Abstract: A disk drive is disclosed comprising a disk including a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises a servo preamble. A head is actuated over the disk, wherein the head is operable to generate a read signal. The disk drive further comprises control circuitry including an analog cutoff filter operable to filter the read signal to generate a filtered read signal. The filtered read signal is sampled to generate read samples. During a normal operating mode, the analog cutoff filter is configured to have a first bandwidth. During a measurement mode, the analog cutoff filter is configured to have a second bandwidth greater than the first bandwidth, and the read samples representing at least part of the servo preamble are processed to measure a signal-to-noise ratio (SNR) and/or a fly height of the head.

Abstract: A method of calculating a Head Media Separation (HMS) from a preamble of embedded servo sectors in a disk drive may include steps of reading the preamble, the read preamble being amplified by a variable gain amplifier (VGA) set at a predetermined gain; transforming samples of the read preamble into a first and a second frequency using a discrete time-to-frequency domain transform such as a Discrete Fourier Transform (DFT); calculating the ratio of the magnitude of the discrete time-to-frequency domain transform of the first frequency to the magnitude of the discrete time-to-frequency domain transform of the second frequency; determining the HMS from the calculated ratio, and enabling the predetermined gain to be updated in synchronism with the transforming step.

Abstract: A method, apparatus, and system are provided for implementing magnetic defect classification using phase modulation for hard disk drives. A magnetic media readback signal of a hard disk drive is processed to identify predefined phase modulation (PM) characteristics to implement magnetic defect classification of magnetic media bump and pit defects.

Abstract: A method for quasi-static testing a magnetic recording head read sensor is described. The method includes applying a first voltage to a heater in the magnetic recording head and measuring an output of the magnetic recording head read sensor while applying the first voltage to the heater and recording the measured output as a first set of measurements. The method further includes applying a second voltage to the heater in the magnetic recording head and measuring the output of the magnetic recording head read sensor while applying the second voltage to the heater and recording the measured output as a second set of measurements. The first and second sets of measurements are then compared.

Abstract: An estimation method includes a heating step in which a recording bit, on which a reference signal is recorded, is heated under each of heating conditions having different heating temperatures, the recording bit being at least one recording bit in the magnetic recording medium, and a measurement step in which a signal intensity with respect to the reference signal recorded in the recording bit after heating is measured under each of the heating conditions of the heating step. Based on the signal intensities with respect to the reference signal respectively measured in the measurement step, the distribution width of the Curie temperatures of the plurality of magnetic grains that form the magnetic recording layer is estimated.

Abstract: A drop sensor detects a drop of a device. When the drop of the device is detected, a sub CPU allows a counter to count a drop time. When the device drops for a predetermined time or more, the sub CPU controls a regulator so that the regulator forcibly disconnects an electric power to be supplied to a hard disc, and writes a drop occurrence flag into a nonvolatile memory. When the power supply is again turned on, a main CPU allows a display section to display information indicating that the power supply is disconnected due to the drop of the device.

Abstract: Methods and systems for measuring variations in head-disk clearance in a hard disk drive. User generated data is randomly selected at a controller of the hard disk drive wherein the user generated data is stored on a disk associated with the hard disk drive. A reference point associated with the user generated data is stored on a storage medium associated with the hard disk drive. The user generated data is read at the controller. The user generated data is analyzed with the reference point using more than two frequencies, at the controller, to obtain a variation in measurement of the head-disk clearance.

Abstract: The present invention enhances reliability by correcting a write error due to unstable oscillation of a spin torque oscillator. In the present invention, a resistance value of a spin torque oscillator is monitored to detect that oscillation becomes unstable during recording. When a measured resistance value is out of a predefined normal range, information for which the recording operation is already performed is rewritten.

Abstract: A method comprises generating first and second magnetic field components in a magnetic medium, the second magnetic field component substantially opposite the first. A pattern is written onto the magnetic medium, and a signal is generated by reading the pattern. The magnitude of the second magnetic field component is controlled based on an asymmetry of the signal.

