Cluster Network Driver

The Cluster Network Driver, CLUSNET.SYS, is a software component that is responsible for:

• Providing highly available communication by monitoring the status of all network paths between nodes and routing messages over the path determined to be the best.
• Detecting the failure of a node by maintaining communication between nodes through the use of periodic messages called heartbeats.

Heartbeats are sent to every node in the cluster and are also exchanged over all network paths between nodes. They are used to monitor the health of a network link and to detect node failure. If a node fails to respond to a heartbeat message or voluntarily leaves the cluster, the Cluster Network Driver notifies the Membership Manager and Node Manager. These Cluster Service components initiate an operation known as regrouping to take the inactive node offline and cancel its membership in the cluster. When the Failover Managers on the surviving nodes learn that a node has failed, they cooperate to redistribute any groups that were hosted by that node.