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Re: SGA and PGA

From: sybrandb <sybrandb_at_gmail.com>
Date: 26 Oct 2006 09:24:56 -0700
Message-ID: <1161879896.834021.179380@i3g2000cwc.googlegroups.com>

aprinsloo_at_sagetelecom.net wrote:
> Oracle 9i Standard Edition
> Red Hat Linux 5
>
> I'd appreciate any help on the following senario and how to divide up
> Oracle mem.
>
> We have 4G total on server and I have allocated based on Oracle
> recomendations for an OLTP system 640 meg to PGA (PGA_AGGREGATE_TARGET
> = (<Total Physical Memory > * 80%) * 20% ).
>
> As a starting point should I set SGA max size to 2500 meg and leave
> the rest to OS? What would I allocate to shared pool, buffer cache,
> large pool and java pool within this area?
>
> Last question, Is buffer cache equivalent to MS Sql server data cache,
> if not what it be in Oracle?
>
> Thx in advance.

I would suggest setting reasonable defaults, make sure db_cache_advice = on and use the advisors to adjust.
2500M is likely unnecessary, or you must be working exclusively with untuned SQL. Even in that case such a value wouldn't help. Shared pool = typically 250M java pool = 150M buffer cache = 512M usually sufficient.
Large pool is only used for shared server and RMAN.

To answer your last question: reading the Oracle Concepts Manual at http://tahiti.oracle.com is compulsory, and will help you see Oracle is not SQL sold by a different vendor.

-- 
Sybrand Bakker
Senior Oracle DBA
Received on Thu Oct 26 2006 - 11:24:56 CDT

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