How much RAM does Oracle REALLY use?

I have a dispute between my Oracle DBA and my Unix system manager

I am running Oracle V6 on a SCO Unix system with 40 Megabytes of RAM.

My Unix system manager says the system is swapping and needs more memory and Oracle is the cause. My Oracle DBA says the system needs to be tuned and Oracle could not possibly be using that much memory.

The Unix system manager is running "monitor" a product from Stallion Technologies. Looking at the memory display he can see 4 background Oracle tasks (PMON, DBWR, LGWR, SMON) each taking up 4.0 megabytes for a total of 16 megabytes. When the system gets about 25 users on running a variety of processes (Office Portfolio, Word Perfect, etc) the system runs out of memory.

I have no problem here, all of this stuff DOES use lots of RAM. My problem is the Oracle DBA saying that Oracle could not POSSIBLY be using that much memory. As my DBA has stated (quoting from the UNIX install book) the RDBMS requires 1,790 KBytes of RAM + 1,100 KBytes of RAM for shared memory. Each SQLplus process requires 356 KBytes of RAM for shared memory plus 93 KBytes for each user. Each SQLforms (v2.3) uses 474 KBytes of RAM for shared memory plus 62 KBytes for each user. The communications area uses 3,779 KBytes of RAM for the Shared Global Segment plus 4 KBytes per user.

This does not anywhere near compare to what this monitor program displays, and yet when the system gets loaded, the system does swap (as indicated by the UNIX tools "vmstat" and "ps", and by the "monitor" program.

Who is correct? It is my feeling that to information in the Oracle book does NOT include the required memory to LOAD the program into memory, and the PMON, SMON, DBWR, and LGWR processes require 4 megabytes a piece. Does anybody real info here? My DBA has called Oracle and that have quoted what is in the book.

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Barry A. Suskind                  Internet:   suskind%edoras_at_mdcbbs.com
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