Subject: Re: Configuration settings for 32GB RAM server
From: Jeff Davis <pgsql@j-davis.com>
To: Mark Lonsdale <mark.lonsdale@wysdm.com>
Cc: pgsql-performance@postgresql.org
In-Reply-To: <673ECBB77DA91F47AD4902A5FD73BCE4D5ED15@mail3>
References: <673ECBB77DA91F47AD4902A5FD73BCE4D5ED15@mail3>
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Date: Mon, 04 Dec 2006 09:42:57 -0800
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On Mon, 2006-12-04 at 12:10 -0500, Mark Lonsdale wrote:

> - 4 physical CPUs (hyperthreaded to 8)
>=20
> - 32 GB RAM
>=20
> - x86_64 architecture
>=20
> - RedHat AS 4
>=20
> - postgres 8.1.5
>=20
> =20
>=20
> Ive been taking a look at the various postgres tuning parameters, and
> have come up with the following settings.  =20
>=20
> =20
>=20
> shared_buffers =E2=80=93 50,000     -  >From what Id read, increasing thi=
s
> number higher than this wont have any advantages ?
>=20

Where did you read that? You should do some tests. Generally 25% of
physical memory on a dedicated box is a good point of reference (on 8.1,
anyway). I've heard as high as 50% can give you a benefit, but I haven't
seen that myself.


> fsm_pages =3D 200,000 =E2=80=93 Based this on some statistics about the n=
umber
> of pages freed from a vacuum on older server.   Not sure if its fair
> to calculate this based on vacuum stats of 7.3.4 server?
>=20

Might as well make it a higher number because you have a lot of RAM
anyway. It's better than running out of space in the FSM, because to
increase that setting you need to restart the daemon. Increasing this by
1 only uses 6 bytes. That means you could set it to 10 times the number
you currently have, and it would still be insignificant.

Regards,
	Jeff Davis