HP P6000 Cluster Extension Software Administrator Guide (5697-0986, June 2011)

links are up. Ensure that the underlying infrastructure is in a healthy state before performing live
migration.
P6000 Cluster Extension has the capability of discovering unfavorable storage-level conditions for
performing live migration. In response to these conditions, P6000 Cluster Extension will stop or cancel
the live migration process and inform the user. This is accomplished with no VM downtime. For
example, if live migration is initiated while VM data residing on the storage arrays is still merging
and not in sync, P6000 Cluster Extension will proactively cancel the live migration and inform the
user to wait until the merge is in progress. Without this feature, live migration might fail or the VM
might come online in the remote data center with inconsistent data.
The P6000 Cluster Extension StatusRefreshInterval property, which you can configure in a UCF for
each application, specifies the time interval between consecutive array status gathering operations
before the live migration to the target cluster node occurs. By adjusting this property, you can increase
the probability of getting the correct P6000 array status to ensure a successful live migration. The
default StatusRefreshInterval value is 300 seconds. For more information about configuring this property,
see Setting P6000 Cluster Extension properties using a UCF.
Using Hyper-V Live Migration with Cluster Shared Volumes is not supported with P6000 Cluster
Extension.
TIP:
For more information about using Hyper-V Live Migration with P6000 Cluster Extension, see the white
paper Live Migration across data centers and disaster tolerant virtualization architecture with HP
Cluster Extension and Microsoft Hyper-VTM on the white papers website:
www.hp.com/storage/whitepapers.
Timing considerations for MSCS
P6000 Cluster Extension Software gives priority to storage system operations over cluster software
operations. If P6000 Cluster Extension is invoked during a DR group member resynchronization
operation (merging) or is gathering information about the remote storage system, it waits until the
requested status information is reported. This ensures the priority of data integrity over cluster software
failover behavior. However, this behavior can cause a failure of P6000 Cluster Extension resources
in some cases.
• When P6000 Cluster Extension uses HP SMI-S to communicate with the HP P6000/EVA storage
system, depending on the settings of the SMI-S request timeout property and the number of retries,
the online operation could time out. This can occur if the list of management servers is populated
with many management servers and the P6000 storage system is busy processing other management
commands.
• When a DR group member resynchronization (merge) is in progress, the software waits until the
DR group is in a normal state if the ApplicationStartup resource property is set to RESYNCWAIT.
In case of merge/resynchronization, the delta data (stored in the history log) between the source
and destination vdisks could be large enough for the copy process to exceed the resource
PendingTimeout value.
• The values of the ResyncWaitTimeout and DataSyncTimeout properties must be less than the con-
figured resource PendingTimeout value.
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 P6000 Cluster Extension resource and the service or
application using that resource, must be adjusted, based on failover tests performed to verify the
proper configuration setup: FailoverPeriod, RestartPeriod, PendingTimeout, LookAlive, and IsAlive.
Configuring P6000 Cluster Extension for Windows52