HP XP7 Storage - Manual (Page 111)

the delta resync operation. When the failure at the local site is corrected, host operations are
transferred back to the local site and the delta resync configuration is reestablished.
Prerequisite information
•
For information and illustrations on the configuration covered in this procedure, see “Delta
resync configuration ” (page 144) .
•
You can specify options for recovery in the event that the delta resync operation fails. See the
Delta resync Failure step in
“Changing options used by mirrors ” (page 94) . This also provides
important information if you share the delta resync S-VOL with Business Copy, Fast Snap, or
a THP V-VOL.
Procedure 41 To recover a delta resync configuration failure
1. Make sure that the Cnt Ac-J Z pair is in Duplex status and then run the YKSUSPND Flush
FORWARD command.
2. Run the YKSUSPND REVERSE command on the Cnt Ac-S Z pair. This suspends the pair and
stops copy operation temporarily.
3. Start host operations to the Cnt Ac-S Z S-VOL.
4. Reverse the copy flow of the Cnt Ac-S Z pair, if possible, using the YKRESYNC REVERSE
command.
5. Perform the delta resync operation using the YKRESYNC DELTAJNL command on the volume
in the Cnt Ac-S Z intermediate site.
See “Performing the delta resync operation” (page 149) .
Note that pair status must be Hold before the operation. When the operation completes, pair
status is Duplex or Pending Duplex.
NOTE: Pair status also changes for the original Cnt Ac-J Z pair in the primary and Cnt Ac-J
Z remote sites, from Duplex or Pending Duplex to Hold.
However, the status of the original pair may not change to the required state after the delta
resync operation. If this occurs, host operations cannot be resumed in the local site. See
“Problems with pair status during delta resync recovery” (page 111) and make the necessary
corrections.
6. Restore the problem at the local site. This must be done before proceeding.
7. Make sure the Cnt Ac-J Z pair is in Duplex status, then run the YKSUSPND Flush FORWARD
command on the pair.
8. If the Cnt Ac-S Z pair is suspended, resynchronize the pair and reverse the copy flow using
the YKRESYNC REVERSE command.
9. Stop host operations to the Cnt Ac-S Z intermediate site.
10. Suspend the Cnt Ac-S Z pair using the YKSUSPND FORWARD command.
11. Resume host operations to the Cnt Ac-S Z P-VOL in the local site.
12. Run the YKRESYNC FORWARD command on the Cnt Ac-S Z pair to resynchronize and return
the copy flow to its original direction.
13. Perform the delta resync operation on the volume in the Cnt Ac-S Z local site. Pair status must
be Hold. When the operation completes, pair status is Duplex or Pending Duplex.
Also, pair status changes for the delta resync Cnt Ac-J Z pair from the Cnt Ac-S Z intermediate
to the Cnt Ac-J Z remote site, from Duplex or Suspend to Hold.
The system becomes a delta resync configuration again.
Problems with pair status during delta resync recovery
After performing the delta resync, it is necessary for the original Cnt Ac-J Z pair from the primary
to Cnt Ac-J Z remote sites to be in Hold status, in order to resume operations at the local site.
However, the pair may not be in this status.
Recovery for 3 Cnt Ac-J Z/Cnt Ac-S Z data centers 111