Abstract: A method comprises performing a write operation using a heat-assisted magnetic recording (HAMR) drive operating at a plurality of temperatures. The method involves measuring a metric of write performance subsequent to the write operation at each of the operating temperatures. The method also involves detecting one or more laser mode hops using the metrics, and determining a temperature at which each of the detected mode hops occurred. The method further involves storing the temperature for each detected mode hop in a non-volatile memory of the drive. The method may involve mitigating laser mode hopping, such as by the drive avoiding the stored temperature(s).

Abstract: A method of removing a magnetic domain from a slider structure, such as a shield of a write head, in a storage assembly having a storage media. The method includes passing the slider structure in close proximity to a region on the storage media having a magnetic field sufficiently large to remove a magnetic domain in the slider structure.

Abstract: Implementations disclosed herein provide a method comprising applying voltage to a read head during an unload state, detecting characteristic read head data, and storing the detected characteristic read head data in a buffer. In another implementation, the method further comprises performing a read retry operation in response to a read failure, reading the detected characteristic read head data from the buffer, determining if the detected characteristic read head data meets a threshold for a first predetermined criterion, performing a correction operation if the threshold for the first the first predetermined criterion is met, determining whether a media sector is read successfully, and ending the read retry operation if the media sector is read successfully.

Abstract: An apparatus and method provide for performing, using a heat-assisted magnetic recording head, multiple sequential writes to a recording medium, and recording a metric of write performance for each of the writes. The apparatus and method further provide for calculating fluctuations in the metric, detecting whether the head has a laser mode hopping problem using the metric fluctuations, and categorizing a severity of the laser mode hopping problem.

Abstract: A computer-implemented method, according to one embodiment, includes: receiving a first output signal from a write driver, the write driver having an operating voltage applied thereto, receiving a second output signal from a comparator circuit, the comparator circuit having a reference voltage applied thereto, comparing a voltage of the first output signal with a voltage of the second output signal, and detecting a high resistance condition in response to determining that the voltage of the first output signal is less than the voltage of the second output signal. According to the present embodiment, the high resistance condition indicates open and/or partially open circuitry in the write driver. Moreover, the operating voltage is equal to the reference voltage. Other systems, methods, and computer program products are described in additional embodiments.

Abstract: An information recording and reproducing apparatus including: a reproducing unit which generates a digital signal from an analog signal; a recording compensation unit which generates an expectation signal from the digital signal, detects a signal difference between the digital signal and the expectation signal, and adjusts a recording condition for recording the information; and a recording unit configured to record the information based on the recording condition. First recording compensation is performed for adjusting the recording condition using first recording where lengths of a preceding space and a succeeding space of a first recording mark and lengths of a preceding space and a succeeding space of a second recording mark are not in intersymbol interference; and second recording compensation is performed for adjusting the recording condition for the first recording mark using second recording data for changing a length of the second recording mark.

Abstract: A combination user data signal is read from two or more inner tracks of a recording medium via a first reader that encompasses the inner tracks. First and second data signals are read from respective first and second outer tracks that surround the inner tracks via second and third co-planar readers that are on a same head-gimbal assembly as the first reader. The first reader is centered between and downtrack from the first and second co-planar readers on the read head. User data is recovered based on the combination user data signal and the first and second data signals.

Abstract: A data writer may suspend a transducing head from an actuator. The transducing head can consist of a writer coil positioned proximal a write pole. A protruding signal may be passed through the write coil to contact a data storage medium with the transducing head. A write signal can be passed through the write coil to write a data bit on the data storage medium.

Abstract: Methods, systems, and computer program product embodiments for improving track-follow control in a tape storage system, by a processor device, are provided. In one embodiment, a method comprises, using an accelerometer to dynamically detect device vibration for determining whether to implement a vibration compensation control mechanism.

Abstract: A computer program product is provided for performing symbol timing recovery in a parallel recording channel system. The computer program product comprises a computer readable storage medium having program instructions embodied therewith. The program instructions are executable by a processor to cause the processor to receive a plurality of timing-error estimates for a plurality of read channels. Each of the timing-error estimates corresponds to one of the read channels. Also, the program instructions are executable by the processor to cause the processor to calculate a common phase based on the plurality of timing-error estimates. Moreover, the program instructions are executable by the processor to cause the processor to calculate a skew of a transducer array based on the plurality of timing-error estimates, and to calculate a different total phase estimate for each read channel based on the calculated common phase and the calculated skew of the transducer array.

