HP Hitachi TrueCopy for Mainframe User Guide (T5211-96014, November 2011)

After all logical MCU-RCU paths are established, make sure to specify the desired SCP time
(0-600 seconds) for the MCU using the CU Option dialog box.
If the specified MCU does not have any TrueCopy for Mainframe M-VOLs, the FREEZE command
is executed without performing any operations (paths are not blocked, SCP is not indicated).
For 2105 and 2107 emulation, use the CESTPATH CGROUP option to control freeze.
• RUN: When CGROUP is issued with the RUN option, the MCU:
Presents a state-change-interrupt (SCI) to the host(s), so that the host(s) re-issue the I/Os
which were waiting while the M-VOLs were in the SCP state.
◦
◦ Changes the TrueCopy for Mainframe M-VOL fence level to Never (PPRC CRIT=NO), so
that the suspended M-VOLs accept host write I/O operations.
“TrueCopy for Mainframe Pair Status During CGROUP (FREEZE/RUN) Operations” (page 208)
shows the TrueCopy for Mainframe pair status for TrueCopy for Mainframe M-VOLs and R-VOLs
during CGROUP (FREEZE/RUN) operations.
Table 68 TrueCopy for Mainframe Pair Status During CGROUP (FREEZE/RUN) Operations
After CGROUP/RUNAfter CGROUP/FREEZEBefore CGROUP (FREEZE/RUN)
R-VOLM-VOLR-VOLM-VOLR-VOLM-VOL
---Simplex---Simplex---SimplexTrueCopy for
Mainframe
Pair Status
PendingSuspendedPendingSuspendedPendingPending
DuplexSuspendedDuplexSuspendedDuplexDuplex
SuspendedSuspendedSuspendedSuspendedSuspendedSuspended
Using the CGROUP Command
“Overview of GDPS Operations” (page 209) shows a simplified operational example of the CGROUP
(FREEZE/RUN) command implemented in a GDPS environment. The CGROUP (FREEZE/RUN) TSO
command can be issued by the user or through automation (such as GDPS) to perform the following
sequence of actions:
1. Suspend host updates to all TrueCopy for Mainframe M-VOLs on the specified MCU.
2. Block the specified MCU-RCU path to stop update copy operations to the R-VOLs.
3. Change all TrueCopy for Mainframe M-VOLs on the specified MCU to suspended.
4. Resume host updates to the suspended M-VOLs.
5. The add RCU operation (CESTPATH) must be performed to re-establish the blocked logical
paths. After the MCU-RCU path is re-established, the resynchronize pair operation
(CESTPAIR/RESYNC) must be performed to resynchronize the suspended pairs.
208 Using PPRC Commands for TrueCopy for Mainframe