Hi, I'm fairly Mac literate (15+ years using), and have searched high and low online to try and find an answer, but have had no luck - hoping someone here can help me out. Here's my setup: Mac Mini (late 2012, running 10.8.4, 1TB) External "Wayne" (3TB - used for videos, photos, and anything I don't use day-to-day on my internal drive) External "Garth" (4TB - Time Machine) All are formatted to Mac OS Extended (Journaled) So, I've been running Garth as my Time Machine backup for just over a month now, and have had no problems with backing up my internal drive. However, the idea behind getting a 4TB drive was so I could backup the 1TB internal, and the 3TB external (neither will ever be full-full, so there'll always be 'working room' for Time Machine to do its thing - I've never seen the 'space limit' warning that other people talk about). I have removed "Wayne" from the Excluded Items list in TM System Prefs, so that isn't the problem. No amount of toggling TM options, rebooting, reformatting...seems to work. Any suggestions so I can backup both hard drives onto one disk? Thanks!