Patent ID: 7518821

Claim:
A hard disk drive comprising: a discrete track medium (DTM) magnetic disk which has a plurality of tracks, each track being divided into a plurality of sectors; a write/read head which writes sector data onto one side of said DTM magnetic disk, and which reads sector data from the one side of said DTM magnetic disk; a sector data buffer memory unit; a recording/reproducing unit which provides sector data from said sector data buffer memory unit, to said write/read head, and which provides sector data from said write/read head, to said sector data buffer memory unit; and a seek control unit which controls said write/read head in terms of position, in accordance with a sector number of a sector where a piece of sector data is to be written or read and with a sector number of a sector where said write/read head is located, wherein the piece of sector data to be written or read is pre-associated with the sector number of the sector where the piece of sector data is to be written or read, said seek control unit corrects first-order run-out relative to a revolution axis of said DTM magnetic disk and permits second-and-higher order run-out relative to the revolution axis of said DTM magnetic disk, and moves said write/read head gradually in a radial direction of said DTM magnetic disk at a shift pitch smaller than the track pitch for each revolution in accordance with sector numbers of sectors where pieces of sector data are to be written or read, within a range of tracks containing the sector numbers of the sectors where the pieces of sector data are to be written or read, and said recording/reproducing unit writes or reads, in accordance with a present sector number of a sector where said write/read head is located, a corresponding piece of sector data onto or from said DTM magnetic disk, independently of the order of the sector numbers.