How to mount ext3,ext4 sitting on VDI VirtualBox HDD?

Question

How to mount ext3, ext4 partition sitting on "Fixed-Size VDI" VirtualBox HardDisk ?

To be more specific, I ma interested in case when VM is not running.

Answer 1

The package virtualbox-fuse installs the vdfuse command which can be used to mount either dynamic or fixed VDI files.

apt-get install virtualbox-fuse
mkdir /mnt/point
mkdir /mnt/p1
vdfuse -f file.vdi /mnt/point
mount /mnt/point/Partition1 /mnt/p1

Answer 2

I've found very helpful answer on:

https://wiki.archlinux.org/index.php/VirtualBox#Mounting_.vdi_Images

The tip is to use offset option of ext4 mount (to be more specific, in back scenes it uses offset as option for loopback device losetup)

It's about

• taking offData info from VDI image
• adding magic number 32256
• and using result as offset

Here is my way of automating it:

VDIfile=VirtData.vdi
mountingpoint=/mnt/VDI
offData=$( VBoxManage internalcommands dumphdinfo "$VDIfile" |grep offData | sed 's:.*offData=\([0-9]*\).*:\1:' )
offset=$(( $offData + 32256 ))
mount -t ext4 -o rw,noatime,noexec,loop,offset="$offset" "$VDIfile" "$mountingpoint"

For /etc/fstab you might like to add: (123456789 is counted previously offset)

/path/VirtData.vdi      /mnt/VDI        ext4 rw,noatime,noexec,loop,offset=123456789,user,noauto

Of course rw can be changed to ro or you might not need noatime or noexec - taylor them to your needs

Btw. if your path contains spaces there is a trick of changing spaces into \040 (source: https://wiki.archlinux.org/index.php/Fstab )