Bug#419209: lvm2: Hangs during snapshot creation

[Xan Charbonnet]

Package: lvm2
Version: 2.02.95-4
Followup-For: Bug #419209

Hello,

It looks like this bug still exists in wheezy.  I use LVM to keep snapshots of
the database partitions on my backup servers.  Every half hour, a new snapshot
is created (and, usually, an old one destroyed).  This worked perfectly in
squeeze.

A few days ago, I configured a new backup server with a fresh install of
wheezy, and I'm seeing what I believe are the symptoms of this bug.  Sometimes
the snapshot creation goes just fine, but sometimes lvcreate hangs, blocked
for I/O forever.  I have to use sysrq to force the system to reboot.

There's no RAID involved.  (The system is on an md RAID1 mirror, but the LVM
volume lives on /dev/sdb1, straight-up.)  I've tried ext4 and ext3.  I've
tried creating the snapshot with the partition mounted and with the partition
unmounted.  I've tried a different hard drive.  Whatever I try, lvcreate hangs
very regularly.

I can do whatever experiments on this system might be helpful.  Please let me
know how I can help to track this down.  Thanks!

-Xan



-- System Information:
Debian Release: 7.0
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 3.2.0-4-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages lvm2 depends on:
ii  dmsetup                   2:1.02.74-4
ii  initscripts               2.88dsf-34
ii  libc6                     2.13-38
ii  libdevmapper-event1.02.1  2:1.02.74-4
ii  libdevmapper1.02.1        2:1.02.74-4
ii  libreadline5              5.2+dfsg-1
ii  libudev0                  175-7
ii  lsb-base                  4.1+Debian8

lvm2 recommends no packages.

lvm2 suggests no packages.

-- no debconf information