From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id q56Dd2Y8222086 for ; Wed, 6 Jun 2012 08:39:02 -0500 Received: from ipmail07.adl2.internode.on.net (ipmail07.adl2.internode.on.net [150.101.137.131]) by cuda.sgi.com with ESMTP id Ubpa0YtjEf0c1lIP for ; Wed, 06 Jun 2012 06:39:01 -0700 (PDT) Date: Wed, 6 Jun 2012 23:38:59 +1000 From: Dave Chinner Subject: Re: Segmentation fault in xfs_db frag, xfsprogs-3.1.8 Message-ID: <20120606133859.GM22848@dastard> References: <4FCC77E1.4030600@cape-horn-eng.com> <20120605234528.GD22848@dastard> <4FCF2BAC.6050100@cape-horn-eng.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4FCF2BAC.6050100@cape-horn-eng.com> 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: Richard Ems Cc: xfs@oss.sgi.com On Wed, Jun 06, 2012 at 12:06:36PM +0200, Richard Ems wrote: > On 06/06/2012 01:45 AM, Dave Chinner wrote: > > No surprise if you have a large filesystem and the filesystem is > > changing while xfs_db is running. xfs_db is not coherent with > > mounted filesytems, and it is not recommended that you use it that > > way.s xfs-db is a debugging tool, not a filesystem state reporting > > tool. > > Ok, thanks, didn't know that. > I would like to monitor the fragmentation value for all my mounted XFS. > I think I read in previous list messages that also other people are > using xfs_db this way. Or is there another way to get the fragmentation > value? No, and what xfs_db reports is mostly useless. You don't have a fragmentation problem unless you are noticing performance problems, and no fragmentation number will ever tell you that.... > I found this segmentation fault error very strange, since I have been > using "echo frag | xfs_db -r" for months already on other big > filesystems - 2 x 17 TB, 1 x 25 TB, 1 x 20 TB - and NEVER got a > segmentation fault. All 4 filessystems are mounted read-write and are in > heavy IO use, nevertheless "echo frag | xfs_db -r" runs as expected (by > me), no one xfs_db run crashed with a segmentation fault at all for > months, running every weekend. > It also ran several times without giving any errors on this 80 TB XFS, > but then started to throw segmentation faults some weeks ago. It's entirely possible it is running out of memory, failing to capture the failure and dereferencing a null pointer.... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs