C.4.6 Sun Cluster HA for SAP Fault Probes

The Sun Cluster HA for SAP fault probe monitors the availability of the Central Instance, specifically the message server, the enqueue server, and the dispatcher. The probe monitors only the local node by checking for the existence of the critical SAP processes. It also uses the SAP utility lgtst to verify that the SAP message server is reachable.

Upon detecting a problem, such as when a process dies prematurely or lgtst reports an error, the fault probe will first try to restart SAP on the local node for a configurable number of times (configurable through hadsconfig(1M)). If the number of restarts that the user has configured has been exhausted, then the fault probe initiates a switchover by calling hactl(1M), if this instance has been configured to allow failover (also configurable through hadsconfig(1M)). The Central Instance is shut down before the switchover occurs, and then is restarted on the remote node after the switchover is complete.