Performance planning for clusters
When changes are made to a cluster, the overhead necessary to manage the cluster can be affected.
The only resources that clustering requires are those necessary to perform heartbeat monitoring, to manage the cluster resource groups and the cluster nodes, and to handle any messaging taking place between cluster resource groups and cluster nodes. After your clustering environment is operational, the only increase in overhead is if you make changes to the cluster.
During a normal operating environment, clustering activity should have minimal effect on your clustered systems.