Abstract: A magnetic disk device includes a disk, first and second heads, a motor, and a controller. The disk includes a first surface and a second surface opposite to the first surface. The first head is configured to perform reading and writing with respect to the first surface. The second head is configured to perform reading and writing with respect to the second surface. The motor is configured to move the first and second heads with respect to the first and second surfaces, respectively, along a radial direction of the disk. The controller is configured to alternately activate the first and second heads to perform writing of a plurality of spiral patterns on the first and second surfaces of the disk, respectively, while controlling the motor to move the first and second heads at a predetermined constant speed with respect to the first and second surfaces in the radial direction.

Abstract: A method of writing to a data storage drive having a first media partition having a first write speed and a second media partition having a second write speed slower than the first write speed includes mapping a plurality of logical block addresses (LBAs) to a plurality of physical block addresses (PBAs) of the first media partition, and writing to the plurality of LBAs mapped to the PBAs of the first media partition. It is determined whether the first media partition is at or above a predetermined storage level, and, when the first media partition is at or above the predetermined storage level, data is moved moving data from the first media partition to a plurality of PBAs in the second media partition, and mapping of LBAs and PBAs in the data storage device is updated.

Abstract: System and method for high speed data storage. An unmounted unformatted direct access storage device (DASD) may be opened via an operation system (OS) application programming interface (API). A maximum amount of storage space afforded by the DASD may be determined, and the DASD locked, thereby limiting write access to the DASD to a first application process and excluding writes to the DASD by any other application process. A single data type data stream is received, and stored on the DASD in linear fashion as it is received without using a file system architecture, metadata, indices, or keys associated with the data, including writing a block of the stream of data to the DASD and returning a next contiguous write location on the DASD in an iterative manner. The stored data are readable by multiple readers in a linear manner without using the file system architecture, metadata, indices, or keys.

Abstract: Systems and methods are disclosed for detecting shingled overwrite errors. When a read error is encountered when reading from shingled recording tracks, a processor may determine whether the read error is an error caused by shingled overwriting. The processor may determine whether the read error is caused by shingled overwriting by determining read signal quality of one or more sectors preceding the read error, such as based on a bit error count or bit error ratio (BER), and comparing the read signal quality to a threshold value. The processor may determine that the read error is caused by shingled overwriting when the read signal quality value is lower than the threshold.

Abstract: The invention pertains to a method and apparatus for writing data to an array of Shingled Magnetic Recording (SMR) devices. In an embodiment of the invention a parity band configured to allow random access writes is provided. Next, data is appended sequentially to a stripe on an array of SMR devices. Then the parity band is updated to contain parity data consistent with the data appended to the stripe. In another embodiment of the invention, a shingled parity band is provided. Data is then appended sequentially to a stripe on an array of SMR devices without the user being required to write an entire stripe of data. The provided parity band is then updated to contain parity data consistent with the data that was appended to the stripe. In such an embodiment it is not always necessary to delete all of the parity data in the parity band when updating the parity band.

Abstract: A data storage device is disclosed comprising a head actuated over a disk comprising tracks defined by servo sectors. A location of the head over the disk is measured based on the servo sectors, and a position error signal (PES) is generated representing a difference between a target location for the head and the measured location for the head. An actuator control signal (ACS) is generated in response to the PES, a disturbance compensation signal (DCS) is generated based on the PES and the ACS, and the DCS is filtered with a disturbance observer filter. The ACS is adjusted based on an output of the disturbance observer filter, and the head is actuated over the disk based on the adjusted ACS. The DCS is filtered with a plurality of band-pass filters, and the disturbance observer filter is adjusted based on the plurality of band-pass filters.

Abstract: Implementations disclosed herein provide a method comprising determining used shingled data tracks adjacent to a target track using a track usage monitoring scheme, and reading the used shingled data tracks to perform a write operation to the target track.

