Hitachi ShadowImage for IBM z/OS User"s Guide (T5213-96002, June 2007)

3-12 Preparing for ShadowImage™ for z/OS
®
Operations
Hitachi ShadowImage™ for IBM
®
z/OS
®
User’s Guide
– If the status of an SIz pair is either Pending, Duplex, Split, SP-Pend, V-
Split, Resync or Resync-R, the maintenance for the LDEVs which are
used by that pair will be restricted. In addition, LDEV maintenance
cannot be performed on the LDEVs which are assigned to SIz reserved
volumes. If LDEV maintenance requires access to a SIz reserved
volumes, you need to delete or suspend the pair, or the Reserve
attribute must be reset (un-reserved).
Cautions on Maintaining the Cache
If USP V cache maintenance is performed during a period of high I/O usage,
one or more SIz pairs may be suspended. Reduce the I/O load before cache
maintenance.
Cautions on Switching Off the Power Supply
If you have to switch off the power supply of the USP V storage system during
SIz
operations, make sure to:
• Complete copying for the SIz pair in the SP-pend or V-split status first to
change the pair status from SP-pend or V-split to split, and then switch off
the power supply.
Note: If the shared memory is volatilized when you switch on the power
supply again, the pair in the SP-pend or V-split status changes to suspend.
• First complete the processing of At-Time Split function, and then switch off
the power supply.
Note: If the status of only a part of the pairs in the same consistency
group is changed, the processing of At-Time Split function may not resume
when you switch on the power supply, and the status of some pairs may
remain unchanged.
• Establish a timetable for SIz copying operations according to required
copying time that may take longer because of the power-supply off.
Note: If the shared memory is volatilized when you switch on the power
supply again, the following conditions occur.
– If the SIz pair was in the pending or resync status, data that was
already copied before the power-supply off again becomes the target
data to be copied after the power-supply on. Even if there is no host
I/O, the data consistency rate does not reach 100% when the SIz pair
status changes to duplex. When the SIz pair status changes to duplex,
the target data is copied to the T-VOL.
– If the SIz pair was in the duplex status, data that was already copied
before the power-supply off again becomes the target data to be copied
after the power-supply on. In this case, the data consistency rate is
0%, and the target data is copied to the T-VOL.