Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access for P9000 and XP A.11.00

10. If Delta Resync pair is deleted as part of Step 2:
• Re-create the Delta Resync pair deleted in Step1 using the paircreate command from
DC3 node:
# paircreate -g <Delta Resync-pair> -vr –f async –jp <Journal_id>
-js <Journal-id> -nocsus
• Assign Remote Command devices to journal volumes of Delta Resync pair using
Remote Web Console. For details on assigning remote command devices to journal
volumes, see “Assigning Remote Command Devices to Journal Volumes” (page 118).
11. Start the primary cluster using the cmruncl command.
12. Start the primary package using the cmrunpkg command.
Automatic Failover between DC1 and DC2
All failover operations in the primary cluster of the 3DC DR Solution are similar to a regular Two
Data Center (2DC) Metrocluster environment configured using Continuous Access
Synchronous/Journal replication appropriately.
When using Tri-Link configuration, during the failover of a package from DC1 to DC2, the replication
to the DC3 site is retained using the same Active-CAJ-pair that was being used before the failover.
For example, the application package is running on DC1 and the data is being replicated to DC3
from DC2 (i.e. Multi-hop topology). Upon the failure of application on all nodes in DC1, the
application package fails over to a node in DC2. As part of package startup, the data replication
between DC1 and DC2 is reversed and the data starts replicating from DC2 to DC1. The replication
to DC3 will be continued from DC2 (i.e. Multi-target topology). The same Active-CAJ pair (DC2-DC3
pair) is used even after the failover to replicate the data to DC3 as shown in Figure 45 (page 143).
Figure 45 Package Failover with data being replicated to DC3 from DC2
Similarly, consider another example of the application package is running on DC1 and the data
is being replicated to DC3 from DC1 (i.e. Multi-target topology). Upon the failure of application
on all nodes in DC1, the application package fails over to a node in DC2. As part of package
startup, the data replication between DC1 and DC2 is reversed and the data starts replicating
from DC2 to DC1. The replication to DC3 will be continued from DC1 (i.e Multi-hop topology).
The same Active-CAJ pair (DC1-DC3 pair) is used even after the failover to replicate the data to
DC3 as shown in Figure 46 (page 144).
Automatic Failover between DC1 and DC2 143