Changing The Device Parameters; Device Parameters-Read/Write Timeout And Queue Type; Device Parameters-Queue Depth - HP StorageWorks P9000 - Disk Arrays Configuration Manual

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
Read/write (R/W) timeout value
Queue depth
Queue type
Table 4 Device parameters-read/write timeout and queue type
Parameter
Read/write timeout
Queue type
Table 5 Device parameters-queue depth
Parameter
Queue depth per LU
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.
Table 5.
Default Value
30
None
Required Value
60
Simple
Recommended Value
32
1024
P9000 Configuration Guide: IBM AIX 15