Ubuntu
lvm2 package

  1. Bug #1657646
  2. Comment #5

Comment 5 for bug 1657646

Revision history for this message
Christian Ehrhardt  (paelzer) wrote : Re: VG/LV are not available in /dev/mapper/ after reboot

I tried to recreate.
Note: as it was reported on power + Xenial this test was done on ppc64el Xenial as of today

To do so with as much debugging as possible I created a normal Xenial KVM Guest via
$ uvt-kvm create --cpu 4 --password=ubuntu paelzer-testlvm-xenial release=xenial
Then I added a few more disks to be used as PVs
$ sudo qemu-img create -f qcow2 test-lvm-disk1.qcow2 8
And added those to the Guest.

The guest then initially looks like:
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
vda 253:0 0 8G 0 disk
vdb 253:16 0 8G 0 disk
vdc 253:32 0 8G 0 disk
vdd 253:48 0 366K 0 disk
vde 253:64 0 8G 0 disk
|-vde1 253:65 0 8G 0 part /
 `-vde2 253:66 0 8M 0 part

Then the usual flow is
1. fdisk, create partition set LVM partition type (8e)
$ sudo fdisk /dev/vd[abc]
2. Full PVs on all the three disks
$ sudo pvcreate /dev/vd[abc]
3. vgcreate a single VG out of all of the PVs
$ sudo vgcreate vg /dev/vda1 /dev/vdb1 /dev/vdc1

At this point it looks like this:
$ sudo vgdisplay vg
  --- Volume group ---
  VG Name vg
  System ID
  Format lvm2
  Metadata Areas 3
  Metadata Sequence No 1
  VG Access read/write
  VG Status resizable
  MAX LV 0
  Cur LV 0
  Open LV 0
  Max PV 0
  Cur PV 3
  Act PV 3
  VG Size 23.99 GiB
  PE Size 4.00 MiB
  Total PE 6141
  Alloc PE / Size 0 / 0
  Free PE / Size 6141 / 23.99 GiB
  VG UUID 1QMFbn-5DAW-T9IE-Fdfd-9RZK-t8gl-5nte5r

Ok, create normal as well as thin LVs out of that now.
First of all thin provisioning is not mainstream, the dependency is only a suggest, so install the tools
$ sudo apt-get install thin-provisioning-tools
Then create the normal LV
$ sudo lvcreate -L 5G --name lv_normal vg
And finally a thin LV
$ sudo lvcreate --size 10G --virtualsize 5G --thinpool mythinpool --name lv_thin vg
Lets go harder and overprovision the thinpool
$ sudo lvcreate --virtualsize 5G --thinpool mythinpool --name lv_thin2 vg
$ sudo lvcreate --virtualsize 5G --thinpool mythinpool --name lv_thin3 vg

With that in place my LVs look like:
$ sudo lvdisplay
  --- Logical volume ---
  LV Path /dev/vg/lv_normal
  LV Name lv_normal
  VG Name vg
  LV UUID aCtNC0-gbx1-uHoB-3dC8-dfhl-NBxd-Axm879
  LV Write Access read/write
  LV Creation host, time paelzer-testlvm-xenial, 2017-01-25 12:54:02 +0000
  LV Status available
  # open 0
  LV Size 5.00 GiB
  Current LE 1280
  Segments 1
  Allocation inherit
  Read ahead sectors auto
  - currently set to 256
  Block device 252:0

  --- Logical volume ---
  LV Name mythinpool
  VG Name vg
  LV UUID UCKy8A-ovc6-Qh9n-wrEM-c2s2-myvD-hpLhb0
  LV Write Access read/write
  LV Creation host, time paelzer-testlvm-xenial, 2017-01-25 13:04:03 +0000
  LV Pool metadata mythinpool_tmeta
  LV Pool data mythinpool_tdata
  LV Status available
  # open 4
  LV Size 10.00 GiB
  Allocated pool data 0.00%
  Allocated metadata 0.72%
  Current LE 2560
  Segments 1
  Allocation inherit
  Read ahead sectors auto
  - currently set to 256
  Block device 252:3

  --- Logical volume ---
  LV Path /dev/vg/lv_thin
  LV Name lv_thin
  VG Name vg
  LV UUID ay7Clp-78K7-8UoZ-ueZZ-WYTy-IQlF-oQkjdT
  LV Write Access read/write
  LV Creation host, time paelzer-testlvm-xenial, 2017-01-25 13:04:03 +0000
  LV Pool name mythinpool
  LV Status available
  # open 0
  LV Size 5.00 GiB
  Mapped size 0.00%
  Current LE 1280
  Segments 1
  Allocation inherit
  Read ahead sectors auto
  - currently set to 256
  Block device 252:5

  --- Logical volume ---
  LV Path /dev/vg/lv_thin2
  LV Name lv_thin2
  VG Name vg
  LV UUID Zj5BfS-Cbm1-9TgI-gwk3-vdBG-wwH9-cSmC0B
  LV Write Access read/write
  LV Creation host, time paelzer-testlvm-xenial, 2017-01-25 13:05:11 +0000
  LV Pool name mythinpool
  LV Status available
  # open 0
  LV Size 5.00 GiB
  Mapped size 0.00%
  Current LE 1280
  Segments 1
  Allocation inherit
  Read ahead sectors auto
  - currently set to 256
  Block device 252:6

  --- Logical volume ---
  LV Path /dev/vg/lv_thin3
  LV Name lv_thin3
  VG Name vg
  LV UUID bSPGZH-Thwx-M8qx-QDS2-gIUz-50us-hGCRGu
  LV Write Access read/write
  LV Creation host, time paelzer-testlvm-xenial, 2017-01-25 13:05:16 +0000
  LV Pool name mythinpool
  LV Status available
  # open 0
  LV Size 5.00 GiB
  Mapped size 0.00%
  Current LE 1280
  Segments 1
  Allocation inherit
  Read ahead sectors auto
  - currently set to 256
  Block device 252:7

