[linux-lvm] snapshots filling and hanging up processes

[linux-lvm] snapshots filling and hanging up processes

[Brian J. Murrell]

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I am using LVM2 on FC4 (2.6.15-1.1831_FC4smp) and snapshots.  The
problem seems to be that when a snapshot fills up it craps out.  Trying
to extend it ends up hanging the lvextend process and a reboot is
needed.  After which though the snapshot is corrupted beyond repair.

While hung, lvextend's stack trace looks like:

lvextend      D ffff8100d1b00050     0 14786   7501               18185 (NOTLB)
ffff810105b7fc68 0000000000000086 ffff8101115afc00 ffffffff8016594c
       0000000000000000 0000000000000000 ffff81011748cbe8 0000000000000000
       0000000000000000 000000000001facf
Call Trace:<ffffffff8016594c>{wait_on_page_writeback_range+203}
       <ffffffff8806b694>{:dm_mod:dev_suspend+0} <ffffffff801650c7>{__filemap_fdatawrite_range+87}
       <ffffffff8806b694>{:dm_mod:dev_suspend+0} <ffffffff80357567>{__down_write+137}
       <ffffffff88067c0f>{:dm_mod:dm_suspend+368} <ffffffff80137e56>{default_wake_function+0}
       <ffffffff8035746c>{__down_read+50} <ffffffff8806b694>{:dm_mod:dev_suspend+0}
       <ffffffff8806b7b0>{:dm_mod:dev_suspend+284} <ffffffff8806a68c>{:dm_mod:ctl_ioctl+536}
       <ffffffff8019c84e>{do_ioctl+94} <ffffffff8019caf2>{vfs_ioctl+649}
       <ffffffff8019cb66>{sys_ioctl+91} <ffffffff8010fc60>{tracesys+209}

Trying to look at the volume in this state yields:

    # /usr/sbin/lvdisplay /dev/vg0/centos4.2-i386-boulder
[ I have to hit INTR here]
      CTRL-c detected: giving up waiting for lock
      /var/lock/lvm/V_vg0: flock failed: Interrupted system call
      Can't lock vg0: skipping

Is this a known issue (in this kernel or otherwise)?  Is it fixed in a
later FC kernel like kernel-2.6.15-1.1833_FC4.x86_64.rpm  or
kernel-2.6.15-1.2054_FC5.x86_64.rpm?

Thots?

b.

-- 
My other computer is your Microsoft Windows server.

Brian J. Murrell

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Re: [linux-lvm] snapshots filling and hanging up processes

[Alasdair G Kergon]

On Tue, Mar 21, 2006 at 01:33:24PM -0500, Brian J. Murrell wrote:
> later FC kernel like kernel-2.6.15-1.1833_FC4.x86_64.rpm  or
> kernel-2.6.15-1.2054_FC5.x86_64.rpm?
 
Relevant kernel patches should be going into 2.6.17.

Or download from 
  http://www.kernel.org/pub/linux/kernel/people/agk/patches/2.6/editing/

Alasdair
-- 
agk@redhat.com

Re: [linux-lvm] snapshots filling and hanging up processes

[Mike Snitzer]

On 3/21/06, Alasdair G Kergon <agk@redhat.com> wrote:
> On Tue, Mar 21, 2006 at 01:33:24PM -0500, Brian J. Murrell wrote:
> > later FC kernel like kernel-2.6.15-1.1833_FC4.x86_64.rpm  or
> > kernel-2.6.15-1.2054_FC5.x86_64.rpm?
>
> Relevant kernel patches should be going into 2.6.17.
>
> Or download from
>   http://www.kernel.org/pub/linux/kernel/people/agk/patches/2.6/editing/

Have these patches gone in to the RHEL4 U3 kernel?  Is RHEL4 U3's lvm
snapshot support considered "officially supported by RedHat"?

Thanks for all your hard work on lvm snapshot!
Mike