From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 59D386B004A for ; Tue, 9 Nov 2010 20:34:52 -0500 (EST) Date: Wed, 10 Nov 2010 12:32:55 +1100 From: Dave Chinner Subject: Re: 2.6.36 io bring the system to its knees Message-ID: <20101110013255.GR2715@dastard> References: <20101105014334.GF13830@dastard> <4CD696B4.6070002@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Linus Torvalds Cc: 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 Sun, Nov 07, 2010 at 07:50:13AM -0800, Linus Torvalds wrote: > On Sun, Nov 7, 2010 at 4:08 AM, Jens Axboe wrote: > > > > As already mentioned, ext3 is just not a good choice for this sort of > > thing. Did you have atimes enabled? > > At least for ext3, more important than atimes is the "data=writeback" > setting. Especially since our atime default is sane these days (ie if > you don't specify anything, we end up using 'relatime'). > > If you compile your own kernel, answer "N" to the question > > Default to 'data=ordered' in ext3? > > at config time (CONFIG_EXT3_DEFAULTS_TO_ORDERED), or you can make sure > "data=writeback" is in the fstab (but I don't think everything honors > it for the root filesystem). 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.... 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