Abstract: A storage device controlling apparatus connected to a storage device storing data and connected to an information processing apparatus via a network, the apparatus being accommodated in a chassis, the apparatus comprising a circuit board accommodated in the chassis, the circuit board including: an I/O processor formed thereon, the I/O processor outputting to the storage device I/O requests corresponding to requests to input and output data from the information processing apparatus; an inner connector provided at an end to be located on an inner side of the chassis, at least the I/O processor and a power supply unit being connected through the inner connector; a file access processing section formed thereon, the file access processing section accepting the requests to input and output data on a file basis; and an electric power connector provided at an end to be located on an outer side of the chassis, electric power being supplied to the file access processing section through the electric power connector.