HP StorageWorks HSG80 ACS Solution Software V8.8 for IBM AIX Installation and Configuration Guide (AA-RV1HA-TE, March 2005)

Planning Storage Configurations
95HSG80 ACS Solution Software V8.8 for IBM AIX Installation and Configuration Guide
■ If you have mostly sequential reads or writes (like those needed to work with
large graphic files), make the chunk size for RAID 0 and RAID 0+1 a small
number (for example: 67 sectors). For RAID 5, make the chunk size a
relatively large number (for example: 253 sectors).
Table 10 shows a few examples of chunk size selection.
e
Increasing Sequential Data Transfer Performance
RAID 0 and RAID 0+1 sets intended for high data transfer rates should use a
relatively low chunk size (for example: 67 sectors). RAID 5 sets intended for high
data rate performance should use a relatively large number (for example: 253
sectors).
Save Configuration
The SAVE_CONFIGURATION switch is for a single-controller configuration
only. This switch reserves an area on each of the disks for the container being
initialized. The controller can write subsystem configuration data on this area. If
the controller is replaced, the new controller can read the subsystem configuration
from the reserved areas of disks.
If you specify SAVE_CONFIGURATION for a multi-device storageset, such as a
stripeset, the complete subsystem configuration is periodically written on each
disk in the storageset.
The
SHOW DEVICES FULL command shows which disks are used to backup
configuration information.
Note: DO NOT use SAVE_CONFIGURATION in dual redundant controller
installations. It is not supported and may result in unexpected controller behavior.
Table 10: Example chunk sizes
Transfer Size
(KB)
Small Area of I/O
Transfers
Unknown
Random Areas of I/O
Transfers
241 5979
4 79 113 163
8 157 239 317