That is a good point about stress testing them, if memory serves me well I believe one of the 12TB would disconnect a while back maybe 2 or so years ago when I was using windows and doing large backups. I think the consensus around seems to just mirror the 6TB and mirror the 12TB drives separate, it's probably what I will end up doing since in the end I am tripling the amount of storage and really allowing me to lose two drives albeit two different drives before data loss. Feel I may be getting a bit greedy with what I have and should just be happy with what I am getting with that. Looking at getting an upgrade in about a year or two either way.