To mount a VDH (Virtual Hard Disk) file in linux (e.g. ubuntu):

sudo apt-get install virtualbox-fuse
sudo mkdir /mnt/vhd-mountpoint/
sudo vdfuse -f disk.vhd /mnt/vhd-mountpoint/
mkdir /mnt/vhd-mountpoint
sudo mount -o loop  /mnt/vhd-mountpoint/Part1 /mnt/part1

VDH is mostly used within Windows 7 and newer.