Abstract: An improved disk array storage system shared by first and second processing nodes is comprised of N+2 disks wherein N disk drives are used to store data, and two additional disk drives are provided for the storage of parity information. Data to be saved is divided into portions consisting of one or many blocks of data for storage among the disks. Corresponding parity information, comprised of first and second components, is written to the two dedicated parity disk drives. The first processing node determines the first component of parity information to be written to the first parity disk drive, and a second processing node determines the second component of parity information to be written to the second parity disk drive. The two components of parity information are determined so that the exclusive-OR combination of the first and second components is equivalent to the exclusive-OR combination of the data stored across the remaining data disk drives.