Cautions on switching off the power supply, Cautions on using the xp10000 disk array – HP StorageWorks XP Remote Web Console Software User Manual
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ShadowImage for the XP128/XP1024/XP10000/XP12000
Cautions on Switching Off the Power Supply
If you need to switch off the power supply of the disk array during SI390 operations, make sure to:
•
Complete copying for the SI390 pair in the SP-pend status first to change the pair status from SP-pend
to split, and then switch off the power supply. If the shared memory is volatilized when you switch on
the power supply again, the pair in the SP-pend status changes to suspend.
•
Establish a timetable for SI390 copying operations. If the shared memory is volatilized when you switch
on the power supply again, the following conditions occur:
• If the SI390 pair was in the pending or resync status, data that was already copied becomes the
target data to be copied after the power supply is turned back on. Even if there is no host I/O, the
data consistency rate does not reach 100% when the SI390 pair status changes to duplex. When
the SI390 pair status changes to duplex, the target data is copied to the T-VOL.
• If the SI390 pair was in the duplex status, data that was already copied becomes the target data to
be copied after the power supply is turned back on. In this case, the data consistency rate is 0%,
and the target data is copied to the T-VOL.
• If the SI390 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 the XP10000 Disk Array
The XP10000 disk array has a smaller number of processors than the XP12000 disk array. Therefore,
sometimes copy processing of ShadowImage for z/OS, Compatible Mirroring for IBM FlashCopy
(FlashCopy Mirror), and Compatible Mirroring for IBM FlashCopy Version 2 (FlashCopy Mirror Version 2)
takes a long time, and the host I/O performance may degrade. Mind the following points.
•
Copy processing
When you use the XP10000 disk array, the copy processing for pair creation, pair split, and pair
resynchronization may take longer compared to when you use the XP12000 disk array. Copy
processing time will change according to the number of pairs, and sometimes the XP10000 disk array
needs two to eight times the copy processing time compared to the XP12000 disk array.
•
Host I/O performance
Since the copy processing uses processors, host I/O performance may degrade during the copy
processing. The number of processors in the XP10000 disk array is small, therefore, when you use the
XP10000 disk array, the impact of copy processing on the host I/O performance will be larger than
when you use the XP12000 disk array.
To mitigate the degradation of the host I/O performance, do the following:
• When you are using ShadowImage for z/OS
• 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 Version 2
• Specify the FCv2 Slower Copy1 option
• Specify the FCv2 Slower Copy2 option
For information about how to specify the copy pace, see ”
Resynchronizing ShadowImage Pairs
For details about the Host I/O Performance option, see
Host I/O Performance Option” on page 27
.
For details about the FCv2 Slower Copy1 option, see ”
details about the FCv2 Slower Copy2 option, see
Fcv2 Slower Copy2 Option” on page 28
.