Background Back when I got my GL-AR150 mini router, I was blown away by the powerful capabilities of this $25 OpenWRT router,...
Create full disk image of a hard drive or other block deviceStanislav Khromov
dd bs=1MB if=/dev/sda of=sda.img
Where if is your input device and of is your output file.
Note bs sets how much to read at once, in our case 1MiB. It doesn’t affect the image integrity in any way. Larger values use more memory but can potentially run faster.