From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964912AbWAWTcY (ORCPT ); Mon, 23 Jan 2006 14:32:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964914AbWAWTcY (ORCPT ); Mon, 23 Jan 2006 14:32:24 -0500 Received: from mail.gmx.net ([213.165.64.21]:5297 "HELO mail.gmx.net") by vger.kernel.org with SMTP id S964912AbWAWTcW (ORCPT ); Mon, 23 Jan 2006 14:32:22 -0500 X-Authenticated: #428038 Date: Mon, 23 Jan 2006 20:32:17 +0100 From: Matthias Andree To: John Richard Moser Cc: Michael Loftis , linux-kernel@vger.kernel.org Subject: Re: soft update vs journaling? Message-ID: <20060123193217.GA21783@merlin.emma.line.org> Mail-Followup-To: John Richard Moser , Michael Loftis , linux-kernel@vger.kernel.org References: <43D3295E.8040702@comcast.net> <43D525D8.8080501@comcast.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <43D525D8.8080501@comcast.net> X-PGP-Key: http://home.pages.de/~mandree/keys/GPGKEY.asc User-Agent: Mutt/1.5.11 X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 23 Jan 2006, John Richard Moser wrote: > The idea of Soft Update was to make sure that while you may lose > something, when you come back up the FS is in a safely usable state. Soft Updates are *extremely* sensitive to reordered writes, and more likely to be reordered at the same time than streaming to a linear journal is. Don't even THINK of using softupdates without enforcing write order. ext3fs, particularly with data=ordered or data=journal, is much more forgiving in my experience. Not that I'd endorse dangerous use of file system, but the average user just doesn't know. FreeBSD (stable@ Cc:d) has no notion of write barriers as of yet as it seems, wedging the SCSI bus in the middle of a write sequence causes major devastations with WCE=1, and took me two runs of fsck to repair (unfortunately I needed the (test) machine back up at once, so no time to snapshot the b0rked partition for later scrutiny), and found myself with two hundred files relocated to the lost+found office^Wdirectory. Of course, it's the "Doctor, doctor, it always hurts my right eye if I'm drinking coffee" -- "well, remove the spoon from your mug before drinking then" (don't do that) category of "bug", but it hosts practical relevance... -- Matthias Andree