Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by servo sectors forming a plurality of full wedges and a plurality of mini wedges. The wedge ID field of a servo sector forming one of the full wedges is offset from a beginning of a sync mark by a first offset, and the wedge ID field of a servo sector forming one of the mini wedges is offset from the beginning of the sync mark by a second offset equal to the first offset. A first servo sector is read from the disk to generate a read signal, the read signal is demodulated to detect the wedge ID of the first servo sector, and the detected wedge ID is evaluated to determine whether the first servo sector forms one of the mini wedges.

Abstract: A data storage device is disclosed comprising a disk surface comprising a plurality of tracks, wherein each track comprises a plurality of data sectors and a plurality of servo sectors. The data storage device further comprises a head actuated over the disk surface, the head comprising at least one read element and at least one write element. Control circuitry is configured to use the head to write to a first data sector on the disk surface while simultaneously reading from a first servo sector on the disk surface.

Abstract: A disk drive is disclosed comprising a disk and a head actuated over the disk. A burst metric is generated in response to a burst read signal. The burst metric comprises at least one of an alpha metric comprising a ratio of a first burst amplitude of a first phased based servo burst measured at a first radial offset to a second burst amplitude of a second phased based servo burst measured at a second radial offset, a harmonic metric comprising a ratio of a first harmonic of the burst read signal as the head is moved radially over the disk to a higher harmonic of the burst read signal as the head is moved radially over the disk, and a spiral track crossing metric comprising a first and second interval each representing a partial duration of the read element crossing a spiral track.

Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of servo sectors defining a plurality of servo tracks. The servo tracks form a plurality of servo zones, and at least one servo sector of a servo track comprises a partial track address. A read signal generated by the head is processed to detect a current servo zone for the head, and the read signal is processed to detect the partial track address in one of the servo sectors of the current servo zone. A full track address is generated based on the detected servo zone and the detected partial track address.

Abstract: A system and method for processing track identifier errors to mitigate head instability in data storage devices is disclosed. The system and method includes computing a track id differential between an expected track id and a received track id, encoding the expected track id and the received track id, initiating a first action if the track id differential exceeds a pre-determined threshold and the encoded expected track id varies from the encoded received track id by a pre-configured number of bits, and initiating a second action if the track id differential does not exceed the pre-determined threshold or the encoded expected track id does not vary from the encoded received track id by a pre-configured number of bits.

Abstract: A method is disclosed for recursively determining repeatable runout (RRO) cancellation values in a disk drive having a head disk assembly (HDA) and a sampled servo controller. The HDA includes a disk having distributed position information in servo wedges, a rotary actuator carrying a head that periodically reads the position information, and a voice coil motor circuit that responds to a control effort signal. The servo controller periodically adjusts the control effort signal during a track-following operation. In the method, resonant filter values for developing RRO cancellation values are iteratively learned and updated after each disk rotation during track following operations on a predetermined track until a threshold, such as a particular number of disk rotations, is obtained.

Abstract: A disk drive is connectable to a power supply voltage and includes a spindle motor, a spindle motor driver, a spindle motor controller, and a detector. The spindle motor has windings and a rotatable rotor. The spindle motor driver is connected to the windings and connectable to the voltage. The spindle motor controller commands the spindle motor driver to apply the voltage across at least one of the windings to cause the rotor to rotate, which induces a BEMF having a polarity across each of the windings.

Abstract: A disk drive is connectable to a power supply voltage and includes a spindle motor, a spindle motor driver, a spindle motor controller, and a detector. The spindle motor has windings and a rotatable rotor. The spindle motor driver is connected to the windings and connectable to the voltage. The spindle motor controller commands the spindle motor driver to apply the voltage across at least one of the windings to cause the rotor to rotate, which induces a BEMF having a polarity across each of the windings.