I have nearly 3Tb spread over 4 HDD's. Now I'm looking for a way to back all this up in one 3Tb HDD (or 2 1.5Tb?). What is the best way to proceed with this? Buy a bare internal 3Tb HDD? External WD/Seagate one? I really hate doing fresh OS installs unless I get brand new built, so if I main drive were to fail, I would want to unplug it, plug the back up one, good to go.