A storage server includes a plurality of first disk drives (110) and a plurality of second disk drives (210). Each first disk drive is of a same type. The first disk drives are connected in series. Each second disk drive is of a same type different from each first disk drive. The controller includes a disk drive identifying module (62) and at least one disk drive controller module 64 connected to the disk drive identifying module. The at least one disk drive controller module includes a first disk drive controller module (64) and a second disk drive controller module. The first disk drive controller module is capable of processing a first signal outputting from the first disk drives. The second disk drive controller module is capable of processing a second signal output from a plurality of second disk drives of different type from the first disk drives. The disk drive identifying module is capable of identifying the first signal and the second signal from an input signal and outputting the first signal or the second signal to the corresponding first disk drive controller module or the second disk drive controller module.
