Patent ID: 8429333

Claim:
A memory system with efficient data search processing, the memory system comprising: a nonvolatile semiconductor memory including a plurality of blocks, each one of the plurality of blocks being a unit of data erasing; and a controller configured to allocate at least one of the plurality of blocks in the nonvolatile semiconductor memory to first and second storing areas, wherein the controller is further configured to: in the first storing area, manage corresponding relationships between logical addresses and storage positions of data by a first management unit that is twice or larger a natural number times as large as a sector unit; in the second storing area, manage corresponding relationships between logical addresses and storage positions of data in a second management unit that is twice or larger a natural number times as large as the first management unit; and execute data search processing by referring to identification information provided for each address aligned by the second management unit, the identification information indicating whether or not data in the first management unit belonging to a range of each address aligned by the second management unit is stored in the first storing area.