$ ll /dev/mapper/
total 0
drwxr-xr-x 2 root root 220 Jan 25 13:05 ./
drwxr-xr-x 16 root root 4240 Jan 25 13:05 ../
crw------- 1 root root 10, 236 Jan 25 12:20 control
lrwxrwxrwx 1 root root 7 Jan 25 12:54 vg-lv_normal -> ../dm-0
lrwxrwxrwx 1 root root 7 Jan 25 13:04 vg-lv_thin -> ../dm-5
lrwxrwxrwx 1 root root 7 Jan 25 13:05 vg-lv_thin2 -> ../dm-6
lrwxrwxrwx 1 root root 7 Jan 25 13:05 vg-lv_thin3 -> ../dm-7
lrwxrwxrwx 1 root root 7 Jan 25 13:04 vg-mythinpool -> ../dm-4
lrwxrwxrwx 1 root root 7 Jan 25 13:04 vg-mythinpool-tpool -> ../dm-3
lrwxrwxrwx 1 root root 7 Jan 25 13:04 vg-mythinpool_tdata -> ../dm-2
lrwxrwxrwx 1 root root 7 Jan 25 13:04 vg-mythinpool_tmeta -> ../dm-1

Now lets put it to use
for dev in lv_normal lv_thin lv_thin2 lv_thin3;
do
  sudo mkfs.ext4 /dev/mapper/vg-${dev}
  sudo mkdir -p /mnt/${dev}
  sudo mount /dev/mapper/vg-${dev} /mnt/${dev}
  sudo touch /mnt/${dev}/foobar
done

Things are properly mounted
$ mount | grep lv
/dev/mapper/vg-lv_normal on /mnt/lv_normal type ext4 (rw,relatime,data=ordered)
/dev/mapper/vg-lv_thin on /mnt/lv_thin type ext4 (rw,relatime,stripe=16,data=ordered)
/dev/mapper/vg-lv_thin2 on /mnt/lv_thin2 type ext4 (rw,relatime,stripe=16,data=ordered)
/dev/mapper/vg-lv_thin3 on /mnt/lv_thin3 type ext4 (rw,relatime,stripe=16,data=ordered)

All files written normally
$ ls -laF /mnt/*/foobar
-rw-r--r-- 1 root root 0 Jan 25 13:10 /mnt/lv_normal/foobar
-rw-r--r-- 1 root root 0 Jan 25 13:10 /mnt/lv_thin/foobar
-rw-r--r-- 1 root root 0 Jan 25 13:10 /mnt/lv_thin2/foobar
-rw-r--r-- 1 root root 0 Jan 25 13:10 /mnt/lv_thin3/foobar

lsblk holds the thin LVs as it should
$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
vda 253:0 0 8G 0 disk
`-vda1 253:1 0 8G 0 part
  |-vg-lv_normal 252:0 0 5G 0 lvm /mnt/lv_normal
  |-vg-mythinpool_tmeta 252:1 0 12M 0 lvm
  | `-vg-mythinpool-tpool 252:3 0 10G 0 lvm
  | |-vg-mythinpool 252:4 0 10G 0 lvm
  | |-vg-lv_thin 252:5 0 5G 0 lvm /mnt/lv_thin
  | |-vg-lv_thin2 252:6 0 5G 0 lvm /mnt/lv_thin2
  | `-vg-lv_thin3 252:7 0 5G 0 lvm /mnt/lv_thin3
  `-vg-mythinpool_tdata 252:2 0 10G 0 lvm
    `-vg-mythinpool-tpool 252:3 0 10G 0 lvm
      |-vg-mythinpool 252:4 0 10G 0 lvm
      |-vg-lv_thin 252:5 0 5G 0 lvm /mnt/lv_thin
      |-vg-lv_thin2 252:6 0 5G 0 lvm /mnt/lv_thin2
      `-vg-lv_thin3 252:7 0 5G 0 lvm /mnt/lv_thin3
vdb 253:16 0 8G 0 disk
`-vdb1 253:17 0 8G 0 part
  `-vg-mythinpool_tdata 252:2 0 10G 0 lvm
    `-vg-mythinpool-tpool 252:3 0 10G 0 lvm
      |-vg-mythinpool 252:4 0 10G 0 lvm
      |-vg-lv_thin 252:5 0 5G 0 lvm /mnt/lv_thin
      |-vg-lv_thin2 252:6 0 5G 0 lvm /mnt/lv_thin2
      `-vg-lv_thin3 252:7 0 5G 0 lvm /mnt/lv_thin3
vdc 253:32 0 8G 0 disk
`-vdc1 253:33 0 8G 0 part
vdd 253:48 0 366K 0 disk
vde 253:64 0 8G 0 disk
|-vde1 253:65 0 8G 0 part /
 `-vde2 253:66 0 8M 0 part

Now rebooting to test the reported issue.
But after reboot all looks sane, lsblk, lvdisplay, dev/mapper they all are as expected.

Of course things are not mounted, but I didn't create any fstab entries, so
for dev in lv_normal lv_thin lv_thin2 lv_thin3; do sudo mount /dev/mapper/vg-${dev} /mnt/${dev}; done

All mount just fine and the file is still there.

You reported "I was able to replicate the issue. I created VG and LV and rebooted the system. Found that devicemapper entries for corresponding devices are missing after reboot. However, LVM commands like 'vgdisplay' and 'lvdisplay' show proper info, but 'lsblk' doesn't show the device's LVM related info after reboot."
Could you either
1. report your exact steps on a fresh system to cause this
or
2. modify the steps I reported until the issue shows up