Re: Memory Usage in Oracle

Sybrandb:

Your wording is a little confusing so I just wanted to clarify some things:

We are using the 'CIO' mount option. So this is the command I type to mount the /oracle/oradata directory: mount -o cio /oracle/oradata.

Are you saying I should use 'DIO' instead? Is that what Oracle recommends? If so could you post a link to the article that states that?

What kind of setup do you have? How much memory? Size of DB?

thanks!

sybrandb wrote:
> 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
Received on Thu Jan 11 2007 - 12:04:58 CST