Heartbeating over TCP/IP and disk

A heartbeat is a type of a communication packet that is sent between nodes. Heartbeats are used to monitor the health of the nodes, networks and network interfaces, and to prevent cluster partitioning.

In order for a PowerHA® SystemMirror® cluster to recognize and respond to failures, it must continually check the health of the cluster. Some of these checks are provided by the heartbeat function.

Each cluster node sends heartbeat messages at specific intervals to other cluster nodes, and expects to receive heartbeat messages from the nodes at specific intervals. If messages stop being received, PowerHA SystemMirror recognizes that a failure has occurred. Heartbeats can be sent over:

• TCP/IP networks
• A physical volume (disk) which is accessible from all clusters nodes

The heartbeat function is configured to use specific paths between nodes. This allows heartbeats to monitor the health of all PowerHA SystemMirror networks and network interfaces, as well as the cluster nodes themselves.

The heartbeat paths are set up automatically by RSCT; you have the option to configure disk paths as part of PowerHA SystemMirror configuration.