HP StorageWorks XP Remote Web Console Software - Manual (Page 47)

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.
• 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 based on required copying time that may take
longer because of the power-supply off (PSOFF).
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 (PSOFF) again becomes the target data to be copied after the power-supply
on (PSON). 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 (PSOFF) again becomes the target data to be copied after the power-supply on (PSON). In
this case, the data consistency rate is 0%, and the target data is copied to the T-VOL.
• If the Siz pair was in the split status, the entire volume becomes the differential data. In this
case, the data consistency rate is 0%, and the entire volume is copied to the T-VOL when you
perform the resync pair operation.
Cautions on Using XP10000 Storage System
The XP10000 storage system has fewer processors than the XP12000 storage system. Copy processing of
Siz, HP StorageWorks XP for FlashCopy Mirroring and HP StorageWorks XP for FlashCopy Mirroring 2
may therefore take a long time, and host I/O performance may degrade. Consider the following:
• Copy processing
When you use XP10000 storage system, the time of copy processing such as pair creation, pair
split, and pair resynchronization may take longer than when you use XP12000 storage system.
Copy processing time varies according to the number of pairs, and sometimes XP10000 storage
system needs two to eight times more processing time than XP12000 storage system.
• Host I/O performance
Since copy processing uses processors, host I/O performance may degrade during the copy
processing. The number of processors in XP10000 storage system is small, so when you use
XP10000 storage system, the impact of the copy processing on the host I/O performance is
greater than when you use XP12000 storage system.
To mitigate the degradation of the host I/O performance, do the following:
• When you are using Siz:
Lower the copy pace.
Specify the Host I/O Performance option.
• When you are using FlashCopy Mirror:
Specify the Host I/O Performance option.
• When you are using FlashCopy Mirror V2:
Specify the FCv2 Slower Copy1 option.
Hitachi ShadowImage for z/OS user guide 47