Originally posted by: MarkTaylor
Ref:
http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.doc/aixprggd/kernextc/async_io_subsys.htm How Many AIO Servers Do I Need?
Here are some suggested rules of thumb for determining what value to set maximum number of servers to:
1. The first rule of thumb suggests that you limit the maximum number of servers to a number equal to ten times the number of disks that are to be used concurrently, but not more than 80. The minimum number of servers should be set to half of this maximum number.
2. Another rule of thumb is to set the maximum number of servers to 80 and leave the minimum number of servers set to the default of 1 and reboot. Monitor the number of additional servers started throughout the course of normal workload. After a 24-hour period of normal activity, set the maximum number of servers to the number of currently running aios + 10, and set the minimum number of servers to the number of currently running aios - 10.
In some environments you may see more than 80 aios KPROCs running. If so, consider the third rule of thumb.
3. A third suggestion is to take statistics using vmstat -s before any high I/O activity begins, and again at the end. Check the field iodone. From this you can determine how many physical I/Os are being handled in a given wall clock period. Then increase the maximum number of servers and see if you can get more iodones in the same time period.
As for vmtune :) on aix 5.2+ you use the vmo and ioo commands.... and wholly depends on what your server workload is as to what settings you need to tweak, so can you explain in a little more detail ..
Rgds
Mark Taylor
#AIX-Forum