The present invention provides a technique to efficiently rearrange data in actual regions.A management system acquires load lumped region variation information (access distribution variation amount) indicative of a variation in the position of a virtual region in a virtual volume in a storage subsystem which region corresponds to a hot spot. Then, based on the load lumped region variation information, the management system determines a load position unvaried hour(s) indicative of a hour(s) in which the position of the virtual region corresponding to the hot spot is almost or perfectly unvaried (the hour(s) in which the position of the hot spot is stable). The management system then displays the load position unvaried hour(s) on a display device (see FIG. 19).