VCS Communications, Membership, and I/O Fencing

This chapter describes VCS communications and cluster membership. VCS uses local communications on a node and node-to-node communications.

In a VCS cluster, each node runs as an independent operating system and shares information at the cluster level. On each node, the VCS High Availability Daemon (HAD) maintains a view of the current cluster configuration. The daemon (also called the cluster engine) operates as a replicated state machine (RSM). The RSM design enables each node to participate in the cluster without the need of a shared data storage device for cluster configuration information.