Synology Nas(12TB raid 1)
I have to say that I was really surprised that apparently there isn't a general solution for gluing together different-sized drives in an array reasonably-efficiently other than Synology's Hybrid RAID. I mean, you can build something that works similarly on a Linux machine, but there apparently isn't an out-of-the-box software package that does that. It seems like the kind of thing that'd be useful, but...shrugs