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

Cascading Failover in a Continental Cluster
Data Replication Procedures
Chapter 8386
Failback from the Secondary Site to the Primary Site
Once the problems at the primary site have been fixed, the application
can fail back to the primary site. The current RDF pair states of the
package device groups will be “Split,” which is not handled automatically
by the package control script. The following steps are required to move
the package back to the primary site.
1. Set the RDF pairs between primary Symmetrix and secondary
Symmetrix to fail over state. Either use the following command on a
system that connects to the secondary Symmetrix:
# symrdf -g <secsymdevgrpname> failover -force
or use the following command on a system that connects to the
primary Symmetrix
# symrdf -g <prisymdevgrpname> failover -force
This command can be run while the package application is still
running. The device group has already been failed over, so all this
command will do is change the RDF pair state from “Split” to “Failed
Over.”
2. Now, halt the application package:
# cmhaltpkg <package_name>
3. Split the BCV/R1 in the secondary Symmetrix from the mirror group
to save a good copy of the data. From a system that connects to the
secondary Symmetrix:
# symmir -g <secsymdevgrpname> split
From a system that connects to the primary Symmetrix:
# symmir -g <prisymdevgrpname> split -rdf
4. Start the application package on the primary site. Use the following
command for all hosts in the primary cluster that may run this
package:
# cmmodpkg -e -n <host_name> <package_name>
Then run the package with the following command:
# cmmodpkg -e <package_name>
The package will now start up on its primary host. The package
control script will change the R1 devices from “Not Ready” status to
“WD” (Write Disabled) status, then an RDF failback will be done on