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Created March 23, 2019 00:51
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How to mount encrypted drive with same volume group name

Background/Setup

  • I have two physical 1TB disks with identical setup.
  • Both are encrypted.
  • I unlocked and booted off one of them.
  • The other disk is still locked at this point.
  • I am using fish shell.

1. Identify which disk you want to unlock

root@computer ~# lsblk -f
sda                                                                                                    
├─sda1                                        vfat              7F3B-9703                              /boot/efi
├─sda2                                        ext2              b6220db2-916c-4322-b64b-c86769f6b18b   /boot
└─sda3                                        crypto_LUKS       3a07b8a9-3e75-41a9-88d4-3be937181613   
  └─luks-3a07b8a9-3e75-41a9-88d4-3be937181613 LVM2_member       uCvHaW-RlQc-PT2d-cBg2-SWyY-WS0A-ZCEvA6 
    ├─ubuntu--vg-root                         ext4              a78662e2-d582-4faa-88b6-b6db5e23aed2   /
    └─ubuntu--vg-swap_1                       swap              5c4ba6cc-4735-4417-9e87-74a76a7fc415   [SWAP]
sdb                                                                                                    
├─sdb1                                        vfat              1EC8-1F58                              
├─sdb2                                        ext2              7108fe1d-dc37-4213-a3bc-8070a8f84f31   /media/jsun/7108fe1d-dc37-4213-a3bc-8070a8f84f31
└─sdb3                                        crypto_LUKS       fc560468-588c-4455-af2c-295998c41c88   

We see that sdb3 is the unmounted target.

2. Unlock the partition

root@computer ~# udisksctl unlock -b /dev/sdb3
Passphrase: 
Unlocked /dev/sdb3 as /dev/dm-3.

See which one is the new unlocked

root@computer ~# ls -la /dev/mapper/ | grep dm-3
lrwxrwxrwx  1 root root       7 Mar 22 17:32 luks-fc560468-588c-4455-af2c-295998c41c88 -> ../dm-3

luks-fc560468-588c-4455-af2c-295998c41c88 is our target. Let's remember that with a variable.

set target luks-fc560468-588c-4455-af2c-295998c41c88

3.

The VG Name of both drives is the same; this is problematic and will prevent you from being able to mount the drives both at the same time.

root@computer ~# pvdisplay
  --- Physical volume ---
  PV Name               /dev/mapper/luks-3a07b8a9-3e75-41a9-88d4-3be937181613
  VG Name               ubuntu-vg
  PV Size               930.53 GiB / not usable 2.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              238216
  Free PE               0
  Allocated PE          238216
  PV UUID               uCvHaW-RlQc-PT2d-cBg2-SWyY-WS0A-ZCEvA6
   
  --- Physical volume ---
  PV Name               /dev/mapper/luks-fc560468-588c-4455-af2c-295998c41c88
  VG Name               ubuntu-vg
  PV Size               930.53 GiB / not usable 2.00 MiB
  Allocatable           yes (but full)
  PE Size               4.00 MiB
  Total PE              238216
  Free PE               0
  Allocated PE          238216
  PV UUID               lbvecI-E6w6-fpuj-P61G-5NCb-obOK-ooivpe

Get the uuid of the volume

root@computer ~# pvs -o +vg_uuid
  PV                                                    VG        Fmt  Attr PSize   PFree VG UUID                               
  /dev/mapper/luks-3a07b8a9-3e75-41a9-88d4-3be937181613 ubuntu-vg lvm2 a--  930.53g    0  TAva2M-zNnV-Wh5h-3YcY-Vc5U-W4se-TI27Du
  /dev/mapper/luks-fc560468-588c-4455-af2c-295998c41c88 ubuntu-vg lvm2 a--  930.53g    0  TJgeFw-xDcf-TaJ2-07dL-RlUQ-yCsb-zGGp4v

root@computer ~# pvs -o +vg_uuid | grep $target
  /dev/mapper/luks-fc560468-588c-4455-af2c-295998c41c88 ubuntu-vg lvm2 a--  930.53g    0  TJgeFw-xDcf-TaJ2-07dL-RlUQ-yCsb-zGGp4v

The device UUID is TJgeFw-xDcf-TaJ2-07dL-RlUQ-yCsb-zGGp4v. Let's remember that with a variable.

set uuid TJgeFw-xDcf-TaJ2-07dL-RlUQ-yCsb-zGGp4v

Change the volume group

I'm going to generate a UUID, but you can name whatever you want.

root@computer ~# uuidgen
1ec80451-b05b-4d59-94c1-f1ad70b24255
root@computer ~# vgrename $uuid 1ec80451-b05b-4d59-94c1-f1ad70b24255
  Processing VG ubuntu-vg because of matching UUID TJgeFw-xDcf-TaJ2-07dL-RlUQ-yCsb-zGGp4v
  Volume group "TJgeFw-xDcf-TaJ2-07dL-RlUQ-yCsb-zGGp4v" successfully renamed to "1ec80451-b05b-4d59-94c1-f1ad70b24255"
root@computer ~# pvs -o +vg_uuid
  PV                                                    VG                                   Fmt  Attr PSize   PFree VG UUID                               
  /dev/mapper/luks-3a07b8a9-3e75-41a9-88d4-3be937181613 ubuntu-vg                            lvm2 a--  930.53g    0  TAva2M-zNnV-Wh5h-3YcY-Vc5U-W4se-TI27Du
  /dev/mapper/luks-fc560468-588c-4455-af2c-295998c41c88 1ec80451-b05b-4d59-94c1-f1ad70b24255 lvm2 a--  930.53g    0  TJgeFw-xDcf-TaJ2-07dL-RlUQ-yCsb-zGGp4v

Check/notice the new volume group name 1ec80451-b05b-4d59-94c1-f1ad70b24255.

Confirm the change

root@computer ~# vgchange -a y
  2 logical volume(s) in volume group "ubuntu-vg" now active
  2 logical volume(s) in volume group "1ec80451-b05b-4d59-94c1-f1ad70b24255" now active

Remember to rename your volume group back to ubuntu-vg if you want the volume to still be bootable.

Mount

root@computer ~# mkdir /media/badboy
root@computer ~# mount /dev/1ec80451-b05b-4d59-94c1-f1ad70b24255/root /media/badboy
root@computer ~# cd /media/badboy/
root@computer /m/badboy# ls
bin/   cdrom/  etc/   initrd.img@      lib/    lib64/       media/  opt/   root/  sbin/  srv/  tmp/  var/
boot/  dev/    home/  initrd.img.old@  lib32/  lost+found/  mnt/    proc/  run/   snap/  sys/  usr/  vmlinuz@

You can now access your data.

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