The present invention relates to a system capable of carrying out efficient and stable system operation control even if a usage rate of the entire system varies under a situation in which the characteristics of storage units, such as maximum available total capacity and speed performance, are largely different from each other. Therefore, the system according to the present invention is composed of a monitor unit for monitoring information on a total volume of data stored in each of the storage units or in all the storage units, an index value calculating unit for calculating an index value on the basis of the monitor result and a location unit for distributively locating or relocating logical storage areas in physical storage areas on a plurality of storage units on the basis of the calculated index value.