With the incremental resync support installed, if there is an
intermediate site failure, to restart the recovery environment running
Global Mirror from the local site to the remote site, do the following
steps:
Assumptions:
- Metro Mirror pairs between the local and intermediate sites will
suspend if host writes are done to the local, or A volumes. If not,
A to B pairs need to be suspended.
- Global Mirror is one of the following status:
- Global Mirror is no longer running.
- Global Mirror has gone FATAL.
- Global Mirror is no longer forming consistency groups.
- Depending on the type of failure at the intermediate site, assume
the worst scenario: Global Mirror was in the middle of forming a
consistency group or performing the FlashCopy® step as part of a consistency group, and
was unable to complete. The consistency group will need to be verified
at some point.
Recover steps:
- Perform failover commands to the C volumes at the remote site
(PPRC establish C volumes to B volumes) with the cascade option.
Note: If you want to stop the Global Mirror session,
stop the session after this step. If a stop issued to the master
fails, a intermediate site failure might have happened in the middle
of Global Copy formation. Thus, the Global Mirror and FlashCopies
need to be reverted or committed. In this scenario, you can use the
MASTER=NO parameter to stop the Global Mirror session on any subordinates
that might have been orphaned during the outage.
- Establish paths between A volumes' LSSs and C volumes' LSSs.
- Establish A to C pairs using the incremental resync change recording
bitmaps to copy changed tracks. The configuration at this point will
be from volumes A to C, and then C to B, with A to C running PPRC-XD
and the C to B pair being in failover state.
- Establish paths from control unit that is the intended master
of the global Mirror session at the primary (local) site and the intended
subordinate control units at the primary site.
- Define the Global Mirror session to all LSSs that are going to
participate in the session at the primary site.
- Join the A volumes to the Global Mirror session.
- Start the Global Mirror session at the local site.
When the intermediate site has been recovered, to return to the
original Metro/Global Mirror configuration, the recovery procedure
is the same as that for recovery after a planned outage.