Patent ID: 7466506

Claim:
A method for operating a magnetic recording disk drive, the disk drive having: at least one rotatable magnetic recording disk having a front generally planar surface, a back generally planar surface opposite the front disk surface, and a central axis of rotation perpendicular to said surfaces, each disk comprising a plurality of generally concentric circular data tracks of magnetic material on each of said surfaces, the data tracks being centered about said axis; a plurality of servo sectors on the front surface and forming a pattern of generally arcuate lines extending in a generally radial direction across said data tracks between radially inner and outer circles centered at said axis, each servo sector comprising a plurality of discrete blocks of magnetic material, the blocks being arranged in angularly spaced fields along the data tracks; and a plurality of servo sectors on the back surface forming a pattern of generally arcuate lines identical to the pattern of generally arcuate lines on said front surface; the tracks on the disks being aligned into radially-spaced cylinders; at least one first head, each first head associated with a front surface of a disk for reading and writing to data tracks and for detecting servo sectors on the front surface of a disk; at least one second head, each second head associated with a back surface of a disk for reading and writing to data tracks and for detecting servo sectors on the back surface of a disk; an actuator connected to the heads for positioning the heads to different data tracks and maintaining the heads on the data tracks, the actuator causing the first head to follow a generally arcuate path across a front surface that generally replicates the arcuate lines of servo sectors on said front surface and the second head to follow a generally arcuate path across a back surface that also generally replicates the arcuate lines of servo sectors on said front surface; the generally arcuate path of the second head across said back surface not replicating the arcuate lines of servo sectors on said back surface; and a servo control system coupled to the heads and the actuator, the servo control system including a processor for generating an actuator control signal in response to detection of the servo fields by the heads; the method comprising the processor-implemented steps of: in response to a request to read or write to a data track on a back surface of a disk, causing the actuator to seek from a first cylinder to a second cylinder containing the requested data track; during a first phase of said seek, receiving signals from the servo sectors on a front surface of a disk; and during a second phase of said seek, receiving signals from the servo sectors on a back surface of a disk.