From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with ESMTP id mBTIKTPH009436 for ; Mon, 29 Dec 2008 12:20:29 -0600 Received: from mail.lichtvoll.de (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 909191793663 for ; Mon, 29 Dec 2008 10:20:27 -0800 (PST) Received: from mail.lichtvoll.de (mondschein.lichtvoll.de [194.150.191.11]) by cuda.sgi.com with ESMTP id 2ttoJoTFCY9Yw8aa for ; Mon, 29 Dec 2008 10:20:27 -0800 (PST) Received: from shambhala.lichtvoll.local (DSL01.83.171.154.140.ip-pool.NEFkom.net [83.171.154.140]) by mail.lichtvoll.de (Postfix) with ESMTPSA id 698D45AE4F for ; Mon, 29 Dec 2008 19:20:24 +0100 (CET) From: Martin Steigerwald Subject: massively truncated files with XFS with sudden power loss on 2.6.27 and 2.6.28 Date: Mon, 29 Dec 2008 19:20:33 +0100 MIME-Version: 1.0 Content-Disposition: inline Message-Id: <200812291920.34123.Martin@Lichtvoll.de> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com Hi! Remember http://oss.sgi.com/pipermail/xfs/2008-November/037399.html ? I thought it was resolved and with later TuxOnIce and sync all is better for sure. This all was with barriers and write cache enabled. But I had a hard crash this time while shutting down the system regularily and the KDE addressbook, KDE settings, additional sidebar all was lost due to truncated files. This was without barriers but also without write cache. Curious about the safety of my data I tried to simulate the thing. I shouldn't have done that with my productive data but here are the results: I just switched the machine off after having made a backup of my KDE configuration and after closing my usual apps. Then I waited 30-40 seconds. First time was fine, second time KDE colors were lost again. Third time I didn't wait that long. Side bar was lost. Fourth time I pressed power off after *starting* KDE. Lots of stuff was lost, including: - colors - sidebar - kpanel settings - kgpg settings - one kwallet digital wallet with passwords and stuff, a complete file of 130 KB was just 60 bytes anymore I cannot remember having seen this kind of behavior anywhere between 2.6.17.7 and 2.6.26! And I had sudden interruptions of write activity from time to time. I can't prove anything right now. I possibly could if I dare to test this again with 2.6.26! But from my experiences this never was so massive. Prior to the null file fixes a file or two might have been corrupted and that not all the times. Thats to be expected if thats the file that where written out at the time. But now it seems that almost every file that is opened for writing or not even just for writing is truncated seriously at sudden interruption of write activity. Whereas before it appeared that usually either the change was not made or it was made - at least for small files. Now the file is truncated, no holes, just lots less bytes than before. I think I will go back to 2.6.26 for now - with write barriers, cause thats what used to work. I went too far already with my tests, cause its difficult to be sure that I found all truncated files even when I close all productivity applications in my tests. Altough it seems I was able to recovery everything everytime by mixing the current data set with the broken stuff restored from the last backup this is setting my data at a too high risk. Do you have any idea on how to help to get down to the cause of this - without risking precious data? Did anyone else see this? Does anyone use XFS on laptops and had recent power losses or crashes? I have seen this on a 2.6.27.7, 2.6.28 with tuxonice patches. syncing before a crash occurs seems to fix the issue. Did something change with how aggressively the kernel writes data out? I think it was something along shambhala:/proc/sys/vm> cat dirty_expire_centisecs 2999 shambhala:/proc/sys/fs/xfs> cat xfsbufd_centisecs xfssyncd_centisecs 100 3000 in all recent kernels! I expect to loose the changes for a dirtied file thats in the page cache. But I do not expect to loose the current (old) file on disk in that case, unless the crash happens when its actually written out at that time. And that appears to be highly unlikely expecially at the time just after KDE started up when I did not use any application yet. I would be surprised when the first things applications would be doing was to write out what they just read in. And even then I would be surprised when XFS did write to all the files at once. So I just don't get what I have seen here and I think I see a regression. I am willing to look deeper when I found how to do so safely enough. If there an xfsqa test that simulates sudden interruption of write activity? Actually I am considering to switch to ext3/4. Maybe the people that say don't use XFS on commodity hardware really have a point. But then it did work very well from 2.6.17.7 to 2.6.26, so I think what I face here is a behavorial regression. It might be a performance improvement at the same time, but for laptops and commodity workstations this is too risky IMHO. Is there interest in digging this? I can accept when you tell my not to use XFS on my laptop. But actually I think something changed between 2.6.26 andf 2.6.27 and maybe thats worth looking at. Ciao, -- Martin 'Helios' Steigerwald - http://www.Lichtvoll.de GPG: 03B0 0D6C 0040 0710 4AFA B82F 991B EAAC A599 84C7 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs