I read somewhere that it's a good idea to use Carbon Copy Cloner (CCC) together with Time Machine, but I've been unable to figure out how to do this. Other posts related to the subject discuss using one Time Machine backup drive and another drive having CCC used to back up, but that's impractical for me. It would be great to have a bootable external Time Machine backup drive. Is this possible, and if yes -how do I proceed? (Note: I already have lots of time machine backups on my external drive -will this data be deleted so Time Machine starts from scratch, or will it still be there?).