Abstract: A method of manufacturing a disk drive where the width of the read element is measured at servo-writing time in order to establish a write unsafe (WUS) limit corresponding to a maximum distance during writing that the write element is permitted to move radially offtrack from the centerline of a data track before writing is disabled. The method includes the steps of measuring a width of the read element with a servo track writer and determining a write unsafe (WUS) limit based on the data track pitch and the measured width of the read element. Varying the WUS limit on a drive-by-drive basis enhances the performance of some drives that would otherwise have capability that goes unused.

Abstract: A disk drive implements a technique for improving data storage capacity of data tracks having a servo wedge defect. A servo-fault position threshold is established for aborting a write operation if a transducer head position error from a circular track centerline exceeds the servo-fault position threshold. Servo wedges having operation, the servo-fault position threshold is ignored at a tagged servo wedge thereby preventing the tagged servo wedge from aborting a write operation. The data write operation is prevented for a predetermined number of servo wedges immediately following the tagged servo wedge by skipping data wedges between the tagged servo wedge and a last servo wedge of the predetermined number of servo wedges. Data may be written to a data wedge immediately following the last servo wedge.

Abstract: A phase locked loop (PLL) circuit is disclosed comprising a phase detector for generating a phase error between an input oscillating signal and an output oscillating signal. A fractional frequency synthesizer (FFS) generates the output oscillating signal in response to the phase error, wherein the FFS comprises an input for receiving a reference oscillating signal, and a fractional divider responsive to variables I and Fr. The variable I is an integer value, and the variable Fr is a fractional value, both of which are generated in response to the phase error.

Abstract: A disk drive includes a voice coil motor (VCM) having a narrow coil angle and a magnet magnetized with two or three pole pairs. The VCM magnet may define first, second and third sections, the second section being magnetically polarized in an axial direction that is opposite to that of the first and third sections. The first radial leg of the VCM coil faces the second section and the second radial leg faces the third section when the head is positioned at a non-operational position. The first radial leg faces the first section and the second radial leg faces the second section when the head is reading and/or writing to the data portion of the disk. Alternatively, the VCM magnet defines first and second sections that are magnetized in opposite axial directions.

Abstract: The present invention may be embodied in a method, implemented in a disk drive, for adaptively reducing an effect of vibration during a track following operation. The disk drive includes a disk and a rotary actuator. The disk includes distributed position information in a plurality of servo wedges. The actuator carries a transducer and pivots on a base of the disk drive. The actuator may exhibit an imbalance that may be affected by a linear vibration. In the method, a sensor signal is generated that is responsive to a vibration to the disk drive. The sensor value is modified based on an adaptive-filter gain to generate a position error adjustment signal for modifying a nominal position error signal. The adaptive-filter gain is then altered based on an adjusted position error signal and the sensor value associated with the current servo wedge for use during a next servo wedge.

Abstract: A system and method for performing disk drive diagnostics and restoration using a host-inaccessible partition are disclosed. The system includes a disk drive including: a host-accessible user partition; a host-inaccessible hidden partition independent of the host-accessible user partition; and a disk controller. The user partition includes: a user partition address range; a host-selected operating system; and a host-selected master boot record.

Abstract: A disk drive is disclosed wherein if a write command is aborted, the write command is re-executed according to a rotational position optimization (RPO) algorithm rather than immediately re-executing the write command to better optimize drive performance relative to mechanical latencies. An aborted write command is replaced into an input/output queue together with other pending commands. The aborted write command is eventually re-selected for execution by the RPO algorithm when executing the write command minimizes mechanical latencies relative to the other pending commands.

Abstract: A disk drive comprises a disk, an actuator arm, a head attached to the actuator arm, a voice coil motor, a parking latch for latching the actuator arm in a latched position in order to park the head during a non-operating mode, a post, and an inertial latch for maintaining the actuator arm in the latched position when the disk drive is subjected to a physical shock. The inertial latch comprises a body having a protruding arm and a pivot surface, wherein during the physical shock the body rotates about the pivot surface such that the protruding arm engages the actuator arm. The body of the inertial latch further comprises a strip-spring comprising a first end inserted into a first receptor and a second end inserted into a second receptor such that the strip spring has an initial arc displacement when installed into the body of the inertial latch.

Abstract: A disk drive is disclosed comprising a disk having a plurality of tracks, each track comprising a plurality of blocks. A semiconductor memory comprises a cache buffer having a plurality of segment pools, each segment pool comprising a plurality of cache segments, each cache segment comprises at least one block, and the number of blocks in each cache segment varies between segment pools. When a host command is received, the command size is compared to a threshold in order to allocate a cache segment from a first segment pool or a second segment pool.

Abstract: A spindle motor for use in a disk drive has a spindle motor hub having an axis of rotation, an annular magnet element coupled to the spindle motor hub, and a spindle motor stator. The spindle motor stator includes a stator rim formed of a plurality of laminate layers concentrically disposed about the axis of rotation. The stator rim has a plurality of stator teeth portions in operable communication with the magnet element for rotating the spindle motor hub. The stator teeth portions each have a magnetic flux surface disposed orthogonal to the axis of rotation. The spindle motor stator has a plurality of windings distributed along the stator rim. The windings each have a winding axis parallel to the axis of rotation and being disposed about respective ones of the stator teeth.

Abstract: A disk drive connectable to a host system includes a disk, a buffer memory, and an audiovisual interface responsive to first data from the host system to provide audiovisual data. The disk drive further includes a host command interface adapted to receive host commands from the host system. The disk drive further includes a disk controller coupled to the audiovisual interface, the host command interface, the disk, and the buffer memory. The disk controller is responsive to the host commands to selectively allocate at least a portion of the buffer memory among the audiovisual data, and to selectively transfer the audiovisual data from the audiovisual interface to the buffer memory. The disk controller is further responsive to the host commands to selectively transfer the audiovisual data from the buffer memory to the disk to be stored.