Abstract: A dual-slot waveguide receives energy from a coupling waveguide. The dual-slot waveguide includes first and second light propagating regions of low-index material located side-by-side in a direction normal to a light propagation direction. Inner sides of the first and second light propagating regions are separated by a first region of a high-index material. Second and third regions of the high-index material surround outer sides of the first and second light propagating regions. A near-field transducer receives portions of the energy from the first and second light propagating regions.

Abstract: A nonvolatile memory comprising at least one ferromagnetic region having permeability which changes from a first state to a second state of lower permeability upon heating; at least one laser operatively associated with the at least one ferromagnetic region which selectively provides heat to the ferromagnetic region to change its p permeability; and a plurality of connectors operatively connected to the at least one laser and adapted to be connected to a current source that provides a current which causes the laser to change the at least one ferromagnetic region from a first state to a second state. Optionally, the memory is arranged as an array of memory cells. Optionally, each cell has a magnetic field sensor operatively associated therewith. Optionally, the nonvolatile memory is radiation hard. Also, a method of recording data by heating at least one ferromagnetic region to change its permeability.

Abstract: A data storage device can be tested while spinning at a variety of different speeds. Data may be written to a data sector with a transducing head while at least one disk of a data storage device spins about a spindle at a default speed. One or more tests can subsequently be executed on the disk by reading servo data stored on the disk while the disk spins at a test speed that is greater than the default speed.

Abstract: In one general embodiment, a computer-implemented method includes using, by the computer, a tape head and/or an actuator to detect the presence of external vibration. The method also includes selecting, by the computer, at least one frequency of interest, and using, by the computer, a discrete Fourier transform implemented as a Goertzel filter to determine a magnitude of the external vibration at the at least one frequency of interest. Compensation may optionally be applied to reduce an effect of the external vibration.

Abstract: A storage apparatus of an embodiment includes a magnetic disk, a head, and a controller. The head includes a writing unit that outputs a magnetic field to record write data into a recording region of the magnetic disk to which light is irradiated and a reading unit that reads read data from the recording region of the magnetic disk. Based on a first spectrum of first read data read by the reading unit at a first position of the magnetic disk and a second spectrum of second read data read by the reading unit at a second position which is a following position of the first position, the controller detects whether an offset of the writing unit occurs while writing into the recording region of the magnetic disk is performed by the writing unit.

Abstract: According to one embodiment, a magnetic recording and reproducing device includes a magnetic recording medium, a recording unit and a reproducing unit. The magnetic recording medium includes a first track and a second track, the first track extending in a first direction, the second track extending in the first direction and being arranged with the first track in a second direction intersecting the first direction. The first track includes first and second sub-tracks extending in the first direction. The second track includes third and fourth sub-tracks extending in the first direction. The second sub-track is disposed between the first and fourth sub-tracks. The third sub-track is disposed between the second and fourth sub-tracks. The recording unit records information in the first and second tracks. The reproducing unit reproduces first information recorded in the first track. The reproducing unit reproduces second information recorded in the second track.

Abstract: A light interference module includes an object lens, a first light-guiding element, and a second light-guiding element. The object lens is configured to project a signal light beam to an optical storage media. The first light-guiding element is configured to project a first reference light beam to the optical storage media, in which the first reference light beam and the signal light beam produce a first interference pattern on the optical storage media. The second light-guiding element is configured to project a second reference light beam to the optical storage media, in which the second reference light beam and the signal light beam produce a second interference pattern on the optical storage media, and the first interference pattern is different from the second interference pattern.

Abstract: In one embodiment, a data storage system includes a head configured to produce a signal representing data stored on a storage medium, a bank of noise whitening filters configured to apply one or more noise whitening filters to the signal to produce a filtered signal, and a data-dependent noise mean calculator configured to estimate a data-dependent noise mean from the filtered signal. The system also includes a branch metric calculator configured to perform one or more branch metric calculations on the filtered signal to produce one or more branch metrics, the one or more branch metric calculations accounting for the data-dependent noise mean. Moreover, the system includes an adaptive data-dependent noise-predictive maximum likelihood (D3-NPML) detector configured to generate an output stream from the one or more branch metric calculations.

Abstract: An apparatus comprises a slider and an optical waveguide formed in the slider and configured to receive light from a laser source. A near-field transducer (NFT) is formed on the slider at or near an air bearing surface (ABS) of the slider and optically coupled to the waveguide. A bolometric sensor is positioned proximate the NFT and exposed to at least some of the light. The bolometric sensor is configured to detect changes in output optical power of the laser source and contact between the slider and a magnetic recording medium.

Abstract: A cross-track profile of a known good test track on a recording medium is read during operation of a data storage device. Two or more center locations of the test track are determined at two or more different amplitude levels via a read transducer. A health condition of the read transducer is determined by comparing the two or more center locations of the test track with one another.