HP Storage Mirroring V5.1 Software - Manual (Page 130)

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Restoration and
Failback for High
Availability
With a high availability connection, 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.
Restoration then failback
Restoration before failback 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 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.
5. Configure that IP address so that it does not automatically register with DNS. This option is on
the Advanced TCP/IP Settings dialog box on the DNS tab.
6. Do not enable the modified NIC yet. If you do, you will receive a network name conflict, because
the target has the source’s identity because of failover. There are many variations for dealing
with a name conflict, here are a few examples.

Enable the modified NIC, knowing you will get the name conflict error. Disregard the error.
Change the source name to a unique name in the domain and reboot when prompted.

Change the source name to a unique name in a workgroup, not in the domain, and reboot
when prompted. Enable the modified NIC.

Stop the Workstation and Server services on the source. You may be prompted to stop other
services. Stop those services also and note the service names for later. Enable the modified
NIC. The server will not broadcast its name to the network because of the services you
disabled.
7. Stop any applications that may be running on your source. The files must be closed on the
source so that updated files from the target will overwrite the files on the source.
8. At this point, confirm you have the following configuration.