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

5-64 Performing TrueCopy for z/OS Configuration Operations
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Powering Off/On TrueCopy for z/OS Components
The user is responsible for controlling power-off activities for storage systems
involved in TCz operations. If you need to power off the USP V, please call
your Hitachi representative or the Hitachi Support Center for assistance.
If power is removed from an MCU while TCz operations are in progress, the
TCz pairs are not affected, but the update sequence consistency of the TCzA
groups at the RCU may be affected. When power is restored to an MCU, the
MCU communicates with its RCU(s) to confirm the pair status of the R-VOLs.
Make sure that TCz communications are fully restored (all RCU paths have
normal status) before beginning I/O operations to the M-VOLs. If the MCU
accepts a write I/O operation for an M-VOL before this confirmation is
complete, the MCU will suspend the pair and change the status of the M-VOL
to suspended-by RCU (the MCU will not be able to change the pair status of
the R-VOL).
If power is removed from an RCU or remote copy connection while TCz
operations are in progress, the MCU(s) will detect the communication failure,
suspend all affected pairs, and generate SIMs and console messages reporting
the failures. The MCU will change the status of the M-VOLs to suspended-by
RCU but will not be able to change the status of the R-VOLs.
Note: If an MCU/RCU is powered off and its backup batteries are fully
discharged while TCz pairs are suspended, the M-VOL/R-VOL cylinder maps
will not be retained. In this unlikely case, the MCU/RCU will mark all cylinders
of all suspended TCz volumes as modified, so that the MCU will perform the
equivalent of an entire initial copy operation when the pairs are
resynchronized. (The R-VOL cylinder map is used only for TCzA operations.)
Planned Outage of the MCU
A planned MCU outage does not affect TCz Synchronous pairs. For TCzA
operations, the MCU must communicate with the RCU even when there are no
M-VOL update I/Os from the primary system. During the power-off sequence,
the MCU will automatically suspend all TCzA pairs in the duplex and duplex
pending state (suspend type = MCU P/S-OFF). During power-on-reset
sequence, the MCU will automatically resynchronize these suspended pairs
(pairs with other suspend types are not automatically resynchronized).
If a TCzA group contains M-VOLs in the MCU being powered off and in other
MCU(s) which is/are not being powered off, the pairs behind the other MCU(s)
will not be suspended and will continue to be updated. If you need to maintain
a fully consistent group at the RCU during the planned MCU outage, take the
following steps:
1. Quiesce the applications using all M-VOLs in the consistency group.
2. Suspend the group at the RCU using the Group suspend option. You can use
the Purge or Drain suspend option since the M-VOL updates have stopped.