Originally posted by: SystemAdmin

I have a question about AIO paramters.
(maxreqs, maxservers, minservers)

Many documents are saying different recommendations.
So, I'd like to know how to decide these parameters by monitoring.

(I'm talking about Oracle DB servers.)

<Question 1>
AIX 5.2
What does "pstat -a |grep -c aios" mean exactly?
Does this number mean "Total AIO processes" by nmon?
Is it right that maxserver(40) x lcpu(16) = 640(this number)?

AIX5.3
iostat -AQ
I can find maxg and maxr.
By monitoring iostat, how can I decide whether I increase maxreqs(or maxservers) or not?

<Question 2>
Is it a good recommendation?

maxreqs : 3-4 times of 4096 (default)
maxservers : 10 x disks
minservers : maxservers / 2

Any other recommendation do you have?
Your kindness would be highly appreciated.
#AIX-Forum

Originally posted by: hdkutz

Hello swchae,
you are right. A definitive Setting is unfortunatly not mentioned.
For myself i went into:
http://www.redbooks.ibm.com/abstracts/sg245511.html
http://www-03.ibm.com/servers/aix/whitepapers/db_perf_aix.pdf
and
http://publib.boulder.ibm.com/infocenter/pseries/v5r3/topic/com.ibm.aix.prftungd/doc/prftungd/prftungd.pdf

My AIO Settings on a p55a with 4 Cores and 32 GB Mem:
<snip>

1. lsattr -El aio0

autoconfig available STATE to be configured at system restart True
fastpath enable State of fast path True
kprocprio 39 Server PRIORITY True
maxreqs 16384 Maximum number of REQUESTS True
maxservers 850 MAXIMUM number of servers per cpu True
minservers 150 MINIMUM number of servers True
<snip>

Cheers,
ku
#AIX-Forum

Originally posted by: alethad

Take a look at this document also. It is spcifically geared to Oracle databases and has helped me out alot when setting up new AIX servers running Oracle. I still use it today. Look at page 25 for recommended system settings.

http://www-03.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/WP100883
I have submitted this link on other posts in this forum. It seems to be a popular question.

Good luck.
#AIX-Forum