Patent ID: 8049980

Claim:
A mass data storage system comprising: a plurality of member disks and a spare disk which are organized into an array, each member disk and the spare disk having a plurality of heads and a plurality of platter surfaces respectively serviced by each head during read and write operations; a disk controller of each disk which controls the heads and platter surfaces during the read and write operations and which recognizes errors arising from each head performing read and write operations on the platter surface serviced by each head, the disk controller designating any one head as faulty whenever read and write errors associated with that one head meet a predetermined threshold; and an array controller which communicates with each disk controller and controls the operation of each disk in the array during mass data storage operations, the array controller controlling the disk controllers of the spare disk and the member disk having the designated faulty head to (a), read data from the surfaces of the member disk serviced by non-faulty heads and write that data onto surfaces of the spare disk, (b) to rebuild data on the spare disk written on the surface of the member disk serviced by the faulty head, and (c) thereafter perform subsequent mass data storage read and write operations on the spare disk which would otherwise be addressed to the member disk having the faulty head.