http://askubuntu.com/questions/19901/how-to-make-a-disk-image-and-restore-from-it-later
The “dump” and “restore” backup utilities in the Ubuntu repositories provide you with the ability to backup and recover an entire system's “system state”.
The “dump” and “restore” utilities can be installed from the repositories using:
sudo apt-get install dump
Below are links to the Man pages: ⠀Dump ⠀Restore
In your case, you could backup the system to a portable drive:
dump -0uan -f my_file /
For recovery you would need to:
restore -r -f my_file /my_mount).Note: If you are restoring to a new disk you will need to install your bootloader (GRUB).