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

• In case of the S-JNL, Q-Marker shows the latest sequence number putting on the cache.
• Q-CNT: Displays the number of remaining Q-Marker of a journal group.
Figure 34 Q-Marker and Q-CNT
• U(%): Displays the usage rate of the journal data.
• D-SZ: Displays the capacity for the journal data on the journal group.
• Seq#: Displays the serial number of the XP12000.
• Num: Displays the number of LDEV (journal volumes) configured for the journal group.
• LDEV#: Displays the first LDEV number of journal volumes.
Normal Maintenance
There might be situations when the package has to be taken down for maintenance purposes
without having the package move to another node. The following procedure is recommended for
normal maintenance of the Metrocluster/Continuous Access:
1. Stop the package with the appropriate Serviceguard command.
# cmhaltpkg pkgname
2. Split links for the package.
# pairsplit -g <package device group name> -rw
3. Distribute the Metrocluster with Continuous Access for P9000 and XP configuration changes.
# cmapplyconf -P pkgname.config
4. Start the package with the appropriate Serviceguard command:
# cmmodpkg -e pkgname
Planned maintenance is treated the same as a failure by the cluster. If you take a node down for
maintenance, package failover and quorum calculation is based on the remaining nodes. Make
sure that nodes are taken down evenly at each site, and that enough nodes remain on-line to form
a quorum if a failure occurs. See “Example Failover Scenarios with Two Arbitrators” (page 30).
Resynchronizing
After certain failures, data is no longer remotely protected. In order to restore disaster tolerant data
protection after repairing or recovering from the failure, you must manually run the command
pairresync. This command must successfully complete for disaster-tolerant data protection to be
restored.
Following is a partial list of failures that require running pairresync to restore disaster-tolerant
data protection:
• Failure of all Continuous Access links without restart of the application
• Failure of all Continuous Access links with Fence Level “DATA” with restart of the application
on a primary host
194 Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access for P9000 and XP