From owner-freebsd-questions@FreeBSD.ORG  Mon Sep 29 21:43:58 2008
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id C124F1065690;
	Mon, 29 Sep 2008 21:43:58 +0000 (UTC)
	(envelope-from lreid@cs.okstate.edu)
Received: from a.cs.okstate.edu (a.cs.okstate.edu [139.78.113.1])
	by mx1.freebsd.org (Postfix) with ESMTP id A3B838FC34;
	Mon, 29 Sep 2008 21:43:58 +0000 (UTC)
	(envelope-from lreid@cs.okstate.edu)
Received: from [127.0.0.1] (localhost [127.0.0.1])
	by a.cs.okstate.edu (Postfix) with ESMTP id 9A8EC155250;
	Mon, 29 Sep 2008 16:19:26 -0500 (CDT)
Message-ID: <48E1465A.5040903@cs.okstate.edu>
Date: Mon, 29 Sep 2008 16:19:22 -0500
From: Reid Linnemann <lreid@cs.okstate.edu>
User-Agent: Thunderbird 2.0.0.12 (X11/20080414)
MIME-Version: 1.0
To: freebsd-questions@freebsd.org
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Subject: SATA READ_DMA timeouts - SOLVED?
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 29 Sep 2008 21:43:58 -0000

I've seen a number of people having DMA troubles with SATA disks on 
FreeBSD6 and FreeBSD7, and I'm in the same boat. A while back I posted 
looking for help but none could really be found. Today I finally got to 
the bottom of things (at least so far).

Hardware incompatibility.

According to 
http://en.wikipedia.org/wiki/SATA#SATA_1.5_Gbit.2Fs_and_SATA_3_Gbit.2Fs 
there is an upward compatibility problem between a number of VIA and SiS 
chipsets and SATA300 disks. I happen to have one of those controllers 
(SiS964) and a pair of WD1600AAJS disks, which are SATA300 disks.

I ripped apart my machine, and sure enough I had a jumper on each disk 
labelled 'OPT1', which is documented to force SATA150 operation.

I've since cold booted, warm booted, and booted after a power 
interruption with no READ_DMA timeouts on these disks. I think this 
solved the problem in my case.