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Message #39654
[Bug 1223576] Re: [SRU] lvremove often fails on first attempt when removing snapshot
raring has seen the end of its life and is no longer receiving any
updates. Marking the raring task for this ticket as "Won't Fix".
** Changed in: lvm2 (Ubuntu Raring)
Status: Confirmed => Won't Fix
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https://bugs.launchpad.net/bugs/1223576
Title:
[SRU] lvremove often fails on first attempt when removing snapshot
Status in lvm2 package in Ubuntu:
Fix Released
Status in lvm2 source package in Raring:
Won't Fix
Status in lvm2 source package in Saucy:
Fix Released
Bug description:
[SRU Justification]
[Impact]
* Removing LVM snapshots is unreliable on Raring on some hardware.
* Tools that abstract LVM actions will likely fail if they expect these actions
to function correctly and reliably. Specifically, OpenStack Cinder requires
reliability here.
[Test Case]
The following test case seems to trigger the bug on two classes of
hardware I've used, but not on a virtual machine:
sudo apt-get install lvm2
# A free block device
BDEV="sdb"
# Create original LVM volume.
pvcreate /dev/$BDEV
vgcreate testing-vg /dev/$BDEV
lvcreate -L 1024M -n testing test
# Run a snapshot create/delete cycle and observe frequent failures.
lvcreate -L 1024M --name testing-snapshot --snapshot /dev/testing-vg/testing
lvremove -f /dev/testing-vg/testing-snapshot
Example failure:
$ lvcreate -L 1024M --name testing-snapshot --snapshot /dev/testing-vg/testing
$ lvremove -f /dev/testing-vg/testing-snapshot
Logical volume "testing-snapshot" created
Unable to deactivate open testing--vg-testing-real (252:2)
Failed to resume testing.
[Solution]
Recent updates in Debian+Saucy to the LVM and dm udev rules seem to
alleviate the issue and I no longer see it when applying those changes
from lvm2 2.02.98-6ubuntu1 (Patch attached)
-------
# lsb_release -a
Distributor ID: Ubuntu
Description: Ubuntu Saucy Salamander (development branch)
Release: 13.10
Codename: saucy
# uname -r
3.11.0-4-generic
# dpkg -l | grep lvm2
ii lvm2 2.02.98-1ubuntu5 amd64 Linux Logical Volume Manager
Experiencing this on saucy across a number of boxes, all of similar
hardware. Unable to reproduce in a virtual machine using saucy cloud
images.
# BDEV="sdb"
# apt-get install -y lvm2
# umount /mnt
# pvcreate /dev/$BDEV
# vgcreate testing-vg /dev/$BDEV
# lvcreate -L 1024M -n testing testing-vg
# lvcreate -L 1024M --name testing-snapshot --snapshot /dev/testing-vg/testing
# lvremove -f /dev/testing-vg/testing-snapshot
Unable to deactivate open testing--vg-testing-real (252:2)
Failed to resume testing.
# lvremove -f /dev/testing-vg/testing-snapshot
Logical volume "testing-snapshot" successfully removed
Comparing output of 'dmsetup info' before and after failed attempts:
- The failed attempt removes the -cow device (testing--vg-testing--snapshot-cow), but the -real and -snapshot devices remain.
- Pre failure, the Open Count of testing--vg-testing-real is 2 (which AFAIK is to be expected). After failure, the device remains but with an Open Count of 0.
- After successful lvremove of the snapshot, the -real device persists. On unaffected systems, the post-snapshot removal dm table is the same as it was pre-creation of snapshot. In this case, a single device (testing--vg-testing)
# dmsetup info
Name: testing--vg-testing-real
State: ACTIVE
Read Ahead: 256
Tables present: LIVE
Open count: 2
Event number: 0
Major, minor: 252, 2
Number of targets: 1
UUID: LVM-cYTNHi8q1D1wA2wl0OMDmpgLBzUBsdm3wOGeFtca62anbqn236E0g20fYFhVRXEw-real
Name: testing--vg-testing--snapshot
State: ACTIVE
Read Ahead: 256
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 1
Number of targets: 1
UUID: LVM-cYTNHi8q1D1wA2wl0OMDmpgLBzUBsdm3qlotuThv4tJMHJH7w0CN1B6kEcnNYkdv
Name: testing--vg-testing--snapshot-cow
State: ACTIVE
Read Ahead: 256
Tables present: LIVE
Open count: 1
Event number: 0
Major, minor: 252, 3
Number of targets: 1
UUID: LVM-cYTNHi8q1D1wA2wl0OMDmpgLBzUBsdm3qlotuThv4tJMHJH7w0CN1B6kEcnNYkdv-cow
Name: testing--vg-testing
State: ACTIVE
Read Ahead: 256
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 0
Number of targets: 1
UUID: LVM-cYTNHi8q1D1wA2wl0OMDmpgLBzUBsdm3wOGeFtca62anbqn236E0g20fYFhVRXEw
# lvremove -f /dev/testing-vg/testing-snapshot
Unable to deactivate open testing--vg-testing-real (252:2)
Failed to resume testing.
