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

Building a Continental Cluster
Designing a Disaster Tolerant Architecture for use with ContinentalClusters
Chapter 5 193
Designing a Disaster Tolerant Architecture
for use with ContinentalClusters
The ContinentalClusters product operates as a configuration of two
MC/ServiceGuard clusters, which can run a package on a cluster and a
Recovery Cluster. The key elements providing disaster tolerance in a
continental cluster are:
• Mutual Recovery
• MC/ServiceGuard clusters
• Data replication
• Highly available WAN networking
• Data center processes and procedures coordinated between the two
cluster sites
You have a great deal of latitude in selecting these elements for your
configuration. It is recommended that you record your choices on
worksheets which can be reviewed and updated periodically.
Mutual Recovery
For mutual recovery, any cluster in a continental cluster may contain
both primary and recovery packages for any recovery group. Recovery
groups may be defined, for example, such that cluster A and cluster B
contain recovery packages. In this case, cmrecovercl could be run on
cluster B to recover packages from cluster A, or on cluster A to recover
packages from cluster B.
MC/ServiceGuard Clusters
Each MC/ServiceGuard cluster in a continental cluster provides high
availability for an application at the local level at that particular site.
For optimal performance and to assure adequate capacity on the
recovery cluster, it is best to have similar hardware on both clusters. For
example, if one cluster contains two V class HP 9000 systems with 1Gb of
memory each, it is not a good idea to have a low-end K series HP 9000
with 128 Mb of memory in the other cluster. Each cluster may have as