Installation guide

5.6. 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:
Unrestricted — Allows you to specify that a subset of members are preferred, but that a cluster
service assigned to this domain can run on any available member.
Restricted — Allows you to restrict the members that can run a particular cluster service. If none of
the members in a restricted failover domain are available, the cluster service cannot be started
(either manually or by the cluster software).
Unordered — When a cluster service is assigned to an unordered failover domain, the member on
which the cluster service runs is chosen from the available failover domain members with no
priority ordering.
Ordered — Allows you to specify a preference order among the members of a failover domain. The
member at the top of the list is the most preferred, followed by the second member in the list, and
so on.
Note
Changing a failover domain configuration has no effect on currently running services.
Note
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.
Note
To configure a preferred member, you can create an unrestricted failover domain comprising
only one cluster member. D oing 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 a failover domain, removing a failover domain, and removing
members from a failover domain:
Section 5.6.1, “Adding a Failover Domain”
Section 5.6.2, “ Removing a Failover Domain”
⁠Chapt er 5. Configuring Red Hat Clust er Wit h syst em- config- clust er
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