Memory Utilisation showing very hight + OEL 5.6 with Oracle


Hi ,

            I have an issue with one of our oracle server ( OEL 5.6 with Oracle 11g) , Utilising al most 95% of memory  ( we have around  92GB memory , in that 85 GB is used ). In the top command i cannot find any information that eating up the memory

required an expert comment on this .....


With regards

Mohamed
 
sabirkkAsked:
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woolmilkporcCommented:
I strongly assume that it's shared memory used by Oracle's SGA.

Use "ipcs -m" to display your shared memory segments (find the size under "bytes")

and issue "show parameter sga_max_size" (Oracle 10) and "show parameter memory_target" (Oracle 11)
from sqlplus to display Oracle's memory configuration.

wmp
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sabirkkAuthor Commented:
lpcs -m shows only 10 GB used  

is there any other command where i can see these memory in system level.

need find out , which process eating these memories .
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woolmilkporcCommented:
You can order the output of top by memory consumption - just press "M".

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javeedabdulCommented:
Is this Oracle Enterprise Linux version ?If yes

I think OEL take whole memory and distribute accordingly as needed and rest of the time oracle uses the whole lot..

Hope this give you a clue


Javeed A
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sabirkkAuthor Commented:
but why it is not appearing in the top or any process monitoring tool.
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woolmilkporcCommented:
Where did you find this "95%" information?

If you got it from "top" please be aware that  the "used" value includes disk or filesystem buffers/cache.
It is not identical with the amount of memory actually in use by processes.

"free -m" might give you a better estimation of how much memory is really free for applications to use.
Please pay special attention to the values below "-/+ buffers/cache:".


wmp




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sabirkkAuthor Commented:
Top command output

Cpu(s):  0.3%us,  0.5%sy,  0.0%ni, 99.0%id,  0.2%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:    94.590G total,   91.706G used, 2953.332M free, 4182.422M buffers
Swap:   18.000G total,    0.000k used,   18.000G free,   82.885G cached

free -m

            total       used       free     shared    buffers     cached
Mem:         96860      93919       2940          0       4182      84874
-/+ buffers/cache:       4862      91998
Swap:        18431          0      18431


What is this cached ? , is it taking from physaical memory ?
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woolmilkporcCommented:
Yes, it's taken from physical memory and is used for buffering filesystem requests.

But since this memory is freed whenever the OS needs it for other purposes it can basically be considered as free memory.

As you can see, besides "buffers" (disk I/O buffering) and "cached" (filesystem buffering) yor system is using just roundabout 4.5 GB of real memory, so there is no reason to worry.

See paragrap 3.8.1 of this article for more info on memory caches in Linux:

http://tldp.org/LDP/tlk/mm/memory.html

wmp

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