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free command [message #331148]

Wed, 02 July 2008 07:00

mafc73
Messages: 38
Registered: November 2006

Member

Hi,

I have a linux server with oracle 10.2.0.4, with 512M of memory (it's testing machine). Mi dude is that if a execute "free -m" I get 376M free and 126 used but the sga_target and sga_max_size have 300M. How can is it posible?

Thanks.

COSMOS:(ATLAS):/opt/oracle/product/10.2/rdbms/admin> free -m
             total       used       free     shared    buffers     cached
Mem:           502        482         20          0         19        336
-/+ buffers/cache:        126        376
Swap:         1023         54        969
COSMOS:(ATLAS):/opt/oracle/product/10.2/rdbms/admin> sqlplus / as sysdba

SQL*Plus: Release 10.2.0.4.0 - Production on Jue Jun 26 07:00:47 2008

Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.


Conectado a:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - Production
With the Partitioning, Data Mining and Real Application Testing options

SQL> show sga

Total System Global Area  314572800 bytes
Fixed Size                  1267260 bytes
Variable Size             197134788 bytes
Database Buffers          109051904 bytes
Redo Buffers                7118848 bytes

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Re: free command [message #331219 is a reply to message #331148]

Wed, 02 July 2008 11:20

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

The apparent discrepancy between what Oracle reports for memory usage & what *NIX reports.
The reality is the various values are taken from different perspectives.
My advice is to accept the values & ignore the difference.

The odds are, you don't know what the odds are.

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Re: free command [message #331370 is a reply to message #331148]

Thu, 03 July 2008 03:10

mafc73
Messages: 38
Registered: November 2006

Member

Then,

If I want to know how much free memory have in the system. What can I do?. In this case was easy, but in a production system with a lot of users connect and various instances isn't it.

Thanks

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Re: free command [message #331465 is a reply to message #331370]

Thu, 03 July 2008 08:53

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

mafc73 wrote on Thu, 03 July 2008 01:10

Then,

If I want to know how much free memory have in the system. What can I do?. In this case was easy, but in a production system with a lot of users connect and various instances isn't it.

Thanks

On some/many/most/all *nix systems which are running Oracle RDBMS will sooner or later have free RAM at about 5% of total RAM.

This can be see by running "top".

Any memory not required by Oracle will be consumed by OS as file buffer cache for most file systems (exceptions like OCFCS2 excluded).

[Updated on: Thu, 03 July 2008 08:54] by Moderator

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