RE: Physical Memory Fully Used and Swap is Not Used

  • From: "Mudhalvan Moovarkku" <moovarkku.mudhalvan@xxxxxxxxxxxxxxxx>
  • To: "Mathias Magnusson" <mathias.magnusson@xxxxxxxxx>
  • Date: Tue, 23 Jun 2009 15:26:00 +0900

Mathias,

 

   Thanks for your mail. 

 

    Yes I do understand. Now I have two clarifications.

 

1.       Problem is at this point instead of using Swap My server
response time was very slow and PMON process failed with the message at
alert "PMON failed to acquire latch" and DB went down. 

 

2.       In 8.0.6 on Unix used only 7GB Memory but why in 10.2.0.4 on
Linux uses more than 16GB

 

Regards

Mudhalvan M.M

 

________________________________

From: mathiasmag@xxxxxxxxx [mailto:mathiasmag@xxxxxxxxx] On Behalf Of
Mathias Magnusson
Sent: Tuesday, June 23, 2009 3:15 PM
To: Mudhalvan Moovarkku
Cc: oracle-l@xxxxxxxxxxxxx
Subject: Re: Physical Memory Fully Used and Swap is Not Used

 

Are you trying to tune or to understand memory? There is nothing here
that would indicate a problem. If you use all you memory and no swap,
then that would be optimal. It shows that your box is sized perfectly
and you do not ned to use swap. Using swap reduces performance (if we
compare to having enough memory and not needing swap).

 

If on the other hand you motivation is to understand why these numbers
would be this way, then someone who has spent more time reading RDAs on
Linux would need to answer here. To me the numbers would indicate that
you have just barely reached the point where swap is starting to be used
when more memory is needed.


Mathias
http://mathiasmagnusson.com
http://blog.mathiasmagnusson.com
http://photo.mathiasmagnusson.com
http://oradbdev.mathiasmagnusson.com



On Tue, Jun 23, 2009 at 7:41 AM, Mudhalvan Moovarkku
<moovarkku.mudhalvan@xxxxxxxxxxxxxxxx> wrote:

Dear DBAs,

        We have recently migrated Oracle from 8.0.6 on HP-Unix to
10.2.0.4 on Red Hat Linux

        Earlier the same application worked fine with 7GB RAM on HP-UNIX
on PA-RISC

        Upgraded system on IBM X 3850 with 16GB RAM but still we have
some performance issue. 

        I knew there is some lagging because of Hardware Architecture
but it is too bad 7 GB to 16GB RAM but still have performance. 

        Please look at data collected from RDA. Looking at this scenario
my physical memory is fullly used but Swap is not at all used. 

Total Physical Memory 16032 MiB 

Available Physical Memory 30 MiB 

Swap: Max Size 24575 MiB 

Swap: Available 24505 MiB 

Swap: In Use 70 MiB 

        We know there is some performance issue in application. I would
like to make as much as possible from Database/Linux side tunning to
provide atlease peaceful performance. Can any body through some light on
why the swap is not at all used.

Regards

Mudhalvan M.M

 

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