Abstract: A method of writing data using more than one write head to write to more than one storage media platter surface of a storage device, where one actuator in the storage device controls positions of all of the write heads, includes controlling the position of one of the write heads to a selected radial track location, writing simultaneously to storage media of the storage device at the selected radial track location using a plurality of the write heads, and, during the writing at the selected radial track location, reading servo data using respective read heads associated with each respective one of the plurality of write heads and recording the radial position of the respective heads for the selected radial track location. During reading, the recorded head position for the track of the platter surface to be read is determined, and the read head is served to the recorded head position.

Abstract: An adaptive guard band scheme is disclosed for a data storage device. In illustrated embodiments, the adaptive guard band scheme formats different guard band cylinders and track zeros for different heads depending upon a contact cylinder of the different heads. In an illustrative embodiment, the adaptive guard band scheme utilizes the contact cylinders for the heads and a no fly cylinder to determine track zero(s) and extended data zone(s) for select heads.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks, wherein each track comprises a plurality of servo sectors. When entering an idle mode, the head is floated over the disk, and when exiting the idle mode, a radial velocity of the head is measured, a seek distance is determined in response to the radial velocity, and a seek operation seeks the head the seek distance to a first track.

Abstract: A disk drive is disclosed comprising a disk comprising tracks defined by servo sectors, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors. The head is loaded over the disk during a load operation, and a radial velocity of the head is determined during the load operation. A target track is generated based on the determined radial velocity of the head, and the servo control system seeks the head to the target track.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo sectors defining a plurality of servo tracks. The servo tracks form a plurality of servo zones, where a servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone. A servo control system servos a head over the disk. An estimated servo state of a servo control system is generated, and when the head crosses from a first servo zone to a second servo zone, the estimated servo state is adjusted to compensate for a transient in a circumferential distance between a servo sector in the first servo zone and a servo sector in the second servo zone.

Abstract: A first portion of a track identifier is read from a first servo wedge of a track of a magnetic disk. A second portion of the track identifier is read from a second servo wedge of the track. The second portion includes least-significant bits of the track identifier that are also stored in the first portion. The first and second portions are combined to determine the track identifier for the first and second servo wedges, and the track is identified using the track identifier.

Abstract: According to one embodiment, a disk storage apparatus includes a servo system. The servo system includes a state observer and performs a seek operation up to a target position with a current position of a head undetermined. The servo system performs the seek operation based on initial values including a temporary position, while allowing the state observer to operate based on the initial values, until the current position is determined. The servo system determines the current position based on the servo data read from the plurality of servo areas by the read module and a result of estimation by the state observer.

Abstract: A magnetic storage medium is formed of magnetic nanoparticles that are encapsulated within nanotubes (e.g., carbon nanotubes).

Abstract: A disk drive is disclosed comprising a disk comprising tracks defined by servo sectors, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk in response to the servo sectors. The head is loaded over the disk during a load operation, and a radial velocity of the head is determined during the load operation. A target track is generated based on the determined radial velocity of the head, and the servo control system seeks the head to the target track.

Abstract: A bit-patterned media (BPM) magnetic recording disk has two sizes of dots of magnetic material. The large and small dots are formed together in a hexagonal-close-packed (HCP) pattern. In the data regions none of the larger sized dots are adjacent one another; however in the servo regions some of the larger sized dots are adjacent one another. The adjacent larger sized dots form blocks that provide large amplitude “bursts” as the readback signal, as required for servo burst fields. The disk is made by imprint lithography using an imprint template, which can be made by directed self-assembly (DSA) of a block copolymer (BCP). The imprint template has two sizes of recesses, resulting in BPM disks with two sizes of dots. After the disks are imprinted they are exposed to a DC magnetic field, which magnetizes all the dots in the same direction.

Abstract: Systems, methods, and other embodiments associated with back-EMF detection for motor control are described. In an embodiment, an apparatus includes a drive circuit configured to apply excitation signals to respective inputs of a motor, a signal inhibit circuit configured to convey a signal to inhibit application of the excitation signals during an interval, and a measuring circuit configured to measure a back-electromotive force (EMF) signal crossing a reference signal during the interval.