# dmsetup info
Name: testing--vg-testing-real
State: ACTIVE
Read Ahead: 0
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 2
Number of targets: 1
UUID: LVM-cYTNHi8q1D1wA2wl0OMDmpgLBzUBsdm3wOGeFtca62anbqn236E0g20fYFhVRXEw-real
Name: testing--vg-testing--snapshot
State: ACTIVE
Read Ahead: 256
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 1
Number of targets: 1
UUID: LVM-cYTNHi8q1D1wA2wl0OMDmpgLBzUBsdm3qlotuThv4tJMHJH7w0CN1B6kEcnNYkdv
Name: testing--vg-testing
State: ACTIVE
Read Ahead: 256
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 0
Number of targets: 1
UUID: LVM-cYTNHi8q1D1wA2wl0OMDmpgLBzUBsdm3wOGeFtca62anbqn236E0g20fYFhVRXEw
# lvremove -f /dev/testing-vg/testing-snapshot
Logical volume "testing-snapshot" successfully removed
# dmsetup info
Name: testing--vg-testing-real
State: ACTIVE
Read Ahead: 0
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 2
Number of targets: 1
UUID: LVM-cYTNHi8q1D1wA2wl0OMDmpgLBzUBsdm3wOGeFtca62anbqn236E0g20fYFhVRXEw-real
Name: testing--vg-testing
State: ACTIVE
Read Ahead: 256
Tables present: LIVE
Open count: 0
Event number: 0
Major, minor: 252, 0
Number of targets: 1
UUID: LVM-cYTNHi8q1D1wA2wl0OMDmpgLBzUBsdm3wOGeFtca62anbqn236E0g20fYFhVRXEw
Output of 'udevadm monitor' with comments for contexts (also
attached):
# Original LV creation
KERNEL[3890.419526] add /devices/virtual/bdi/252:0 (bdi)
KERNEL[3890.419572] add /devices/virtual/block/dm-0 (block)
KERNEL[3890.419903] change /devices/virtual/block/dm-0 (block)
UDEV [3890.420177] add /devices/virtual/bdi/252:0 (bdi)
UDEV [3890.420594] add /devices/virtual/block/dm-0 (block)
UDEV [3890.439210] change /devices/virtual/block/dm-0 (block)
KERNEL[3890.440430] change /devices/virtual/block/dm-0 (block)
UDEV [3890.458613] change /devices/virtual/block/dm-0 (block)
KERNEL[3890.493110] change /devices/pci0000:00/0000:00:1c.0/0000:03:00.0/host2/port-2:1/end_device-2:1/target2:0:1/2:0:1:0/block/sdb (block)
UDEV [3890.553035] change /devices/pci0000:00/0000:00:1c.0/0000:03:00.0/host2/port-2:1/end_device-2:1/target2:0:1/2:0:1:0/block/sdb (block)
# Snapshot creation
KERNEL[3915.481512] add /devices/virtual/bdi/252:1 (bdi)
KERNEL[3915.481542] add /devices/virtual/block/dm-1 (block)
KERNEL[3915.481814] change /devices/virtual/block/dm-1 (block)
UDEV [3915.482069] add /devices/virtual/bdi/252:1 (bdi)
UDEV [3915.482468] add /devices/virtual/block/dm-1 (block)
UDEV [3915.503721] change /devices/virtual/block/dm-1 (block)
KERNEL[3915.504157] change /devices/virtual/block/dm-1 (block)
KERNEL[3915.548206] add /devices/virtual/bdi/252:2 (bdi)
KERNEL[3915.548288] add /devices/virtual/block/dm-2 (block)
UDEV [3915.548503] add /devices/virtual/bdi/252:2 (bdi)
KERNEL[3915.548787] add /devices/virtual/bdi/252:3 (bdi)
KERNEL[3915.548882] add /devices/virtual/block/dm-3 (block)
UDEV [3915.549093] add /devices/virtual/block/dm-2 (block)
