HP XP Cluster Extension Software Administrator Guide

Setting HP XP Cluster Extension objects to enable rolling disaster protection
To enable rolling disaster protection with Business Copy, set the BCEnabledA and BCEnabledB
objects for data centers A and B. When these objects are set to YES, rolling disaster protection is
enabled and HP XP Cluster Extension checks whether the configured Business Copy disk pairs are
in PAIR state. Before initiating the resynchronization operation, HP XP Cluster Extension suspends
specified Business Copy disk pairs that are in PAIR state. For information on setting HP XP Cluster
Extension objects, see “User configuration file and HP XP Cluster Extension objects” (page 64).
When using rolling disaster protection, note the following:
• If the BCEnabledA and BCEnabledB objects are set to YES, you must configure specific Business
Copy disk pairs using MU numbers. The MU number defines one of the many disk pair
relationships you can create with Business Copy disk pairs. You can specify as many MU
numbers as the 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 Business Copy disk pairs that have been split by HP XP Cluster
Extension, use the BCResyncEnabledA and BCResyncEnabledB objects for data centers A and
B.
• HP XP Cluster Extension maintains a list of all associated Business Copy disk pairs that were
in PAIR state before a resynchronization attempt. If pairs were suspended, HP XP Cluster
Extension automatically resynchronizes those disk pairs after the Continuous Access remote
mirrored disk pairs have been paired. This feature supports automatic resynchronization of
locally split Business Copy 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, HP XP Cluster Extension automatically resynchronizes the
Continuous Access disk pairs to update the remote disks. If rolling disaster protection is also enabled,
it suspends the Business Copy disk pair that is attached to the remote Continuous Access disk.
If the remote RAID Manager instance is not running or cannot be reached, the remote Business
Copy disk pair cannot be suspended. If this occurs, HP XP Cluster Extension continues the application
service activation without automatic resynchronization of the Continuous Access disk pair and
without the suspending of the Business Copy disk pair. In this case, the Continuous Access 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 Business Copy pairs
to recover suspended or failed Continuous Access disk pairs.
To protect the remote volume of an out-of-sync Continuous Access disk pair against rolling disasters,
use the pair/resync monitor's default settings. Resynchronize the Continuous Access disk pair
manually after splitting off the Business Copy disk pair.
Restoring server operation for rolling disaster protection
Rolling disaster protection automatically recovers the PAIR state of the Continuous Access 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
RAID Manager instance used to manage the Continuous Access disk pairs on those servers. This
enables rolling disaster protection to work correctly during a recovery failover/failback operation.
“Disaster-tolerant configuration with rolling disaster protection” (page 81) depicts a fully configured
HP XP Cluster Extension environment that uses rolling disaster protection. The Business Copy disk
pairs are specified as 0 in the HP XP Cluster Extension BCMuListA and BCMuListB objects. See
“APPLICATION objects ” (page 67) for more information about these objects.
80 Advanced HP XP Cluster Extension configuration