Patent ID: 7519853

Claim:
A disk array subsystem, comprising D disk apparatuses, wherein: there is a redundancy of N (N is an integer equal to or larger than 3); said disk array subsystem includes data regions of each of said disk apparatuses and (N−1) copy regions on each of said disk apparatuses; first copies of data to be stored in said data regions of each of said disk apparatuses are to be distributedly arranged in first copy regions of each of said disk apparatuses other than a disk apparatus from which said copies of data are to be distributedly arranged; and second copies of data to be stored in each of said first copy regions of each of said disk apparatuses are to be distributedly arranged, with respect to each of said first copy regions of each of said disk apparatuses, in second copy regions of each of said disk apparatuses other than a disk apparatus from which said second copies of data are to be distributedly arranged, and any of a disk apparatus that any of original data of said second copies are to be stored in said data region; said disk array subsystem further comprising a segment management table that registers an apparatus number of a disk apparatus in which a segment is placed and an apparatus number of a disk apparatus in which a segment to which data stored in said segment is to be copied, for each said segment arranged in said data region.