Designing Disaster Tolerant High Availability Clusters, 10th Edition, March 2003 (B7660-90013)

Building a Continental Cluster
Restoring Disaster Tolerance
Chapter 5256
Restoring Disaster Tolerance
After a failover to a cluster occurs, restoring disaster tolerance has many
challenges, the most significant of which are:
• Restoring the failed cluster
Depending on the nature of the disaster you may need to create a
new cluster, or you may be able to restore the cluster. Steps for each
scenario are discussed in the following sections.
Before starting up the new or the failed cluster, make sure the
AUTO_RUN flag for all of the ContinentalClusters application
packages is disabled. This is to prevent starting the packages
unexpectedly with the cluster.
• Resynchronizing the data
To resynchronize the data, you either restore the data to the cluster
and continue with the same data replication procedure, or set up
data replication to function in the other direction.
The following sections briefly outline some scenarios for restoring
disaster tolerance.
Restore Clusters to their Original Roles
If the disaster did not destroy the cluster, you can return both clusters to
their original roles. To do this:
1. Make sure that both clusters are up and running, with the recovery
packages continuing to run on the surviving cluster.
2. On each cluster, stop the ContinentalClusters monitor package if it
is still running:
# cmhaltpkg ccmonpkg
3. Compare the clusters to make sure their configurations are
consistent. Correct any inconsistencies.
4. For each recovery group where the new cluster will run the primary
package:
a. Synchronize the data from the disks on the surviving cluster to
the disks on the new cluster. This may be time-consuming.