I've never done it but it's quite common to clone drives using DD. Again, I've never done this, so you should research it if your considering it.
AFAIK all you should have to do is
dd if=/dev/hda of=/dev/hdb
. Where /dev/hda is the drive you need to clone and /dev/hdb is the drive your backing up to. DD will do a bit to bit copy of the orignal drive to the new drive.