HP StorageWorks XP Remote Web Console Software - Manual (Page 176)

176 Hitachi TrueCopy z/OS for HP XP12000/XP10000 and SVS 200 storage systems
• FREEZE (3990 only): When CGROUP is issued with the FREEZE option, the MCU:
• Blocks the logical path(s) between the specified MCU CU image and RCU CU image to stop all
TC390 update copy operations to the R-VOLs in the specified RCU.
• Presents state change pending (SCP) with extended long busy status to host I/O requests, which
causes the host to queue I/Os for the M-VOLs. SCP is indicated until the CGROUP/RUN command
is issued or until the SCP delay time expires.
NOTE: After all logical MCU-RCU paths are established, make sure to specify the SCP delay time
(0-600 seconds) for the MCU using the RCU Option window. To register the SCP delay time, select
OK to close the RCU Option window, even if you did not make any changes.
If the specified MCU does not have any TC390 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:
• Suspends all TC390 pairs with M-VOLs on the specified MCU CU image.
• Presents a state-change-interrupt (SCI) to the host(s) so that the host(s) re-issue the I/Os that were
waiting while the M-VOLs were in the SCP state.
• Changes the TC390 M-VOL fence level to Never (PPRC CRIT=NO) so that the suspended M-VOLs
accept host write I/O operations.
The following table shows the TC390 pair status for TC390 M-VOLs and R-VOLs during CGROUP
(FREEZE/RUN) operations.
Using the CGROUP command
The following figure 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 TC390 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 TC390 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 resume pair operation (CESTPAIR/RESYNC) must be
performed to resume the suspended pairs.
For the following figure:
1. Read/write I/Os are issued from the host.
2. A failure occurs on a TC390 M-VOL and the MCU suspends the pair.
3. Suspend and extended long busy state are reported to the host.
4. Host reports IEA494I with extended long busy state.
Table 45 TrueCopy pair status during CGROUP (FREEZE/RUN) operations
Before CGROUP
(FREEZE/RUN)
After CGROUP/FREEZE After CGROUP/RUN
M-VOL R-VOL M-VOL R-VOL M-VOL R-VOL
TC390
Pair Status
Simplex --- Simplex --- Simplex ---
Pending Pending Pending Pending Suspended Pending
Duplex Duplex Duplex Duplex Suspended Duplex
Suspended Suspended Suspended Suspended Suspended Suspended