Abstract: A clearance heater of a write head is engaged with a boosted current that exceeds a steady-state current. The steady-state current causes the write head to maintain a desired clearance over a disk during writing, the boosted current being applied before a start of the writing. The boosted current is monotonically decreased before the start of the writing and the steady-state current is applied to the heater after the start of the writing.

Abstract: A slider has a read transducer comprising first and second shields surrounding a read sensor. The first shield faces a substrate. A first end of the reader stack is at a media-facing surface of the slider and a second end of the reader stack faces away from the first end. A heater is located farther away from the media-facing surface than the second end of the read transducer. The heater is configured to control a thermal protrusion of the read transducer from the media-facing surface. A heat sink is located between the first shield and the substrate.

Abstract: A signal is monitored that provides an indicator of disturbance affecting a hard disk drive. In response to determining that the indicator of the disturbance satisfies a threshold, a lattice recursive least squares computation is applied to the signal to determine at least one notch frequency. A notch filter is formed using the at least one notch frequency. The notch filter is used by a servo controller loop that positions a read/write head over a disk of the hard disk drive. The notch filter is applied to the servo control loop for subsequent positioning of the read/write head.

Abstract: The present disclosure relates to systems and methods of device firmware update effects as seen by a computing host. In one example implementation according to aspects of the present disclosure, a method includes executing a first firmware received from a computing host, the first firmware including a first firmware revision identifier, executing a second firmware received from the computing host, and returning the first firmware revision identifier to the computing host during the execution of the second firmware and before an event occurs. The returning the first firmware revision identifier enables the computing host to continue executing without detecting an error in response to a change in a value of a returned firmware revision identifier throughout the execution of the first firmware and during execution of the second firmware.

Abstract: A pattern is pre-written using a pre-erase or pre-conditioning magnetic field applied within at least part of a target track of a hard disk via a first write transducer prior to the target track being written. Subsequent to the pre-writing, target user data is written to the part of the target track.

Abstract: An apparatus comprises a laser diode configured to generate modulated light during a write operation in response to receiving modulated current having a mean amplitude that varies or is constant. A slider is configured for heat-assisted magnetic recording and to receive the modulated light. A writer heater of the slider is configured to receive power during the write operation having a magnitude that varies or is constant. A sensor is situated on or within the slider. The sensor is configured to produce a sensor signal representative of output optical power of the laser diode. Measuring circuitry is coupled to the sensor and configured to measure a change in the sensor signal indicative of a laser mode hop during the write operation.

Abstract: A method of forming a feature in a void, the method including filling the void having at least one sloped wall with a polymeric material; forming a layer of photoresist over the polymeric material; forming a gap in the layer of photoresist; and etching the polymeric material exposed by the gap in the layer of photoresist to form a feature.

Abstract: A data storage device can employ one or more transducing heads that have a data reader and data writer each connected to a substrate of the transducing head. The substrate can be electrified with a predetermined surface charge by a charge circuit of the transducing head to maintain, or alter, a head-media spacing.

Abstract: A storage chassis may be adapted, or configured, to secure a plurality of carrierless devices (e.g., without the use of a carrier or drive tray) received thereby. The storage chassis may include a base, a first drive wall coupled to and extending from the base, and a second drive wall coupled to and extending from the base. Each of the first and second drive walls may include a top edge spaced away from a bottom portion of the base. The base, the first drive wall, and the second drive wall may define a row of drive slots and each drive slot may be configured to receive a carrierless device. Further, the storage chassis may include a plurality of locking units configured to extend across corresponding drive slots between the top edge of the first drive wall and the top edge of the second drive wall.

Abstract: A data reader may have a magnetoresistive stack with a magnetically free layer decoupled from a first shield by a cap. The cap can have one or more sub-layers respectively configured with a thickness of 4 nm or less as measured parallel to a longitudinal axis of the magnetoresistive stack on an air bearing surface.

Abstract: Bottom tracks are written to a recording medium using a first setting of a microwave assisted magnetic recording (MAMR) head. Top tracks are interlaced between and partially overlapping the bottom tracks using a second setting of the MAMR head, the second setting resulting in a narrower track width than the first setting.

Abstract: A method for using a variable-size flash translation layer. The method includes reading an entry in a map based on a read logical block address in a read request to obtain both a physical address of a particular page in a memory and information regarding compressed data with a variable size; converting the information to both an address in the particular page and a number of read units in the memory that contain the compressed data; and reading the compressed data from at least the particular page in the memory based on the address and the number of read units.

