A storage device includes a nonvolatile semiconductor memory device, and a controller configured to access the nonvolatile semiconductor memory device. When the controller receives a write command including a logical address, the controller determines a physical location of the memory device in which data are written and stores a mapping from the logical address to the physical location. When the controller receives a write command without a logical address, the controller determines a physical location of the memory device in which data are written and returns the physical location.