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

Extension suspends specified XP Business Copy Software disk pairs that are in PAIR state. For
information on setting XP Cluster Extension objects, see Chapter 8 on page 123.
When using rolling disaster protection, note the following:
• If the BCEnabledA and BCEnabledB objects are set to YES, you must configure specific XP Business
Copy Software disk pairs using MU numbers. The MU number defines one of the many disk pair
relationships you can create with XP Business Copy Software disk pairs. You can specify as many
MU numbers as the XP Business Copy Software supports. Disk pair MU numbers are specified by
the BCMuListA and BCMuListB objects for data centers A and B.
• To enable resynchronization of XP Business Copy Software disk pairs that have been split by XP
Cluster Extension, use the BCResyncEnabledA and BCResyncEnabledB objects for data centers A
and B.
• XP Cluster Extension maintains a list of all associated XP Business Copy Software disk pairs that
were in PAIR state before a resynchronization attempt. If pairs were suspended, XP Cluster Extension
automatically resynchronizes those disk pairs after the XP Continuous Access Software remote
mirrored disk pairs have been paired. This feature supports automatic resynchronization of locally
split XP Business Copy Software disk pairs only. You must specify MU numbers for resynchronization
by using the BCResyncMuListA and BCResyncMuListB objects for data centers A and B.
Setting automatic recovery for rolling disaster protection
If the AutoRecover object is set to YES, XP Cluster Extension automatically resynchronizes the XP
Continuous Access Software disk pairs to update the remote disks. If rolling disaster protection is also
enabled, it suspends the XP Business Copy Software disk pair that is attached to the remote XP
Continuous Access Software disk.
If the remote XP RAID Manager instance is not running or cannot be reached, the remote XP Business
Copy Software disk pair cannot be suspended. If this occurs, XP Cluster Extension continues the
application service activation without automatic resynchronization of the XP Continuous Access
Software disk pair and without the suspending of the XP Business Copy Software disk pair. In this
case, the XP Continuous Access Software disk pair must be recovered manually.
Using the pair/resync monitor with rolling disaster protection
If the ResyncMonitor object is set to YES, the pair/resync monitor does not use XP Business Copy
Software pairs to recover suspended or failed XP Continuous Access Software disk pairs.
To protect the remote volume of an out-of-sync XP Continuous Access Software disk pair against rolling
disasters, use the pair/resync monitor's default settings. Resynchronize the XP Continuous Access
Software disk pair manually after splitting off the XP Business Copy Software disk pair.
Restoring server operation for rolling disaster protection
Rolling disaster protection automatically recovers the PAIR state of the XP Continuous Access Software
disk pair of an application service. Before you fail over (or fail back) an application service from one
data center to the other, you must restore the server operation. After you restart the server, also start
the XP RAID Manager instance used to manage the XP Continuous Access Software disk pairs on
those servers. This enables rolling disaster protection to work correctly during a recovery
failover/failback operation.
Figure 10 on page 143 depicts a fully configured XP Cluster Extension environment that uses rolling
disaster protection. The XP Business Copy Software disk pairs are specified as 0 in the XP Cluster
Extension BCMuListA and BCMuListB objects. See “APPLICATION objects ” on page 128 for more
information about these objects.
Advanced XP Cluster Extension configuration142