Sorry if this has been asked before.  Dual parity just isn't enough with large arrays.  I've had to replace 2 disks a couple of times now, and having the extra peace of mind with that one extra disk would be amazing.   I know it's likely a big CPU overhead with the maths calculations, but if you could give people the choice, who have the hardware to do it, that would be amazing   Once you hit 14+ drives, the chance for an additional failure whilst rebuilding must skyrocket