Hitachi TrueCopy for IBM z/OS User and Reference Guide (T5211-96001, June 2007)

TrueCopy for z/OS Usage Scenarios 7-9
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Switching Operations to the Remote Site
If a disaster or failure occurs at the main site, the first disaster recovery
activity is to switch your operations to the remote backup site. The TCz
Synchronous R-VOLs are recovered individually based on the pair status and
M-VOL fence level information for each pair. The TCzA R-VOLs are recovered
based on pair status, consistency status, and consistency time.
The basic procedures for switching operations to the remote backup site are:
1. Analyze the currency of the TCz Synchronous R-VOLs and the consistency of
the TCzA R-VOLs.
2. Record the consistency time (C/T) of each group. The suspended TCzA R-
VOLs with consistency status of group will indicate the same C/T.
3. Perform file recovery as needed. The C/T of each TCzA group can be used to
retrieve lost updates.
4. At the remote site, suspend all pairs by issuing the CSUSPEND TSO command
to the R-VOLs. Use the TCzA group and drain suspend options to destage
pending updates in cache to the R-VOLs. And then, change the state of R-
VOLs to simplex by issuing the CRECOVER TSO command.
Note: If PPRC is not installed, connect to each RCU, and release all TCz
pairs. For TCzA pairs, select C/T for the Delete Range option on the Delete
Pair dialog box to release all consistent pairs in the group at the same
time. This option prevents you from accidentally using inconsistent pairs
for disaster recovery. Release all TCz sync pairs in the MCU using the
Deleting Mode-All option.
Caution: Once an R-VOL changes to the simplex state, you cannot
distinguish it from a non-TCz simplex volume. The TCzA C/T is also
discarded when the pair is released.
5. If necessary, use ICKDSF REFORMAT to change the labels (VOLSERs) of the
R-VOLs.
6. Make sure that all required file recovery procedures have been completed
before varying the R-VOLs online. If an IPL of the remote host system is not
required, bring the R-VOLs online. If an IPL is required:
a) Clear the remote copy SIMs from the RCUs before OS IPL. Connect to
each RCU, open the TrueCopy for z/OS System Option window, and click
the Clear SIM button.
b) Perform IPL of the remote host system.
c) Wait until the IPL is complete, and then vary the R-VOLs online (if they
did not come online automatically).
7. At this point you may start critical applications at the remote site with the
previous R-VOLs taking the place of their M-VOLs.