Patent ID: 7398459

Claim:
A parity storing method in an external storage subsystem comprising multiple disk drives including a plurality of storage blocks, comprising: determining a number of the storage blocks to be used as data blocks and a number of the storage blocks to be used as parity blocks in a total number of storage blocks of the disk drives; forming a three-dimensional block matrix of virtual data blocks corresponding to the determined number of the storage blocks to be used as the data blocks on Cartesian coordinates (X, Y, Z); allocating virtual parity blocks to block planes related to the X, Y and Z-coordinates of the three-dimensional block matrix, respectively; allocating the virtual data blocks and the virtual parity blocks to the storage blocks of the disk drives, respectively; calculating parity information based upon data bits respectively stored in the storage blocks corresponding to the virtual data blocks of every block plane; and storing the calculated parity information in the storage blocks corresponding to the virtual parity blocks for every block plane, respectively.