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3.7. Configuring a Failover Domain

A failover domain is a named subset of cluster nodes that are eligible to run a cluster service in the event of a node failure. A failover domain can have the following characteristics:


Changing a failover domain configuration has no effect on currently running services.


Failover domains are not required for operation.
By default, failover domains are unrestricted and unordered.
In a cluster with several members, using a restricted failover domain can minimize the work to set up the cluster to run a cluster service (such as httpd), which requires you to set up the configuration identically on all members that run the cluster service). Instead of setting up the entire cluster to run the cluster service, you must set up only the members in the restricted failover domain that you associate with the cluster service.


To configure a preferred member, you can create an unrestricted failover domain comprising only one cluster member. Doing that causes a cluster service to run on that cluster member primarily (the preferred member), but allows the cluster service to fail over to any of the other members.
The following sections describe adding, modifying, and deleting a failover domain:

3.7.1. Adding a Failover Domain

To add a failover domain, follow the steps in this section.
  1. From the cluster-specific page, you can configure Failover Domains for that cluster by clicking on Failover Domains along the top of the cluster display. This displays the failover domains that have been configured for this cluster.
  2. Click Add. Clicking Add causes the display of the Create a Failover Domain window, as shown in Figure 3.7, “luci failover domain configuration page”.
    luci failover domain configuration page
    The luci failover domain configuration page.
    Figure 3.7. luci failover domain configuration page

  3. In the Create a Failover Domain window, specify a failover domain name at the Name text box.


    The name should be descriptive enough to distinguish its purpose relative to other names used in your cluster.
  4. To enable setting failover priority of the members in the failover domain, click the Prioritized checkbox. With Prioritized checked, you can set the priority value, Priority, for each node selected as members of the failover domain.
  5. To restrict failover to members in this failover domain, click the Restricted checkbox. With Restricted checked, services assigned to this failover domain fail over only to nodes in this failover domain.
  6. To specify that a node does not fail back in this failover domain, click the No Failback checkbox. With No Failback checked, if a service fails over from a preferred node, the service does not fail back to the original node once it has recovered.
  7. Configure members for this failover domain. Click the Member checkbox for each node that is to be a member of the failover domain. If Prioritized is checked, set the priority in the Priority text box for each member of the failover domain.
  8. Click Create. This displays the Failover Domains page with the newly-created failover domain displayed. A message indicates that the new domain is being created. Refresh the page for an updated status.