Hgst Netherlands, B.v.

Hitachi Global Storage Technologies Netherlands B.v.

International Business Machines Corporation

Western Digital Technologies, Inc.

Ampex Corporation

Roger William Wood

Richard Leo Galbraith

Jonathan Darrel Coker

Weldon Mark Hanson

Michael Paul Salo

Masafumi Mochizuki

Yimin Hsu

James Terrence Olson

Quang Le

Bruce Alexander Wilson

Martin Aureliano Hassner

Alexander M Taratorin

Kirk Hwang

Ju-Hi John Hong

Zhen Jin

Anton R De La Fuente

Pantas Sutardja

Kuok San Ho

Barry C Stipe

Takuya Matsumoto

Wayne Isami Imaino

Ching Hwa Tsang

Bruno Jean Marchon

Michael Grobis

Petrus Antonius Van Der Heijden

Razmik Karabed

Fu-Ying Huang

Niranjay Ravindran

Travis Roger Oenning

Pierre-Olivier Jubert

Mantle Man-Hon Yu

Constantin Michael Melas

Beverley R Gooch

Jiann-Chang Lo

Daniel Rugar

Paul H Siegel

Xiaodong Che

James Wilson Rae

Ikuya Tagawa

Kazuhiro Saito

Sridhar Chatradhi

Mark A Nichols

Yaw-Shing Tang

Hemant K Thapar

Patrick C Arnett

James William Reiner

Thomas C Arnoldussen

Rex Niedermeyer

Lyle J Fredrickson

Richard Michael Brockie

Kei Akiyama

Virat Vasav Mehta

Wei-Min Lu

Charles L Matson

A method and data storage system receives a confidence vector for a non-binary symbol value read from a memory cell of a non-volatile memory device, where the confidence vector includes a first plurality of confidence values and transforms the first plurality of confidence values into a first plurality of likelihood values using a forward tensor-product transform. A respective binary message passing decoding operation is performed with each of the first plurality of likelihood values to generate a second plurality of likelihood values, and the second plurality of likelihood values are transformed into a second plurality of confidence values of the confidence vector using a reverse tensor-product transform.

Non-binary decoding using tensor product transforms

According to one embodiment, a system includes a head, where the head includes: an optical signal source configured to emit a first optical signal, and a near-field transducer (NFT) configured to focus the first optical signal on a moving ferroelectric storage medium positioned below the head. The system also includes a detector operatively coupled to the head, where the detector is configured to detect a second optical signal generated in and reflected from the ferroelectric storage medium, and where the second optical signal has twice the optical frequency as the first optical signal.

System and method for reading data recorded on ferroelectric storage medium by means of a near-field transducer

A method, apparatus, and system are provided for implementing track following using signal asymmetry metrics monitored during read back in hard disk drives (HDDs). Signal asymmetry metrics monitored during read back are used together with a position error signal (PES) to correct and guide the position of a read sensor with respect to a written track in the HDD.

Implementing enhanced track following during read back using head asymmetry metrics in hard disk drives

According to one embodiment, a heat assisted magnetic recording system includes a magnetic recording medium comprising a magnetic recording layer, where the magnetic recording layer includes a plurality of physical bits. Each physical bit has a perpendicular magnetic anisotropy and one of at least three magnetic states, where the at least three magnetic states include a +1 magnetic state, a 0 magnetic state, and a &#x2212;1 magnetic state.

Heat assisted magnetic recording system having at least three possible magnetic configurations per physical bit

In general, techniques are described for performing track-error-correcting code on data. A hard drive comprising a storage device and a read channel may be configured to perform the techniques. The read channel may be configured to read data from a track comprising a plurality of data sectors each comprising a plurality of bits, and a parity sector comprising a plurality of parity bits, wherein the data includes a plurality of bit groups, each bit group including a single bit from each data sector, and wherein each parity bit corresponds to a respective bit group, perform a track parity check, and, responsive to determining that the data includes an error, identify one or more data sectors as possible sources of the at least one error and adjust a log-likelihood ratio for at least one bit from the bit group.

Track error-correcting code extension

A heat-assisted magnetic recording (HAMR) disk drive has a disk with at least two independent data layers (RLand RL), each data layer storing an independent data stream. At a high laser power both RLand RLare heated to above their respective Curie temperatures and a first data stream is recorded in both RLand RL. At a lower laser power only upper RLis heated to above its Curie temperature and a second data stream is recorded only in RL. The data layers are separated by a nonmagnetic spacer layer (SL) that prevents lower RLfrom being heated to above its Curie temperature at low laser power. The first and second data streams are typically asynchronous. Recorded data is read back from both data streams simultaneously as a composite readback signal. A joint Viterbi detector detects the asynchronous data streams simultaneously from the composite readback signal.