Abstract: An inspection device or inspection method for a magnetic head or magnetic disc which can form a servo pattern applicable to a write system, and a magnetic disc recording device or magnetic disc recording method. In inspection or recording of a magnetic disc, which rotates the magnetic disc, a servo pattern is written into a servo pattern region of the magnetic disc by a write-in element of a magnetic head, and is read by a read-in element of the magnetic head. Servo following of a position of the magnetic head on the magnetic disc is performed based on the servo pattern which comprises a plurality of patterns. The patterns are written-in with a first frequency for causing the patterns to be subjected to the servo following and, the patterns are overwritten with a second frequency different from the first frequency, except a servo following width used in the servo following.

Abstract: A method for accurately adjusting skew in the presence of tape motion includes performing a calibration run of magnetic tape in a tape drive. During the calibration run, the method records skew readings at selected intervals. The method then finds a range associated with the skew readings, such as by finding a high and low skew reading. The method then finds a center point of the range, and a difference between the center point and a desired center point. The method applies the difference to each recorded skew reading to generate a target skew reading for each recorded skew reading. The method generates a skew error signal that reflects the difference between each recorded skew reading and each corresponding target skew reading. The skew error signal will generally be consistent even as the tape moves, thereby allowing a technician to easily adjust and optimize the skew.

Abstract: A disk storage apparatus according to one embodiment includes a head, a storage device, a write module and a controller. The head writes data on a disk. The storage device has a storage area for temporarily storing the data written by the head. The write module writes data to tracks on a disk, while partially overlapping the data with previously written data to adjacent track. The controller detects a drift-off write of the head while writing data, determines a drift-off write area in which the drift-off write is occurred, and protects the data written in the storage area, if the data is written in the drift-off write area.

Abstract: A disk controller for a hard disk drive includes a disk formatter interfaced via an NRZ bus to a read channel for the disk. The disk formatter includes an LFSR accumulator coupled to the NRZ bus, as well as an LSFR generator that generates synthetic test data for the disk formatter. Under control of a test flag which signifies a test mode, the LSFR generator generates synthetic test data, which is used by the disk formatter to drive the NRZ bus. The LSFR accumulator accumulates data on the NRZ bus, together with data on servo information and sector information. An interface is provided through which the accumulated information is provided to test equipment, for offline analysis of the accumulated information, so as to confirm proper operation of the disk subsystem and/or to detect failures therein.

Abstract: Monochromatic or multichromatic images may be created on surfaces. The surface is moved to first, second and third stations. The surface is electrically biased, and powder is transferred to the surface electrostatically at the first station. The powder is fused or sintered selectively on the surface at the second station. Unfused or unsintered portions of the powder are removed from the surface at the third station.

Abstract: A method of storing data in a storage medium includes determining a compensation unit for a portion of the storage medium, reading a first set of bit values from the portion of the storage medium, determining a compensation value based at least in part on an erroneous bit value of the first set of bit values and the compensation unit, and storing the compensation value in association with the portion of the storage medium.

Abstract: According to one embodiment, a disk storage apparatus includes a first storage device, a second storage device, and a controller. The first storage device stores data for use in determining influence imposed on tracks peripheral to a designated track in which data should be written on a disk. The second storage device has a nonvolatile cache area for temporarily storing data. The controller performs a cache process of storing the data in the nonvolatile cache area if the influence is determined, from the data, to exceed a reference value, in preparation for writing the data in the designated track.

Abstract: A test rack for a storage device testing system includes a plurality of test slot carriers. Each of the test slot carriers includes a plurality of test slot assemblies. The test slot assemblies are configured to received and support storage devices for testing. The test rack also includes a chassis. The chassis includes a plurality of carrier receptacles for releasable receiving and supporting the test slot carriers. The test slot carriers are interchangeable with each other among the various carrier receptacles.

Abstract: Various embodiments of the present invention provide systems and methods for calibrating write pre-compensation values.

