Mount docker logical volume

Question

I'm trying to access to a logical volume where previously was used by docker. This is the result of various command:

lsblk

NAME                          MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
nvme0n1                       259:2    0  80G  0 disk
├─nvme0n1p1                   259:3    0  80G  0 part /
└─nvme0n1p128                 259:4    0   1M  0 part
nvme1n1                       259:0    0  80G  0 disk
└─nvme1n1p1                   259:1    0  80G  0 part
  ├─docker-docker--pool_tdata 253:1    0  79G  0 lvm
  │ └─docker-docker--pool     253:2    0  79G  0 lvm
  └─docker-docker--pool_tmeta 253:0    0  84M  0 lvm
    └─docker-docker--pool     253:2    0  79G  0 lvm

fdisk

Disk /dev/nvme1n1: 85.9 GB, 85899345920 bytes, 167772160 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x00029c01

        Device Boot      Start         End      Blocks   Id  System
/dev/nvme1n1p1            2048   167772159    83885056   8e  Linux LVM
WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion.

Disk /dev/nvme0n1: 85.9 GB, 85899345920 bytes, 167772160 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: gpt
Disk identifier: 358A5F86-3BCA-4FB2-8C00-722B915A71AB


#         Start          End    Size  Type            Name
 1         4096    167772126     80G  Linux filesyste Linux
128         2048         4095      1M  BIOS boot       BIOS Boot Partition

lvdisplay

  --- Logical volume ---
  LV Name                docker-pool
  VG Name                docker
  LV UUID                piD2Wx-aDjf-CkpN-b4s4-YXWE-6ERm-GWTcOz
  LV Write Access        read/write
  LV Creation host, time ip-172-31-39-159, 2020-02-16 09:18:57 +0000
  LV Pool metadata       docker-pool_tmeta
  LV Pool data           docker-pool_tdata
  LV Status              available
  # open                 0
  LV Size                79.03 GiB
  Allocated pool data    80.07%
  Allocated metadata     31.58%
  Current LE             20232
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:2

But when I try to mount the volume docker-docker--pool_tdata I get the following error:

mount  /dev/mapper/docker-docker--pool_tdata /mnt/test
mount: /dev/mapper/docker-docker--pool_tdata is already mounted or /mnt/test busy

I've also tried to reboot the machine, to uninstall docker and to see if there is file opened on that volume using lsof

Do you have any clue about how can I mount that volume? Thanks

That looks like an LVM devicemapper tree from an old version of Docker. Even if you could mount the volume, the image and container contents there won't be stored in a way that's easy to extract. — David Maze, Feb 21 '20 at 14:37
The purpose of this was just try to understand why `docker info` and `docker system df` show different space used. several question have been asked, but with no answer so far. https://forums.docker.com/t/docker-system-df-doesnt-add-up-to-docker-info-data-space/60238 https://forums.docker.com/t/questions-about-the-docker-storage-usage/60269 — mirobertod, Feb 21 '20 at 15:35
Did you try mounting it to another directory? The output suggests that `/mnt/test` might be busy. — SebDieBln, Dec 21 '21 at 22:12

score 1 · Answer 1 · answered Dec 22 '21 at 05:45

Uninstalling docker does not really help as purge and autoremove only delete the installed packages and not the images, containers, volumes and config files.

To delete those you have to delete a bunch of directories contained in etc, var/lib, bin andvar/run

Clean up the env

try running docker system prune -a to remove unused containers, images etc remove the volume with docker volume rm {volumeID} create the volume again docker volume create docker-docker--pool_tdata

Kill the process

run lsof +D /mnt/test or cat ../docker/../tasks this should display the PIDs of alive tasks.

Kill the task with kill -9 {PID}

Mount docker logical volume

1 Answers1