Planning For Performance - HP StorageWorks P9000 - Disk Arrays User Manual

Table 4 Volume information for Business Copy Z for z/OS (continued)
CU LDEV
0 0F
0 10
0 1 1
0 12
etc... ...

Planning for performance

Pair operations affect I/O performance on the storage system. The following information is provided
to help calibrate your system:
Performance versus number of pairs. Compare the importance of performance with the number
of pairs and copy pace (rate at which data is copied).
Assigning multiple T-VOLs to an S-VOL uses more system resources and lowers
◦
performance.
The slower the copy pace, the less impact on I/O performance; a fast pace has a greater
◦
impact on performance. (You assign copy pace during the create, split, and resync
operations.)
Load sharing on parity groups.
A parity group should contain an even distribution of S-VOLs and T-VOLs, rather than a
◦
concentration of one or the other.
When multiple pair operations are to be performed simultaneously, the pairs should be
◦
in different parity groups.
◦ For copy pace, specify Slower when you create, split, or resynchronize.
◦ When you need to perform a copy operation on multiple pairs on the same parity group,
perform the operation on one pair at a time.
If the system is overloaded, increase parity groups, cache, channel adapters (CHAs),
◦
and/or disk adapters (DKAs). Assign T-VOLs to newly installed parity groups.
Preparing for resynchronization by Quick Restore. During a quick restore operation, in which
the contents of the S-VOL and T-VOL are swapped, the RAID levels, HDD types, and Cache
Residency settings of the two volumes are also exchanged. To avoid performance impact,
consider the following:
Both pair volumes should have the same RAID level and HDD type before performing the
◦
quick restore operation. You can resume the original RAID levels after the quick restore
by again splitting the pair and performing the quick restore.
◦ Set the same Cache Residency settings (locations) for the S-VOL and T-VOL before the
quick restore operation.
Alternatively, you can release Cache Residency settings before the quick restore operation,
then reset them when the operation is completed.
14 Requirements and planning
S-VOL? Associated T-VOLs
Yes 0:2E, 0:2F
No NA
No NA
No NA
... ...
T-VOL? Associated S-VOL
No NA
Yes 0:00
Yes 0:00
Yes 0:01
... ...