Western Digital Technologies, Inc.

Alain Chahwan

Duc T Phan

Chuanwen Ji

Jianguo Zhou

Niranjay Ravindran

Wei Xi

Yanan Huang

Robert P Ryan

Weldon Mark Hanson

Timothy A Ferris

Orhan Beker

Kuang-Yang Tu

Mingji Lou

Hien T Chu

Don Brunnett

Jifang Tian

Hideki Zaitsu

Min Chen

Choo-Bhin Ong

Alexander Babinski

Jonathan V Nguyen

Erik Jesper Eklund

Shan Tang

William Flynn

Qixing Zheng

So Ogiwara

Meiman Lin Syu

Toshihisa Komai

Shang-Chen Wu

Kevin Chiteh Chao

Various illustrative aspects are directed to a data storage device comprising data tracks N and N&#x2212;1, and one or more processing devices, configured to measure signal to noise ratio (SNR) metrics for corresponding sectors of at least one of the data tracks N&#x2212;1 and N, where the measuring is based at least in part on reading one or more of the data tracks N and N&#x2212;1 using one or more read offsets, estimate a position of at least one of the data tracks based on measuring the one or more SNR metrics, and reconstruct one or more of risk values for at least a portion of the data track N&#x2212;1 based on the one or more SNR metrics for the data track N&#x2212;1, and a position error signal (PES) for at least one of the data tracks N&#x2212;1 and N based on the corresponding estimated positions.

Position and risk reconstruction in shingled magnetic recording data storage devices

A data storage device is disclosed comprising a head actuated over a disk comprising a plurality of data tracks, including consecutive data tracks N&#x2212;1 and N. A first write to data track N is performed using a first position error signal (PES) representing a position of the head relative to the data tracks. A track squeeze metric is generated for data track N&#x2212;1 based on at least the first PES of the first write. The track squeeze metric for data track N&#x2212;1 is accumulated during the first write, and the first write is aborted when the accumulated track squeeze metric for data track N&#x2212;1 exceeds a first threshold.

Data storage device aborting write operation based on accumulated track squeeze metric for adjacent data track

A data storage device is disclosed comprising a head actuated over a disk comprising servo data for defining a plurality of data tracks, including consecutive data tracks N&#x2212;1, N, and N+1. Data is written to data track N using a position error signal (PES) generated by reading the servo data, and a read track trajectory for data track N is generated based on the PES of the write. Data is read from data track N based on the read track trajectory for data track N.

Data storage device employing dynamic track trajectories

A device adapted to capture vehicle data or surveillance data that includes a disk and a Non-Volatile Solid-State Memory (NVSM). The vehicle or surveillance data is received in a buffer of the device for storage on the disk, and an input is received indicating a level of mechanical shock. It is determined whether the input indicates the level of mechanical shock exceeds a first threshold indicative of an impact. If the input indicates the level of mechanical shock exceeds the first threshold, the vehicle or surveillance data is stored in the NVSM from the buffer and a status is determined for storing data on the disk.

Mechanical shock mitigation for data storage

A method and system to monitor stability of magnetic head loading and unloading beside media for a data storage system is described. A shock sensor is utilized to detect shock during preloading of a magnetic head beside recording media, during loading of a magnetic head beside recording media, during pre-unloading of a magnetic head from the recording media, and/or during unloading of a magnetic head from the recording media. In an aspect, a desired pitch static attitude (PSA) and roll static attitude (RSA) of a slider is determined. In an aspect, the stability of a magnetic head is assessed and screened while on the fly and during head gimbal assembly (HGA) design and testing to improve overall data storage device reliability.

Method and system to monitor magnetic head loading and unloading stability for a data storage system

Example implementations described herein are related to methods for dynamically throttling host commands (up or down) to disk drives that include cache memory and rotating media, based on environmental conditions and/or drain rate from the cache memory to the rotating media, to provide consistent throughput for extended periods of time, and to avoid dramatic swings in performance from the pre-saturation state to the post-saturation state. The example implementations may be further extended to dynamically throttling host commands to devices that have HDD and SSD portions.

Dynamically throttling host commands to disk drives

A disk drive is disclosed comprising a first disk surface and a second disk surface, a first head operable to be positioned over the first disk surface, a second head operable to be positioned over the second disk surface, a first microactuator operable to actuate the first head, and a second microactuator operable to actuate the second head. The first head is actuated over the first disk surface using the first microactuator while processing a second sensor signal generated by the second microactuator, and the second head is actuated over the second disk surface using the second microactuator while processing a first sensor signal generated by the first microactuator.

