From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Thu, 26 Apr 2007 15:55:14 -0700 (PDT) Received: from postoffice.aconex.com (mail.app.aconex.com [203.89.192.138]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with ESMTP id l3QMt7fB014517 for ; Thu, 26 Apr 2007 15:55:09 -0700 Subject: Re: Unexpected XFS SB number 0x00000000 From: Nathan Scott Reply-To: nscott@aconex.com In-Reply-To: <200704262146.59921.martin.eisenhardt@wiai.uni-bamberg.de> References: <200704262146.59921.martin.eisenhardt@wiai.uni-bamberg.de> Content-Type: text/plain Date: Fri, 27 Apr 2007 08:57:19 +1000 Message-Id: <1177628239.6273.374.camel@edge> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Martin Eisenhardt Cc: xfs@oss.sgi.com On Thu, 2007-04-26 at 21:46 +0200, Martin Eisenhardt wrote: > Hello list(s), > > I run XFS on a software raid on Linux 2.6.19. When I invoke xfs_db in > read-only mode, I get: > > # xfs_db -r /dev/md0 > xfs_db: unexpected XFS SB magic number 0x00000000 > xfs_db: read failed: Invalid argument > xfs_db: data size check failed > Segmentation fault I think this segfault is fixed in recent xfs_db versions. > The system is still running, the filesystem seems to be fine (except for the > above): files are created, written, and deleted without any problem. > > So, I have two questions: > > * Is there a real problem, or might a quick reboot solve this? It looks like a real problem to me - something has written zeroes to the start of your partition, where the primary XFS superblock should be. If the filesystem is still mounted(?), I'd a/ make a backup copy of anything/everything precious there b/ try to get the incore copy of the XFS superblock flushed out (this assumes still mounted) - creater a file & use sync(1) - you might get lucky. > * If there is a real problem with the file system: What steps do you recommend > to overcome this problem? > * How safe is it to run xfs_check and xfs_repair? If you really have zeroes over your primary superblock, xfs_repair is your only option to fix that really (after unmounting). You wont get much joy from xfs_check, as its just a shell script wrapper around the xfs_db "check" command. > P.S.: Sorry for cross-posting, I just figure that maybe the XFS users on > non-linux systems might have a hint or two for me ... ;-) Theres only one list (both addresses point to the same place). cheers. -- Nathan