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

Cascading Failover in a Continental Cluster
Data Replication Procedures
Chapter 8380
3. Start the application to load the data to the R1 devices in the
primary Symmetrix.
Refer to the sample script datainit 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.
2. Mirroring from the Secondary to the Recovery Symmetrix
This procedure is illustrated in Figure 8-8.
Figure 8-8 Mirroring from the Secondary to the Recovery Symmetrix
Execute the following commands from a node that connects to the
primary Symmetrix:
1. Freeze the application I/O to prevent the application from writing
data to the R1 devices in the primary Symmetrix (in case of adding
the recovery cluster to the existing MetroCluster). The method of
freezing the I/O is application dependent
2. Split the BCV/R1 devices in the secondary Symmetrix from the
mirror group
# symmir -g <prisymdevgrpname> split -rdf
3. Resume the application I/O to the R1 devices in the primary
Symmetrix if needed. The method of resuming the I/O is application
dependent.
4. Incrementally establish the SRDF volume pairs between secondary
Symmetrix and the recovery Symmetrix. The data is copied from
BCV/R1 devices on the secondary Symmetrix to the R2 devices on the
recovery Symmetrix.