Disk drive actuating first head microactuator while sensing signal from second head microactuator

An apparatus includes: a media; a head assembly over the media; a head actuation motor coupled to the head assembly; control circuitry, coupled to the head actuation motor, configured to position the head assembly; and a microphone, coupled to the control circuitry, configured to generate a signal in response to a vibration; and wherein: the control circuitry is further configured to: generate a compensation value based on the signal; and control the head actuator motor based on the compensation value.

Electronic system with vibration management mechanism and method of operation thereof

A computer system is disclosed comprising a disk drive comprising a head stack assembly (HSA), the HSA comprising a spindle motor for rotating at least one disk, and at least one head actuated over the disk. The computer system further comprises a host coupled to the disk drive, wherein the host comprises a microprocessor operable to first boot the host by reading boot data from a secondary storage device. After first booting the host, the microprocessor commands the disk drive to accumulate performance data for the HSA, and after accumulating the performance data, the microprocessor second boots the host by reading boot data from the HSA.

Booting from a secondary storage device in order to accumulate disk drive performance data

A disk drive is disclosed comprising a disk, a head, and control circuitry comprising a servo control system operable to actuate the head over the disk. A plurality of disturbance signals is generated in response to a vibration. A plurality of correlations is generated in response to each disturbance signal and an error signal of the servo control system. At least one of the disturbance signals is selected in response to the correlations. A feed-forward compensation value is generated in response to the selected disturbance signal, and the feed-forward compensation value is applied to the servo control system to compensate for the vibration.

Disk drive selecting disturbance signal for feed-forward compensation

A disk drive is disclosed comprising a head actuated over a disk, and control circuitry comprising a first shock detector and a second shock detector. A first number of shock events is detected based on the first shock detector, and when the first number of shock events exceeds an upper event threshold, a sensitivity of the first shock detector is decreased. After decreasing the sensitivity of the first shock detector, a second number of shock events is detected based on the second shock detector operating at a higher sensitivity than the first shock detector. When the second number of shock events falls below a lower event threshold, the sensitivity of the first shock detector is increased.

Disk drive implementing hysteresis for primary shock detector based on a more sensitive secondary shock detector

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 frequency component of a servo signal in the DSA servo loop is evaluated, wherein the frequency component is based on a peak frequency of an error rejection curve of the DSA servo loop. A degradation of the microactuator is detected based on the frequency component of the servo signal.

Disk drive detecting microactuator degradation by evaluating frequency component of servo signal

A disk drive is disclosed comprising a head actuated over a disk, and control circuitry including a vibration sensor. A position error signal (PES) is generated representing a radial location of the head over the disk, and the head is servoed radially over the disk in response to the PES. A first vibration signal is generated in response to the vibration sensor, and a second vibration signal in response to the PES. The first vibration signal is combined with the second vibration signal to generate a third vibration signal, and a vibration event is detected in response to the third vibration signal.

Disk drive evaluating multiple vibration sensor outputs to enable write-protection

A disk drive is disclosed wherein N data wedges of write data are buffered in a buffer. After writing at least two of the data wedges to the disk including a first data wedge and a second data wedge, a first servo metric value is measured when reading a first servo sector, and a second servo metric value is predicted based on the first servo metric value, wherein the second servo metric value corresponds to a second servo sector following the first servo sector. When the first servo metric value indicates a safe write condition and the second servo metric value indicates an unsafe write condition, the first data wedge is released from the buffer, and when the first servo metric value indicates a safe write condition and the second servo metric value indicates a safe write condition, the first and second data wedges are released from the buffer.

Disk drive releasing variable amount of buffered write data based on sliding window of predicted servo quality

A disk drive is disclosed comprising a disk comprising a plurality of servo tracks defined by servo sectors, wherein each servo sector comprises servo data and a servo compensation value. While servoing a head over a target data track during a write operation, a position error signal (PES) is generated at each servo sector based at least in part on the servo data. When the servo compensation value of a first servo sector is recoverable, the write operation is aborted when the PES generated at the first servo sector exceeds a first write unsafe threshold. When the servo compensation value of the first servo sector is unrecoverable, the write operation is aborted when the PES generated at the first servo sector exceeds a second write unsafe threshold less than the first write unsafe threshold.

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Irvine, CA, United States of America

Alain Chahwan