Size of USB Hard Drive

I have 2 3TB external drives 3.0 (Seagate & Toshiba) both work great. I also used the 3TB WD 2.0 and worked great until my wife knocked it over on to the floor while she was cleaning and while it was playing, must have messed up the read arm, all it does now is make clicking noises and will not read on either the SMP or PC. Oh well, Glad I back them up on two other 3TB drives I have in my office, just for this such an emergency. I can’t imagine losing all my shows, music and pictures. Sometimes I think about, God forbid, the house burn down. I would lose them all. Maybe I should get two more and back everything up again and store in my safe deposit box at the bank!