Hgst Netherlands, B.v.

Western Digital Technologies, Inc.

Abhishek Dhanda

Toshiki Hirano

Tetsuo Semba

Guoxiao Guo

Jie Yu

Satoshi Yamamoto

Jianguo Zhou

Sanghoon Chu

Zvonimir Z Bandic

Michael Grobis

Darya Amin-Shahidi

Wei Xi

Wei Guo

David Berman

Young-Hoon Kim

Michael A Chang

Gary Allan Herbst

Huanxiang Ruan

Russ A Quisenberry

Teddy T Chen

Honge Wang

Chris Gimenez

Eugene C Wu

Systems, software, devices, and methods of distributing a workload among available data storage devices in a thermal aware manner are described herein. More specifically, the examples herein discuss distributing the workload among the available data storage devices in a thermal aware manner that optimizes collective IOPs of the data storage devices in an enclosure. The thermal aware distribution of the storage operations is determined by a thermal model that predicts thermal characteristics of the data storage system based on inlet air characteristics of the enclosure, performance characteristics and thermal constraints of the data storage devices, and constraints of the workload.

Thermal aware workload scheduling

The examples described herein discuss various systems, software, devices, and methods for managing a primary command queue by ordering and/or reordering and distributing incoming commands based, at least in part, on positional information of one or more components of data storage devices. More specifically, in some embodiments, the examples discussed herein describe ordering and distributing incoming commands from a primary command queue in a position-aware manner that takes into account disk rotation (e.g., rotational position) and/or actuator head location for the various data storage devices of a data storage system enclosure. Among other benefits, ordering incoming commands at the primary command queue and distributing the ordered commands to individual device queues improves overall command execution latency.

Position-aware primary command queue management

A magnetic recording hard disk drive (HDD) includes, in addition to conventional servo sectors with position error signal (PES) blocks, data position error signal (DPES) blocks that are written into the data sectors when data is written in the data sectors of the data tracks. During readback the PES blocks from the servo sectors are decoded into PES values to allow the head to follow the servo track, while the DPES blocks are decoded to obtain DPES values that are used in the servo control loop to modify the head position so the head follows the center of the data track. In a shingled magnetic recording HDD, wherein the write head is at least two shingled data tracks wide, a DPES block is written in two radially adjacent data tracks when data is written into the data sectors of the shingled data tracks.

Magnetic recording disk drive with position error signal (PES) blocks in the data tracks for compensation of track misregistration

A hard disk drive with adjustable data track pitch has repeatable runout (RRO) fields stored in he servo sectors for each servo sector of each servo track, and thus without the need to store the RRO fields in the data tracks. The RRO fields for each servo sector have a radial length of at least two servo tracks (i.e., equal to or greater than twice the servo track pitch). The RRO fields in each servo track are shifted radially from RRO fields in adjacent servo tracks and circumferentially spaced from RRO fields in adjacent servo tracks. The read head reads two different RRO fields from the two servo tracks closest to the data track and the servo electronics interpolates a RRO value from these two RRO values. Thus even if the data track pitch is changed, RRO values can be obtained.

Magnetic recording disk drive with adjustable data track pitch and compensation for repeatable runout (RRO)

A data storage device with improved data storage densities, coupled with lower hard error and write-inhibit events is described. A feed-forward write inhibit (FFWI) method enables data tracks to be written more densely. Alternatively, the FFWI method may reduce the hard error and write inhibit events to improve data storage performance. A concept of virtual tracks enables the FFWI method to be applied to the writing of circular data tracks with non-circular servo tracks, or to the writing of non-circular data tracks with PES data from circular servo tracks&#x2014;in both cases, improvements to performance and/or storage densities are enabled. The FFWI method may also be applied to the case of both non-circular servo and data tracks.

Method and structure for improving performance and storage density in a data storage device

A two-dimensional magnetic recording (TDMR) disk drive has a disk with servo tracks with a track pitch that varies across the radius of the disk. The servo track pitch (STP) is related to the cross-track spacing (CTS) of the multiple read sensors in the TDMR head structure. The CTS is given by the equation: CTS=(CTO)cos &#x3b8;+(ATO)sin &#x3b8;, where &#x3b8; is the skew angle, and CTO is the cross-track spacing and ATO the along-the-track spacing of the read sensors at zero skew angle. The optimal variable STP profile results in track misregistration reduction because it allows each read sensor to read a different servo half-track and thus noise sources not correlated to noise sources read by the other read sensors. The servo tracks may be arranged into a plurality of annular bands, with the STP in each band being fixed and different from the STP in the other bands.