Abstract: A disk drive is disclosed comprising a disk comprising tracks defined by servo sectors, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk based on the servo sectors. An estimated acceleration EstAccel of the head over the disk is generated based on at least one of the servo sectors. When the EstAccel is determined to be reliable, an estimated velocity EstVel of the head over the disk is generated based on the EstAccel. When the EstAccel is determined to be unreliable, the EstAccel is adjusted to generate an adjusted acceleration AdjAccel and the EstVel of the head over the disk is generated based on the AdjAccel.

Abstract: A disk drive is disclosed comprising a head, a disk surface, and a dual stage actuator (DSA) servo loop comprising a voice coil motor (VCM) servo loop comprising a VCM and a microactuator servo loop comprising a microactuator operable to actuate the head over the disk surface. A microactuator compensator processes a position error signal (PES) to generate a first control signal, and a disturbance sinusoid is injected into the first control signal to generate a second control signal, wherein the microactuator is controlled in response to the second control signal. Feed-forward compensation is generated corresponding to the injected disturbance sinusoid, and a third control signal is generated in response to the PES and the feed-forward compensation, wherein the VCM is controlled in response to the third control signal. A gain of the microactuator is estimated in response to the feed-forward compensation.

Abstract: A memory system includes a storage medium having tracks arranged on the storage medium. The tracks include data track portions configured to store data. The tracks have a data track width and offset correction portions having a width that is greater than the data track width of the associated data track. Each offset correction portion stores one or both of positional offset correction values and timing offset correction values. The positional offset correction values are configured to correct for errors that occur in cross track positioning relative to the medium and the timing offset correction values are configured to correct for errors that occur in down track timing relative to the medium.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. As an example, a data processing system is disclosed that includes Various embodiments of the present invention provide data processing systems that include an analog to digital converter circuit and a phase and gain computation circuit. The analog to digital converter circuit is operable to convert an analog input into a series of digital samples. At least a portion of the series of digitals samples represent a periodic signal from a servo data region. The phase and gain computation circuit is operable to: determine an approximate amplitude of the periodic signal based at least in part upon the digital samples representing the periodic signal from the servo data region; determine a gain based at least in part on the approximate amplitude; and determine a phase based at least in part on the approximate amplitude.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks, wherein each track comprises a plurality of servo sectors. When entering an idle mode, the head is floated over the disk, and when exiting the idle mode, a radial velocity of the head is measured, a seek distance is determined in response to the radial velocity, and a seek operation seeks the head the seek distance to a first track.

Abstract: According to one embodiment, a disk storage apparatus includes a servo system. The servo system includes a state observer and performs a seek operation up to a target position with a current position of a head undetermined. The servo system performs the seek operation based on initial values including a temporary position, while allowing the state observer to operate based on the initial values, until the current position is determined. The servo system determines the current position based on the servo data read from the plurality of servo areas by the read module and a result of estimation by the state observer.

Abstract: An extended servo mark word is used when an error is detected from a servo mark. For example, a servo mark associated with a disk drive track may be detected during a data access operation. In response to an error in detecting the servo mark, at least one adjacent bit is evaluated together with the servo address mark to overcome the error.

Abstract: A disk drive is disclosed comprising a first head actuated over a first disk surface and a second head actuated over a second disk surface. A first servo sector of the first disk surface is read to generate a read signal which is processed to generate a first phase error. A first clock is generated at a frequency proximate a servo data rate of the first data sector. Read signal samples are synchronized in response to the first phase error and the first clock to generate synchronous samples, and servo data in the first servo sector is detected in response to the synchronous samples. The read signal is processed to generate a second phase error, a second clock is generated in response to the second phase error, and a spiral servo track is written to the second disk surface using the second clock.

