Moving a Global Mirror session to the recovery site in a planned outage

Figure 1. Moving a Global Mirror Session to Recovery Site in a Planned Outage

1. Quiesce applications at the primary site to reduce the risk of data loss.
2. Allow two consistency group formations to complete. Use the RQUERY command to confirm that the GoodCGCount increases by two.
3. Terminate the Global Mirror session using the RSESSION command specifying the STOP ACTION.
   1. If the master does not stop, reissue the command. If the master still does not stop, reissue RSESSION specifying the MASTER YES and FORCE parameters.
   2. Issue RQUERY to determine if any storage control subordinates are still running.
   3. Issue RSESSION to each subordinate storage control still running, specifying the MASTER NO parameter.
4. Issue the PPRC Establish Pair command to the B volume as the DEVN, specifying FAILOVER for ACTION, reversing the original primary and secondary parameters. This command changes the B volumes from secondaries to suspended primaries.
5. Issue the FCQUERY command to each of the suspended primary (B) volumes at the recovery site.
   Note: The revertible status (column headed RV) and the FlashCopy® sequence numbers (column headed SEQNUM) in order to determine which step to perform next.

   • If all the FlashCopy relationships are non-revertible and the FlashCopy sequence numbers of the relations are equal, then the consistency groups on the C volumes are intact. Proceed to step 5.
   • If all the FlashCopy relationships are revertible and the FlashCopy sequence numbers of the relations are equal, then you must issue the FlashCopy Withdraw command specifying the REVERT ACTION to all FlashCopy relationships in the consistency group. This restores the relationships to their prior state, resets the revertible state, and removes write inhibit on the B volumes. When the FlashCopy Withdraw command completes, proceed to step 5.
   • If the FlashCopy sequence numbers of the relationships are equal and at least one of the relationships is in a non-revertible state, then you must issue a FlashCopy Withdraw specifying COMMIT to all of the FlashCopy relationships in the consistency group. This commits the FlashCopy relationships to the current state, resets the revertible state, and removes write inhibit on the B volumes. When the FlashCopy Withdraw command completes, proceed to step 5.
   • If more than two non-zero FlashCopy sequence numbers are present, then the consistency groups have been corrupted and the recovery program cannot continue.
6. Restart applications at the recovery site.

   Once a site switch is in progress, the Global Mirror session can now be reversed with the following steps.

7. Use the PPRC Establish Paths command to provide a path for data flow from the recovery site to the primary site. Paths are required between all LSSs in which PPRC pairs reside.
8. Issue the PPRC Establish Pair command to the B volume as the DEVN specifying the FAILBACK ACTION, again reversing the original primary and secondary parameters. This copies any changes from the B volumes to the A volumes.
9. Use the FlashCopy Withdraw command to end the FlashCopy relationship at the recovery site.
10. Start a new FlashCopy relationship between A and C′ volumes at the primary site, using the FlashCopy Establish command and specifying ASYNC with the MODE parameter.
11. Issue the RSESSION DEFINE command at the recovery site to specify the topology of the new Global Mirror session.
12. Use the PPRC Establish Paths command to provide a path for data flow between the Master and storage control subordinates at the recovery site.
13. Use the RVOLUME JOIN command to populate the session with primary volumes at the recovery site.
14. Issue RSESSION START to the Master at the recovery site to begin the Global Mirror session.

A Global Mirror session is now running at the recovery site, with the B volumes acting as the primary volumes, the A volumes acting as the secondary volumes, and the C′ volumes acting as the tertiary volumes.