Heat-assisted magnetic recording (HAMR) disk drive with disk having multiple continuous magnetic recording layers

A hard disk drive is adapted to take the most recent estimated read head positions (the position error signal or PES values) that are obtained during writing and write those values into the data sectors as written PES (WPES) values. The WPES values are available on readback for use as a predictor of the positions in which subsequent data sectors were written and are also available for use in a data recovery procedure should a particular data sector fail to be recovered. In two-dimensional magnetic recording, the difference between the WPES value and the read PES value is a quantity required to rapidly select the best 2D equalizer. The PES values may be encoded prior to being written into the data sectors. The WPES values are appended to the data sectors after the preamble and sync fields, which occur after every servo sector.

Magnetic recording disk drive with write position error signal values written in the data tracks for compensation of track misregistration

A method of testing a one or more components of a data storage system introduces a first plurality of micro-transitions into a first data write pattern, which is then written to a magnetic media. A read-back signal is generated, and a frequency response of the read-back signal is analyzed to determine performance of the one or more components of the data storage system.

System and method for testing data storage systems utilizing micro-transitions

Disk drives are described in which blocks of data spanning multiple sectors are encoded into a plurality of codewords which are then divided into segments that are physically separated (distributed) on the disk surface over multiple sectors in a distributed codeword block so that the codewords have an improved worst case SNR in comparison to individual sectors. This results in more even SNR performance for each codeword, which improves the performance for portions of a track which have lower than the average SNR. Embodiments are described in which the distributed codeword blocks span across tracks.

Disk drive with distributed codeword blocks

A dual-stack read sensor is utilized in a storage device having an actuator arm that positions the read sensor over a rotating storage medium. The dual-stacked read sensor includes a primary read sensor having a first set of read sensor characteristics and a secondary read sensor having a second set of read sensor characteristics that differ from the first set of read sensor characteristics, wherein the secondary read sensor is positioned relative to the primary read sensor to be radially offset from the primary read sensor relative to a data track being read.

System and methods utilizing dual read sensors

A method, apparatus and a data storage device are provided for implementing track following and data recovery with readback of shingled data written in overlapping shingled data tracks on a recordable surface of a storage device. Positional information is identified with data readback of shingled data written in overlapping shingled data tracks. The identified positional information is used to selectively modify at least one predefined channel parameter, for example, to provide enhanced track following and enhanced data recovery.

Implementing track following using data characteristics for positional information

A technique for recovering of 'squeezed' sectors in a set of sequential sectors such as are used in Shingled Magnetic Recording (SMR) is described. Embodiments of the invention use a programmable erased sector recovery scheme, which is a concatenation of a 'Cauchy-type' track erasure correction code, together with a media-error correction code that generates N-weighted parity-sectors per track and is capable of replacing up to N-erased sectors per track in any possible combination.

Scalable repair block error correction for sequential multiple data blocks in a magnetic data storage device

In one embodiment, a system includes a writer for shingled recording which includes a write pole having a trailing edge and first and second side edges extending from the trailing edge. The writer further includes a shield extending along and about parallel to at least an entire length of the trailing edge, the shield also extending along at least a portion of the first side edge. Other systems are also presented which include advanced shingled writing head designs.

Asymmetric writer for shingled magnetic recording

A 'write-squeeze-verify' method is used for verification of the data that has been written in the annular bands of a shingled magnetic recording disk drive. The writing of data along a track overwrites a portion of the previously written track and thus 'squeezes' the data of the previously written track to thereby form a &#x201c;shingled data track&#x201d; (SDT). The data in each SDT is read back and verified by an error correction check using error correction bits associated with the data written in the SDT, or by comparing the readback data with the data stored in memory. If the data read back is not verified, a write error counter is incremented and a write error frequency is calculated. One or more attempts to write the data can be performed. If the data in the SDT cannot be verified after the attempted rewrite(s), then a &#x201c;re-try fail&#x201d; is reported.

Shingled magnetic recording (SMR) disk drive with verification of written data

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.

Measuring variations in head-disk clearance in a hard disk drive

Growing community of inventors

Gilroy, CA, United States of America

Roger William Wood