Mounting a VM disk outside of Proxmox (in Debian)

[anderstn]

Hi

Firstly sorry if this is a question that has been asked before. I tried using the search feature on the forum and also Google just in case, but didn't find a question that was this specific.

My server went down and I had to replace the motherboard. Proxmox does not like some aspect of the new board and I really don't have time or money to buy another one right now so temporarily I would like to set up some of the VM's using other options that work with the hardware I have. However I need to grab some configuration files from these VM's. Hence I am wondering if I can mount these disks somehow in a Debian live environment and grab the files I need.

 

[fiona]

Hi,
that depends on the disk format and what filesystems are on the disk.

For raw with a filesystem, you can just directly mount it with mount /path/to/image /path/to/mount/point.

If there are partitions, you can install kpartx and do:

root@pve8a1 ~ # kpartx -av /path/to/image
add map loop0p1 (252:23): 0 2095104 linear 7:0 2048
root@pve8a1 ~ # mount /dev/mapper/loop0p1 /path/to/mount/point

After being done and unmounting, do

root@pve8a1 ~ # kpartx -dv /path/to/image
del devmap : loop0p1
loop deleted : /dev/loop0

to clean up.

For qcow2, you can do

modprobe nbd
qemu-nbd -c /dev/nbd0 /path/to/image.qcow2
mount /dev/nbd0 /path/to/mount/point
# or for partition number 1
mount /dev/nbd0p1 /path/to/mount/point

Use fdisk -l /dev/nbd0 to check what the partitions are. After you're done, use qemu-nbd -d /dev/nbd0 to clean up.

 

[anderstn]

That's a great summary thanks. Do I see which of these file systems is in use via "fdisk -l" or file extensions? Alternatively can I just try the various options without the commands themselves messing up anything if it's the wrong type?

 

[fiona]

That's a great summary thanks. Do I see which of these file systems is in use via "fdisk -l" or file extensions? Alternatively can I just try the various options without the commands themselves messing up anything if it's the wrong type?

To see information about filesystems, wipefs /path/to/partition/or/image is best (scary name I know, but doesn't remove anything without additional flags). Mount will also try to detect the filesystem type and simply fail if it can't do anything sensible.

EDIT: Another alternative is lsblk -f /path/to/device e.g. lsblk -f /dev/loop0 and lsblk -f /dev/nbd0 in the examples above.