Subject: Re: [SPAM?] Re: PG8 Tuning
From: "Jeffrey W. Baker" <jwbaker@acm.org>
To: Steve Poe <spoe@sfnet.cc>
Cc: paul@oxton.com, pgsql-performance@postgresql.org
In-Reply-To: <1123836428.19976.26.camel@amd64-laptop-spoe>
References: <1536.217.45.209.171.1123763001.squirrel@www.gradwell.com>
	<1123836428.19976.26.camel@amd64-laptop-spoe>
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Date: Thu, 11 Aug 2005 09:58:44 -0700
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On Fri, 2005-08-12 at 08:47 +0000, Steve Poe wrote:
> Paul,
> 
> Before I say anything else, one online document which may be of
> assistance to you is:
> http://www.powerpostgresql.com/PerfList/
> 
> Some thoughts I have:
> 
> 3) You're shared RAM setting seems overkill to me. Part of the challenge
> is you're going from 1000 to 262K with no assessment in between. Each
> situation can be different, but try in the range of 10 - 50K.
> 
> 4) pg_xlog: If you're pg_xlog is on a spindle is *only* for pg_xlog
> you're better off.

Like Mr. Stone said earlier, this is pure dogma.  In my experience,
xlogs on the same volume with data is much faster if both are on
battery-backed write-back RAID controller memory.  Moving from this
situation to xlogs on a single normal disk is going to be much slower in
most cases.

-jwb