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

Using PPRC Commands for TrueCopy for z/OS A-29
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
CGROUP (FREEZE/RUN) Support
The TCz feature supports the CGROUP (FREEZE/RUN) TSO command for PPRC,
which is also used in IBM’s Geographically Dispersed Parallel Sysplex (GDPS)
environment. The CGROUP TSO command is used to control I/O operations for
TCz Synchronous pairs on a specific MCU-RCU pair. The CGROUP command is
supported for USP V functioning as TCz MCUs. The USP V provides all required
host reporting for CGROUP operations (e.g., IEA494I with extended long busy
(ELB) state), which is a key component of GDPS operations. For disaster
recovery implementations, you must use USP Vs at both sites, since the RCUs
will become MCUs in the event of a disaster.
The CGROUP command has two parameters, FREEZE and RUN. The
CGROUP/FREEZE command stops all host I/O operations to the specified TCz
M-VOLs as well as all TCz update copy operations to their associated R-VOLs.
The CGROUP/RUN command changes the pair status to suspended and allows
the M-VOLs to start accepting host I/Os.
Note: For 2105 and 2107 controller emulation, do not use the FREEZE option.
Use the CGROUP option of the CESTPATH command.
Caution: The USP V executes the CGROUP command on TCz Synchronous
pairs. TCzA does not support the CGROUP TSO command. If CGROUP is issued
to a TCzA volume, the USP V will reject the command. CGROUP (FREEZE/RUN)
operations on TCz Synchronous pairs do not affect TCzA pairs in any way.
Caution: The USP V supports the Business Continuity Manager Freeze/Run
commands that are equal to the CGROUP command. Even if both commands
are performed simultaneously, the USP Vs find the appropriate volumes, and
can execute the commands. On the other hand, the host cannot detect which
command is performed. Therefore, do not use the Business Continuity
Manager Freeze/Run commands and the CGROUP command at the same time.
For further information and instructions on Business Continuity Manager,
please refer to the Business Continuity Manager User's Guide.
Requirements
The CGROUP command can only be issued to a TCz Synchronous M-VOL or a
simplex volume in the MCU. If CGROUP is issued to a TCz R-VOL, the RCU will
reject the CGROUP command (F/M=0F, TCz error code=58).
The requirements for CGROUP (FREEZE/RUN) support are:
• MCU: The MCUs to which the CGROUP command will be issued must be
USP V storage systems (all-mainframe and multiplatform storage systems are
both supported). For disaster recovery implementations, you must use USP V
storage systems at both sites, since the RCUs will become MCUs in the event
of a disaster.