Failure of the local storage system and of the local system

If the local Data Center fails, processing can be continued on the standby system.
If the home pubset of the local system has been duplicated with SRDF, and if the standby system is to be started with the same home pubset, a further system is required to activate the target path before startup (/SET-REMOTE-COPY-ACCESS with TARGET-ACCESS= *DIRECT). There may be data inconsistency if asynchronous processing mode was set before local failure, or if local failure was preceded by failure of the remote link or target unit.

In concurrent SRDF configurations it is first necessary to select the storage system or location where operation is to be resumed.

Actions on the standby system

1. Use /ATTACH-DEVICE to attach the target units (see the “Commands” manual [1])

2. Activate the target path (set target units to READY).
   If the remote storage system contains only target units affected by the failure, the entire remote storage system can be specified. Switchover takes place simultaneously for all the devices affected.

   /SET-REMOTE-COPY-ACCESS
     UNIT=*BY-SYMMETRIX(SERIAL-NUMBER=<remote serialnumber>
     ,LOGICAL-VOLUMES=*ALL-TARGETS)
     ,TARGET-ACCESS=*DIRECT
   

   For this function, the values DETACHED-DEVICES=*ACCEPT and NOT-DEFINED-DEVICES=*ACCEPT must be set for SYSTEM-ADMIN-SCOPE or TASK-ADMIN-SCOPE in the /MODIFY-SHC-PROCESSING command.

   If not all target units of the remote storage system are affected by the failure, the units must be specified separately. Device selection depends on the settings for SYSTEM-ADMIN-SCOPE or TASK-ADMIN-SCOPE and is made using:

   /SET-REMOTE-COPY-ACCESS
     UNIT=*BY-VOLUME(VOLUME=<vsn>) / *BY-PUBSET(PUBSET=<cat-id>) /
          <MN of target unit>
     ,TARGET-ACCESS=*DIRECT
   

   The *BY-VOLUME operand can be only used if the target unit was READ-ONLY and is unique, or if the source unit was accessible, i.e. VSN on the source unit was readable. The *BY-PUBSET operand cannot be used for the switchover because of the failure.

   If the target unit was not synchronized with the source unit, transition to READY is rejected if PENDING-UPDATES are not allowed for the unit.

   This setting can be overridden by the following command:

   /SET-REMOTE-COPY-ACCESS
     UNIT=*BY-VOLUME(VOLUME=<vsn>) / *BY-PUBSET(PUBSET=<cat-id>) /
          <MN of target unit>
     ,TARGET-ACCESS=*DIRECT(ALLOW-PEND-UPDATES=*YES)
   

3. Check data integrity (see "Data integrity after a failure")

4. Import the pubsets and start the applications