HP StorageWorks Disk Array XP operating system configuration guide for IBM AIX XP24000, XP12000, XP10000, SVS200, v01 (A5951 - 96047, June 2007)

The recommended queue depth settings may not provide the best I/O performance for your system.
You can adjust the queue depth setting to optimize the I/O performance of the disk array.
Displaying the device parameters using the AIX command line
At the command line prompt, enter lsattr -E -l hdiskx, where hdiskx is the device file name.
Example
# lsattr –E -l hdisk2
Changing the device parameters using the AIX command line
1. To change the R/W timeout parameter, enter:
chdev –1 hdisk x –a rw_timeout='60'
2. To change the queue depth parameter, enter:
chdev –l hdisk x –a queue_depth=' x '.
where x is a value from the above table.
3. To change the queue type parameter, enter:
chdev –l hdisk x –a q_type='simple'
Example
# chdev –l hdisk3 –a queue_depth='2'
This changes the queue depth for device hdisk3.
4. Verify that the parameters for all devices were successfully changed.
Example
# lsattr –E –l hdisk3
5. Repeat these steps for each OPEN-x device on the disk array.
TIP:
The lsattr command also shows other useful information, such as LUN ID of the mapped
LDEV, worldwide name of the disk array FC port, and N-Port ID.
Another useful command for determining the slot position and port worldwide name of the
HBA is the lscfg –v –l hdiskx command.
Changing the device parameters using SMIT
1. Start SMIT. (Optional) For an ASCII session, use the smit –C command.
2. Select Devices.
Example
XP Disk Array Configuration Guide for IBM AIX 21