Hitachi TrueCopy for IBM z/OS User and Reference Guide (T5211-96001, June 2007)

Performing TrueCopy for z/OS Pair Operations 6-25
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
The resynchronize options are:
• M-VOL: the LDKC number, CU number, and device ID of the selected M-
VOL. If you selected more than one M-VOL, the M-VOL with the lowest device
ID is displayed. Note: If "#" is added to the end of the device ID like
00:00:3F#, the LDEV that the LDEV number indicates is an external volume.
For details on an external volume, please refer to the Universal Volume
Manager User's Guide.
• M-VOL Fence Level (sync only): if desired, you can change the fence level
of the pair(s).
• Initial Copy Parameters:
– Copy Pace (3 or 15): select the number of the tracks for the
resynchronize operation(s) (default = 15).
– Priority (from 0 to 256): set the desired priority (0-256) (scheduling
order) for the resynchronize operations (default = 32).
Note: 0 is the value for pairs created by CESTPAIR command or Business
Continuity Manager.
• Asynchronous Parameters:
– Resume Range (default = Group):
Group: all suspended TrueCopy for z/OS Async pairs in the same
group as the selected pair will be resynchronized.
Volume: only the selected TrueCopy for z/OS Async pair(s) will be
resynchronized. Note: For the Volume resynchronize range setting, if
you select pairs with duplex status and other than duplex status in the
same consistency group, unexpected suspend may occur during the pair
operations (suspend, resynchronize, release) under heavy I/O load
conditions. You can estimate whether the I/O load is heavy or not from
the rate of sidefile cache (around 30%), or if you cannot see the sidefile
cache rate, from the frequency of host I/O. The resynchronize pair
operations should be performed under light I/O load conditions.
– Error Level: if desired, you can change the error level of the pair(s).
This option is available only when the Volume Resume Range option is
selected.
Note: If an MCU or RCU is powered off and its backup batteries are fully
discharged while TrueCopy for z/OS pairs are suspended, the M-VOL/R-VOL
differential data will not be retained. In this unlikely case, the MCU/RCU will
mark all tracks of all suspended TrueCopy volumes as modified, so that the
MCU will perform the equivalent of an entire initial copy operation when the
pairs are resynchronized. (The R-VOL cylinder/track map is used only for TCz
Asynchronous operations.)
Note: The CESTPAIR (MODE=RESYNC) command can be used to
resynchronize suspended TCz Synchronous and TCzA pairs.