We are having RHEL 5.8 server.It is the db tier of our test oracle application R12.1.3 .
For the past 20 days it always using the full RAM memory.Before 2 weeks the server has 4 GB ram and we thought that we may have insufficient memory.So we increased the RAM size by 6 GB.Now the total RAM memory is 10G. But again the server started to use the full RAM memory..
The Linux kernel automatically uses all available RAM for caching the file system to increase file access performance. Should the system require more RAM for processes, the memory for the buffer cache will automatically shrink as required. Looking at your output, I'd say there is nothing to worry about.
Btw, Oracle processes use shared memory, either Posix /dev/shm (AMM) or conventional (normal 4k or non-swap 2 MB hugepages). You can check it with the ipcs -m command and df /dev/shm. /dev/shm is 50 % of physical RAM by default, allocated only when used.
there are many times the CPU usage increases upto 100% usage and the swap space usage is empty..
There are two oracle database server (using for oracle application r12.1.3) sitting on this redhat server.Now only one db server is up and running since it CPU memory usage is going to 100 % we are unable to up the other one oracle server.
Please suggest how i can identify the root cause of this problem..
FYI - The problem is happening after we cloned our Oracle Application.
it should be your sga.
oracle processes maps sga. code, libraries it seems mapped files are also calculated.
VM size almost irrelevant to measure memory usage.
For example on the "top" command there is VIRT column.
VIRT -- Virtual Image (kb)
The total amount of virtual memory used by the task. It
includes all code, data and shared libraries plus pages that
have been swapped out.