Memory Question
Parekh, Ketan
KParekh at maxis.com
Wed Jul 28 22:21:29 UTC 2004
As a general rule of thumb how much memory should be left for the OS ?
Assuming I have 4 GB physical memory ?
Thanks
Ketan
-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com] On Behalf Of Tobias Speckbacher
Sent: Wednesday, July 28, 2004 2:31 PM
To: General Red Hat Linux discussion list
Subject: RE: Memory Question
Looking at your kernel version you are using AS2.1.
The only parameters you should have had to change are shmmax, sem
,shmall, semmni (some of the default are acceptable)
The commands indeed should return the correct output.
The OS should be using far less than 500MB.
As you can see in the info you posted.
Free: 154764
Buffers: 333072
Total "free" = 476MB
So OS memory used should be 4GB - 476MB - SGA - PGA
In any case an SGA this large with 4GB memory will cause issues as you
start using the DB from my experience.
-Tobias
-----Original Message-----
From: redhat-list-bounces at redhat.com
[mailto:redhat-list-bounces at redhat.com] On Behalf Of Parekh, Ketan
Sent: Wednesday, July 28, 2004 12:07 PM
To: redhat-list at redhat.com
Subject: Memory Question
HI! Folks,
I need some help with memory stats. I have an Oracle database running.
Below is he OS version :
Linux tsonode1 2.4.9-e.25enterprise #1 SMP Fri Jun 6 17:55:13 EDT 2003
i686 unknown
oracle at tsonode1[tsodev1]$ free -t
total used free shared buffers
cached
Mem: 2058760 1814816 243944 742204 243924
213272
-/+ buffers/cache: 1357620 701140
Swap: 2096472 217516 1878956
Total: 4155232 2032332 2122900
>From the above as to what I understand is
Total Physical memory is : 2 GB
USED 1.35 GB is used
Free 701 Megs
So of the 1.35 used
Oracle SGA is 950 Megs
Oracle PGA ( Process memory ) 260 Megs
Other non-oacle process 150 Megs
Total 1.35 GB
Now there is a limitation on RH 2.1 Advanced server for having oracle
SGA > 1.8 GB. To increase the SGA we had to
Changes to the memory settings and relinked the oracle binaries as
explained in the RH doc.
OS : Linux tsonode2 2.4.9-e.46enterprise #1 SMP Wed Jun 30 18:11:26 EDT
2004 i686 unknown
total used free shared buffers
cached
Mem: 3863184 3708420 154764 2461228 333072
587348
-/+ buffers/cache: 2788000 1075184
Swap: 2096472 1116 2095356
Total: 5959656 3709536 2250120
SGA : 2.75 GB
PGA : 837 Megs
Total Physical memory is 4 GB on ths host.
So now the confusion part is is Oracle has sucked in 2.75 + 537 = 3.5 GB
- is the OS using only 500 megs ?
Does free -t , top vmstat commands show the right numbers after this
change in the kernel ?
BTW : both the free -t outputs are from diff nodes - I put them to
compare and see where am I going wrong here.
Thanks for your help..
Ketan
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