Tuning HA for SAP liveCache Fault Monitors

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Fault monitoring for the HA for SAP liveCache data service is provided by the following fault monitors:

The SAP liveCache fault monitor
The SAP xserver fault monitor

Each fault monitor is contained in a resource whose resource type is shown in the following table.

Table 3 Resource Types for HA for SAP liveCache Fault Monitors

Fault Monitor	Resource Type
SAP liveCache	`SUNW.sap_livecache`
SAP xserver	`SUNW.sap_xserver`

System properties and extension properties of these resources control the behavior of the fault monitors. The default values of these properties determine the preset behavior of the fault monitors. The preset behavior should be suitable for most Oracle Solaris Cluster installations. Therefore, you should tune the HA for SAP liveCache fault monitors only if you need to modify this preset behavior.

Tuning the HA for SAP liveCache fault monitors involves the following tasks:

Setting the interval between fault monitor probes
Setting the timeout for fault monitor probes
Defining the criteria for persistent faults
Specifying the failover behavior of a resource

For more information, see Tuning Fault Monitors for Oracle Solaris Cluster Data Services in Planning and Administering Data Services for Oracle Solaris Cluster 4.4. Information about the HA for SAP liveCache fault monitors that you need to perform these tasks is provided in the subsections that follow.

Tune the HA for SAP liveCache fault monitors when you register and configure HA for SAP liveCache. For more information, see Registering and Configuring the HA for SAP liveCache.

Factors That Affect the Interval Between Fault Monitor Probes

To determine whether SAP xserver and SAP liveCache are operating correctly, the HA for SAP liveCache fault monitors probe these resources periodically. The optimum interval between fault monitor probes depends on the time that is required to respond to a fault in a resource. This time depends on how the complexity of the resource affects the time that is required for operations such as restarting the resource.

Operations by the HA for SAP liveCache Fault Monitors During a Probe

The optimum timeout for fault monitor probes depends on the operations that a fault monitor performs to probe the resource.

Operations by the SAP liveCache Fault Monitor During a Probe

During a probe, the SAP liveCache fault monitor performs the following operations:

The SAP liveCache fault monitor determines whether SAP liveCache is online.
If liveCache is online, the SAP liveCache fault monitor determines whether the liveCache parent process is running.
If liveCache is not online, the SAP liveCache fault monitor determines whether a user stopped liveCache outside the control of Oracle Solaris Cluster.

A user can stop liveCache by using the Stop liveCache button in LC10 or the lcinit command.
If a user did not stop liveCache outside the control of Oracle Solaris Cluster, the SAP liveCache fault monitor determines whether SAP xserver is available.

Operations by the SAP xserver Fault Monitor During a Probe

During a probe, the SAP xserver fault monitor determines whether SAP xserver is available.

Faults Detected by the HA for SAP liveCache Fault Monitors

Faults that each HA for SAP liveCache fault monitor detects are described in the subsections that follow.

Faults Detected by the SAP liveCache Fault Monitor

The SAP liveCache fault monitor detects the following faults in SAP liveCache:

Unexpected termination of liveCache

Note - The liveCache fault monitor also detects the expected termination of liveCache, which is not a fault. For more information, see Monitoring the Termination of liveCache by a User.
Unexpected termination of the liveCache parent process
System failures

SAP liveCache can be stopped or restarted only if SAP xserver is available. Therefore, the SAP liveCache fault monitor also detects the unavailability of SAP xserver. This fault monitoring supplements the fault monitoring that the SAP xserver fault monitor provides. This additional fault monitoring enforces the cross-resource group resource dependency between SAP xserver and SAP liveCache.

Faults Detected by the SAP xserver Fault Monitor

The SAP xserver fault monitor detects following faults:

Unavailability of SAP xserver. Unavailability of SAP xserver is also detected by the SAP liveCache fault monitor.
System errors. The SAP xserver fault monitor treats a system error as a partial failure.
Persistent system errors. A persistent system error is a system error that occurs four times within the retry interval. If a persistent system error occurs, the fault monitor restarts SAP xserver.

Recovery Actions in Response to Detected Faults

To minimize the disruption that transient faults in a resource cause, a fault monitor restarts the resource in response to such faults. For persistent faults, more disruptive action than restarting the resource is required:

For the SAP liveCache resource, the fault monitor fails over the resource to another node. The SAP liveCache resource is a failover resource.
For the SAP xserver resource, the fault monitor takes the resource offline. The SAP xserver is a multiple master data resource.

Monitoring the Termination of liveCache by a User

The SAP liveCache fault monitor detects when a user stops liveCache outside the control of Oracle Solaris Cluster. A user can stop liveCache by using the Stop liveCache button in LC10 or the lcinit command.

In this situation, the liveCache fault monitor updates the status of the liveCache resource to indicate that liveCache is stopped. However, the liveCache fault monitor performs no recovery action.

If a user restarts liveCache, the liveCache fault monitor updates the status of the liveCache resource to indicate that liveCache is running again.