Sun Cluster Overview for Solaris OS

Cluster Membership

The Cluster Membership Monitor (CMM) is a distributed set of agents that exchange messages over the cluster interconnect to complete the following tasks:

The main function of the CMM is to establish cluster membership, which requires a cluster-wide agreement on the set of nodes that participate in the cluster at any time. The CMM detects major cluster status changes on each node, such as loss of communication between one or more nodes. The CMM relies on the transport kernel module to generate heartbeats across the transport medium to other nodes in the cluster. When the CMM does not detect a heartbeat from a node within a defined timeout period, the CMM considers the node to have failed and the CMM initiates a cluster reconfiguration to renegotiate cluster membership.

To determine cluster membership and to ensure data integrity, the CMM performs the following tasks:

See Split Brain and Amnesia for more information about how the cluster protects itself from partitioning into multiple separate clusters.