Abstract: A disk drive is disclosed comprising a head actuated over a disk, the disk comprising a plurality of servo sectors defining a plurality of servo tracks, wherein the servo tracks form a plurality of servo zones. A servo data rate of servo sectors in a first servo zone is different than a servo data rate of servo sectors in a second servo zone. A boundary of a first servo zone overlaps with a boundary of a second servo zone over a transition zone. The servo sectors of the first servo zone are interleaved with the servo sectors of the second servo zone within the transition zone. At least one servo parameter is adjusted when the head is over the transition zone in order to transition between the first servo zone and the second servo zone.

Abstract: Disk drives are described in which the conventional write-to-read gap is omitted in selected sectors which frees up space that can be used for other purposes including writing a higher number of bits in the user data area in the gapless selected sectors. Alternative embodiments can use the additional space for servo information such as a repeatable run out (RRO) field. Conventional servo sector SID formats can be used for both gapped and gapless SIDs, which means that during seeking and reading operations full SIDs can be read for every wedge. The tradeoff for being able to write data much closer to the gapless SIDs is that the servo system does not detect the SAM or read the TID in the gapless SIDs during write operations.

Abstract: A disk drive is disclosed comprising a disk comprising a plurality of servo tracks defined by servo sectors. The disk drive further comprises a head comprising a read element offset linearly from a write element by a gap such that when the disk rotates, the read element reaches a servo sector before the write element. During a first operation, a first length of a beginning of the servo sector is read, and during a write operation, a second length of the beginning of the servo sector shorter than the first length is read to enable data to be written while the read element is over at least part of the servo sector.

Abstract: A drive is disclosed comprising a head actuated over a disk comprising a plurality of data tracks. A random access write zone is defined on the disk comprising a first plurality of the data tracks, and a circular buffer write zone is defined on the disk comprising a second plurality of the data tracks. Write commands are received comprising logical block addresses (LBAs). First frequency and second frequency write LBAs are identified, where the second frequency is higher than the first frequency. Data associated with the first frequently write LBAs is stored in the circular buffer write zone, and data associated with the second frequency write LBAs is stored in the random access write zone.

Abstract: A disk drive comprises a disk, an actuator arm and a servo controller using a position error signal to generate a controller output signal to control the actuator arm. A plant mechanically models at least a portion of the disk drive, receives a control command to which an unknown disturbance is added and generates a plant output. A disturbance observer (DOB) uses the control command and the plant output to generate a delayed and estimated version of the disturbance. The DOB comprises a Q filter having a selected center frequency. A perfect phase cancellation filter (PPCF) is configured to receive the delayed and estimated version of the disturbance, to reject selected disturbances and to align the desired attenuation frequency with the selected center frequency. The output of the PPCF is subtracted from the controller output signal to generate the control command.

Abstract: A method of self servo-writing servo information to a plurality of disk surfaces in a disk drive that includes writing servo information to a plurality of disk surfaces in a first direction, writing servo information to a plurality of disk surfaces in a second direction, and determining an amount of overlap to be written on a reference surface with the reference head that will produce an overlap of servo information on each of the surfaces in the disk drive to which servo information is to be written. The method also includes switching to different tables when seeking across the overlap or border areas.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo sectors that define a plurality of servo tracks, wherein the servo sectors comprise a plurality of servo bursts. A radial velocity of the head is detected relative to the servo tracks. At least two of the servo bursts are read to generate servo burst signals, and the servo burst signals are adjusted in response to the radial velocity of the head. A position error signal is generated for the head in response to the adjusted servo burst signals.

Abstract: According to one embodiment, a disk storage device includes: a disk on which a servo pattern is recorded; a head; a driver; a signal generator; a demodulator; and a controller. Position signals for detecting an offset position from a center of a track are recorded in a recording area of a servo pattern. The signal generator generates a first timing signal indicating a timing for reading the position signals. When the controller performs a seek operation for moving the head to a target track, the signal generator generates a second timing signal. The period of the second timing signal for reading each of the position signals is made shorter than that of the first timing signal. A center time of the period of the second timing signal is shifted closer to a demodulation center time corresponding to a center of the recording area than that of the first timing signal.

