To ensure that data is kept safe from corruption, all nodes must reach a consistent agreement on the cluster membership. When necessary, the CMM coordinates a cluster reconfiguration of cluster services (applications) in response to a failure.
The CMM receives information about connectivity to other nodes from the cluster transport layer. The CMM uses the cluster interconnect to exchange state information during a reconfiguration. A problem called split brain can occur when the cluster interconnect between cluster nodes is lost and the cluster becomes partitioned into subclusters, and each subcluster believes that it is the only partition. A subcluster that is not aware of the other subclusters could cause a conflict in shared resources, such as duplicate network addresses and data corruption. The quorum subsystem manages the situation to ensure that split brain does not occur, and that one partition survives. For more information, see Quorum and Quorum Devices.
After detecting a change in cluster membership, the CMM performs a synchronized configuration of the cluster. In a synchronized configuration, cluster resources might be redistributed, based on the new membership of the cluster.