Designing Disaster Recovery Clusters using Metroclusters and Continentalclusters, Reprinted October 2011 (5900-1881)

NOTE: After a recovery, it is not possible to reverse directions and return a package to its original
cluster without first reconfiguring the data replication hardware and/or software and synchronizing
data. Therefore, be very cautious when deciding to use the cmrecovercl command. It is for this
reason, HP recommends that stringent procedures and processes are in place to aid in making the
decision to complete a recovery process.
Performing Recovery Group Rehearsal in Continentalclusters
During a recovery in Continentalclusters, a configuration inconsistency at the recovery cluster can
result in an unsuccessful recovery attempt. Rehearsing the recovery procedure provides you a
method to proactively identify and fix these configuration inconsistencies so that there are no issues
during an actual recovery. Continentalclusters provides the environment and a set of required tools
to complete a Disaster Recovery (DR) Rehearsal.
Continentalclusters allows recovery groups to be configured with a special rehearsal package for
DR rehearsal. You must configure the rehearsal package in the recovery cluster and specify it as
part of the recovery group definition. The rehearsal package is identical to the recovery package
and can be effectively used in place of the recovery package to verify the environment. This
rehearsal package bundles the same application and uses the same storage devices as the recovery
package.
During a DR rehearsal process, Continentalclusters will start the rehearsal package and validate
the recovery cluster environment. However, to stop clients from using the recovery package
application instance, it is necessary that the client access network IP address be different for the
rehearsal package. For more information on configuring a rehearsal package, see “Configuring
Recovery Groups with Rehearsal Packages” (page 58).
Also, you must configure Continentalclusters to enable the maintenance mode feature for recovery
groups. For more information on the maintenance mode, see “Maintenance Mode for Recovery
Groups” (page 42).
Disaster Recovery Rehearsal for a recovery group is done in the following phases:
• Rehearsal Preparation Phase
In this phase, you must prepare your environment for rehearsal. To prepare a recovery group
for rehearsal, complete the following steps:
1. Enter the cmrecovercl -d command to move the recovery group into the maintenance
mode by disabling it.
2. Suspend replication from the primary cluster.
3. Prepare a business copy (BC/BCV) of the storage on the recovery cluster.
4. Make the storage system read-write on the recovery cluster.
5. Import the volume manager entities such as LVM or SLVM volume groups or the VxVM
or CVM disk groups in the recovery cluster.
• Rehearsal Run Phase
Start the DR rehearsal for the recovery group using the Continentalclusters command
cmrecovercl -r. This command starts the rehearsal package for the recovery group and
validates the Continentalclusters configuration and environment for the recovery group. Once
rehearsal is started, use the regular Serviceguard commands to manage the rehearsal package.
You can run any test load on the rehearsal package to validate the recovery of the application.
• Rehearsal Restoration Phase
Once rehearsal process is complete, you must restore recovery for the recovery group. You
must halt and disable the rehearsal package in the cluster and synchronize the recovery cluster
storage with the primary site storage with the latest application data. Also, you must resume
Understanding Continentalclusters Concepts 45