Patent ID: 8375274

Claim:
A disk drive comprising: a disk comprising a plurality of tracks, wherein each track comprises a plurality of data sectors including a parity sector, the parity sector comprising at least a P 0 parity codeword and a P 1 parity codeword; a head actuated over the disk; and control circuitry operable to: read a plurality of the data sectors to generate a plurality of data codewords CW 0 -CWn; read the parity sector; decode the data sectors using an error correction code (ECC) decoder; when a single data codeword in the CW 0 -CWn is unrecoverable using the ECC decoder, recover the single data codeword using the P 0 parity codeword; and when two data codewords in the CW 0 -CWn are unrecoverable using the ECC decoder, recover the two data codewords using the P 0 and P 1 parity codewords; wherein: the P 0 parity codeword is generated according to: P0=CW0⊕CW1⊕ . . . CWn; and the P 1 parity codeword is generated according to: P1=α 0 {circle around (x)}CW0⊕α 1 {circle around (x)}CW1⊕ . . . α n {circle around (x)}CWn.