Full disk image: creating and opening in Linux

September 10, 2021

In this guide I will explain how do a full disk image and successively mount it.

Create disk image with `dd`

First of all, you have to identify the path of your source disk. You can accomplish this step executing with administrator permissions fdisk -l command.

sudo fdisk -l
...
Disk /dev/sdb: 238,49 GiB, 256060514304 bytes, 500118192 sectors
Disk model: SanDisk SD8SBAT2
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x16742145

Device     Boot     Start       End   Sectors   Size Id Type
/dev/sdb1  *         2048   1187839   1185792   579M  7 HPFS/NTFS/exFAT
/dev/sdb2         1187840 365901823 364713984 173,9G  7 HPFS/NTFS/exFAT
/dev/sdb3       365901824 449787903  83886080    40G 83 Linux
/dev/sdb4       449787904 500117503  50329600    24G 82 Linux swap / Solaris


Disk /dev/sdc: 931,53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: CT1000MX500SSD1 
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 59A18AC5-7D15-AC4B-A37A-E1940988757C

Device     Start        End    Sectors   Size Type
/dev/sdc1   2048 1953519615 1953517568 931,5G Microsoft basic data
...

In this example I chose /dev/sdb.

For the image creation you have to use

sudo dd if=/dev/sdb of=/path_of_image/ssd240gb.img conv=noerror

and you wait end.

Image mounting with `kpartx` software

For the image mount is necessary create a device for every partition, for this you need to use the kpartx software. Usually this software isn’t included in the linux distributions. To install you have to use the package manager, with command

sudo apt/yum/dnf install kpartx

After installation, you have to execute in this way

sudo kpartx -a -v /path_of_image/ssd240gb.img
add map loop6p1 (253:0): 0 1185792 linear 7:6 2048
add map loop6p2 (253:1): 0 364713984 linear 7:6 1187840
add map loop6p3 (253:2): 0 83886080 linear 7:6 365901824
add map loop6p4 (253:3): 0 50329600 linear 7:6 449787904

How you can see in the output, the sofware have created 4 devices loop*p* in path /dev/mapper/. This can mounted as any partition, that is

sudo mount /dev/mapper/loop6p2 /mnt/part1

After ended the work, you have to umount the partition

umount /mnt/part1

and eliminate these devices

kpartx -d -v /path_of_image/ssd240gb.img