Cascading Failover in a Continentalclusters, December 2005

4. Re-establish the recovery replication pairs between the recovery disk array and the secondary
disk array. Move the data from the recovery disk array (device C) to the secondary disk
array (device B’).
5. Check the data resynchronization progress of the recovery replication group.
6. Once the data resynchronization completes, split the data replication link between secondary
disk array and recovery disk array.
7. Re-establish the local mirror devices (device B’) in the secondary disk array. Restore the data
from the local mirror devices to the devices in the primary replication group (device B).
8. Check the data restore progress between the local mirror and the devices in the primary
replication group.
9. For LVM, Since the recovery cluster has a different cluster ID, the data restored from the
recovery disk array to the secondary disk array also copies the recovery cluster’s ID to the
secondary disk array. Do the following to change the cluster’s ID on each cluster aware
volume group in the secondary disk array before starting the application package:
# vgchange -c n /dev/<vg_name>
# vgchange -c y /dev/<vg_name>
For VxVM, the disk group needs to be imported with a force flag in order to clear the hostid
of a node from the recovery site. Perform the following command on each disk group on a
node in the primary cluster:
# vxdg –tfC <disk_group_name>
10. Start the application package at the secondary site. Issue the following command for all hosts
in secondary site that may run this package:
# cmmodpkg -e -n <host_name> <package_name>
11. Then issue the following command from any node on the primary cluster:
# cmmodpkg -e <package_name>
12. Start the Continentalclusters monitor package.
Failback from the Recovery Site Directly to the Primary Site in the Primary
Cluster
The current configuration does not support the application failback to the primary site in the primary
cluster unless the secondary site in the primary cluster is up and running. The secondary site has to
be repaired first. The application can temporarily fail back to the secondary site while the primary
site is still down. Before the application can failback to either the secondary site or the primary site,
the current data needs to be restored from the recovery disk array to the secondary disk array and the
primary disk array.
This procedure is used when both the secondary site and the primary site are fixed and up and
running. The package application fails back directly from the Recover cluster to the primary site in the
primary cluster.
1. Halt the Continentalclusters monitor package at the recovery site.
2. Halt the Continentalclusters recovery packages at the recovery site.
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