The Cluster Membership Manager is implemented by the nhcmmd daemon. There is a nhcmmd daemon on each peer
node.
The nhcmmd daemon on the master node has the current
view of the cluster configuration and communicates its view to the nhcmmd daemons on the other peer nodes. The nhcmmd
daemon on the master node determines which nodes are members of the cluster,
assigns the roles and attributes to the nodes, detects the failure of nodes
and configures routes for reliable transport.
The nhcmmd daemon on the vice-master node monitors
the health of the master node. If the master node fails, the vice-master node
is able to take over as the master node.
The nhcmmd daemon on each of the peer nodes do not
communicate with each other. Each nhcmmd daemon exports
an API to the notify clients of changes to the cluster, and to notify services
and applications when the cluster membership or master changes. Notification
messages describe the membership change and the nodeid
of the affected node, making it possible for clients to maintain an accurate
view of the peer nodes of the cluster.
For information about the CMM API, see the Intro(3CMM) man page.