From owner-freebsd-hardware@FreeBSD.ORG Mon Jun 27 07:11:51 2011 Return-Path: Delivered-To: freebsd-hardware@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id C91B01065672 for ; Mon, 27 Jun 2011 07:11:51 +0000 (UTC) (envelope-from perryh@pluto.rain.com) Received: from agora.rdrop.com (agora.rdrop.com [IPv6:2607:f678:1010::34]) by mx1.freebsd.org (Postfix) with ESMTP id AC3118FC1C for ; Mon, 27 Jun 2011 07:11:51 +0000 (UTC) Received: from agora.rdrop.com (66@localhost [127.0.0.1]) by agora.rdrop.com (8.13.1/8.12.7) with ESMTP id p5R7BoUb066614 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Mon, 27 Jun 2011 00:11:50 -0700 (PDT) (envelope-from perryh@pluto.rain.com) Received: (from uucp@localhost) by agora.rdrop.com (8.13.1/8.12.9/Submit) with UUCP id p5R7BoKD066612 for freebsd-hardware@freebsd.org; Mon, 27 Jun 2011 00:11:50 -0700 (PDT) Received: from fbsd61 by pluto.rain.com (4.1/SMI-4.1-pluto-M2060407) id AA13435; Mon, 27 Jun 11 00:07:11 PDT Date: Mon, 27 Jun 2011 00:10:51 -0700 From: perryh@pluto.rain.com To: freebsd-hardware@freebsd.org Message-Id: <4e082cfb.RsTdPgXYWUCS9sX7%perryh@pluto.rain.com> User-Agent: nail 11.25 7/29/05 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Subject: UDMA cables vs speeds X-BeenThere: freebsd-hardware@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: General discussion of FreeBSD hardware List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Jun 2011 07:11:51 -0000 Should an 80-wire Ultra-ATA data cable intended for use at UDMA66 or UDMA100 also work at UDMA133, or does the higher speed require different cabling? Background: I've been experiencing occasional UDMA ICRC errors on the IDE port of a PCI SATA/IDE controller card using the VIA VT6421 chipset, and I've noticed that "atacontrol mode" reports the port speed as UDMA133. The data cable is brand new, but it came with a UDMA100 card. (I got much worse results with a different 80-pin cable, which looked similar but may have been intended only for UDMA66.) I've found several similar reports in the forum and mailing-list archives, with no definitive solution but quite a few "it works for me" responses, and one observation that the VT6421 seems to work well with some drives and not so well with others. It occurs to me that the difference might, perhaps, involve the DMA speeds (which aren't mentioned).