Abstract: A disk drive is disclosed comprising a disk including a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors. The disk drive further comprises an actuator for actuating a head over the disk in response to an actuator control signal. The servo sectors are read to generate a first sequence of control samples x[k] at a sample rate corresponding to a frequency of the servo sectors. The first sequence of control samples x[k] is upsampled by a factor of N to generate a second sequence of control samples y[ki] according to: y ? [ k i ? | i = 1 : N ] = ( 1 - i N - ? ) ? u ? [ k - 1 ] + ( i N + ? ) ? u ? [ k ] where ? is a scalar greater than or equal to zero and less than one. The actuator control signal is generated in response to the second sequence of control samples y[ki].

Abstract: A method of self servo-writing servo information to a plurality of disk surfaces in a disk drive that includes writing servo information to a plurality of disk surfaces in a first direction, writing servo information to a plurality of disk surfaces in a second direction, and determining an amount of overlap to be written on a reference surface with the reference head that will produce an overlap of servo information on each of the surfaces in the disk drive to which servo information is to be written. The method also includes switching to different tables when seeking across the overlap or border areas.

Abstract: A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of servo sectors that define a plurality of servo tracks. The servo sectors comprise a plurality of servo bursts including a first servo burst, a second servo burst following the first servo burst and offset radially by approximately one half of a servo track from the first servo burst, a third servo burst following the second servo burst and offset radially by approximately one full servo track from the second servo burst, and a fourth servo burst following the third servo burst and offset radially by approximately one half of a servo track from the third servo burst. A PES is generated form the servo bursts that is substantially insensitive to a radial velocity of the head.

Abstract: A self servo writing disk controller detects a plurality of spiral sync marks and a plurality of spiral bursts corresponding to one of a plurality of servo spirals from a read signal from the read/write head. A timing reference signal is generated based on timing of at least one of the plurality of the spiral sync marks. A position error signal is generated based on timing of at least one of the plurality of spiral sync marks and a magnitude of at least one of a plurality of spiral bursts. The timing reference signal and the position error signal are used by the disk drive for timing and positioning in self writing initial servo wedges to the disk.

Abstract: A method for controlling a hard disk drive, includes a track seeking servo routine in which seek time is measured in a mode of the routine after the trajectory mode, the measured seek time is compared with a predetermined period of time, and an alarm mode is induced when the measured seek time exceeds the predetermined period of seek time.

Abstract: A method of writing a servo pattern of a hard disk drive includes measuring the speed of a head of the hard disk drive by reading a basic servo pattern written to only select ones of the data tracks of the disk, realizing a feedforward current profile when the difference between the actual speed of the head and a target speed of the head is within a predetermined range, and writing a reference servo pattern using the realized feedforward current profile. A final servo pattern is then written using the reference servo pattern.

Abstract: According to one embodiment, a disk drive has a DTM type disk. The DTM type disk has a servo area on one recording surface. In the servo area, a servo pattern is recorded. The servo pattern is composed of a projection-depression pattern and an N- and P-pole magnetic pattern. The N- and P-pole magnetic pattern is recorded in an address-data region that contains a cylinder code.

Abstract: A disk drive is disclosed comprising a first disk surface and a second disk surface, wherein the first disk surface comprises a plurality of concentric servo sectors extending across substantially an entire radius of the first disk surface. The concentric servo sectors are read across substantially the entire radius of the first disk surface using the first head to generate a read signal. The read signal is processed to generate a position error signal (PES) representing a radial location of the first head relative to the first disk surface. The PES is processed to generate a control signal applied to the VCM to move the second head radially over the second disk surface while writing a spiral servo track on the second disk surface.

