If you use a Debian or Ubuntu derived distribution, you can take advantage of a great backup tool: remastersys. This tool is able to create a complete backup of your system or (and this is the very interesting thing!) live/installable dvd.
In the web site's tool you can get instructions to install this wonderful software. The use is very straightforward; for create a complete backup (system+data):
sudo remastersys backup full_system.iso
If you want create a live/installable dvd (system), just type at your shell prompt:
sudo remastersys dist core_system.iso
As you can see the program create an iso image: this file is good for burning a dvd, but can also be used with virtualization software (changing the virtual optical device with the iso image file).
Try it, you'll love it! Thank you Tony Brijeski, you've done a great software.
Good DVD burning!