A method of recovering two data columns in a row diagonal parity redundant array comprising at least four data columns and two parity columns, comprising: (1) calculating as an accelerator row, a missing chain parity based on available data columns and the two parity columns; (2) defining a recoverable data cell in each of the two columns to be recovered; and (3) iteratively calculating a value for each recoverable data cell based on the available columns, parity information, previously recovered data cells, and the accelerator row and storing the calculated value in the data matrix.