From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 4BF0A6B004A for ; Wed, 10 Nov 2010 03:25:33 -0500 (EST) Received: from dastard (unverified [121.44.100.105]) by mail.internode.on.net (SurgeMail 3.8f2) with ESMTP id 45888754-1927428 for ; Wed, 10 Nov 2010 18:55:30 +1030 (CDT) Date: Wed, 10 Nov 2010 19:24:58 +1100 From: Dave Chinner Subject: Re: 2.6.36 io bring the system to its knees Message-ID: <20101110082458.GU2715@dastard> References: <20101105014334.GF13830@dastard> <4CD696B4.6070002@kernel.dk> <20101110013255.GR2715@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: owner-linux-mm@kvack.org To: Evgeniy Ivanov Cc: Linus Torvalds , Jens Axboe , dave b , Sanjoy Mahajan , Jesper Juhl , Chris Mason , Ingo Molnar , Pekka Enberg , Aidar Kultayev , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Peter Zijlstra , Nick Piggin , Arjan van de Ven , Thomas Gleixner , Ted Ts'o , Corrado Zoccolo , Shaohua Li , Steven Barrett List-ID: On Wed, Nov 10, 2010 at 11:08:17AM +0300, Evgeniy Ivanov wrote: > On Wed, Nov 10, 2010 at 4:32 AM, Dave Chinner wrote: > > Don't forget to mention data=writeback is not the default because if > > your system crashes or you lose power running in this mode it will > > *CORRUPT YOUR FILESYSTEM* and you *WILL LOSE DATA*. Not to mention > > the significant security issues (e.g stale data exposure) that also > > occur even if the filesystem is not corrupted by the crash. IOWs, > > data=writeback is the "fast but I'll eat your data" option for ext3. > > > > So I recommend that nobody follows this path because it only leads > > to worse trouble down the road. Your best bet it to migrate away > > from ext3 to a filesystem that doesn't have such inherent ordering > > problems like ext4 or XFS.... > > Is it save to use "data=writeback" with ext4? I believe the same issues exist with data=writeback in ext4, but you probably should have an ext4 developer answer that question for certain. > At least are there security issues? > Why do you say, that fs can be corrupted? Metadata is still > journalled, so only data might be corrupted, but FS should still be > consistent. Data corruption is still a filesystem corruption. Cheers, Dave. -- Dave Chinner david@fromorbit.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org