Mounting a VirtualBox VDI disk on linux.txt

Mounting a VirtualBox VDI disk on linux

I just had an “Unsupported version 13 of data unit 'pgm' (instance #1, pass 0xffffffff) (VERR_SSM_UNSUPPORTED_DATA_UNIT_VERSION).” error on a Windows VirtualBox machine where I had some important python scripts.

I couldn't boot the machine at all, so in order to recover those files I had to search on how to mount a VDI disk file and here is the how-to:

First of all you will need the qemu-nbd binary, so look up how is packaged in your distro, in my case (openSUSE 11.4) it is within virt-utils, in (openSUSE 12.2) it is within qemu-tools.

After you installed the package, execute these commands as root:
Mounting

# Load the nbd kernel module
modprobe nbd max_part=16

# Link a block device named /dev/nbd0 to the vdi file
# Partitions will appear as /dev/nbd0p1 and so on
qemu-nbd -c /dev/nbd0 <vdi-file>

# Mount the first partition within /mnt/tmp
mount /dev/nbd0p1 /mnt/tmp

Now you can copy your files to the local filesystem
Un-mounting

# Unmount the partition
umount /mnt/tmp/

# Unlink the vdi file
qemu-nbd -d /dev/nbd0

# Remove the kernel module
rmmod nbd