Re: SGA size limited to 1GB?

From: <jackconnolly_at_my-deja.com>
Date: Wed, 08 Sep 1999 03:06:25 GMT
Message-ID: <7r4jr8$k8n$1@nnrp1.deja.com>

In article <37cc5b54.351147890_at_news.mindspring.com>, robertch_at_mindspring.com wrote:
>
> We have a Unix machine with 16 giga bytes of physical memory running a
> huge Oracle database. Problem is, since maximum Oracle SGA size is
> only 1 giga bytes, most of physical memory sits idle, not being used.
> For example, according to glance, 80% of physical memory has not been
> used at all for whole day today. Is there any clever way to put these
> idle memory to use? Thanks in advance.
>
>

Robert,

I work with Oracle/Sun customers on this issue alot. Sun wrote a pretty decent infodoc on "Extending the SGA past 256 MB" and it is posted to their sunsolve site (http://sunsolve.sun.com). It involves changing the attach address for your shared memory segment. You do this by running the genksms -b 0x######### > O_H/rdbms/lib/ksms.s and then relinking oracle with a: make -f ins_rdbms.mk ioracle ... I don't have it memorized but the infodoc is numbered something like 15###. It will give you a table of the various attach addresses. BE CAREFUL ... you won't get 3.75 GB of SGA. The formula I use everyday (and has worked for 2 years now) is:

((DB_BLOCK_SIZE * DB_BLOCK_BUFFERS) + SHARED_POOL_SIZE) * 1.2 = SGA I've seen 1 GB Shmmax's manage well designed 800 GB databases and not break a sweat, so your 3 GB SGA should/can handle alot more. If this doesn't make sense to you, just repost and I'll do my best to make it clearer.

:-)Jack

Jack Connolly
Technical Specialist - Oracle Corp
UNIX Product Line Support Team
Rocky Mountain Support Center

The opinions expressed here are my own and do not necessarily relect those of Oracle Corp.

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Share what you know. Learn what you don't. Received on Tue Sep 07 1999 - 22:06:25 CDT