This invention can reduce the load on a recording apparatus, efficiently design the overall system, and accurately calculate a data amount recordable on a recording unit in accordance with setting change of each communication apparatus or the like. A portable remote storage transmits information on a data amount storable in the portable remote storage to digital cameras. The information on the data amount storable in the portable remote storage is based on the remaining area of a shared storage area commonly available for the digital cameras except for an exclusive storage area assigned to each digital camera.