Patent ID: 7823010

Claim:
A disk array system comprising: a controller, adapted to be coupled to a host computer, and controlling receiving/transferring data from/to said host computer and controlling reading/writing data; a plurality of first disk drives, coupled to said controller, and being related to a first RAID group and storing data in accordance with controlling by said controller and each comprising a Serial ATA (SATA) interface; a plurality of second disk drives, coupled to said controller, and being related to a second RAID group and storing data in accordance with controlling by said controller and each comprising a same type of interface other than a SATA interface, said plurality of second disk drives having an improved performance characteristic relative to said plurality of first disk drives; and at least one third disk drive, coupled to said controller, and comprising an interface other than at least one SATA interface, said at least one third disk drive having an improved performance characteristic relative to each of said plurality of first disk drives, wherein, if said controller performs sparing of at least one of said plurality of first disk drives related to said first RAID group to said at least one third disk drive as at least one spare disk drive, said controller relates said at least one third disk drive to said first RAID group even though an interface type of said plurality of first disk drives is different from an interface type of said at least one third disk drive so that said at least one third disk drive and said plurality of first disk drives other than said at least one of said plurality of first disk drives are used to store at least data received from said host computer, whereby sparing can be effectively performed even when a spare disk drive having a SATA interface is not readily available.