Patent ID: 7330932

Claim:
A disk array system, comprising: data parity groups including logic drives and being composed of data physical drives; a spare parity group composed of a plurality of spare physical drives, which are used as saving destinations for said plurality of data physical drives; a memory for storing information of said parity groups, said physical disk drives and said logic drives; spare logic drive retaining means for retaining a spare logic drive of a desired capacity in said spare parity group, in case a data physical drive to be data-saved exists in said plurality of data physical drives of said data parity group, said spare logic drive being not a spare physical drive of said plurality of spare physical drives, but being a logical area created by using at least one of areas of said plurality of spare physical drives; data saving means for saving the data of said data physical drive to be data-saved, in said spare logic drive; data parity group reconfiguring means for defining virtual physical drives corresponding to said spare logic drive and for removing said data physical drive to be data-saved from said data parity group and incorporating at least one of said virtual physical drives instead of said data physical drive to be data saved into said data parity group; a disk controller that accepts a data reading demand for one of said logic drives from a host and determines one of said parity groups to which the one logic drive belongs from the logic drive information, and determines the plurality of data physical drives composing the one parity group from the parity group information; said disk controller determining whether the plurality of data physical drives are virtual drives or data physical drives on the basis of the physical drive information; a virtual drive controller that controls access to the virtual drives; if the plurality of data physical drives are the actual physical drives, the disk controller issues the data reading demand to the physical drive controller; and if the data physical drives are the virtual drives, the disk controller issues the data reading demand to the virtual drive controller.