Apparatus and method for magnetic head control in storage accesses

A control apparatus that controls access to a storage medium for data, the storage medium including a storage area that includes a plurality of unit areas in at least a part of the storage area, each unit area being a respective discrete non-overlapping subdivision of said storage area and including a respective plurality of physical sectors, the control apparatus comprising:

• an access-area setting unit that dynamically specifies one of the unit areas, in which logical sectors of a set of logical sectors are assigned to respective physical sectors, as an access area for data, wherein for each of said unit areas, each physical sector within the respective unit area corresponds to a respective one of said logical sectors of said set of logical sectors;
• an addressing unit that updates a first address specified as a write address in a data write request with a second address that represents a physical sector, within the unit area specified as the access area by said access-area setting unit, which corresponds to a logical sector of said set of logical sectors associated with the first address;
• and
• a valid-area changing unit that, at a predetermined time, migrates whole data in a first physical sector to a second physical sector, said second physical sector being within the unit area currently specified as the access area by said access-area setting unit, said first physical sector being within one of the unit areas that was specified as the access area before the unit area currently specified as the access area had been specified as the access area by said access-area setting unit, said first and second physical sectors corresponding to the same logical sector of said set of logical sectors.

A data storage unit comprising:

• a storage medium that includes a storage area that includes a plurality of unit areas in at least a part of the storage area, each unit area being a respective discrete non-overlapping subdivision of said storage area and including a respective plurality of physical sectors;
• and
• a control circuit that controls data read and write operation on the storage medium,
• wherein the control circuit comprises:
• an access-area setting unit that dynamically specifies one of the unit areas, in which logical sectors of a set of logical sectors are assigned to respective physical sectors, as an access area for data, wherein for each of said unit areas, each physical sector within the respective unit area corresponds to a respective one of said logical sectors of said set of logical sectors,;
• an addressing unit that updates a first address specified as a write address in a data write request for the part of the storage area, in which the unit areas are provided, with a second address that represents a physical sector, within the unit area specified as the access area by said access-area setting unit, which corresponds to a logical sector of said set of logical sectors associated with the first address, and
• a valid-area changing unit that, at predetermined time, migrates whole data in a first physical sector to a second physical sector, said second physical sector being within the unit area currently specified as the access area by said access-area setting unit, said first physical sector being within one of the unit areas that was specified as the access area before the unit area currently specified as the access area had been specified as the access area by said access-area setting unit, said first and second physical sectors corresponding to the same logical sector of said set of logical sectors.

A method for controlling a data storage unit that includes a storage area that includes a plurality of unit areas in at least a part of the storage area, each unit area being a respective discrete non-overlapping subdivision of said storage area and including a respective plurality of physical sectors, the method comprising steps of:

• dynamically specifying one of the unit areas, in which logical sectors of a set of logical sectors are assigned to respective physical sectors, as an access area for data, wherein for each of said unit areas, each physical sector within the respective unit area corresponds to a respective one of said logical sectors of said set of logical sectors;
• updating, in a case where a data write request for the storage area is submitted, a first address specified as a write address in the data write request with a second address that represents a physical sector within the unit area specified as the access area by said access-area setting unit, which corresponds to a logical sector of said set of logical sectors associated with the first address;
• and
• migrating whole data, including data that is read from a third physical sector in one of the unit areas that was specified as the access area before the unit area currently specified as the access area had been specified as the access area by said dynamically specifying one of the unit areas, to a fourth physical sector, said fourth physical sector being within the unit area currently specified as the access area by said dynamically specifying one of the unit areas, said fourth physical sector corresponding to the same logical sector as the logical sector to which the third physical sector corresponds when the data is read from the third physical sector after dynamically specifying the unit area currently specified as the access area.

A program tangibly embodied as a plurality of machine-executable instructions recorded on a machine-readable media for controlling access by a computer to an external storage unit for data, the external storage unit including a storage area that includes a plurality of unit areas in at least a part of the storage area, each unit area being a respective discrete non-overlapping subdivision of said storage area and including a plurality of physical sectors, said program performing functions as:

• an access-area setting function that dynamically specifies one of the unit areas, in which logical sectors of a set of logical sectors are assigned to respective physical sectors, as an access area for data, wherein for each of said unit areas, each physical sector within the respective unit area corresponds to a respective one of said logical sectors of said set of logical sectors;
• an addressing function that, in a case where a CPU submits a data write request for the external storage unit, updates a first address specified as a write address in the data write request with a second address that represents a physical sector, within the unit area specified as the access area by said access-area setting unit, which corresponds to a logical sector of said set of logical sectors associated with the first address;
• and
• a valid-area changing function that, at predetermined time, migrates whole data in a first physical sector to a second physical sector, said second physical sector being within the unit area currently specified as the access area by said access-area setting unit, said first physical sector being within one of the unit areas that was specified as the access area before the unit area currently specified as the access area had been specified as the access area by said access-area setting unit, said first and second physical sectors corresponding to the same logical sector of said set of logical sectors.