Two-dimensional magnetic recording (TDMR) disk drive with varying servo track pitch

A data storage device with compensation for coercivity variations in a magnetic disk storage medium is disclosed. Two procedures are executed to perform the coercivity compensation. In a first procedure, typically performed prior to writing of data, the coercivity at a number of locations on the disk is measured and stored. A second procedure writes data to locations on a magnetic disk storage medium having varying coercivities. To maintain writing widths within predefined limits, a writing parameter is varied according to a predetermined relationship between the value of the writing parameter and the coercivity. Choices of writing parameter comprise the writing current and fly height. The method may be employed for both data writing and self-servo writing of servo patterns.

Write current and fly height adjustment for compensating media coercivity variation

A disk drive is disclosed comprising a disk comprising a plurality of servo tracks, wherein each servo track comprises a plurality of servo sectors. A position of the head is measured based on the servo sectors, and a compensated position of the head is generated based on the measured position of the head and a fly height of the head. The head is actuated over the disk based on the compensated position of the head.

Disk drive compensating for non-linearity of a head based on a fly height of the head

A disk drive is disclosed comprising a disk and a head actuated over the disk. A burst metric is generated in response to a burst read signal. The burst metric comprises at least one of an alpha metric comprising a ratio of a first burst amplitude of a first phased based servo burst measured at a first radial offset to a second burst amplitude of a second phased based servo burst measured at a second radial offset, a harmonic metric comprising a ratio of a first harmonic of the burst read signal as the head is moved radially over the disk to a higher harmonic of the burst read signal as the head is moved radially over the disk, and a spiral track crossing metric comprising a first and second interval each representing a partial duration of the read element crossing a spiral track.

Disk drive evaluating burst metric

A magnetic recording hard disk drive has a servo clock that provides a varying frequency to the sync mark detector as a function of the radial position of the head as it crosses a servo section. The varying frequency compensates for circumferential misalignment of the sync marks in the servo sections. As the head moves radially across the tracks in a servo section during a seek, the frequency of the servo clock is continually adjusted based on the known radial velocity of the head and the known sync mark circumferential misalignment. The sync mark misalignment as a function of radius is measured as part of a calibration process, typically during disk drive manufacturing. The adjusted frequency adjusts the sample rate at which the sync mark detector samples the incoming sync marks.

Magnetic recording disk drive with frequency adjustment for misaligned servo patterns

A magnetic recording disk has nondata regions that contain a group of first nondata islands with one area and a magnetization in one perpendicular direction, and a group of second nondata islands with a smaller area and a magnetization in the opposite direction. To magnetize the nondata islands with the proper magnetization directions, a DC magnetic field much greater than the coercive field of the magnetic recording layer is applied in one direction to the entire disk to magnetize all of the nondata islands in the same direction. Then the disk is heated to a predetermined temperature, and while the disk is at this temperature, a second DC magnetic field less than the first DC magnetic field is applied for a predetermined time in the opposite direction to the entire disk. This reverses the magnetization direction of the smaller islands without switching the magnetization of the larger islands.

Magnetic recording disk with patterned nondata islands with different sizes and opposite polarity and method for making the disk

A method, apparatus and a data storage device are provided for implementing data track pitch adjustment for data written on a recordable surface of a storage device under operational vibration conditions. An operational vibration disturbance spectrum is detected during a write operation and the data track pitch is selectively adjusted based on the detected operational vibration disturbance spectrum. The adjusted track pitch information is saved and used during a read operation.

Method and apparatus for compensating vibration by adjusting track pitch

A disk drive is disclosed comprising a disk having a plurality of servo tracks defined by servo sectors, and a head actuated over the disk. The disk drive further comprises control circuitry comprising a servo control system operable to position the head over the disk. A disturbance is induced in the servo control system, and while positioning the head over the disk, a data track is accessed. The disturbance induced in the servo control system causes the data track to be non-circular relative to a rotation axis of the disk such that the non-circular data track crosses multiple of the servo tracks over a revolution of the disk.

Disk drive defining non-circular data tracks relative to a rotation axis of the disk

A disk drive is disclosed comprising a head actuated over a disk comprising a plurality of tracks defined by a plurality of servo sectors. An estimated track ID is generated representing an estimated radial location of the head. A high order Gray code in a first servo sector is detected, and errors in the high order Gray code are corrected using the estimated track ID to generate a corrected Gray code. The corrected Gray code is decoded into a first part of a detected track ID. A low order track code is detected in the first servo sector, and the low order track code is decoded into a second part of the detected track ID. The first part of the detected track ID is combined with the second part of the detected track ID.

Growing community of inventors

San Jose, CA, United States of America

Abhishek Dhanda