HP XP P9500 Storage - Manual (Page 98)

Procedure 34 To recover a 3DC cascade configuration failure
1. Check consistency of the secondary volume in the intermediate site.
2. Run the horctakeover command on the secondary volume.
3. Wait until the secondary volume in the intermediate site is suspended (in SSWS status) or
changes to a primary volume, then use the volume to resume host operations.
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 primary site only — see “Recovering from primary site failure ” (page 98) .
•
For failure in the primary and Continuous Access Synchronous intermediate sites — see
“Recovering from primary and secondary site failure (3DC multi-target)” (page 99)
See “3DC multi-target configuration ” (page 143) or “3 Cnt Ac-J DC multi-target configuration”
(page 129) for information and illustrations on the configuration covered in this procedure.
Recovering from primary site failure
For 3 Cnt Ac-J/Cnt Ac-S configurations, host operations are transferred to the secondary volume
in the intermediate site when disaster or failure occurs in the primary site in a 3DC multi-target
configuration. Replication occurs from the intermediate site to the primary site. Alternatively, a
temporary Cnt Ac-J system can be set up. Meanwhile, you correct the failure at the primary site,
then transfer host operations back to it and set up a 3DC configuration.
Procedure 35 To recover a primary 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 primary 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 primary 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
Figure 14 (page 99) .
2. Restore the primary 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 primary 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
Figure 14 (page 99) .
2. Restore the primary 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 primary site.
98 Disaster recovery operations