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

3-10 Preparing for ShadowImage™ for z/OS
®
Operations
Hitachi ShadowImage™ for IBM
®
z/OS
®
User’s Guide
– Specify Slower for the copy pace when you create, split, or
resynchronize SIz pairs.
– If SIz pairs that you want to perform copy operation are in the same
parity group, reduce the number of pairs at one copy operation. For
example, if you want to split multiple SIz pairs in the same parity
group, wait until one pair is completely split before splitting another
pair.
If the USP V storage system is overloaded, you must increase cache, disk
adapters, and/or parity groups. It is recommended that SIz T-VOLs are
assigned in the newly installed parity groups. If you continue SIz
operations with an overloaded storage system, host I/O performance may
be degraded.
• When you resynchronize a pair by Quick Restore:
During the quick restore operation, the RAID levels, Cache Residency
Manager for IBM z/OS settings, and HDD types of the S-VOL and
T-VOL are exchanged. For example, if the S-VOL has a RAID-1 level and
the T-VOL has a RAID-5 level, the quick restore operation changes the
RAID level of the S-VOL to RAID-5 and of the T-VOL to RAID-1. This also
applies to RAID-6 volumes. To avoid any performance impact due to the
quick restore operation:
– Make sure that the S-VOL and T-VOL have the same RAID level and
HDD type before performing the quick restore operation. If you want to
restore the original RAID levels after quick restore, stop host I/Os to
the pair, split the pair, perform the quick restore operation for that pair
again, and then restart the host I/Os to the pair.
– Because the Cache Residency Manager for IBM z/OS settings are
exchanged during a quick restore operation, you must perform one of
the two following operations:
• Set the same Cache Residency Manager for IBM z/OS settings
(locations) for the S-VOL and T-VOL before performing the quick
restore operation.
• Release the Cache Residency Manager for IBM z/OS settings of the
S-VOLs and T-VOLs before the quick restore operation, and then
reset the Cache Residency Manager for IBM z/OS settings of the
S-VOLs and T-VOLs after the pair changes to duplex status as a
result of the quick restore operation.
If you do not do one of the abovementioned operations, the change of
location of the cache residence areas may cause I/O performance to the
Cache Residency Manager for IBM z/OS data to be down. For details about
Cache Residency Manager for IBM z/OS settings, see the Cache Residency
Manager User’s Guide.