Failback process for synchronous PPRC in a planned outage
Figure 1. Failback in a Synchronous PPRC Environment
Quiesce applications at the recovery site to reduce the risk of
data loss.
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.
Issue the PPRC Establish Pair command to the B volume as the DEVN,
specifying the FAILBACK ACTION and once again reversing the original
PRIMARY and SECONDARY parameters. This copies any changes recorded
on the B volumes back to the A volumes
Withdraw the optional FlashCopy® relationship
at the recovery site if no longer needed.
Verify that paths are still established from the primary site
to the recovery site. Issue PPRC Establish Paths commands if necessary.
Allow PPRC pairs to achieve full duplex state, indicating that
all data has been copied from B to A volumes. Use the PPRC Query command
to determine status or check for console message IEA494I.
Issue the PPRC Suspend command to the B volume as the DEVN, suspending
the reversed pairs.
Issue the PPRC Establish Pair command to the A volume as the DEVN,
specifying the FAILOVER ACTION with the original PRIMARY and SECONDARY
parameters. This reestablishes the A volumes as suspended primaries,
begins change recording on the A volumes, and releases write inhibit
on the A volumes.
Restart applications at the primary site.
Issue the PPRC Establish Pair command to the A volume as the
DEVN, specifying the FAILBACK ACTION with the original PRIMARY and
SECONDARY parameters. This resynchronizes the A and B volumes in the
recovery configuration and restores the pairs to full duplex state.