A status of the SAP DB database instance that is not ONLINE, for example, OFFLINE or ADMIN
Unexpected termination of the parent kernel process of the SAP DB database instance
The SAP DB fault monitor also responds to the unavailability of SAP xserver. This fault monitoring supplements the fault monitoring that the SAP xserver fault monitor provides.
Unavailability of SAP xserver
Persistent system errors
The Sun Cluster HA for SAP DB fault monitors enable you to specify the response to these faults. Specifying the response to a fault involves the following tasks:
Defining the criteria for persistent faults
Disabling the failover of the SAP DB resource
Forcing the SAP DB database instance to be restarted if the parent kernel process is terminated
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 DB resource, the fault monitor fails over the resource to another node. The SAP DB resource is a failover resource.
For the SAP xserver resource, the fault monitor takes the resource offline. The SAP xserver is a scalable resource.
The fault monitors treat a fault as persistent if the number of attempts to restart a resource exceeds a specified threshold within a specified retry interval. Defining the criteria for persistent faults enables you to set the threshold and the retry interval to accommodate the performance characteristics of your cluster and your availability requirements.
Thorough_probe_interval system property
Probe_timeout extension property
To ensure that you allow enough time for the threshold to be reached within the retry interval, use the following expression to calculate values for the retry interval and the threshold:
retry-interval ≥ threshold × (thorough-probe-interval + probe-timeout)
To set the threshold and the retry interval, set the following system properties:
Set these properties for each resource that contains a Sun Cluster HA for SAP DB fault monitor that you need to tune. The resource types of these resources are shown in Table 1–3.
Besides defining a criterion for persistent faults, the retry interval affects the response of a fault monitor to the following faults:
Unavailability of SAP xserver that the SAP DB fault monitor detects. If the SAP DB fault monitor detects that SAP xserver is unavailable twice within the retry interval, the SAP DB fault monitor restarts SAP xserver.
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.
By default, failover of the SAP DB resource is enabled. The fault monitor fails over the SAP DB resource in response to a persistent fault. A persistent fault occurs if the number of attempts to restart exceeds Retry_count within the time that Retry_interval specifies.
Disable the failover of the SAP DB resource if you require the fault monitor to restart the SAP DB even in response to a persistent fault. When failover is disabled, the fault monitor reports a persistent fault in a resource by setting the status of the resource to faulted.
By default, unexpected termination of the parent kernel process does not cause the SAP DB fault monitor to restart the SAP DB database instance. The SAP DB database instance can continue to function without the parent kernel process. Restarting the SAP DB database instance in this situation might cause unnecessary unavailability of the SAP DB database instance. Therefore, you should force the SAP DB database instance to be restarted only if you require a feature that the parent kernel process provides. An example of such a feature is maintaining the integrity of the log history.