Patent ID: 7447840

Claim:
A disk array comprising: a plurality of Error Correction Code (ECC) groups each including a plurality of disks; a group of spare disks, each spare disk serving as a spare for at least one disk of said ECC groups; a first control unit, to be coupled to a host unit, for controlling input and output between said host unit and a cache memory; and a second control unit, coupled to said disks and said spare disks, for controlling input and output between said cache memory, said disks and said spare disks, wherein said second control unit includes a plurality of loop control portions each being connected to a fibre channel loop which is connected to one of the disks of said ECC groups, wherein data of a disk of one ECC group, connected to one fibre channel loop, can be recovered using data of another disk of said one ECC group, connected to another fibre channel loop, wherein each fibre channel loop, which is connected to one of the loop control portions, is connected to at least one spare disk, wherein each loop control portion of the second control unit performs copying of data stored in a first disk of the disks, which is connected to a first fibre channel loop, into a spare disk connected to said first fibre channel loop which is connected to the first disk of the ECC group when errors in said first disk exceeds a predetermined threshold, and wherein when the first disk fails, a loop control portion of the plurality of loop control portions performs processing of a read request from a host unit by recovering the data of the first disk based on data read out from at least a second disk which is a disk other than the first disk included in the same ECC group which includes the first disk, the second disk being connected to a second fibre channel loop, which is a fibre channel loop other than the first fibre channel loop connected to the first disk, and transmits the recovered data to said host unit.