Oracle 10g Using 99% of 7GB RAM on Solaris10

Question

Hi All,
I am working on three database instances each installed on a single solaris server. Now, the server had 3GB of RAM and all the dbs were up and running fine. However, 95% of RAM was getting utilized so we went for RAM upgradation frm 3 to 7GB. To my utter amazment the Ora10g user is still shown to be using 99% of current memory. Ideally I should be having atleast 30% of the current memory free.
Please advice how can i reduce this excess RAM usage by Ora10g user.
This is a shared server env for all the three dbs.

Answer 1

I tihnk you're counting the memory wrong.
If, for example, from top, you see a process is using, let's say 700M. Now, let's assume that the SGA is 500m. That 700m being reported includes the 500m shared memory segment.
So, if you have 10 processes, each reporting 700m, that's 7000m, but, in reality, they're only using 200m*10+500m = 2500m. The shared memory segment(s) should only be counted once.
In Solaris, to see how much memory is allocated/mapped where for a given process, try the pmap command.
pmap -x <pid of process>This will show how the memory for that process breaks out, including what portion is the shared memory segment.
As to why you're getting errors when trying to allocate additional memory, well, it could be that you're really out of memory, or it could be that you're being artificially limited, by some O/S parameter, SHMMAX, etc.
Finally, see MetaLink Doc IDs 115753.1 and 1008866.6 for more information.
-Mark