I am thinking about taking the plunge and buying a Drobo. I have one question for all the owners out there. If I buy a 4 bay drobo and fill it with 4-1tb hard drives. Is the drobo going to mount as one 4tb hard drive? or can I make 2 hard drives mount as one and two hard drives mount as another drive. I want to get it for Time Machine but do not want 4 bays dedicated to time machine. Thanks