Group operations – HP StorageWorks XP Remote Web Console Software User Manual
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TrueCopy for the XP128/XP1024/XP10000/XP12000
When a TC390A volume pair is suspended, the C/T of the suspended R-VOL is frozen. If the RCU can
ensure the update sequence consistency between the suspended R-VOL and the other R-VOLs in the
consistency group, the R-VOL C/T is frozen at the latest consistency time of the group. Otherwise, the
R-VOL C/T is frozen at the time-stamp value of the most recent update that was successfully copied to the
R-VOL. The C/T of a suspended R-VOL may be older than the C/T of other R-VOLs in the group, and if the
entire group was not also suspended, the consistency time of the group is still ticking. For suspended
TC390A R-VOLs, the TC390 Pair Status window displays whether the C/T was frozen to the group or
R-VOL time.
After you have established TC390A operations, you should monitor the consistency time of each group at
the RCU(s). If the average delay is longer than your disaster recovery design can accept, you should
consider adding remote copy resources (for example, paths or cache) and/or reducing the I/O workload
to improve disk array performance. If the delay between the M-VOL update and the corresponding R-VOL
update reaches the time specified by the Time Out [Copy Pending] group option, the MCU will suspend all
affected volume pair(s) due to the heavy I/O workload (at MCU or RCU). To prevent timeout errors, you
can increase the Time Out [Copy Pending] value, reduce I/O workload, and/or add remote copy
resources.
Group Operations
TC390A provides the following group-based operations to simplify and expedite disaster/failure recovery
procedures:
•
Group operations at the MCU:
• Suspend all pairs in a consistency group. For a description of the TC390A Group suspend option
(supported by CSUSPEND TSO command), see ”
Suspending TrueCopy Pairs (Suspend Pair)
• Resume all suspended pairs in a consistency group. For a description of the TC390A
Resume-Group pair option (supported by the CESTPAIR TSO command with the parameter
MODE=RESYNC), see ”
Resuming TrueCopy Volume Pairs (Resume Pair)
• Delete all pairs in a consistency group. For a description of the TC390A Group delete option
(supported by CDELPAIR TSO command), see ”
Deleting TrueCopy Volume Pairs (Delete Pair)
•
Group operations at the RCU:
• Suspend all pairs in a consistency group. For a description of the TC390A Group suspend option
(supported by CSUSPEND TSO command), see ”
Suspending TrueCopy Pairs (Suspend Pair)
• Delete all suspended pairs in a consistency group except for any inconsistent pairs. For a
description of the TC390A C/T delete option (not supported by CDELPAIR, CDELPAIR cannot be
issued to the RCU), see ”
Deleting TrueCopy Volume Pairs (Delete Pair)
• Delete all pairs in a consistency group regardless of their consistency status. For a description of the
TC390A Group delete option (not supported by CDELPAIR, CDELPAIR cannot be issued to the
RCU), see ”
Deleting TrueCopy Volume Pairs (Delete Pair)
TC390A also provides the Error level pair option (see ”
Creating TrueCopy Volume Pairs (Add Pair)
page 115) that is used to trigger automatic suspension of an entire consistency group. When a TC390A
pair is suspended due to failure (not user-requested), this TC390A pair option determines whether all pairs
in the same consistency group will also be suspended. If you select the Group error level for a TC390A
pair, all pairs in the same group will be suspended. If you select the Volume error level, only the affected
TC390A pair will be suspended.
NOTE:
The Error level pair option is very important for managing TC390A groups and planning for
disaster recovery. The Group error level should be selected for all TC390A volumes that are essential to
disaster recovery. Suspended TC390A R-VOLs that have the Volume error level should not be used for
disaster recovery.