Abstract: The present invention may be embodied in a method, and related apparatus, for determining a repeatable runout (RRO) compensation value sets for a plurality of tracks on a disk in a disk drive, wherein the disk drive is initially manufactured and then shipped for installation in a host system. Each track comprises a plurality of embedded servo sectors that define a circumferential path that may have RRO requiring compensation during track following. The method comprises determining first RRO value sets for a first portion of the tracks to a first desired learning level by measuring the RRO for the first portion tracks based on a first predetermined number of disk rotations during the initial manufacturing of the disk drive. The first portion tracks are not adjacent to each other.

Abstract: An aspect of the invention can be regarded as a disk drive that includes a disk drive base and a spindle motor hub rotatably coupled to the disk drive base. The disk drive further includes a first disk disposed about the spindle motor hub. The disk drive further includes a second disk disposed about the spindle motor hub. The disk drive further includes a first disk spacer disposed between and in mechanical communication with the first and second disks. The first disk spacer has a first disk spacer first side disposed adjacent the first disk and an opposing first disk spacer second side disposed adjacent the second disk. The first disk spacer first side is defined by a first disk spacer first surface pattern. The first disk spacer second side is defined by a first disk spacer second surface pattern different than the first disk spacer first surface pattern.

Abstract: A disk drive includes a disk drive base and a latch attached to the disk drive base. The latch includes a latch impact surface having a latch impact surface perimeter. The latch impact surface perimeter defines a latch impact surface area. The disk drive includes a head stack assembly coupled to the disk drive base. The head stack assembly includes a tang. The head stack assembly is sized and configured to rotate to a parked position with the tang in mechanical communication with the latch. The tang has a tang impact surface. The disk drive includes a damping member disposed upon and disposed between the latch and the tang for damping impact between the tang and the latch and mitigating contact between the tang impact surface and the latch impact surface. The damping member has a damping member surface area less than the latch impact surface area.

Abstract: The present invention may be embodied in a method, implemented in a disk drive, for analyzing a magnetic media surface for indications of rough handling or “head slap.” In the method, a media surface is scanned to detect errors indicative of media defects. Location information is recorded for each detected error. Defect clusters are identified based on the location information. A confidence factor is generated based on a comparison between the defect clusters and a representation of the physical dimensions of the head. Whether the confidence factor indicates an impact between the head and the media surface is determined.

Abstract: A method of balancing a disk pack for use in a disk drive according to an aspect of the present invention. The disk pack includes a spindle motor and a rotatable disk. The spindle motor is configured to rotate the disk about an axis of rotation of the spindle motor. The spindle motor has a spindle motor imbalance location indicia upon the spindle motor indicative of a location of a spindle motor location imbalance. The method includes detecting the spindle motor imbalance location indicia. The method further includes placing the disk upon the spindle motor. The method further includes attaching the disk to the spindle motor with the disk being off-set from the axis of rotation based upon the detected spindle motor imbalance location indicia for balancing the disk pack by producing a disk off-set imbalance in relation to the axis of rotation.

Abstract: A disk drive includes a spindle motor assembly mounted on an enclosure and at least two disks. The disks are mounted on a hub of the spindle motor assembly. Each of the disks have a magnetic medium deposited between an inner circumference and an outer circumference. The disks define a volume therebetween wherein airflow is generated when the disks rotate. The disk drive also includes an airflow spoiler positioned between the disks. The airflow spoiler has a spoiler mounting portion and a non-data bearing extending portion. The spoiler mounting portion is configured to be mounted on the hub of the spindle motor assembly. The non-data bearing extending portion is connected to the spoiler mounting portion and extends outwardly therefrom into the volume defined between the disks. The non-data bearing extending portion extends at least partially over the magnetic medium.

Abstract: A disk drive is disclosed comprising a head disk assembly (HDA) including an enclosure for housing a disk and a head actuated radially over the disk. A printed circuit board assembly (PCBA) is attached to the HDA enclosure, wherein the PCBA comprises at least one attached electrical component. A non-electrically conductive coating is bonded to at least part of the PCBA after attaching the electrical component to the PCBA.

Abstract: A switched node is disclosed for use in a switched fabric network. The switched node comprises a disk and a head actuated over the disk. An integrated disk controller within the switched node comprises more than two bi-directional ports for simultaneously transmitting data in multiple directions through the switched fabric network, each port comprising an input port and an output port. The disk controller circuitry further comprises interface circuitry for interfacing with the head, a data buffer for storing data received from the input ports and data received from the head via the interface circuitry, and routing circuitry responsive to header data received from the input ports and header data received from the interface circuitry.

Abstract: A disk drive includes a disk drive base and a disk stack, the disk stack comprising a first disk including a first recording surface and a second recording surface. A spindle motor attached to the disk drive base rotates the disk stack about a spindle motor rotation axis. A ramp load engages at least the first and second lift tab of a head stack assembly. The ramp load includes a shaft coupled to the disk drive base, the shaft defining a shaft axis that is parallel to the spindle motor rotation axis. The ramp load also includes a first ramp defining a first lift tab engaging surface for engaging the first lift tab and a first facing surface configured to face the first recording surface of the first disk at a first distance, and a second ramp defining a second lift tab engaging surface for engaging the second lift tab and a second facing surface configured to face the second recording surface of the first disk at a second distance.