Storage device, system, and method that determines a physical address of a memory unit allocated to a logical address or allocates a logical address to a physical address of a memory unit, based on access speed information of the logical address

Abstract

A memory management device which is capable of allocating a memory unit accessible at a higher speed to data which is stored in a storage device having memory units different in access speed, without being limited in an storage area. The storage device comprises a BLC flash memory accessible at a predetermined access speed, an MLC flash memory accessible at a lower access speed than the predetermined access speed, a controller, and a RAM. The controller manages the BLC flash memory and the BLC flash memory in units each formed by a plurality of physical pages, and writes data in the physical pages, and the RAM holds page allocation information in which logical pages designated when writing data and the physical pages are associated with each other.