Abstract: Approaches are provided for a hard-disk drive (HDD) and a method for measuring the contact potential between head and disk interfaces within a hard-disk drive. In one example, a voltage bias is applied to a head slider at discrete increments, and the touchdown power is determined at each increment. The voltage bias at which the TDP maximizes equals the inverse polarity of the inherent contact potential between the head slider and disk, and this value may be used to apply a voltage that neutralizes the contact potential.

Abstract: A magnetic tape apparatus performs at least one of data reading processing and data writing processing on LTO wound around a reel. The magnetic tape apparatus causes the reel to rotate and move the LTO to a position at which the data writing processing or the data reading processing can be performed by a magnetic head. The magnetic tape apparatus is arranged along the width direction of the magnetic tape of LTO, which is driven, to detect medium abnormality that occurred in either a start-end or a stop-end in the width direction of the magnetic tape.

Abstract: Various embodiments of the present invention provide systems and methods for data processing. For example, a data processing system is discussed that includes: a buffer circuit, an equalizer circuit, a data processing circuit, and a retry determination circuit. The buffer is operable to store digital samples as a buffered output, and the equalizer circuit is operable to equalize the buffered output using a first equalization target to yield a first equalized output, and to yield a second equalized output using a second equalization target. The retry determination circuit is operable to select the second equalization target based at least in part on an occurrence of an error.

Abstract: Various embodiments of the present invention provide systems and methods for detecting contact. For example, a method for detecting head contact is disclosed that includes: receiving an interface signal operable to indicate a physical contact between a sensing device and a storage medium; band pass filtering a data set derived from the interface signal to yield a band pass filtered output; comparing the band pass filtered output to a level threshold to yield a comparator output; summing the comparator output with at least one prior instance of the comparator output to yield an aggregated value; and comparing the aggregated value to an aggregate threshold to yield a contact output.

Abstract: A hard disk of a computer system includes a platter, a spindle motor, a magnetic head, a cache, an interface for connections, and a main control chip. The main control chip within the hard disk detects whether or not each of the cache, the platter, the spindle motor, and the magnetic head are individually working normally. When any of the cache, the platter, the spindle motor, and the magnetic head is not working normally, the main control chip outputs a signal accordingly to an external device connected to the interface.

Abstract: An apparatus comprises a root mean square (‘RMS’) value generator; an integrator coupled to the RMS value generator; a sample and hold switch coupled to an output of the integrator; a capacitor coupled between the sample and hold switch and a ground; an input of the analog to digital convertor (‘ADC’) coupled to the capacitor; an adder coupled to an output of the ADC; a register, wherein an output of the register is coupled to an input of the adder; and wherein an output of the adder is coupled to an input of the register; and a logic coupled to the register for comparing an output of the register to an RMS threshold value for determining whether a touch-down has occurred.

Abstract: A storage device includes a storage medium having a plurality of tracks of data. Reading apparatus for reading a current track of data that has been subject to previous encroachment to an extent from at least one adjacent track of data includes a write head that writes interfering data to the adjacent track of data while intentionally encroaching at least to that extent onto the current track of data, and circuitry that recovers data on the current track of data using the interfering data. A method for reading a current track of data, that has been subject to previous encroachment to an extent from at least one adjacent track of data, includes writing interfering data to the adjacent track of data while intentionally encroaching at least to that extent onto the current track of data, and recovering data on the current track of data using the interfering data.

Abstract: A method of writing data to a storage device includes writing current data to a first track of data, monitoring write head position, and on detection of encroachment of the write head position on a second track of previously written data, using the current data to recover the previously written data on the second track, and rewriting the current data to the first track. A storage controller includes a device controller that writes data to a current track of data on a storage device. The device controller monitors write head position. On detection of encroachment of the write head position on a second track of previously written data uses the current data to recover the previously written data on the second track, and rewrites the current data to the first track. A storage system includes a storage medium having a plurality of tracks of data thereon, and a storage controller.

