KVM mount guest disk on host

Howto mount a guest LVM disk on host

Note: guest is called bup in the example

Setup¶

1. Snapshot the guests running LVM volume (guests virtual disk)

   $ sudo lvcreate --size 100m --snapshot --name snap-bup /dev/vg_raid1/bup
   Logical volume "snap-bup" created
   

2. Setup a loop device for the virtual disk snapshot

   $ sudo losetup -f /dev/vg_raid1/snap-bup
   /dev/loop0: [0005]:49084 (/dev/mapper/vg_raid1-snap--bup)
   

3. Create device maps from the loop back device

   $ sudo kpartx -av /dev/loop0
   add map loop0p1 (251:16): 0 3817472 linear /dev/loop0 2048
   add map loop0p2 (251:17): 0 272386 linear /dev/loop0 3821566
   add map loop0p5 (251:18): 0 272384 251:17 2
   

4. mount

Now you can mount a partition the the snapshot of the guest disk, example mounting partition one.

    $ sudo mount /dev/mapper/loop0p1 /mnt/ -o ro

Clean-up¶

1. Un-mount all mounted partitions

   $ sudo umount /mnt
   ...
   

2. Delete partition mappings

   $ sudo kpartx -dv /dev/loop0
   del devmap : loop0p5
   del devmap : loop0p2
   del devmap : loop0p1
   

3. Detach loop device

   $ sudo losetup -d /dev/loop0
   

4. Remove LVM snapshot

   $ sudo lvremove /dev/vg_raid1/snap-bup
   Do you really want to remove active logical volume snap-bup? [y/n]: y
   Logical volume "snap-bup" successfully removed