Storage performance tuning on AIX - part 2
ok, so you've done the tweaks mentioned in part 1 but job performance is still poor, what next?
you will have to increase the queue_depth of your disks. queue_depth determines how many requests can be sent to your disks at any one time. the larger the queue, and increasing it can increase disk I/O throughput
you will first need to figure out what your current queue_depth is set at:
# lsattr -El [pv_name]
you'll then have to figure out what you want to change it to. i would say try doubling or tripling it at first, then monitor your job again and see what your %tm_act is at. you do want it so that there's some activity on the %tm_act but not in such a way that it's consistently high
changing the queue_depth, however is a disruptive change and you will want to change it to all the pv/disks that are in the vg you're trying to tune:
# varyoffvg [vg_name]
# chdev -l [pv_name] -a queue_depth=[new_value]
# varyonvg [vg_name]