Abstract: A system provides tape having at least one longitudinal data track and a tape head operative to move along a single axis line lateral to the data track. The storage tape moves across the tape head. The tape head moves along the axis line such that a write element of the tape head intersects the data track and writes data to a section of the data track. A controller determines that the storage tape is skewed. In response to determining that the storage tape is skewed, the controller determines a position along the axis line and a time to move the tape head such that the read elements intersects the section of the data track. At the determined time, the tape head pauses writing of data and moves to the position along the axis line. The tape head reads the section of the data track to verify the written data.

Abstract: A tool for testing a magnetic disk for use in a magnetic disk drive. The tool detects surface defects or asperities by detecting a change in electrical resistance corresponding to a temperature change in a thermally sensitive layer. The apparatus includes a slider body having a thermally insulating layer formed on an air bearing surface of the slider body and a thermal sensor layer formed on the thermally insulating layer. The thermally insulating layer prevents thermal heat spikes in the thermal sensor layer (such as resulting from contact with an asperity) from dissipating quickly into the slider body itself. The thermal sensor layer is a material that exhibits a change in electrical resistance in response to a change in temperature and is preferably a PTC thermistor material which exhibits a large change in electrical resistance when a transition temperature has been reached.

Abstract: A method of correcting repeatable run out (RRO) errors for a HDD in which RRO data is instead stored in consolidated form within the reserved area of the disk, instead of storing RRO data in the servo patterns for each HDD track or sector. RRO data is preferably stored in the reserved area of a hard disk drive in compressed form. The compressed RRO data is subsequently read into DRAM in compressed form and then decompressed for use. Predictive techniques determine what compressed RRO data is needed for upcoming read/write operations.

Abstract: A tape edge sensor system for detecting lateral movement of a storage tape includes a first photo-emitter, a first photo-detector positioned to receive a first light signal from the first photo-emitter, a first aperture disposed between the first photo-emitter and the first photo-detector, and a feedback system connected to the first photo-emitter and the first photo-detector. The first aperture defines a first region at a first tape edge through which the first light signal is received by the first photo-detector with the storage tape blocking a portion of the first light signal. The feedback system determines the first photo-detector's signal amplitude and adjusts the first light signal such that the first photo-detector signal amplitude is within a first average amplitude range. A tape edge sensor system using compensating photo-interrupters is also provided.

Abstract: Methods and architecture for monitoring hard disk drive operation is provided. The hard disk drive system provided includes a spindle, a head and a disk with a disk medium including a buried servo layer having a first frequency of data on a first track and a second frequency of data on a second track, the second track adjacent to the first track. The method includes the steps of writing a wide track pattern having a predetermined frequency on a track of a hard disk drive medium, generating a readback signal by reading the pattern from the track, processing the readback signal by mixing the readback signal with a reference signal to obtain a mixed signal having a summed signal and a difference signal, and filtering the mixed signal by a filter centered around the difference signal to generate a measurement signal corresponding to a relative speed change of the spindle and a head-to-disk motion.

Abstract: According to one embodiment, there is provided a method for determining whether a defect on a disk in an apparatus includes head is a recess or a protrusion. The method detects a first defect on the disk using a read element provided in the head. The method detects a second defect on the disk using a head disk interference sensor provided in the head. The method further determines whether a third defect is a recessed defect or a protruding defect based on a ratio between a first width of the first defect in a radial direction on the disk and a second width of the second defect in the radial direction of the disk. The third defect is identified based on the first defect and the second defect.

Abstract: Embodiments described herein include systems and methods for correcting for errors caused by disturbances to disk drives, such as disturbances due to shocks or vibrations incident on the drive. For example, systems and methods described herein advantageously correct for corruption to current data as well as previously written. Data may be rewritten in the current track that was being written to when the disturbance occurred, and may also be rewritten to one or more nearby previously written tracks, such as one or more adjacent tracks. According to some aspects, the direction of head deviation is used to select the appropriate corrective action.