Abstract: An apparatus includes a memory and a controller. The memory may be configured to store data. The controller may have a host interface circuit connectable to a host. The controller may be configured to process a plurality of input/output requests to read/write to/from the memory, compute a first bandwidth consumed by the controller while servicing the memory with one or more tasks hidden from the host, compute a second bandwidth of the memory that is available to the host through the host interface circuit based on the first bandwidth consumed by the controller, receive a hypothetical consumption of additional bandwidth by the host, update the second bandwidth based on the hypothetical consumption, and report the second bandwidth as updated to the host through the host interface circuit.

Abstract: Methods and apparatus are provided for adaptive read threshold voltage tracking with separate characterization on each side of a voltage distribution about a distribution mean. A read threshold voltage for a memory is adjusted by determining statistical characteristics of two adjacent memory levels based at least in part on a type of statistical distribution of the memory levels and a distribution of data values read from cells using a plurality of read threshold voltages, wherein the statistical characteristics of the two adjacent memory levels are characterized independently on two sides about at least one mean of the statistical distribution; computing an adjusted read threshold voltage associated with the two adjacent memory levels by using the statistical characteristics of the two adjacent memory levels; and updating the read threshold voltage based on the adjusted read threshold voltage. The adjustment is optionally performed responsive to one or more read errors.

Abstract: A directional control valve comprising: a body, an actuator configured to switch the directional control valve between two or more states, a manual activation button configured to initiate actuation of the actuator when pressed, a safety member configured to slide along a guide of the body between a first position and a second position, a coupling member configured to couple the directional control valve to other directional control valves, and a guard removably disposed between the safety member and the coupling member. The safety member prevents the manual actuation button from being actuated when it is in the first position and the manual actuation button can be manually actuated when the safety member is in the second position. In addition, the guard is configured to prevent the safety member from sliding to the second position when the guard is disposed between the safety member and the coupling member.

Abstract: A method involves determining bit aspect ratios for interlaced tracks written to a magnetic recording medium. The interlaced tracks include top tracks that are written partially overlapping with bottom tracks. Isolated test tracks are written at first different bit aspect ratios to determine a top bit aspect ratio that achieves a first target areal density for the isolated test tracks. Test tracks are written at second different bit aspect ratios to determine a bottom bit aspect ratio that achieves a second target areal density for the test tracks. Top test tracks of the test tracks are written at the top bit aspect ratio. The top and bottom bit aspect ratios are selected to subsequently write partially-overlapping tracks on the magnetic recording medium.

Abstract: Systems and methods for calculating random values based on data errors are presented. A message collection circuit may collect sets of data having data errors and store them to a memory. The stored sets of data may then be processed to produce a random value based on errors in the sets of data. The random value(s) may be provided to random number generator(s), encryption circuit(s), or other circuit(s).

Abstract: Pseudorandom bit sequences are recorded to a heat-assisted recording medium at a laser power that is stepped while recording the pseudorandom bit sequences. The pseudorandom bit sequences are read from the heat-assisted recording medium to determine timing differences between bits written before and after the laser power is stepped. A thermal gradient of bits written to the heat-assisted recording medium is determined based on the timing differences.

Abstract: Apparatus and method for data security in a data storage device. In some embodiments, an alternating pattern is written to a magnetic recording medium as a sequence of symbols at a selected clock rate. A repeatable magnetic signature is generated by reading the alternating pattern from the medium, the magnetic signature having relatively weak entropy at boundaries of the symbols. A multi-bit digital sequence is extracted from the repeatable magnetic signature, the digital sequence having relatively strong entropy. The digital sequence is stored in a separate memory coupled to the medium. Access to data stored on the medium is authenticated responsive to the digital sequence stored in the separate memory.

Abstract: A method includes receiving a first set of testing data associated with a first group of electronic devices. The first set of testing data is generated during a tuning test applying a first range of testing parameters. The method further includes receiving a second set of testing data associated with the first group of electronic devices. Further, the method includes determining, based on the first set of testing data and the second set of testing data, a second range of testing parameters that is less than the first range of testing parameters. The method includes testing a second group of electronic devices using a tuning test applying the second range of testing parameters.