Method and means for encoding and rebuilding data contents of up to two unavailable DASDs in an array of DASDs

摘要: A method and means for encoding data written onto an array of M synchronous DASDs rebuilding spare DASD capacity when up to two fail. Data is mapped into the using (M-1)*M as storage model where a prime number. Pairs simple parities are recursively encoded over in respective diagonal major intersecting row order directions. The traverse covering topologically cylindrical path. Rebuilding upon unavailability no more than merely requires accessing repeating step diagonals oppositely sloped writing rebuilt back inclusive capacity.