STORAGE DEVICE, CONTROL METHOD AND CONTROLLER

A storage device comprises a recording/reproducing module which positions a head at an arbitrary position of a storage medium to record or reproduce data and a nonvolatile memory in which a parameter storage area is defined. An adjustment module adjusts various types of parameters necessary for controlling a positioning control module and the recording/reproducing module. A parameter save processing module saves adjusted parameters obtained by the adjustment module in the nonvolatile memory during adjustment, while leaving the minimum number of the adjusted parameters necessary to access a system area of the storage medium at the end of the parameter adjustment, and saves the remaining adjusted parameters in the system area of the storage medium to form a free area in the parameter storage area of the nonvolatile memory. The free area processing module uses the free area of the nonvolatile memory as a storage area for firmware, a log or the like other than the parameters.