Looking at runqueue in topas is often a good predictor. 

Are you running nmon? I recommend that you do.

On thing to look at there is vmstat -v, and watch to see if the I/O's
blocked because of various buffers being unavailable increases day to day
(or even hour-to-hour).

The other thing in UD is to be sure that the SBCS shared memory segment is
large enough. As in Highlander, there can be only one. Well, there _should_
be only one, anyway. If you ever have more than one, it's too small. Perhaps
run for a day or so with a cron job that counts those every minute or so. If
you're right on the cusp, where you shmget another, then fall under the
threshold, releasing it, then rise gain to need another, you'll see the
system crawling to the point where you'll be typing in a field, and it won't
even echo until 15 seconds later, when all of a sudden dozens of characters
will appear.

You may also want to capture user counts throughout the day; that would be a
strong hint about memory configuration. I forget: at 7.1, can you run in
64-bit? In 32-bit UD, there's some memory addressing constraints, as I
recall.

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
[email protected]
Sent: Wednesday, January 27, 2010 2:46 PM
To: U2 Users List
Subject: [U2] Predicting application performance

I haven't found anything in the archives and I don't remember seeing this 
specific question addressed by the group. Please forgive if this has 
already been discussed.

This is a mystery upon which I'm hoping this list can shed some light. 
I'll sit and watch nmon display CPU stats and see *tons* of waits but the 
end users experience no slowdowns. At other times nmon may show waits more 
in the 30% - 40% range and users start complaining about bad response 
times. We've tried watching I/O and memory/paging space also and don't see 
any discernible patterns.

Does anyone have thoughts on how to predict UD app performance based on 
CPU, I/O or other system stats? 

UD 7.1
AIX 5.3
Disk: SAN (EMC)
U.S. BANCORP made the following annotations
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