Pazu

Hi all, I'm looking at using DrivePool to replace my mirrored software raid setup, I'm looking for only protection from one a single drive failure. So I'm assuming X2 duplication will be fine, what I can't find though is the penalty hit when using duplication, IE, I have 4 x 2TB disks, is it a 50% hit or 33% hit (Raid5 style) if I enable duplication (will I get 4tb or 6tb of usable disk space). I also have a 5th 2TB external drive I may look at adding into the pool as well. Cheers, Matt