Originally Posted by jefro
I agree that dd to identical drives may be a very good way. Kind of a dangerous task when backing up anything. dd is a very unforgiving command as well as most backup or clone tools. There is no substitute to being careful with any app or command on this task.
The advice I recommend to anyone running dd on a system which uses sudo is to type the command and after checking it go back and put sudo in front of it.
Personally I love this command and shun using any specialty program where the functionality is available in dd. However as always , "with great power, comes great responsibility." dd can do nearly anything, including destroy your system.