Abstract: Various embodiments of the present invention provide systems and methods for phase compensated harmonic sensing. For example, a circuit for harmonics calculation is disclosed that includes a phase difference estimation circuit and a phase offset compensation circuit. The harmonic calculation circuit is operable to calculate a first harmonic based on a periodic data pattern and a second harmonic based on the periodic data pattern. The phase difference estimation circuit operable to calculate a phase difference between the first harmonic and the second harmonic. The phase offset compensation circuit operable to align the second harmonic with the first harmonic to yield an aligned harmonic.

Abstract: A method and system for a sequence estimation in a receiver, such as for use when receiving a sample of a received inter-symbol correlated (ISC) signal corresponding to a transmitted vector of L symbols, with L being a integer greater than 1, and with symbol L being a most-recent symbol and symbol 1 being least recent symbol of the vector. A plurality of candidate vectors may be generated, wherein element L-m of each candidate vector holding one of a plurality of possible values of the symbol L-m, with m is an integer greater than or equal to 1, and elements L-m+1 through L of each candidate vectors holding determined filler values. A plurality of metrics may be generated based on the plurality of candidate vectors, and based on the generated plurality of metrics, a best one of the possible values of the symbol L-m may be selected.

Abstract: The present invention realizes reduction of position information demodulation errors caused by the eccentricity of the magnetic disk and improvement of position signal detection accuracy, as well as enabling quick eccentricity clock correction for arbitrary clock frequencies. An inspection device in accordance with the present invention comprises: a servo demodulation unit which demodulates servo information; a PLL clock generating unit which generates a reference clock and supplies the reference clock to the servo demodulation unit; and a tester control unit. The PLL clock generating unit includes an eccentricity correction circuit for correcting the frequency of the reference clock depending on the eccentricity of the magnetic disk. The tester control unit generates correction data for correcting the frequency of the reference clock, multiplies the correction data by the inverse of a transfer function of the PLL clock generating unit, and supplies the product to the eccentricity correction circuit.

Abstract: A disk drive is disclosed comprising a head actuated over a disk including a plurality of contiguous servo tracks for defining a plurality of data tracks. A first write command comprising first write data is received, and a first density of first data tracks over a first plurality of the contiguous servo tracks is selected, wherein the first write data is written to the first data tracks. A second write command comprising second write data is received, and a second density of second data tracks over the first plurality of the contiguous servo tracks is selected, wherein the second density is different than the first density. The second write data is written to the second data tracks.

Abstract: A method is described for allowing disk drives, such as shingle-written magnetic recording (SMR) drives, to be shipped for customer use with portions of the magnetic media being left untested. The testing is then completed by the drive self-testing in the field. The drive is made functional at the factory by fully testing at least one operational set of regions including an I-region, an E-region and a write cache region. The operational set of regions works as a separate self-contained virtual disk drive and can be used immediately. The remaining untested areas on the media can be tested in the field by a background task and/or when the first write command is received that requires a new track or operational set of regions (on-the fly testing).

Abstract: A hard disk drive (HDD) including a slider. The slider includes a resistive temperature detector (RTD) configured to detect a temperature generated by one or more of slider spacing and contact with a media of said HDD. HDD also includes a slider signal controller configured to control bias signal of a slider with respect to a media potential, a real-time media-disk fly-height and contact detector configured to detect one or more of temperature generated by real-time media-disk slider spacing and real-time media-disk contact, and a real-time relative fly-height determiner configured to detect real-time relative fly-height of the slider based on analysis of a modulated portion of a high-frequency signal coupled to an element of the slider.

Abstract: A shingled magnetic recording (SMR) disk drive has concentric shingled data tracks having data sectors with physical block addresses (PBAs), with the tracks being arranged in annular bands separated by annular inter-band gaps. The disk drive also has an on-disk extended cache region and may have writable inter-band cache (IBC) tracks in the inter-band gaps. A count is maintained in memory for each band and each IBC, and the count is incremented for each writing to a band or an IBC. When a count for a band or IBC reaches a predetermined threshold, the data is read from the tracks in the boundary region of the adjacent band that are within the range of the FTE and that data is then written to the extended cache. The FTE-affected tracks are then invalidated, meaning that PBAs can no longer be assigned to the data sectors in those tracks.