KERNEL[3915.549173] change /devices/virtual/block/dm-3 (block)
UDEV [3915.549240] add /devices/virtual/bdi/252:3 (bdi)
UDEV [3915.549710] add /devices/virtual/block/dm-3 (block)
UDEV [3915.553716] change /devices/virtual/block/dm-3 (block)
KERNEL[3915.563685] change /devices/virtual/block/dm-2 (block)
KERNEL[3915.563823] change /devices/virtual/block/dm-1 (block)
KERNEL[3915.563915] change /devices/virtual/block/dm-0 (block)
UDEV [3915.567734] change /devices/virtual/block/dm-2 (block)
UDEV [3915.586136] change /devices/virtual/block/dm-1 (block)
UDEV [3915.603960] change /devices/virtual/block/dm-0 (block)
UDEV [3915.611925] change /devices/virtual/block/dm-1 (block)
KERNEL[3915.625968] change /devices/pci0000:00/0000:00:1c.0/0000:03:00.0/host2/port-2:1/end_device-2:1/target2:0:1/2:0:1:0/block/sdb (block)
UDEV [3915.672978] change /devices/pci0000:00/0000:00:1c.0/0000:03:00.0/host2/port-2:1/end_device-2:1/target2:0:1/2:0:1:0/block/sdb (block)
# Failed snapshot delete
KERNEL[3937.161806] change /devices/virtual/block/dm-3 (block)
KERNEL[3937.161839] change /devices/virtual/block/dm-2 (block)
KERNEL[3937.161929] change /devices/virtual/block/dm-1 (block)
KERNEL[3937.162154] remove /devices/virtual/block/dm-3 (block)
KERNEL[3937.162305] remove /devices/virtual/bdi/252:3 (bdi)
KERNEL[3937.162375] remove /devices/virtual/block/dm-3 (block)
UDEV [3937.162842] remove /devices/virtual/bdi/252:3 (bdi)
UDEV [3937.169283] change /devices/virtual/block/dm-3 (block)
UDEV [3937.172103] remove /devices/virtual/block/dm-3 (block)
UDEV [3937.172217] remove /devices/virtual/block/dm-3 (block)
KERNEL[3937.176945] change /devices/virtual/block/dm-0 (block)
KERNEL[3937.177255] change /devices/pci0000:00/0000:00:1c.0/0000:03:00.0/host2/port-2:1/end_device-2:1/target2:0:1/2:0:1:0/block/sdb (block)
UDEV [3937.220478] change /devices/virtual/block/dm-2 (block)
UDEV [3937.221039] change /devices/virtual/block/dm-1 (block)
UDEV [3937.222593] change /devices/virtual/block/dm-0 (block)
UDEV [3937.297968] change /devices/pci0000:00/0000:00:1c.0/0000:03:00.0/host2/port-2:1/end_device-2:1/target2:0:1/2:0:1:0/block/sdb (block)
# Successful snapshot delete
KERNEL[3953.366547] remove /devices/virtual/block/dm-1 (block)
KERNEL[3953.366713] remove /devices/virtual/bdi/252:1 (bdi)
KERNEL[3953.366805] remove /devices/virtual/block/dm-1 (block)
UDEV [3953.367431] remove /devices/virtual/bdi/252:1 (bdi)
UDEV [3953.369726] remove /devices/virtual/block/dm-1 (block)
UDEV [3953.369849] remove /devices/virtual/block/dm-1 (block)
KERNEL[3953.439220] change /devices/pci0000:00/0000:00:1c.0/0000:03:00.0/host2/port-2:1/end_device-2:1/target2:0:1/2:0:1:0/block/sdb (block)
UDEV [3953.510027] change /devices/pci0000:00/0000:00:1c.0/0000:03:00.0/host2/port-2:1/end_device-2:1/target2:0:1/2:0:1:0/block/sdb (block)
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