster management page displays a screen from which you can set permissions for local users, allowing read-only or read-write access to the cluster configuration by using access control lists (ACLs). To assign ACL permissions, you create a role and define the access permissions for that role. Each role can have an unlimited number of permissions (read/write/deny) applied to either an XPath query or the ID of a specific element. After defining the role, you can assign it to an existing user or group. 2.3.5. Cluster Properties Selecting the Cluster Properties option from the menu along the top of the cluster management page displays the cluster properties and allows you to modify these properties from their default values. For information on the Pacemaker cluster properties, see Chapter 12, Pacemaker Cluster Properties .