Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Re: SGA

Re: SGA

From: Mitchell <mitchell.lee_at_rogers.com>
Date: Fri, 15 Aug 2003 08:24:26 -0800
Message-ID: <F001.005CAED1.20030815082426@fatcity.com>


Hi Jared

I have reset to previous value and restarted the database anyway. Since I have 8G Memory and I may set SGA more than 3G. Actually I did at our AIX SP that set SGA total up to 5G of 8G memory.

Anyway I found a solution on metalink ( Note 115753.1 and 1028623.6. ) to set SGA to higher. You may be interest to read it.

You are right it is best to find a root cause of poor performance. The reason I want to increases db buffer is our customer complain slow on our database and Statpack report suggest to increase it as well

Thanks
Mitchell

> Was a low cache hit ratio the only 'problem'?
>
> Were jobs taking longer than normal?
>
> Were users complaining of a slow system?
>
> Did your average response time shoot up dramatically?
>
> I'm afraid you may have succumbed to the dreaded disease,
> CTD, or Compulsive Tuning Disorder.
>
> This is the urge to tweak database parameters due to some
> arbitrary threshold. even though everything seems to be
> working fine.
>
> It isn't your fault, as a number of publications in the
> past, including Oracle's, have taught that having a block
> cache hit ratio, or BCHR, lower than 90 or 95% meant that
> your system was performing poorly.
>
> The first thing to do is set your db_block_buffers size
> back to a value that allows you to start the database.
>
> Then head on over to http://www.hotsos.com and register
> for the site. Click on 'Knowledge On-Line' at the top
> of the page, and get the paper "Why 99% Database Buffer
> Cache Hit Ratio is NOT Ok".
>
> There are other useful papers there as well, and indeed
> many other sites where you can find useful information
> about BCHR. This will get you started.
>
> Of course, someone (Connor McDonald I think) wrote a nice
> utility that will increase your BCHR for you, but I don't
> think you want to use it in production. :) It's chief
> purpose is to underscore the futility of trying to tune
> via the block cache hit ratio.
>
> HTH
>
> Jared
>
>
>
>
> On Thu, 2003-08-14 at 16:19, Mitchell wrote:
> > Hi DBAs
> >
> > We have Sun Sparc system (Sun Fire 880) with 8G memeory. We has setting
> > /etc/system to the max and data buffer catch 1000m and total SGA 1745MB
on
> > our . Oracle 8.1.7.3.0 Server. Since Dat Buffer Cache hit ration
> > lower then 50% for last a few days, So We decide to increase another
400MB
> > to DB buffer. We faile to restart instance then, reside to 1200M, still
> > failed. I have no clue at all for why. (I have checked the Metalink, no
> > solution but redece SGA size). Anybody has any idea?
> >
> > Thanks in advance.
> >
> > Mitchell
> >
> >
> >
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: Mitchell
> > INET: mitchell.lee_at_rogers.com
> >
> > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > San Diego, California -- Mailing list and web hosting services
> > ---------------------------------------------------------------------
> > To REMOVE yourself from this mailing list, send an E-Mail message
> > to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
> > the message BODY, include a line containing: UNSUB ORACLE-L
> > (or the name of mailing list you want to be removed from). You may
> > also send the HELP command for other information (like subscribing).
> >
>
>

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Mitchell
  INET: mitchell.lee_at_rogers.com

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from).  You may
also send the HELP command for other information (like subscribing).
Received on Fri Aug 15 2003 - 11:24:26 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US