Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763146AbYARUfc (ORCPT ); Fri, 18 Jan 2008 15:35:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759396AbYARUfY (ORCPT ); Fri, 18 Jan 2008 15:35:24 -0500 Received: from srv5.dvmed.net ([207.36.208.214]:33280 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758218AbYARUfX (ORCPT ); Fri, 18 Jan 2008 15:35:23 -0500 Message-ID: <47910D6E.3070801@garzik.org> Date: Fri, 18 Jan 2008 15:34:54 -0500 From: Jeff Garzik User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: ric@emc.com CC: Theodore Tso , Bryan Henderson , Al Boldi , Alan Cox , David Chinner , linux-kernel@vger.kernel.org, Pavel Machek , Daniel Phillips , Rik van Riel , Valerie Henson Subject: Re: [Patch] document ext3 requirements (was Re: [RFD] Incremental fsck) References: <478FE22D.9030907@emc.com> <20080118142308.GD12796@mit.edu> <4790C50F.2080704@emc.com> In-Reply-To: <4790C50F.2080704@emc.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -4.4 (----) X-Spam-Report: SpamAssassin version 3.2.3 on srv5.dvmed.net summary: Content analysis details: (-4.4 points, 5.0 required) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1489 Lines: 43 Ric Wheeler wrote: > Theodore Tso wrote: >> On Thu, Jan 17, 2008 at 04:31:48PM -0800, Bryan Henderson wrote: >>> But I heard some years ago from a disk drive engineer that that is a >>> myth just like the rotational energy thing. I added that to the >>> discussion, but admitted that I haven't actually seen a disk drive >>> write a partial sector. >> >> Well, it would be impossible or at least very hard to see that in >> practice, right? My understanding is that drives do sector-level >> checksums, so if there was a partially written sector, the checksum >> would be bogus and the drive would return an error when you tried to >> read from it. > > There is extensive per sector error correction on each sector written. > What you would see in this case (or many, many other possible ways > drives can corrupt media) is a "media error" on the next read. Correct. > You would never get back the partially written contents of that sector > at the host. Correct. > Having our tools (fsck especially) be resilient in the face of media > errors is really critical. Although I don't think the scenario of a > partially written sector is common, media errors in general are common > and can develop over time. Agreed. Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/