HP XP7 Storage - Manual (Page 123)

For disaster recovery implementations, XP7s must be used at both sites, because the RCUs will be
switched to MCUs.
CAUTION: XP7 also supports the Business Continuity Manager Freeze and Run commands,
which are equivalent to the TSO CGROUP command. If both commands are performed
simultaneously, the XP7s find the appropriate volumes and run the commands.
However, in this situation, the host cannot detect which command is performed. Therefore, it is
important not to use the Business Continuity Manager Freeze/Run commands and the CGROUP
command at the same time.
CGROUP and FREEZE/RUN requirements
The CGROUP command can only be issued to an P-VOL or a simplex volume in the MCU. If issued
to an S-VOL, the RCU rejects it with F/M=0F, reason code=58.
The requirements for CGROUP FREEZE/RUN support are:
•
MCU: The MCUs to which the CGROUP command will be issued must be XP7 storage systems
(all mainframe and multi-platform systems are supported). For disaster recovery implementations,
you must use XP7 storage systems at both sites, because the RCUs will become MCUs in the
event of a disaster.
•
PPRC: The host systems at the main and remote sites must have IBM PPRC support and the
PPRC ERP PTF
•
SSIDs: The MCUs to which the CGROUP command will be issued must have consecutive SSIDs.
The HP representative configures the SSIDs on the XP7 SVP.
CAUTION: MVS requires that the storage system be offline during SSID changes.
Reconfiguring SSIDs is therefore a disruptive event that must be carefully planned.
Also, SCP time specified from Remote Web Console's CU Option dialog box is invalid for
pairs created using a consistency group from Business Continuity Manager. You can, however,
specify SCP time for these pairs using the YKFREEZE command (range from 1 to 5 seconds).
If a failure suspension occurs, then SCP time becomes fixed at 120 seconds and cannot be
changed.
•
When you run CGROUP FREEZE or RUN, the following information must be specified:
The device, which is the P-VOL or simplex volume LDEV ID (DEVN parameter) ◦
◦ The MCU, which consists of the serial number and lowest SSID in the CU (PRIM parameter).
◦ The RCU, which consists of the serial number and lowest SSID in the CU (SEC parameter).
Pair status before and after CGROUP FREEZE/RUN
The following table shows pair status for P-VOLs and S-VOLs before and after CGROUP FREEZE/RUN
operations.
After CGROUP/RUN After CGROUP/FREEZE Before CGROUP FREEZE/RUN
S-VOL P-VOL S-VOL P-VOL S-VOL P-VOL
— Simplex — Simplex — Simplex Status
Pending Suspended Pending Suspended Pending Pending
Duplex Suspended Duplex Suspended Duplex Duplex
Suspended Suspended Suspended Suspended Suspended Suspended
I/O control after failure—with CGROUP FREEZE/RUN 123