Method and means for b-adjacent coding and rebuilding data from up to two unavailable DASDS in a DASD array

摘要

B-Adjacent coding is used to correct up to two DASDs in error in an array of N data DASDs and two redundant DASDs. When two of the data DASDs fail, their data can be recreated as a function of a pair of syndromes constituting up to two Boolean equations in two unknowns. Prestoring of the matrices of the powers of the polynomial terms of the code primitive together with pipeline processing operate to expedite data recovery and balance the write operations load on the DASDs across the array. Recovery from the failure of a data and a redundant DASD involves resolving one linear Boolean equation with one unknown.