RE: Physical Memory Fully Used and Swap is Not Used

From: Mudhalvan Moovarkku <>
Date: Tue, 23 Jun 2009 15:26:00 +0900
Message-ID: <>


   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 on Linux uses more than 16GB


Mudhalvan M.M  

From: [] On Behalf Of Mathias Magnusson
Sent: Tuesday, June 23, 2009 3:15 PM
To: Mudhalvan Moovarkku
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.


On Tue, Jun 23, 2009 at 7:41 AM, Mudhalvan Moovarkku <> wrote:

Dear DBAs,

        We have recently migrated Oracle from 8.0.6 on HP-Unix to 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.


Mudhalvan M.M  

Received on Tue Jun 23 2009 - 01:26:00 CDT

Original text of this message