Changing the device parameters
When the device files are created, the system sets the device parameters to the system default values.
You might need to change a few of those values for each new OPEN-x device: For more information,
see Table 4 and Table 5.
• Read/write (R/W) timeout value
• Queue depth
• Queue type
Table 4 Device parameters-read/write timeout and queue type
Required ValueDefault ValueParameter
6030Read/write timeout
SimpleNoneQueue type
Table 5 Device parameters-queue depth
Recommended ValueParameter
32
Queue depth per LU
1024
Queue depth per port (MAXTAGS)
The recommended queue depth settings might 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 hdiskx –a rw_timeout='60'
2. To change the queue depth parameter, enter:
chdev –l hdiskx –a queue_depth='x'
where x is a value from the above table.
P9000 Configuration Guide: IBM AIX 15
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