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Re: shmmax vs. SGA

From: Charlie Mengler <charliem_at_mwh.com>
Date: Tue, 29 May 2001 09:20:06 -0700
Message-ID: <F001.003120A2.20010529090135@fatcity.com>

You need to change sgabeg & re-link Oracle. The values below are/were valid for V7 and should be used with caution on V8.

HTH & YMMV!

sgabeg = 0xe0000000 ! 256MB  SGA
sgabeg = 0xd0000000 ! 512MB  SGA
sgabeg = 0xc0000000 ! 768MB  SGA
sgabeg = 0xb0000000 ! 1.00GB SGA
sgabeg = 0xa0000000 ! 1.25GB SGA
sgabeg = 0x90000000 ! 1.50GB SGA
sgabeg = 0x80000000 ! 1.75GB SGA
sgabeg = 0x77000000 ! slightly less than 2GB (2030043136 bytes)
sgabeg = 0x70000000 ! 2.00GB SGA
sgabeg = 0x60000000 ! 2.25GB SGA
sgabeg = 0x50000000 ! 2.50GB SGA
sgabeg = 0x40000000 ! 2.75GB SGA
sgabeg = 0x30000000 ! 3.00GB SGA
sgabeg = 0x20000000 ! 3.25GB SGA
sgabeg = 0x10000000 ! 3.50GB SGA
sgabeg = 0x01000000 ! 16MB less than 3.75 GB

"Miller, Jay" wrote:
>
> Hi all,
>
> We had gotten some extra memory for our production server and I was trying
> to increase our buffer cache again (I was leery of doing it all at once so I
> just doubled it the first time). I got a
> ORA-27123: unable to attach to shared memory segment
> with my first try (it worked after I reduced the buffer cache a bit) and I'm
> trying to figure out why.
>
> Total memory on the machine is 4Gig.
>
> shmmax=2048000000 (2000M)
>
> 4K Block size
>
> I was able to start the database with a db_block_buffers of 350000 but not
> of 400000.
>
> Current SGA:
> NAME VALUE
> -------------------- ----------
> Fixed Size 47296
> Variable Size 248659968
> Database Buffers 1433600000
> Redo Buffers 1040384
>
> This gives a total of 1605M which should leave 295M still available. An
> extra 50000 blocks is only 195M. Is there something other than the total in
> v$sga that counts towards the shmmax? I can't find anything in my Oracle8 &
> Unix Performance Tuning book.
>
> Thanks for any guidance!
>
> Jay Miller
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Miller, Jay
> INET: JayMiller_at_TDWaterhouse.com
>
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-- 
Charlie Mengler                          Maintenance Warehouse  
charliem_at_mwh.com                         10641 Scripps Summit Ct.
858-831-2229                             San Diego, CA 92131    
If you don't agree with what I've said, then execute a 4Q command!
-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Charlie Mengler
  INET: charliem_at_mwh.com

Fat City Network Services    -- (858) 538-5051  FAX: (858) 538-5051
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Received on Tue May 29 2001 - 11:20:06 CDT

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