Abstract: An apparatus includes: a signal module to process data signals corresponding to data on a storage medium to generate signal samples; a defect detector to receive the signal samples, apply a set of parameters to the signal samples, and generate an output based on a count of signal samples that are associated with abnormal signal quality, the signal samples that are associated with abnormal signal quality being included in a portion of the signal samples determined in accordance with the set of parameters; and circuitry to receive the output from the defect detector and identify one or more media defects based on the output.

Abstract: A method, apparatus, and system for implementing channel signal processing assist with an embedded contact sensor (ECS) in hard disk drives. An ECS signal is captured during write and idle operation of the hard disk drive. A read channel monitors changes in the ECS signal providing a clearance monitor function for insuring write integrity.

Abstract: An indication circuit includes a control unit, a decode unit, and a display unit. The control unit is configured to obtain a transfer rate of a hard disk drive (HDD) from a power on self test (POST) code transmitted by a basic input-output system (BIOS) chip, and transmit a rate signal corresponding to the transfer rate of the HDD. The decode unit is configured to decode the rate signal to obtain the transfer rate, and output a decode signal corresponding to the transfer rate. The display unit is configured to display the transfer rate.

Abstract: In an optical tape drive having optical heads for writing data in tracks on an optical tape, each track having an off-track threshold, a system and method are disclosed for off-track write prevention. The system includes multiple actuators, each actuator configured to control a position of an associated optical heads. The system also includes a controller configured to determine a position of each of the optical heads relative to an associated track on the optical tape and to prevent, in response to an event causing an optical heads to have a position outside the off-track threshold of the associated track, only that optical head from writing data to the optical tape and to buffer a stream of data for that optical head for later processing.

Abstract: A disk drive is disclosed comprising a head actuated over a disk. An analog touchdown (TD) signal is compared to a TD threshold in order to generate a calibrated TD threshold for a plurality of different dynamic fly height (DFH) settings. The calibrated TD thresholds and corresponding DFH settings are fitted to an estimated curve. At least one of the TD threshold and the DFH setting is adjusted, and a corresponding next point in the estimated curve is predicted. An actual next point corresponding to the adjustment is determined, and a prediction error is generated based on a difference between the predicted next point and the actual next point. A touchdown of the head on the disk is detected when the prediction error exceeds a prediction threshold.

Abstract: A computer-implemented method, apparatus and computer-program product for writing data to a tape data storage medium. The method comprises providing a system service that an application invokes to handle data synchronization events associated with writing a group of files to the tape medium; keeping track of the files and data blocks in each file while writing the files to the tape medium based on file boundaries; and responsive to a data writing failure, invoking the system service to determine the files affected by the data writing failure.

Abstract: Disclosed is a method of storing data on a tape medium in at least one data recording session employing a tape drive apparatus operable to record the data in accordance with a format specifying an unused area of the tape medium. The method comprises formatting the tape medium according to the format, and recording a tape medium identifier in the specified unused area of the tape medium.

Abstract: Techniques to use a model associating condition of a tape head with tape head usage are described. The tape head is for use in a magnetic tape drive. In examples, a condition of the tape head is determined using a model. In examples, the model fits determined values of the condition parameter.

Abstract: A defect inspection is performed for each of glass substrates by a surface defect detector. The distance from the center of the glass substrate to a detected defect, as a radius of a nonmagnetic region to be formed circular, is recorded along with an ID assigned to the glass substrate. Such defect information is recorded in a defect list using a printer or recorded in an RFID tag using an RFID writer. The defect list or the RFID tag is attached to a glass-substrate case. Each glass substrate and its defect information are in one-to-one correspondence and are provided to a customer as a magnetic disk manufacturer. Based on the obtained defect information, the customer manufactures magnetic disks each being a discrete track recording medium having the nonmagnetic region formed at the position where the defect is present.

Abstract: A hard disk drive with a read channel that averages data before the data is provided to a viterbi detector of the channel. Averaging the data reduces the zero mean noise in the data.