The <rm> tag in the CMAN configuration file usually begins with the definition of a failover domain, but configuring a failover domain is not required for normal operation of the cluster.
A failover domain is a set of cluster nodes with configured failover rules. The failover domain is attached to the cluster service configuration; in the event of a cluster node failure, the configured cluster service's failover domain rules are applied.
Failover domains are configured within the <rm> RGManager tag. The failover domain configuration begins with the <failoverdomains> tag and ends with the </failoverdomains> tag. Within the <failoverdomains> tag, you can specify one or more failover domains in the following form:
<failoverdomain failoverdomainname failoverdomain_options> </failoverdomain>