A storage control system comprises a storage resource and a controller. If the controller receives a write command which specifies an address belonging to a virtual volume, to the area belonging to the address, unassigned pages in a pool which is a storage area based on a plurality of media types of physical storage media and which is divided into a plurality of pages are supposed to be assigned. The storage control system comprises a plurality of management entries which are a plurality of entries for page management information which is the information related to the pages. The plurality of management entries include two or more page entries and two or more statistical entries. A statistical entry about a certain media type corresponds to M pages based on the storage media of the certain media type (M is an integral number which is 2 or larger). The statistical entry corresponding to the M pages comprises the information related to the I/O performance value for those M pages.