I'm trying to better manage my growing library and ensure consistent back up. I have a LaCie 2big 6TB (3TBx2) in a RAID 1 configuration. My 3TB is at 2TB full so I'd like to start upgrading. Does it matter which drive bay I upgrade since they're theoretically supposed to be identical in a RAID 1 configuration? Can I add a 6TB drive to just one of the bays and once I exceed the 3TB, add another 6TB drive to the second bay? I'm also thinking of getting a third drive so I can keep one off site and rotate them every month or so. Will that work with RAID 1 and this particular LaCie set up?