Re: Memory Usage in Oracle

dawaves wrote:
> Hello,
>
> I'm an AIX Systems Administrator who is kind of confused w/ Oracle's
> use of memory and I wanted to see if maybe some Oracle DBA's out there
> can help me out.
>
> Here is our situation:
>
> We have a 16GB Oracle Production Database running on AIX 5.3 ML04. We
> have a total of 16GB of RAM.
>
> It seems every time we had more physical RAM, the Oracle DB wants to
> use all the available RAM. Now when I mount the /oradata directory w/
> the 'cio' option, the Oracle Processes tend to use less which make
> sense since it is eliminating the file buffer portion in memory.
>
> Now is this normal for Oracle to use as much RAM as it can?
>
> What kind of systems are other DBA's running their Oracle Servers on
> and with how much RAM? How do you deal w/ Paging?
>
> If we cap the use of memory for our Oracle DB from the OS, can that
> lead to ramifications for our Oracle DB?
>
> Thanks for reading this and hopefully some Oracle DBA's out there can
> respond to some of my questions.
>
> thanks!

Looks like you don't use direct i/o (as recommended and as included with the concurrent I/O option) and any Oracle access is going through the file system cache.
As a 16 Gb database shouldn't need 16 Gb RAM, it also looks like there is something seriously wrong with your database, and your firm has resorted to 'more is better' tuning.
This won't help, ever.
Taking O/S measures to trim down Oracle memory usage would however bring you further down on the path to disaster.

-- 
Sybrand Bakker
Senior Oracle DBA