"You can always delete and trash extraneous data, but you can???t recreate it if it doesn???t exist.The WhereBacking up data using a Mac???or any other computer system???requires access to the source computer (with the data you want to preserve); a target site (a drive, tape, CD, DVD, or other medium to hold the transferred data); a software program that will create what you want (a bootable clone," . . . . .