Reference Guide

Understanding Your Failover Cluster 49
Configuring Group Affinity
On N + I (active/passive) Failover Clusters running Windows Server 2008,
some resource groups may conflict with other groups if they are running on
the same node. For example, running more than one Microsoft Exchange
virtual server on the same node may generate application conflicts. Use
Windows Server 2008 to assign a public property (or attribute) to a
dependency between groups to ensure that they failover to similar or separate
nodes. This property is called group affinity.
Group affinity uses the AntiAffinityClassNames public property,
which ensures that designated resources are running on separate nodes, if
possible.
For example, in Table 4-5, the AntiAffinityClassNames string for
cluster resource group A and group B are identical (AString), which indicates
that these groups are assigned to run on separate nodes, if possible. If node 1
fails, resource group A fails over to the next backup node (node 7). If node 2
then fails, because their AntiAffinityClassNames string value
(AString) identifies group A and group B as conflicting groups, group B
skips node 7 and instead fails over to node 8.
To set the public property for the cluster groups shown in Table 4-5:
1
Open a command prompt.
2 Type the following:
cluster group "A" /prop AntiAffinityClassNames=
"AString"
3 Repeat step 2 for the remaining cluster groups.
To specify group affinity in your N + I cluster configuration, use the Cluster
Data Form in the Dell Failover Cluster Hardware Installation and
Troubleshooting Guide for the specific storage array on the Dell Support
website at support.dell.com.
Failover Pair
Failover pair is a policy in which each application can failover between two
specific nodes in a multinode cluster. The Possible Owners list in Cluster
Administrator determines which nodes run the failed over applications.