topic Re: Mem utilization in Operating System - Linux

Mem utilization

Ammad — Tue, 29 Mar 2011 11:31:32 GMT

Hello,

I have two server running oracle EBS on OEL 5.3 (HP DL380), there is some changes either in application or OS level.
The problem is from past two days one of the server is not utilizing memory as cache, as you knows that linux by default cache process in memory.

whereas the DB server is using cache memory.

DB Server
# free -m
total used free shared buffers cached
Mem: 31871 31840 30 0 124 26223
-/+ buffers/cache: 5493 26378
Swap: 10239 117 10122
______________________________________________

Oracle Application Server
total used free shared buffers cached
Mem: 31871 8278 23592 0 523 2570
-/+ buffers/cache: 5185 26685
Swap: 10239 0 10239

Two days before the Application server was using memory, and there was no free memory, but right now its most of memory is free.

Any idea to verify the settings on OS level

Re: Mem utilization

Matti_Kurkela — Wed, 30 Mar 2011 05:55:15 GMT

> Two days before the Application server was using memory, and there was no free memory, but right now its most of memory is free.

Oracle Application Server uses Java. Did someone un-deploy a buggy version of some .ear/.war/etc and replace it with a fixed version? This might have allowed the Java Virtual Machine to garbage-collect a large amount of used RAM and free it.

Or perhaps some memory-hungry process has crashed and someone would have to restart it? Are all the applications working OK?

If there is no change in the OAS configuration, and everything works OK, perhaps the server has reached an equilibrium state where it does not have to load anything more from disk: everything it needs to keep running is either already in RAM or in the database. Basically, the cache will not grow if no program is writing much nor reading anything that isn't already cached.

MK

Re: Mem utilization

Alzhy — Thu, 31 Mar 2011 01:43:33 GMT

Or perhaps - backups were running prior?

Note and observe -- memory would also tend to be used fully (as cache) during and after backups.

BTW. do you have Virtual mapping swappiness tweaked as well as vm.dirty* "customised"?