Abstract: A method of tuning a seek operation of a disk drive is disclosed, the disk drive comprising a disk, an actuator arm, a head coupled to a distal end of the actuator arm, a voice coil motor (VCM) for rotating the actuator arm about a pivot, and a closed loop servo system for generating a VCM control signal applied to the VCM. A function h is applied to the closed loop servo system and a corresponding output g of the closed loop servo system is measured. A reference signal is generated in response to a summation of a plurality of the function h, wherein each of the plurality of the function h is shifted by an offset and scaled by a coefficient, and the coefficients are generated in response to the measured output g.

Abstract: An apparatus, system, and method are disclosed for detecting a periodic sequence. A value detector module detects a plurality of values of a periodic sequence. In one embodiment, a transformation module transforms the plurality of values into transformed values. A confinement module confines the values to a limited set of confined values. A correlation module correlates the confined values with a plurality of instances of the periodic sequence. In addition, a selection module selects an instance of the periodic sequence with the highest correlation to the confined values as an observed periodic sequence.

Abstract: A servo-mark search control unit detects in a magnetic disk a servo mark matching a servo mark selected by a servo-mark candidate selecting unit. In this case, according to an instruction from a servo-mark search control unit, a non-volatile memory managing unit writes servo-write-mode identification information corresponding to the detected servo mark in a servo-write-mode identification-information storage unit of a non-volatile memory. In this manner, a magnetic disk device can recognize by itself a servo write mode with which servo patterns were written in a magnetic disk included in the magnetic disk device.

Abstract: A hard disc drive (HDD) data read control apparatus, medium, and method reading data from a disc having non-uniform track-to-track spacing. The data read control method of the HDD, in which data is read from a disc including non-uniform track-to-track spacing, includes seeking a target track by adopting an off track amount applied to a previously followed track, and reading the data while following the sought target track. Accordingly, production yield can be increased by making failure processing unnecessary even if a track-to-track spacing of a HDD is non-uniform.

Abstract: Controlling seeking of a transducer includes accelerating the transducer to a seek velocity, generating a linearized switching curve defining a position and velocity of the transducer at which deceleration should begin, and controlling the velocity of the transducer in response to the current position and seek velocity of the transducer relative to the linearized switching curve. The linearized switching curve has a slope and an offset that are determined in response to the seek velocity and a current position of the transducer relative to a nonlinear switching curve.

Abstract: A method and apparatus to safely repress disturbances from being applied to a system from the surroundings in which the system is used. The method of adaptively repressing disturbances includes estimating frequency components of a disturbance applied to a system in a user environment; and optimizing parameter values determining characteristics of a disturbance compensating servo control loop including a disturbance observer, based on the estimated frequency components of the disturbance.

Abstract: A disk drive is disclosed comprising a disk having a plurality of tracks, wherein each track comprises a plurality of data sectors and a plurality of servo sectors. The disk drive further comprises a head actuated over the disk, the head comprising a read element radially offset from a write element by a reader/writer offset. In order to rewrite a marginal servo sector detected in a target track, control circuitry within the disk drive relocates user data recorded in a first data sector of a near adjacent track to a staging memory. Servo data is written over the first data sector, and the read element is used to read the servo data written over the first data sector to actuate the head to rewrite the marginal servo sector of the target track. The user data stored in the staging memory is then rewritten to the first data sector.

Abstract: A disk calibration and search method in a disk drive is provided, in which, after an initialization step, a pickup is jumped to a first position and moved radially in a predetermined direction in response to pulses generated by a frequency generator. During this radial movement the number of tracks crossed are is counted. The counting is continued until a predetermined number of the pulses generated by the frequency generator have been generated. A calculated frequency generator track number is then obtained by dividing the counted number of tracks by the predetermined number of pulses generated by the frequency generator, i.e., calculating a unit track number of the disk per a single movement of the pickup, that is, the number of tracks the pickup moves per pulse generated by the frequency generator. The calculated frequency generator track number is stored in memory used to control the frequency generator for jumping the pickup during a search for a target track.