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

Create the Metrocluster package directory on the newly added node.a.
b. Copy Metrocluster environment file from one of the existing nodes to the same pathname
on the newly added node:
# rcp <package_directory>/<Metrocluster_environment_file>
<new_node_name>:<package_directory>
5. If you are using Metrocluster modular package and if the node names are explicitly specified
for node_name parameter in Metrocluster package configuration, then add the newly added
node in a Metrocluster package by editing the Metrocluster package configuration and
applying the configuration:
# cmapplyconf –P <package_config_file>
Maintaining a Cluster that uses Metrocluster with EMC SRDF
While the cluster is running, all EMC Symmetrix disk arrays that belong to the same Serviceguard
package, and are defined in a single SRDF group must be in the same state at the same time.
Manual changes of these states can cause the package to halt due to unexpected conditions. In
general, it is recommended that no manual change of states should be performed while the package
and the cluster are running.
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 Metrocluster EMC SRDF:
1. Stop the package with the appropriate Serviceguard command.
# cmhaltpkg pkgname
2. Split the logical SRDF links for the package. In the pre.cmquery script, replace the device
group name with the device group in your environment.
# /opt/cmcluster/toolkit/SGSRDF/Samples/pre.cmquery
3. Distribute the Metrocluster EMC SRDF configuration changes.
# cmapplyconf -P pkgconfig
4. Restore the logical SRDF links for the package. In the pre.cmquery script, replace the device
group name with the device group in your environment.
# /opt/cmcluster/toolkit/SGSRDF/Samples/post.cmapply
5. Start the package with the appropriate Serviceguard command.
# cmmodpkg -e pkgname
No checking of the status of the SA/FA ports is done. It is assumed that at least one PVLink is
functional. Otherwise, the Volume Group activation will fail.
Planned maintenance is treated the same as a failure by the cluster. If the node is taken down for
maintenance, package failover and quorum calculation is based on the remaining nodes. Make
sure that the nodes are taken down evenly at each site, and enough nodes remain on-line to form
a quorum if a failure occurs. For examples of failover scenarios, see section, “Example Failover
Scenarios with Two Arbitrators” (page 30).
Managing Business Continuity Volumes
The use of Business Continuity Volumes is recommended with all implementations of Metrocluster
EMC SRDF, and it is required with M by N configurations, which employ consistency groups. These
BCV devices will provide a good copy of the data when it is necessary to recover from a rolling
disaster—a second failure that occurs while attempting to recover from the first failure.
Protecting against Rolling Disasters
The following is an example of a rolling disaster with Metrocluster with EMC SRDF
Building a Metrocluster Solution with EMC SRDF 285