Installation guide

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.
Failback — Allows you to specify whether a service in the failover domain should fail back to the
node that it was originally running on before that node failed. Configuring this characteristic is
useful in circumstances where a node repeatedly fails and is part of an ordered failover domain.
In that circumstance, if a node is the preferred node in a failover domain, it is possible for a
service to fail over and fail back repeatedly between the preferred node and another node,
causing severe impact on performance.
Note
The failback characteristic is applicable only if ordered failover is configured.
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 can 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, modifying, and deleting a failover domain:
⁠Chapt er 3. Configuring Red Hat Hig h Availabilit y Add- O n Wit h Conga
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