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?
>

No, in a word. I'd guess it's a reporting issue on AIX, but you know that system and I don't. The (hideously oversimplified) memory usage of Oracle is as follows.

1, A large shared memory area called the SGA. This is of fixed (or at least capped) size. You can see how large this is by typing show sga at a sqlplus prompt.
2. Private memory areas for use by client processes. This is either fixed overall, or fixed per connection.

-- 
Niall Litchfield
Oracle DBA
http://www.orawin.info/services