How can I mount a partition from dd-created image of a block device (e.g. HDD) under Linux?

I have an image of the entire disk created using dd. The disk structure follows:

kent@cow:~$ sudo fdisk -l

Disk /dev/sda: 750.1 GB, 750156374016 bytes
255 heads, 63 sectors/track, 91201 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000b8508

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           5       90872   729929303+  83  Linux
/dev/sda2           90873       91201     2642692+   5  Extended
/dev/sda5           90873       91201     2642661   82  Linux swap / Solaris

The image was created using:

dd if=/dev/sda of=image750.img

How would I, if it is possible, mount /dev/sda1 from the image so that I'm able to read the contents?

It's not an option to clone the HDD again, I know how to do it if I had only cloned the single partition by itself. I hope it's still possible with the current image.

Solution 1:

Nowadays, there is a better way, no need to use offsets or kpartx anymore:

losetup --partscan --find --show disk.img

mount /dev/loop0p1 /mnt

to free up loop0, use after umount:

losetup -d /dev/loop0

Solution 2:

I ran into this problem today and wanted to update the answers just as a reminder for myself. Instead of calculating the offset on your own, you can use a tool that provides you with mountable devices from a dd image: kpartx

http://robert.penz.name/73/kpartx-a-tool-for-mounting-partitions-within-an-image-file/

http://linux.die.net/man/8/kpartx

In the given case, it would need something like

sudo kpartx -a image750.img
sudo mount /dev/mapper/loop1p1 /mount/point -o loop,ro

where loop1p1 stands for the first partition, loop1p2 for the second, etc.

Solution 3:

You've got the first part: fdisk -l to find the start offset. Take that number, multiply by 512, and you'll get the offset option to mount. So, for sda1 in your case, 5 * 512 = 2560. Then run the mount:

mount -o loop,offset=2560 -t auto /path/to/image.dd /mount/point