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

Performing TrueCopy for z/OS Pair Operations 6-31
Hitachi Universal Storage Platform V TrueCopy for IBM z/OS User’s Guide
Asynchronous Parameters:
• Delete Range: The delete range option simplifies disaster recovery
operations for TCz Asynchronous consistency groups at the RCU (secondary
(remote) storage system).
– Group (MCU or RCU): all pairs in the same consistency group(s) as the
selected pair(s) will be released, regardless of pair status and consistency
status. You must select only one pair in each consistency group. Caution:
Do not use this option when releasing pairs at the RCU during disaster
recovery.
Note: If you release the TCzA pair from the RCU with the Group
option, while the M-VOL continues accepting I/Os, the TCzA pair is
forcibly suspended. This suspend is due to R-VOL failure (not user-
requested). This status is temporary and will eventually change to
Simplex. In this case, it is possible that all pending recordsets are not
settled.
– C/T (RCU only): the RCU will release all TCz Async pairs which have the
same consistency time.
– Volume (MCU or RCU): the MCU/RCU will release only the specified
pair(s). This option can be used to remove individual volumes from
consistency groups. Note: For the Volume delete 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 release pair operations
should be performed under light I/O load conditions.
The default delete range settings are:
– Two or more pairs in a group are selected: Volume.
– One pair is selected in each group and one or more M-VOLs are selected:
Group.
– One pair is selected in each group and all selected volumes are R-VOLs:
C/T.
Note: When the Force Deleting Mode option is selected for an asynchronous
pair, the Delete Range option is set to Group to protect the integrity of the
consistency group. This ensures that one or more pairs in a consistency group
cannot be forcibly deleted.
To release one or more TCz pairs:
1. If you need to release the pair(s) from the RCU in order to access the R-
VOL(s) (e.g., to perform ICKDSF), connect to the MCU(s) and suspend the
pair(s) first.
2. Connect to the MCU or RCU* of the pair(s) to be released, open the TrueCopy
for z/OS Pair Operation window.