RAID 1+0 vs. RAID 0+1: It’s not the same →
https://marco.org/2007/11/15/raid-1-0-vs-raid-0-1-its-not-the-same
I had no idea it mattered. RAID 1+0 (a mirrored set of 2-disk striped subsets) is far superior, and RAID 0+1 is far less tolerant of drive failures than I thought.
(Geek level: 96%)