HP StorageWorks XP Cluster Extension Software Administrator Guide (T1656-96035, April 2010)

• If running in fence level ASYNC, the default value of the AsyncTakeoverTimeout can cause the
resource group online process to fail because its value is set very high. This is because the takeover
process for fence level ASYNC can take longer when slow communication links are in place.
To prevent takeover commands from being terminated prematurely by the takeover timeout,
measure the time to copy the installed XP disk array cache. To measure the copy time, use only
the slowest XP Continuous Access Software link. This ensures that the XP disk array cache can be
transferred from the remote XP disk array, even in the event of a single surviving replication link
between the XP disk arrays.
Because the failover environment is dispersed into two (or more) data centers, the failover time cannot
be expected to be the same as it would be in a single data center with a single shared disk device.
Failure behavior
XP Cluster Extension will run in an endless loop if either of the following is discovered:
• A configuration error
• An XP disk pair state that does not allow automated actions
This event is logged in the log files:
/var/opt/hpclx/log/clxhacmp.log and /tmp/hacmp.out.
To return control to the HACMP cluster software, you must remove the lock file:
application_dir/application_name.LOCK.
For example: /etc/opt/hpclx/OracleRG.LOCK
This process has been adopted from HACMP's behavior. In the case of a failure, HACMP will also
run in an endless loop until you recover all errors and manually start the application. After all errors
have been recovered, invoke the command clruncmd to return control to the cluster software.
Restrictions for IBM HACMP with XP Cluster Extension
The following is a summary of restrictions that apply for HACMP configurations when XP Cluster
Extension is used to enable failover between two XP disk arrays:
• The FastFailbackEnabled object is not used by the XP Cluster Extension integration with HACMP.
• XP Cluster Extension must not be used with concurrent resource group configurations (for example,
parallel databases).
• XP Cluster Extension must not be used with raw devices without volume groups.
• Target mode SCSI: Serial networks within HACMP based on target mode SCSI (TMSCSI) are not
supported.
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