Installation guide

Note
Make sure to configure other parameters that may be affected by changes in this section. Refer
to Section 5.1, “Configuration Tasks”.
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. T he
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. 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 a failover domain, removing a failover domain, and removing
members from a failover domain:
Red Hat Enterprise Linux 4 Cluster Administration
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