HP StorageWorks XP Remote Web Console Software - Manual (Page 212)

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 212)
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/RUN After CGROUP/FREEZE Before CGROUP (FREEZE/RUN)
R-VOL M-VOL R-VOL M-VOL R-VOL M-VOL
--- Simplex --- Simplex --- Simplex TrueCopy for
Mainframe
Pair Status
Pending Suspended Pending Suspended Pending Pending
Duplex Suspended Duplex Suspended Duplex Duplex
Suspended Suspended Suspended Suspended Suspended Suspended
Using the CGROUP Command
“Overview of GDPS Operations” (page 213) 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.
212 Using PPRC Commands for TrueCopy for Mainframe