What is Cluster Manager (cman)?
It depends on which version of the code you are running. Basically, cluster manager is a component of the cluster project that handles communications between nodes in the cluster. In the latest cluster code, cman is just a userland program that interfaces with the OpenAIS membership and messenging system. In the previous versions, cman was a kernel module whose job was to keep a “heartbeat” message moving throughout the cluster, letting all the nodes know that the others are alive. It also handles cluster membership messages, determining when a node enters or leaves the cluster.
