root on dm-cache : always do full resync after reboot

Bug #1577206 reported by Laurent Riffard on 2016-05-01
18
This bug affects 3 people
Affects Status Importance Assigned to Milestone
lvm2 (Ubuntu)
High
Unassigned

Bug Description

Hi,

I added an SSD drive and convert my LVs to cached LVs :

# pvs
  PV VG Fmt Attr PSize PFree
  /dev/sda6 vg_acer lvm2 a-- 90,00g 6,00g <= rotational drive
  /dev/sda7 lvm2 --- 9,46g 9,46g
  /dev/sdb vg_acer lvm2 a-- 29,50g 4,95g <= SSD drive

# lvs
  LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
  lv_docker vg_acer Cwi-aoC--- 7,00g [cache_docker] [lv_docker_corig] 100,00 6,35 0,00
  lv_home vg_acer Cwi-aoC--- 60,00g [cache_home] [lv_home_corig] 11,06 19,24 0,03
  lv_root vg_acer Cwi-aoC--- 14,00g [cache_root] [lv_root_corig] 100,00 9,73 0,00
  lv_swap vg_acer -wi-ao---- 3,00g

# mount | grep mapper
/dev/mapper/vg_acer-lv_root on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
/dev/mapper/vg_acer-lv_home on /home type ext4 (rw,relatime,data=ordered)
/dev/mapper/vg_acer-lv_docker on /var/lib/docker type ext4 (rw,relatime,data=ordered)

The problem is : after each boot, the system does a full resync of the lv_root LV :

# lvs -o+cache_dirty_blocks,cache_read_hits,cache_read_misses,cache_write_hits,cache_write_misses
  LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert CacheDirtyBlocks CacheReadHits CacheReadMisses CacheWriteHits CacheWriteMisses
  lv_docker vg_acer Cwi-aoC--- 7,00g [cache_docker] [lv_docker_corig] 100,00 6,35 0,19 78 605182 1144143 200214 516198
  lv_home vg_acer Cwi-aoC--- 60,00g [cache_home] [lv_home_corig] 11,05 19,24 0,12 34 334339 238365 656695 352970
  lv_root vg_acer Cwi-aoC--- 14,00g [cache_root] [lv_root_corig] 100,00 9,73 90,38 88844 32320 44223 1508 2924
  lv_swap vg_acer -wi-ao---- 3,00g

The problem only occurs on lv_root, which is the root filesystem. lv_home and lv_docker seem to be OK after boot.

I guess this might be related to this message I get on shutdown :
   Systemd-shutdown: Failed to finalize DM devices, ignoring.

# uname -r
4.4.0-21-generic
# lvm version
  LVM version: 2.02.133(2) (2015-10-30)
  Library version: 1.02.110 (2015-10-30)
  Driver version: 4.34.0
# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04 LTS
Release: 16.04
Codename: xenial

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: lvm2 2.02.133-1ubuntu10
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.20.1-0ubuntu2
Architecture: amd64
CurrentDesktop: GNOME-Flashback:Unity
Date: Sun May 1 19:19:54 2016
SourcePackage: lvm2
UpgradeStatus: Upgraded to xenial on 2016-04-24 (6 days ago)

Laczkó Richárd (lacric85) wrote :

I experience same after adding a new SATA drive and extending the VG ang LV.
I get the "Systemd-shutdown: Failed to finalize DM devices, ignoring." message after "shutdown -h now" or "shutdown -P now" command and right after a "click" sound from the computer case. I have to manually reset the computer. The computer reboots fine.

# pvs
  PV VG Fmt Attr PSize PFree
  /dev/sda1 datavg lvm2 a-- 298,09g 0
  /dev/sdb2 sysvg lvm2 a-- 18,62g 468,00m
  /dev/sdb5 datavg lvm2 a-- 55,42g 0
  /dev/sdc1 datavg lvm2 a-- 149,05g 0
  /dev/sdd1 datavg lvm2 a-- 37,27g 0

# lvs
  LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert
  lvdata datavg -wi-ao---- 539,82g
  lvroot sysvg -wi-ao---- 16,77g
  lvswap sysvg -wi-ao---- 1,39g

# mount | grep mapper
/dev/mapper/sysvg-lvroot on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
/dev/mapper/datavg-lvdata on /mnt/data type ext4 (rw,nosuid,nodev,noexec,relatime,data=ordered)

# uname -r
4.4.0-38-generic

# lvm version
  LVM version: 2.02.133(2) (2015-10-30)
  Library version: 1.02.110 (2015-10-30)
  Driver version: 4.34.0

# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.1 LTS
Release: 16.04
Codename: xenial

Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in lvm2 (Ubuntu):
status: New → Confirmed
Changed in lvm2 (Ubuntu):
importance: Undecided → High
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