Sometimes we need to mount a partition stored in a dumped hard drive
image. This howto will learn you how to cope with this sort of
problems. You will also learn how to make such partition visible to the
whole system resources.



MOUNTING HARD DRIVE IMAGE PARTITION

Prerequisities: fdisk, bc, mount, umount

Howto:

1. use fdisk to get the start of a partition in sectors
2. multiply the start position by sector size to get the right offset
3. mount the partition at obtained offset

fdisk -lu /tmp/hd.img

Disk /tmp/hd.img: 40.0 GB, 40007761920 bytes
255 heads, 63 sectors/track, 4864 cylinders, total 78140160 sectors
Units = sectors of 1 * 512 = 512 bytes

   Device    Boot      Start         End      Blocks   Id  System
/tmp/hd.img1   *          63      192779       96358+  83  Linux
/tmp/hd.img2          192780    19727819     9767520   83  Linux
/tmp/hd.img3        19727820    74413079    27342630   83  Linux
/tmp/hd.img4        74413080    78140159     1863540   82  Linux swap / Solaris

Interested in the columns titled "Start" pick up the number where the
partition you need to mount starts and multiply it by sector size which
information can be found in the line starting "Units". For the third
partition it will be:

echo '19727829 * 512' | bc
10100648448

Now, mount the partition somewhere.

mount -o rw,loop,offset=10100648448 /tmp/hd.img /mnt

If everything went OK you have now /tmp/hd.img3 mounted on /mnt
directory. Do not forget to umount it after you finish your work with
it.

umount /mnt



WORKING WITH HARD DRIVE IMAGE PARTITION ITSELF

Prerequisities: fdisk, bc, losetup

Howto:

1. use fdisk to get the start of a partition in sectors
2. multiply the start position by sector size to get the right offset
3. setup loop device

fdisk -lu /tmp/hd.img

Disk /tmp/hd.img: 40.0 GB, 40007761920 bytes
255 heads, 63 sectors/track, 4864 cylinders, total 78140160 sectors
Units = sectors of 1 * 512 = 512 bytes

   Device    Boot      Start         End      Blocks   Id  System
/tmp/hd.img1   *          63      192779       96358+  83  Linux
/tmp/hd.img2          192780    19727819     9767520   83  Linux
/tmp/hd.img3        19727820    74413079    27342630   83  Linux
/tmp/hd.img4        74413080    78140159     1863540   82  Linux swap / Solaris

We picked up second partition for this example:

echo '192780 * 512' | bc
98703360

Get next unused loop device:

losetup -f
/dev/loop0

Setup the loop device:

losetup -o 98703360 /dev/loop0 /tmp/hd.img

You can now work with the loop device in a way as if it were regular
hard drive partition.



Check: http://vger.cz/hacks/awk/mountraw.awk