From owner-freebsd-performance@FreeBSD.ORG  Tue May  3 11:45:34 2005
Return-Path: <owner-freebsd-performance@FreeBSD.ORG>
Delivered-To: freebsd-performance@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id 018AB16A4CE; Tue,  3 May 2005 11:45:34 +0000 (GMT)
Received: from ms1.as.pvp.se (dns.pvp.se [213.64.187.226])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 4BACD43D1D; Tue,  3 May 2005 11:45:33 +0000 (GMT)
	(envelope-from kama@pvp.se)
Received: by ms1.as.pvp.se (Postfix, from userid 1001)
	id 57C48A7; Tue,  3 May 2005 13:45:30 +0200 (CEST)
Received: from localhost (localhost [127.0.0.1])
	by ms1.as.pvp.se (Postfix) with ESMTP
	id 537E7A6; Tue,  3 May 2005 13:45:30 +0200 (CEST)
Date: Tue, 3 May 2005 13:45:30 +0200 (CEST)
From: kama <kama@pvp.se>
X-X-Sender: kama@ns1.as.pvp.se
To: Poul-Henning Kamp <phk@phk.freebsd.dk>
In-Reply-To: <17442.1115039706@critter.freebsd.dk>
Message-ID: <20050503134451.P22614@ns1.as.pvp.se>
References: <17442.1115039706@critter.freebsd.dk>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: Robert Watson <rwatson@freebsd.org>
cc: freebsd-performance@freebsd.org
cc: Eric Anderson <anderson@centtech.com>
cc: =?ISO-8859-15?Q?=22Arne_=5C=22W=F6rner=5C=22=22?= <arne_woerner@yahoo.com>
Subject: Re: Very low disk performance on 5.x 
X-BeenThere: freebsd-performance@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Performance/tuning <freebsd-performance.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-performance>,
	<mailto:freebsd-performance-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-performance>
List-Post: <mailto:freebsd-performance@freebsd.org>
List-Help: <mailto:freebsd-performance-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-performance>,
	<mailto:freebsd-performance-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 03 May 2005 11:45:34 -0000



On Mon, 2 May 2005, Poul-Henning Kamp wrote:

> In message <427626DC.5030702@centtech.com>, Eric Anderson writes:
>
> >Don't mean to be terse here, but I'm talking about the same test done an
> >two different RAID5 configurations, with different disks, and not just
> >me - other users in this very thread see the same issue..
>
> Uhm, if you are using RAID5 and your requests are not aligned and
> sized after the RAID5 you should *expect* read performance to be poor.
>
> If you your request ends up accessing two different blocks even just
> once per stripe, this totally kills performance.

My system is setup with RAID 1+0. So its not a RAID5 issue...