I''m trying to snapshot my mdt using lvm and back it up. After i take the snapshot and go to mount the volume (as ldiskfs) I end up with all kinds of warnings about orphaned inodes. Is this normal? Is this a sign of potential problems with my MDT? Jan 28 14:30:21 disk kernel: kjournald starting. Commit interval 5 seconds Jan 28 14:30:21 disk kernel: LDISKFS FS on dm-2, internal journal Jan 28 14:30:26 disk kernel: LDISKFS-fs: dm-2: 6868 orphan inodes deleted Jan 28 14:30:26 disk kernel: LDISKFS-fs: recovery complete. Jan 28 14:30:28 disk kernel: LDISKFS-fs: mounted filesystem with ordered data mode. Aaron Knister Associate Systems Analyst Center for Ocean-Land-Atmosphere Studies (301) 595-7000 aaron at iges.org
On Mon, 2008-01-28 at 14:34 -0500, Aaron Knister wrote:> I''m trying to snapshot my mdt using lvm and back it up. > > After i take the snapshot and go to mount the volume (as ldiskfs) I > end up with all kinds of warnings about orphaned inodes. Is this > normal?It is. You are trying to mount a (copy of a) filesystem that is in an "open" state rather than the state it would be in if you were mounting a filesystem that had had gone through an "unmount".> Is this a sign of potential problems with my MDT?No. But your backup will not truly be a snapshot in time at the exact moment you took it since any transactions which have not been flushed from the journal at the snapshot time will be backed out when you mount it. Ideally, you could have ldiskfs close off the journal and quiesce the filesystem before you take your snapshot and you would not see those errors and would have a real snapshot it time copy. I don''t know that there is a way to do that though, and really the result is probably close enough if you are doing something like a daily backup or such. b. -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 189 bytes Desc: This is a digitally signed message part Url : http://lists.lustre.org/pipermail/lustre-discuss/attachments/20080128/2d333c04/attachment-0002.bin
Thanks! That helps. I thought there was a way to tell an ext3 (ldiskfs) filesystem to somehow flush the journal? I don''t know if thats the correct terminology. On Jan 28, 2008, at 2:44 PM, Brian J. Murrell wrote:> On Mon, 2008-01-28 at 14:34 -0500, Aaron Knister wrote: >> I''m trying to snapshot my mdt using lvm and back it up. >> >> After i take the snapshot and go to mount the volume (as ldiskfs) I >> end up with all kinds of warnings about orphaned inodes. Is this >> normal? > > It is. You are trying to mount a (copy of a) filesystem that is in an > "open" state rather than the state it would be in if you were > mounting a > filesystem that had had gone through an "unmount". > >> Is this a sign of potential problems with my MDT? > > No. But your backup will not truly be a snapshot in time at the exact > moment you took it since any transactions which have not been flushed > from the journal at the snapshot time will be backed out when you > mount > it. > > Ideally, you could have ldiskfs close off the journal and quiesce the > filesystem before you take your snapshot and you would not see those > errors and would have a real snapshot it time copy. I don''t know that > there is a way to do that though, and really the result is probably > close enough if you are doing something like a daily backup or such. > > b. > > _______________________________________________ > Lustre-discuss mailing list > Lustre-discuss at lists.lustre.org > http://lists.lustre.org/mailman/listinfo/lustre-discussAaron Knister Associate Systems Analyst Center for Ocean-Land-Atmosphere Studies (301) 595-7000 aaron at iges.org
On Jan 28, 2008 14:44 -0500, Brian J. Murrell wrote:> On Mon, 2008-01-28 at 14:34 -0500, Aaron Knister wrote: > > I''m trying to snapshot my mdt using lvm and back it up. > > > > After i take the snapshot and go to mount the volume (as ldiskfs) I > > end up with all kinds of warnings about orphaned inodes. Is this > > normal?> It is. You are trying to mount a (copy of a) filesystem that is in an > "open" state rather than the state it would be in if you were mounting a > filesystem that had had gone through an "unmount".Partly true, partly not. It is normal if you expect that applications are keeping files open after unlinking them...> > Is this a sign of potential problems with my MDT? > > No. But your backup will not truly be a snapshot in time at the exact > moment you took it since any transactions which have not been flushed > from the journal at the snapshot time will be backed out when you mount > it. > > Ideally, you could have ldiskfs close off the journal and quiesce the > filesystem before you take your snapshot and you would not see those > errors and would have a real snapshot it time copy. I don''t know that > there is a way to do that though, and really the result is probably > close enough if you are doing something like a daily backup or such.Well, the LVM kernel code _does_ flush everything to disk (including the journal) and block all device IO before taking the snapshot. The orphan inodes are the one thing it can''t clean up before the snapshot, since that would lose the open-unlinked files otherwise. This isn''t harmful or inconsistent for the snapshot, because those files have actually been deleted already. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.
Great! Thanks for the info. -Aaron ----- Original Message ----- From: "Andreas Dilger" <adilger at sun.com> To: "Brian J. Murrell" <Brian.Murrell at sun.com> Cc: "Lustre-discuss" <lustre-discuss at clusterfs.com> Sent: Tuesday, January 29, 2008 4:22:04 AM (GMT-0500) America/New_York Subject: Re: [Lustre-discuss] MDT Snapshot orphaned inodes On Jan 28, 2008 14:44 -0500, Brian J. Murrell wrote:> On Mon, 2008-01-28 at 14:34 -0500, Aaron Knister wrote: > > I''m trying to snapshot my mdt using lvm and back it up. > > > > After i take the snapshot and go to mount the volume (as ldiskfs) I > > end up with all kinds of warnings about orphaned inodes. Is this > > normal?> It is. You are trying to mount a (copy of a) filesystem that is in an > "open" state rather than the state it would be in if you were mounting a > filesystem that had had gone through an "unmount".Partly true, partly not. It is normal if you expect that applications are keeping files open after unlinking them...> > Is this a sign of potential problems with my MDT? > > No. But your backup will not truly be a snapshot in time at the exact > moment you took it since any transactions which have not been flushed > from the journal at the snapshot time will be backed out when you mount > it. > > Ideally, you could have ldiskfs close off the journal and quiesce the > filesystem before you take your snapshot and you would not see those > errors and would have a real snapshot it time copy. I don''t know that > there is a way to do that though, and really the result is probably > close enough if you are doing something like a daily backup or such.Well, the LVM kernel code _does_ flush everything to disk (including the journal) and block all device IO before taking the snapshot. The orphan inodes are the one thing it can''t clean up before the snapshot, since that would lose the open-unlinked files otherwise. This isn''t harmful or inconsistent for the snapshot, because those files have actually been deleted already. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. _______________________________________________ Lustre-discuss mailing list Lustre-discuss at lists.lustre.org http://lists.lustre.org/mailman/listinfo/lustre-discuss