It's not about parity The essence of draid is that, instead of keeping a spare drive unused in case one of the working drives fail, it incorporates the spare d

It's not about parity The essence of draid is that, instead of keeping a spare drive unused in case one of the working drives fail, it incorporates the spare drive to the array and uses it, but one drive worth of free space is reserved randomly across the entire array. That way, if one disk fails, the reserved space is used to write the data necessary to keep the array consistent. Because the free space is distributed randomly across the array, the write performance of a single drive doesn't become a bottleneck.