Steve:

That's a good idea. I'll check the alert logs for Oracle. Another
sampling from vmstat shows me that every night when Oracle does it's
backup the (fre) drops and stays low and the (wa) stays high for about
40 minutes.

Thanks for the feedback.
-Greg

steven_nospam at Yahoo! Canada wrote:
> Greg wrote:
> > So I have two basic questions that I'm hoping somebody can offer some
> > guidelines for:
> > 1. What should I watch to determine if we're short on memory
> > 2. What is something out of the ordinary or something to be concerned
> > about (is pi > 5 bad, or don't get excited until it's over 100, for
> > example)
>
> > We have a p660 with 4GB RAM, 2 CPUs. It hosts an ERP application
> > using Oracle and some web services for user access. Our one paging
> > space is also 4GB. Below is a sample of vmstat -I grabbed every 5
> > seconds with nothing special running, just typical activity:
>
> Greg,
>
> First I will start by stating that I am not a AIX performance expert. I
> have not taken the system performance analysis or tuning courses with
> IBM, although I want to as soon as my company will send me on the
> course.
>
> On that note, there are a couple of things I noticed about the vmstat
> info you published. At twopoints during the sampling, your free memory
> allocation (fre) dropped to nearly zero and the CPU wait time (wa)
> jumped up dramatically.
>
> If this is typical of daily behaviour, then you defintely have a
> problem. My guess is that your Oracle instances are using up all of the
> available memory for some reason, which in turns causes the system to
> start paging, and all the reading/writing to the disks are causing the
> CPU to have to wait for the I/O to clear up.
>
> You may want to go post this in the Oracle newsgroups and they can
> suggest improvements. One thought I have is that Oracle (at least 8i
> and 9i) may be spending its time trying to write archive log
> information and that is affecting the performance of the system.
>
> Try checking your alert logs in $ORACLE_HOME/rdbms/log and compare the
> times that it writes a log to the times that you see the memory drop
> and the CPU wait time go up. You may need an Oracle DBA rather than an
> AIX Admin ;-)
>
> Steve