Abstract: A disk drive is disclosed comprising a disk, a head actuated over the disk, a host interface for receiving disk access commands from a host, a command queue for queuing the disk access commands, and a stream detection engine for evaluating the disk access commands to detect a plurality of streams accessed by the host. The stream detection engine maintains a stream data structure for each detected stream, wherein the stream data structure comprises a frequency counter for tracking a number of disk access commands associated with the stream out of a predetermined number of consecutive disk access commands received from the host. A disk controller selects one of the streams for servicing in response to the frequency counters.

Abstract: A disk drive is disclosed comprising an actuator arm, a head attached to a distal end of the actuator arm, a voice coil motor for rotating the actuator arm about a pivot, and an optical sensor operable to generate a first position signal representing a position of the actuator arm with respect to the disk, wherein the first position signal is substantially unaffected by a vibration mode of the actuator arm. Servo sectors recorded on the disk are processed to generate a second position signal representing a position of the head with respect to the disk, wherein the second position signal comprises a significant component due to the vibration mode of the actuator arm. A control signal is applied to the voice coil motor in response to the first and second position signals.

Abstract: A method for remotely power cycling a peripheral data storage system (PDSS) from a host system. The method comprises powering-up the PDSS from the host system based on a host-scheduled backup operation; transmitting pre-selected data to the PDSS from the host system based on the host-scheduled backup operation; and powering-down the PDSS from the host system based on the host-scheduled backup operation. Another method is for operating a PDSS for use with a host system configured to perform scheduled backup operations to the PDSS, the PDSS comprising a peripheral data storage device, a PDSS controller, and a peripheral data storage controller host interface adapted for communication with the host system. The method comprises powering-up the PDSS based on a host-scheduled backup operation; receiving data from the host system for storing in the peripheral data storage device; and powering-down the PDSS based on the host-scheduled backup operation.

Abstract: Disclosed is a magnetic disk having servo sectors for defining data tracks. Each servo sector includes a preamble field and a null servo burst field. The preamble field is for synchronizing a phase-locked loop oscillator and defines a reference phase angle. The null servo burst field includes first and second servo bursts that are radially adjacent and have opposed phase angles such that a read along a null path that is equally between the first and second servo bursts generates a read signal of substantially zero amplitude, and a read along a path that is offset from the null path generates a read signal having an amplitude indicating a distance between the offset path and the null path, and having a phase indicating an offset direction. Further, the phase angle of the first and second servo bursts are substantially different from the reference phase angle.

Abstract: A method is disclosed for writing repeatable runout (RRO) correction values to a disk of a disk drive. The disk has distributed position information in a plurality of embedded servo sectors. The transducer head has a read element that is offset from a write element. The write element is positioned over a target track while the distributed position information from a followed track is read using the read element. The target track is different from the followed track due to the offset between the read element and the write element. Previously determined RRO correction values associated with the target track are written at radial positions on the target track. The radial positions are based on the distributed position information of the followed track, previously determined RRO correction values associated with the followed track, and a portion of the previously determined RRO correction values associated with the target track.