Encoder/ decoder for RAID-6 and tape systems using redundant symbols

摘要

A system (610) for encoding m-bit data symbols from k data disks(612) to produce m-bit redundant symbols for r redundant disks (614) by encoding corresponding symbols from each of the k data disks comprises a means for receiving data from corresponding sectors of the k data disks, encoding mess for producing (m+1)-bit redundant symbols cSBy/SB (y=0,1,...,r-1) using a polynomial for each symbol in an (m+1)-bit representation of an element of the Galois field GF(2SPm/SP) with m+1 prime, the coefficients of each term of the polynomial each being data from a corresponding data disk, a shift register for each cSBy/SB performing multiplication operations as y-bit cyclic shifts, an adder for each cSBy/SB adding to the contents of the shift register the corresponding data from the next data disk, converting mess for converting the (m+1)-bit redundant symbols to m-bit redundant symbols, and mess for storing these symbols in corresponding sectors of the r redundant disks. The system may also be applied to multiple tracks of a tape drive. A decoder (620) which operates in a similar manner to the encoder is also disclosed.