From: James Jackson (James.Jackson@MAIL.STATE.AR.US)
Date: Wed Oct 16 2002 - 09:33:26 EDT
You can't really look at memory utilization from a %free point-of-view.
Simon is correct: unless you specifically tell AIX not to freely use
memory, it will try to use almost all of it, which can be beneficial
depending on your workload.
In monitoring memory utilization, I find that the some of the best
memory-specific metrics for assessing system health are associated with
vmtune; i.e., the real time values for minperm, maxperm and numperm; and
vmstat; i.e., the values for fr (page free rate) and sr (page scan rate).
Numperm varies with the system load with respect to the number of memory
pages associated with persistent (file cache) pages and working pages. The
relative value of numperm compared to minperm and maxperm can help you
predict your proclivity to page out working pages to paging space, allowing
you to modify minperm and maxperm accordingly.
In analyzing your vmstat data, a consistently high sr/fr ratio indicates
that you may have a memory bottleneck.
You can read up on vmtune in the Performance Management guide for your
version of AIX. Nmon and the Nmon_Analyser provide data collection and
charting capability for memory metrics as well as a wealth of other system
health metrics. You can get them at
http://www-1.ibm.com/servers/esdd/articles/analyze_aix/ and
http://www1.ibm.com/servers/esdd/articles/nmon_analyser/, respectively.
Regards,
James Jackson
-----Original Message-----
From: Habeebulla Suhail [mailto:suhail@ALRAJHIBANK.COM.SA]
Sent: Wednesday, October 16, 2002 6:18 AM
To: aix-l@Princeton.EDU
Subject: how to calculate memory utilization on a AIX box
Hi all,
I have to give a system resources utilization report to my management,
on a weekly basis.
I have written some scripts to collect data. For CPU utilization I'm
using sar and for memory utilization I'm using vmstat.
I'm just using the free mem column and getting an average value. Then
calculating the percentage from total real memory of the system.
My question:
1. Is it correct what I'm doing for memory utilization?
2. Can someone give a URL name where I can get more information on how
to calculate memory utilization on AIX boxes?
Regards,
Habeebulla Suhail
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