Using The Cgroup Command - HP StorageWorks P9000 User Manual

FREEZE: When CGROUP is issued with the FREEZE option, the MCU:
◦ Blocks the logical path(s) between the specified MCU CU and RCU CU to stop all
Continuous Access Synchronous Z 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 time expires.
Suspends all Continuous Access Synchronous Z pairs with M-VOLs on the specified MCU
◦
CU.
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 Continuous Access Synchronous Z M-VOLs, the FREEZE
command is executed without performing any operations (paths are not blocked, SCP is not
indicated).
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
◦
that were waiting while the M-VOLs were in the SCP state.
◦ Changes the Continuous Access Synchronous Z M-VOL fence level to Never (PPRC
CRIT=NO), so that the suspended M-VOLs accept host write I/O operations.
Table 37 (page 91)
Synchronous Z M-VOLs and R-VOLs during CGROUP (FREEZE/RUN) operations.
Table 37 Pair status during CGROUP (FREEZE/RUN) operations
Continuous
Access
Synchronous Z
pair status

Using the CGROUP command

Figure 12 (page 92)
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 Continuous Access Synchronous Z 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 Continuous Access Synchronous Z 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 reestablish the blocked logical
paths. After the MCU RCU path is reestablished, the resynchronize pair operation
(CESTPAIR/RESYNC) must be performed to resynchronize the suspended pairs.
shows the Continuous Access Synchronous Z pair status for Continuous Access
Before CGROUP (FREEZE/RUN)
M-VOL R-VOL
Simplex —
Pending Pending
Duplex Duplex
Suspended Suspended
shows a simplified operational example of the CGROUP (FREEZE/RUN)
After CGROUP/FREEZE
M-VOL R-VOL
Simplex —
Suspended Pending
Suspended Duplex
Suspended Suspended
After CGROUP/RUN
M-VOL R-VOL
Simplex —
Suspended Pending
Suspended Duplex
Suspended Suspended
CGROUP (FREEZE/RUN) support 91