HP XP Cluster Extension Software Administrator Guide

number of remote instances, the online operation could time out. This can occur if the local
RAID Manager instance cannot reach the remote RAID Manager instance.
• HP XP Cluster Extension tries to resynchronize disk pairs and waits until the RAID Manager
device/copy group is in PAIR state if the ApplicationStartup resource property is set to
RESYNCWAIT. RAID Manager and the XP fully support delta resynchronization; however, the
delta between the primary and secondary disks could be large enough for the copy process
to exceed the resource PendingTimeout value.
• The ResyncWaitTimeout object can cause HP XP Cluster Extension resources to fail if its value
is higher than the resource PendingTimeout value.
• If running in fence level ASYNC, the default value of AsyncTakeoverTimeout can cause the
resource to fail because its value exceeds the resource PendingTimeout value. The takeover
process for fence level ASYNC can take much longer when slow communications links are in
place.
To prevent takeover commands from being terminated by the resource PendingTimeout, measure
the time required to copy the installed disk array cache and adjust the resource PendingTimeout
value. When measuring the copy time, measure only the slowest link used for Continuous
Access Software. This ensures that the disk array cache can be transferred from the remote
disk array, even in the event of a single surviving replication link between the disk arrays.
In general, because the failover environment is dispersed into two (or more) data centers, the
failover time cannot be expected to be the same as that in a single data center with a single shared
disk device. Therefore, the following values of the HP XP Cluster Extension resource and the service
and application using that resource must be adjusted, based on failover tests performed to verify
the proper configuration setup: FailoverPeriod, RestartPeriod, PendingTimeout, LookAlive, and
IsAlive.
In addition, the service or application's FailoverPeriod value must be higher than the resource’s
RestartPeriod value, and both must be higher than the resource’s PendingTimeout value.
MSFC provides two parameters to adjust state change recognition/resolution:
• IsAlive
• LookAlive
HP XP Cluster Extension automatically calls the IsAlive function whenever the cluster service calls
the LookAlive function. Therefore, both functions must be set to the same value.
Bouncing service or application
HP XP Cluster Extension will alternate (start and fail) between local nodes if the ApplicationStartup
property has been set to FASTFAILBACK and no remote system is available until the service or
application restart limit has been reached. For more information, see “ApplicationStartup” (page 68).
The FastFailbackEnabled property is not used by the HP XP Cluster Extension integration with
MSFC.
Administration
HP XP Cluster Extension administration includes remote management of resources and monitoring
of system resources and logs.
42 Configuring HP XP Cluster Extension