HP StorageWorks Storage Mirroring Recover User's Guide (T5437-96008, November 2009)

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Failback for data workloads
Failover occurred because the target was monitoring the source for a failure, and when a
failure occurred, the target stood in for the source. User and application requests that
were directed to the failed source are routed to the target.
While the users are accessing their data on the target, you can repair the issue(s) on the
source. Before users can access the source again, you will need to restore the data from
the target back to the source and perform failback. Failback is the process where the
target releases the source identity it assumed during failover. Once failback is complete,
user and application requests are no longer routed to the target, but back to the source.
Ideally, you want to restore your data from the target back to the source before you
failback. This allows users who are currently accessing their data on the target because
of failover to continue accessing their data. Restoration before failback reduces user
downtime. The procedure to restore and then failback varies widely with server and
network configuration. Another method, which may be easier in some environments,
allows you to failback first and then restore the data from the target to the source. A
possible disadvantage to this process is that users may experience longer downtime,
depending on the amount of data to be restored, because they will be unable to access
their data during both the restoration and the failback.
● Restoring then failing back
● Failing back then restoring
Restoring then failing back
Restoring before failing back allows your users to continue accessing their data on the
failed over target, which is standing in for the source, while you perform the restoration
process. The key to this process is to keep the users off of the source, but allow the
source and target to communicate to perform the restoration.
1. Locate the file connect.sts on the source where you installed Storage Mirroring
Recover and rename it to connect.sts.old. This will keep the original connection
from reconnecting when you bring the source online.
2. Resolve the problem(s) on the source that caused it to fail. Make sure in resolving
the problems, that you do not bring the source on the network at this time because
the target currently has the source’s identity because of failover.
3. Disable all of the NICs on the source.
4. Change one of the NICs on the source to a unique IP address that the target can
access.