Batala,

If your system starts using swap area, then the problem is not just due to memory being used as cache, as jtomas suggests. It means that the memory manager can no longer free enough cache pages to make room for application memory pages, and it starts moving other ("cold") application memory pages to swap to make room for new ones.

You will need to monitor memory usage of your applications, and see which process is responsible for exceeding the available memory. It could be the database processes, if they're executing memory intensive requests, or it could be the java processes.

I would suggest you start by monitoring the RSS or RES (resident set size) of processes, which shows the number of physical memory pages in use by that particular process. The database processes will share some (or most) of the pages that are in the SGA (shared memory segment), so you may want to subtract the size of the SGA from the RSS of oracle processes to see roughly how many non-shared pages they have.

The top and ps commands can give you this information. I find it useful to sort the top output by RES, but if your database has a large SGA, you will find mostly oracle processes on top, and the processes with the most private RSS may not be visible if they're not oracle processes.

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