From: Ilia Mirkin <imirkin@alum.mit.edu> To: Dave Chinner <david@fromorbit.com> Cc: Roman Kononov <roman@binarylife.net>, xfs@oss.sgi.com, linux-kernel@vger.kernel.org Subject: Re: WARNING in xfs_lwr.c, xfs_write() Date: Sun, 13 Jun 2010 23:27:59 -0400 [thread overview] Message-ID: <AANLkTilqrYxnRzB3FNNE3k3hX2Sp1U63gyTo3T4CIzWV@mail.gmail.com> (raw) In-Reply-To: <20100614012933.GB6590@dastard> On Sun, Jun 13, 2010 at 9:29 PM, Dave Chinner <david@fromorbit.com> wrote: > On Sun, Jun 13, 2010 at 07:10:30PM -0400, Ilia Mirkin wrote: >> On Sun, Jun 13, 2010 at 6:47 PM, Dave Chinner <david@fromorbit.com> wrote: >> > On Sat, Jun 12, 2010 at 01:00:52AM -0400, Ilia Mirkin wrote: >> >> Sorry to pick up an old-ish thread, but I have a similar situation: >> >> >> >> On Sun, May 23, 2010 at 9:19 PM, Dave Chinner <david@fromorbit.com> wrote: >> >> > On Sun, May 23, 2010 at 09:23:44AM -0500, Roman Kononov wrote: >> >> >> On 2010-05-23, 20:18:56 +1000, Dave Chinner <david@fromorbit.com> wrote: >> >> >> > Can you find out what the application is triggering this? >> >> >> >> I noticed this happening with mysql and xtrabackup -- the latter opens >> >> up mysql's files while mysql is still running (and modifying its own >> >> files) and backs them up in a (hopefully) safe way. >> > >> > That's not safe at all - there's no guarantee you'll end up with a >> > consistent database image doing backups like this. Have you ever >> > tried to restore and use one of these backups? >> >> Yep, works great. [Used it to initialize a slave, did the full >> checksums, so it's unlikely to have randomly corrupt data.] > > You were lucky, I'd say. xtrabackup is supposed to be tightly > integrated with mysql, so perhaps it should be using the same IO > methods that the admin has selected for their database. Maybe you > need to talk to the xtrabackup folks to get them to add a "backup > via direct IO" method if the mysql database is using direct IO so > that other uses don't have the same issues. Maybe. We've been using this technique, although on a different physical machine and with ext3, for quite some time (and we verify all backups). I did notice that there is a minor difference in configuration, esp wrt direct IO, so I'll check it out in more detail. [We're now setting innodb_flush_method to O_DIRECT whereas we weren't before... although based on the documentation and a cursory understanding of how xtrabackup works, this shouldn't be harmful.] > And from a "I read it on the interwebs so it must be true" > perspective, without a loud obnoxious warning we'll never hear about > problems until someone flames us about silent data corruption on a > random blog that gets slashdotted and then referenced for the next > 10 years as the next canonical "XFS eats my data!" reference for the > clueless.... Instead it will be "mysql works fine on ext3, but with xfs it spams the logs with warnings, therefore xfs must be broken". I don't think there's anything realistically that you can do about uninformed users and FUD. Although I wasn't suggesting to get rid of the warning, rather to make it more explicit as to what it's warning about. I interpret a WARN as a BUG that can be recovered but where the underlying system needs a careful look; my first inclination after seeing a fs-related WARN would be to take the system down and run an fsck. What's happening here seems more akin to getting a WARN when calling an ioctl with invalid parameters. --- Ilia Mirkin imirkin@alum.mit.edu
WARNING: multiple messages have this Message-ID (diff)
From: Ilia Mirkin <imirkin@alum.mit.edu> To: Dave Chinner <david@fromorbit.com> Cc: Roman Kononov <roman@binarylife.net>, linux-kernel@vger.kernel.org, xfs@oss.sgi.com Subject: Re: WARNING in xfs_lwr.c, xfs_write() Date: Sun, 13 Jun 2010 23:27:59 -0400 [thread overview] Message-ID: <AANLkTilqrYxnRzB3FNNE3k3hX2Sp1U63gyTo3T4CIzWV@mail.gmail.com> (raw) In-Reply-To: <20100614012933.GB6590@dastard> On Sun, Jun 13, 2010 at 9:29 PM, Dave Chinner <david@fromorbit.com> wrote: > On Sun, Jun 13, 2010 at 07:10:30PM -0400, Ilia Mirkin wrote: >> On Sun, Jun 13, 2010 at 6:47 PM, Dave Chinner <david@fromorbit.com> wrote: >> > On Sat, Jun 12, 2010 at 01:00:52AM -0400, Ilia Mirkin wrote: >> >> Sorry to pick up an old-ish thread, but I have a similar situation: >> >> >> >> On Sun, May 23, 2010 at 9:19 PM, Dave Chinner <david@fromorbit.com> wrote: >> >> > On Sun, May 23, 2010 at 09:23:44AM -0500, Roman Kononov wrote: >> >> >> On 2010-05-23, 20:18:56 +1000, Dave Chinner <david@fromorbit.com> wrote: >> >> >> > Can you find out what the application is triggering this? >> >> >> >> I noticed this happening with mysql and xtrabackup -- the latter opens >> >> up mysql's files while mysql is still running (and modifying its own >> >> files) and backs them up in a (hopefully) safe way. >> > >> > That's not safe at all - there's no guarantee you'll end up with a >> > consistent database image doing backups like this. Have you ever >> > tried to restore and use one of these backups? >> >> Yep, works great. [Used it to initialize a slave, did the full >> checksums, so it's unlikely to have randomly corrupt data.] > > You were lucky, I'd say. xtrabackup is supposed to be tightly > integrated with mysql, so perhaps it should be using the same IO > methods that the admin has selected for their database. Maybe you > need to talk to the xtrabackup folks to get them to add a "backup > via direct IO" method if the mysql database is using direct IO so > that other uses don't have the same issues. Maybe. We've been using this technique, although on a different physical machine and with ext3, for quite some time (and we verify all backups). I did notice that there is a minor difference in configuration, esp wrt direct IO, so I'll check it out in more detail. [We're now setting innodb_flush_method to O_DIRECT whereas we weren't before... although based on the documentation and a cursory understanding of how xtrabackup works, this shouldn't be harmful.] > And from a "I read it on the interwebs so it must be true" > perspective, without a loud obnoxious warning we'll never hear about > problems until someone flames us about silent data corruption on a > random blog that gets slashdotted and then referenced for the next > 10 years as the next canonical "XFS eats my data!" reference for the > clueless.... Instead it will be "mysql works fine on ext3, but with xfs it spams the logs with warnings, therefore xfs must be broken". I don't think there's anything realistically that you can do about uninformed users and FUD. Although I wasn't suggesting to get rid of the warning, rather to make it more explicit as to what it's warning about. I interpret a WARN as a BUG that can be recovered but where the underlying system needs a careful look; my first inclination after seeing a fs-related WARN would be to take the system down and run an fsck. What's happening here seems more akin to getting a WARN when calling an ioctl with invalid parameters. --- Ilia Mirkin imirkin@alum.mit.edu _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs
next prev parent reply other threads:[~2010-06-14 3:28 UTC|newest] Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-05-23 5:20 WARNING in xfs_lwr.c, xfs_write() Roman Kononov 2010-05-23 5:20 ` Roman Kononov 2010-05-23 10:18 ` Dave Chinner 2010-05-23 10:18 ` Dave Chinner 2010-05-23 14:23 ` Roman Kononov 2010-05-23 14:23 ` Roman Kononov 2010-05-24 1:19 ` Dave Chinner 2010-05-24 1:19 ` Dave Chinner 2010-06-12 5:00 ` Ilia Mirkin 2010-06-12 5:00 ` Ilia Mirkin 2010-06-13 22:47 ` Dave Chinner 2010-06-13 22:47 ` Dave Chinner 2010-06-13 23:10 ` Ilia Mirkin 2010-06-13 23:10 ` Ilia Mirkin 2010-06-14 1:29 ` Dave Chinner 2010-06-14 1:29 ` Dave Chinner 2010-06-14 3:27 ` Ilia Mirkin [this message] 2010-06-14 3:27 ` Ilia Mirkin 2010-06-14 15:11 ` Roman Kononov 2010-06-14 15:11 ` Roman Kononov 2010-05-24 4:12 ` Stan Hoeppner 2010-05-24 5:16 ` Stewart Smith 2010-05-24 19:34 ` Roman Kononov 2010-05-26 7:06 ` Dave Chinner 2010-05-26 15:07 ` NOW: o_direct -- WAS: " Stan Hoeppner 2010-05-27 11:05 ` Michael Monnerie 2010-05-27 11:47 ` Christoph Hellwig 2010-05-27 13:58 ` Stewart Smith 2010-05-27 14:57 ` Christoph Hellwig 2010-05-27 15:45 ` Stewart Smith 2010-05-28 0:25 ` Stan Hoeppner 2010-05-27 14:05 ` Stewart Smith 2010-05-28 0:42 ` Stan Hoeppner
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