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Date: Mon, 15 Mar 2010 14:01:02 -0700
Message-ID: <dcc563d11003151401v630a05c8ub3875a0f34e89e85@mail.gmail.com>
Subject: Re: shared_buffers advice
From: Scott Marlowe <scott.marlowe@gmail.com>
To: Paul McGarry <paul@paulmcgarry.com>
Cc: Ben Chobot <bench@silentmedia.com>,
	Postgresql Performance list <pgsql-performance@postgresql.org>
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On Thu, Mar 11, 2010 at 5:19 PM, Paul McGarry <paul@paulmcgarry.com> wrote:
> On 11 March 2010 16:16, Ben Chobot <bench@silentmedia.com> wrote:
>
>> I *can* say a 10GB shared_buffer value is working "well" with my 128GB o=
f RAM..... whether or not it's "optimal," I couldn't say without a lot of e=
xperimentation I can't afford to do right now. You might have a look at the=
 pg_buffercache contrib module. It can tell you how utilized your shared bu=
ffers are.
>
> Thanks Ben and Greg,
>
> I shall start with something relatively sane (such as 10GB) and then
> see how we go from there.
>
> Once this server has brought online and bedded in I will be updating
> our other three servers which are identical in hardware spec and all
> have the same replicated data so I'll be able to do some real world
> tests with different settings withn the same load.
>
> (Currently one is currently running postgresql 8.1 on 32bit OS under a
> VM, the other two running 8.3 on 64bit OS with 64gig of memory but
> with Postgres still tuned for the 8 gigs the servers originally had
> and under a VM).

Definitely look at lowering the swappiness setting.  On a db server I
go for a swappiness of 1