Running Global Mirror for a planned failover and failback

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Use this process to manage the local (production) and remote (recovery) sites for a planned failover through Global Mirror.

About this task

During a planned outage, all storage systems, servers, and networks are functional. Last and current states of all components are well-defined.

Examples for planned outages are system maintenance, disaster recovery tests, and training. The objective of the failover and failback procedures is to continue with consistent and current data (without any loss of transactions).

The following conditions are likely to apply:
  • All storage systems (local and remote) are functional and accessible.
  • Applications are updating the primary volumes of the local site.
  • Paths are created from the local to the remote site.
  • You created an environment to manage a planned outage.

Procedure

Complete the following steps to begin the planned failover.

  1. Quiesce host I/O that is updating the primary volumes of the local site.
  2. Check the status of Global Mirror to ensure that Global Mirror is in a good state. Also, ensure that a consistency group is formed successfully at the set interval.
  3. Wait until two consistency groups form successfully.
  4. Pause Global Mirror and suspend the Global Copy pairs (A to B).
  5. Create paths from the B volumes to the A volumes.
  6. Run recovery failover on the B volumes (B to A).
  7. Run the fast reverse restore process from the C volumes to the B volumes, with the initiate background copy option.
    Notes:
    1. When you initiate the fast reverse restore process, Volume C becomes unusable.
    2. I/O must not be allowed to the B or C volumes during the fast reverse restore process.
  8. Before the next step, await completion of the background copy process. The C to B FlashCopy relationship ends when the background copy completes.
  9. Initiate the FlashCopy from Volume B back to Volume C. Ensure that you specify the enable change recording and inhibit writes to target volume options. These options create a backup copy of the consistency group before applications begin to update the B volumes.
  10. Start the host I/O at the remote site on the B volumes. Production continues on the remote site in this configuration until you are ready to return production to the local site.
  11. When you are ready to return production to the local site, run recovery failback (B to A) to resynchronize the A volumes. The application at the remote site remains active.
  12. After the resynchronize process completes its first pass, quiesce the applications at your remote site so that the resynchronization can complete.
  13. When the resynchronization is completed (no out-of-sync tracks), run recovery failover and failback with Global Copy on volume A to establish the Metro Mirror relationship of volumes A and B.
  14. Start the host I/O at the local site on the A volumes.
  15. Resume the Global Mirror process.