Oracle on RHEL AS3 Cluster
 

I am a sysadmin for an Oracle DB instance running on an active/passive RHEL AS3 cluster. I have 16GB of RAM in each node and 4 procs. My concern is memory utilization. Oracle seems to soak up all but 20 or so MB of RAM consistantly. I have verified with the DBA that all is well from his view and I have not seen any OS or application related problems as of yet. Can anyone tell me if this is normal? Thanks!

Hi,

Your problem is very complicated and need detailed informations.

1- What is your kernel version? Check it with uname?
2- What is your kernel parameters for oracle? (see Oracle installation documentation)

If these two parameters satisfy then we need to work on the dba side.

3- How many users are there in the system?
4- Is the system shared or dedicated
5- Are you using rac?
6- what is the result for ps - ef | grep oracle
7- check shared memory with pmap, vmstat or other commands.
8- Is your system hanging or crashing for that reason?
9- Are users getting any oracle error messages?
10- Can you post 'show parameters' output from the sqlplus.

I cant be sure at that point but it is most likely a performance tuning problem if it is not releated to redhat kernel (I think Redhat is the least reliable among other linux systems).

This sounds like your oracle parameters are a bit oversized. I don't know what version of oracle you are running but if it is pre 9 then I would first look at DB_BLOCK_BUFFERS multiplied by DB_BLOCK_SIZE. This will tell you how large the SGA is. If your db version is 9 or higher then you can use the parameter DB_CACHE_SIZE and that will tell you the size of your sga. There are other parameters as well to look at, so if you post your init.ora parameters here I can tell you if your parameters are causing the high memory usage. I work with very large oracle systems (solaris active passive) that run SAP and I know that you can control the amount memory oracle uses.

Hope this helps