[Bug 1577206] Re: root on dm-cache : always do full resync after reboot

[Laczkó Richárd]

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

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

Status in lvm2 package in Ubuntu:
  New

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)

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