HP 3PAR StoreServ Cluster Extension Software Administrator Guide (5697-2442, July 2013)

Using Hyper-V Live Migration with HP 3PAR StoreServ Cluster Extension
Live migration is a managed failover of VM resources. Live migration should be performed when
all of the solution constituents are in a healthy state, all the servers and systems are running, and
all the links are up. Ensure that the underlying infrastructure is in a healthy state before performing
live migration.
HP 3PAR StoreServ Cluster Extension has the capability of discovering unfavorable storage-level
conditions for performing live migration. In response to these conditions, HP 3PAR StoreServ Cluster
Extension stops or cancels the live migration process and notifies you. This is accomplished with
no VM downtime. For example, if live migration is initiated while VM data residing on the storage
system is still merging and not in sync, HP 3PAR StoreServ Cluster Extension proactively cancels
the live migration and notifies you to wait until the disks are fully in sync. Without this feature, live
migration might fail or the VM might come online in the remote data center with inconsistent data.
The HP 3PAR StoreServ 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 HP 3PAR StoreServ Storage
status to ensure a successful live migration. The default StatusRefreshInterval value is 300
seconds. For more information about configuring this property, see “Setting HP 3PAR StoreServ
Cluster Extension properties using a UCF” (page 37).
TIP: For more information about using Hyper-V Live Migration with HP 3PAR StoreServ Cluster
Extension, see the white paper Live Migration across data centers and disaster tolerant virtualization
architecture with HP StorageWorks Cluster Extension and Microsoft Hyper-V on the white papers
website: www.hp.com/storage/whitepapers.
Timing considerations for Windows Clustering (MSFC)
HP 3PAR StoreServ Cluster Extension gives priority to storage system operations over cluster software
operations. If HP 3PAR StoreServ Cluster Extension is invoked during a virtual volume
synchronization/full synchronization operation, 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 HP
3PAR StoreServ Cluster Extension resources in some cases:
• When HP 3PAR StoreServ Cluster Extension communicates with the HP 3PAR StoreServ Storage,
online operations could time out depending on the settings of the command time out
configuration.
• When a virtual volume resynchronization/ full synchronization is in progress, the software
waits until the Remote Copy volume group is in a synced state if the ApplicationStartup
resource property is set to RESYNCWAIT. In case of resynchronization, the delta between the
source and destination virtual volume could be large enough for the resynchronization process
to exceed the resource PendingTimeout value.
• The values of the ResyncWaitTimeout properties must be less than the configured 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 HP 3PAR StoreServ 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.
In addition, FailoverPeriod value of the service or application must be higher than the
RestartPeriod value of the resource and both must be higher than the resource's
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