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

Cascading Failover in a Continental Cluster
Data Replication Procedures
Chapter 8 383
5. Split the BCV devices in the recovery Symmetrix from the mirror
group. This is required to preserve an old copy of the data just in
case a failure occurs during data synchronization between the
secondary Symmetrix and the recovery Symmetrix that may cause
data corruption on the R2 devices in the recovery Symmetrix.
# symmir -f <recbcvdev_textfile> -sid <recsymid> split
The <recbcvdev_textfile> is a file that contains a list of the standard
device and BCV device pair in the recovery Symmetrix.
6. Incrementally establish the SRDF volume pairs between the
secondary Symmetrix and the recovery Symmetrix. The data is
copied from secondary Symmetrix BCV/R1 devices to the recovery
Symmetrix R2 devices
# symrdf -g <prisymdevgrpname> est -rbcv
7. Use the following command to check the data synchronization from
the BCV/R1 devices to the R2 devices. If the "RDF Pair STATE"
column shows the state "Synchronized" for all the devices, the
copying completed:
# symrdf -g <prisymdevgrpname> query -rbcv
8. Once the copy completes, split the SRDF link between the secondary
Symmetrix and the recovery Symmetrix:
# symrdf -g <prisymdevgrpname> split -rbcv
9. Re-establish the BCV devices in the recovery Symmetrix as mirrors
of the standard devices:
# symmir -f <recbcvdev_textfile> -sid <recsymid> est
10. Re-establish the BCV/R1 devices in the secondary Symmetrix as
mirrors of the standard devices.
# symmir -g <prisymdevgrpname> est -rdf
Refer to the sample script prirefreshrec in the
/opt/cmcluster/toolkit/SGSRDF/cascade/Samples directory for
examples of how these commands are used. This script is designed to
run only on a node that connects to the primary Symmetrix.
Data Replication in Failover and Failback Scenarios
This section describes the data replication procedures for various failover
and failback scenarios.