METHOD FOR RECODING PARITY AND RESTORING DATA OF FAILED DISKS IN AN EXTERNAL STORAGE SUBSYSTEM AND APPARATUS THEREFOR

摘要

PURPOSE: A parity storing and disk data recovering method in an external storing sub-system and an apparatus of the same are provided to recover an error even when an error occurs in at least two disks in a disk array and overcome a performance down problem due to a bottle-neck phenomenon of a parity disk. CONSTITUTION: An N-number of disks and each disk of the same are grouped based on a (N-1) number of block unit, and a disk array formed of (N-1)*N matrix is formed, the blocks of each row of the matrix are defined as a horizontal parity group, the blocks which is diagonal in the upper right portion of the matrix are defined as a diagonal parity group, and the horizontal parity blocks are arranged in each disk in such a manner that the horizontal parity blocks are diagonal in the first block of the (N-1)th disk, and the diagonal parity blocks are arranged in the (N-1)th block of each disk. The data values of the horizontal and diagonal parity groups are XORed and are stored in the horizontal and diagonal parity block of a corresponding group. The blocks are recovered using the diagonal parity group included in a fail block when an error occurs in two disks, and the fail block of the horizontal parity block is recovered using the horizontal parity group of the recovered fail block, and the fail blocks of two disks having an error are recovered by repeatedly performing the above processes.