HP XP7 Storage - Manual (Page 90)

Recovery for 3 Cnt Ac-J/Cnt Ac-S DC multi-target configuration
The recovery procedure you perform in a 3DC multi-target configuration depends on the location
of the failure:
•
For failure in the local site only — see “Recovering from local site failure ” (page 90) .
•
For failure in the local and Continuous Access Synchronous intermediate sites — see
“Recovering from local and remote site failure (3DC multi-target)” (page 91)
See “3DC multi-target configuration ” (page 126) for information and illustrations on the configuration
covered in this procedure.
Recovering from local site failure
Host operations are transferred to the secondary volume in the intermediate site when disaster or
failure occurs in the local site in a 3DC multi-target configuration. Replication occurs from the
intermediate site to the local site. Alternatively, a temporary Cnt Ac-J system can be set up.
Meanwhile, you correct the failure at the local site, then transfer host operations back to it and set
up a 3DC configuration.
Procedure 34 To recover a local site failure
1. Release the Cnt Ac-J pair.
2. Run the horctakeover command on the primary-remote site pair.
3. Start host operations to the remote site secondary volume.
Running the horctakeover results in one of the following conditions:
•
The original copy flow of the primary-remote site pair reverses and flows from the
primary-remote secondary volume to the primary volume.
•
The original copy flow does not reverse because of failure in the local site or data path.
Depending on the result, proceed as follows:
If the original Cnt Ac-S data flow reverses
1.
Re-create the Cnt Ac-J pair from the Cnt Ac-S local site to the Cnt Ac-J remote site. This results
in a 3DC cascade configuration, with the original Cnt Ac-S S-VOL as the primary volume. See
the lower right configuration in the following figure.
2. Restore the local site or data path, or both. This must be done before proceeding.
3. Stop host operations to the Cnt Ac-S intermediate site.
4. Run the horctakeover command on the Cnt Ac-S pair.
5. Resume host operations to the Cnt Ac-S P-VOL in the local site.
The system changes back to the original 3DC multi-target configuration.
If the original Cnt Ac-S data flow did not reverse
1.
To back up the data, create a new Cnt Ac-J pair from the Cnt Ac-S S-VOL in the intermediate
site to the Cnt Ac-J secondary volume in the remote site.See the upper-right configuration in
the following figure.
2. Restore the local site or data path, or both. This must be done before proceeding.
3. Release the Cnt Ac-J pair.
4. Resynchronize the Cnt Ac-S pair to start the replication to the local site.
5. Release the current Cnt Ac-J pair, which extends between the Cnt Ac-S remote site and the
Cnt Ac-J remote site.
6. Stop host operations at the Cnt Ac-S intermediate site.
7. Run the horctakeover command on the Cnt Ac-S pair.
8. Resume host operations to the local site Cnt Ac-S volume.
9. Re-create the Cnt Ac-J pair from the local site to the remote site. The system is now changed
back to the original 3DC multi-target configuration.
90 Cnt Ac-J disaster recovery operations