International Business Machines Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Globalfoundries Inc.

Awemane Ltd.

Roy Daron Cideciyan

Thomas Mittelholzer

Evangelos Stavros Eleftheriou

Robert Allan Hutchins

Simeon Furrer

Keisuke Tanaka

Mark Alfred Lantz

Richard Leo Galbraith

Giovanni Cherubini

Paul Joseph Seger

Sedat Oelcer

Travis Roger Oenning

Jonathan Darrel Coker

Ajay Dholakia

Steven Ross Bentley

Kenji Ohtani

Glen Alan Jaquette

Jens Jelitto

Nhan Xuan Bui

Kazuhiro Tsuruta

Ilias Iliadis

Xiao-yu Hu

David James Stanek

Robert Haas

Kevin Dale Butt

Hisato Matsuo

Ernest Stewart Gale

Mario Blaum

Thomas Helmut Toifl

Weldon Mark Hanson

Roman Alexander Pletka

Robert Allen Hutchins

Marcel A Kossel

Edwin Ralph Childers

Masayuki Iwanaga

Paul Merril Greco

Hazar Yüksel

Hazar Yuksel

Bruce Alexander Wilson

Ksenija Lakovic

Todd Carter Truax

Dharmendra S Modha

Steven Robert Hetzler

Yuan Xing Lee

Frank Ray Keyser, Iii

Xiao-Yu Hu

Laurent A Dellmann

John Jeffrey Stephenson

Wolfgang H Schott

Scott Jeffrey Schaffer

Pierre R Chevillat

Francois Bernard Dolivo

Theodore Antonakopoulos

Brian Harry Marcus

Erwin A Zurfluh

Michael Joseph Ross

Allen Prescott Haar

Theodoros A Antonakopoulos

Radley Wahl Olson

Gregory Scott Bush

Marcel Rupf

Hazar Yueksel

Dave James Stanek

Thomas Mittleholzer

Ilias Iliadas

Ismail Demirkan

Pierre Rene Chevillat

Wolfgang Hans Schott

The present disclosure includes systems and methods for reducing rewrite overhead in a sequential access storage system. The method may comprise writing a data set to a sequential access medium using a magnetic head, wherein the data set comprises a plurality of encoded data blocks, classifying each of the plurality of encoded data blocks on the sequential access medium into one of at least three classes of write quality, and rewriting the encoded data blocks in a rewrite area of the sequential access medium based at least in part on the write quality class. In some embodiments, the at least three classes of write quality may comprise a hard rewrite class for which rewrites are necessary to prevent data loss, a soft rewrite class for which rewrites are desirable but not necessary, and a no rewrite class for which no rewrite is needed or desired.

Selective hard and soft rewrites

Mechanisms are provided to receive encoded header information stored on a tape of a tape drive, wherein the encoded header information has been generated by: generating, for a plurality of tracks of the tape of the tape drive, a header information in a plurality of symbols, wherein the plurality of symbols is comprised of a first set of symbols and a second set of symbols, wherein the first set of symbols include identical information across all tracks of the plurality of tracks, and wherein the second set of symbols are configurable to include different information across all tracks of the plurality of tracks; and modifying, for writing to the tape of the tape drive, the first set of symbols of the plurality of tracks to include parity information corresponding to information included in the second set of symbols of the plurality of tracks. The received encoded header information is decoded.

Header decoding mechanism for tape storage

A data storage system comprises: a head configured to produce a signal representing data stored on a storage medium; an estimator configured to determine an estimated signal comprising a superposition of an estimated linear portion of a partial-response equalizer output and an estimated nonlinear portion of the signal; a bank of noise whitening filters configured for filtering a difference between the signal and the estimated signal; a branch metric calculator configured to calculate branch metrics based on the filtered signal; and an adaptive data-dependent noise-predictive maximum likelihood sequence detector configured to generate an output stream representing the data based on the one or more branch metrics.

Adaptive data detection on a nonlinear channel

In one embodiment, a system includes a processor, and logic integrated with the processor, executable by the processor, or integrated with and executable by the processor. The logic is configured to cause the processor to write, by the processor, data to a storage medium of a data storage system using a partial reverse concatenated modulation code. The partial reverse concatenated modulation code comprises encoding the data by applying a C2 encoding scheme prior to encoding the data by applying one or more modulation encoding schemes, followed by encoding the data by applying a C1 encoding scheme subsequent to the encoding of the data with the one or more modulation encoding schemes.

Partial reverse concatenation for data storage devices using composite codes

Methods and apparatus are provided for calculating branch metrics, associated with possible transitions between states of a trellis, in a sequence detector for detecting symbol values corresponding to samples of an analog signal transmitted over a channel. For each sample and each transition, the method calculates a plurality of distance values indicative of distance between that sample and respective hypothesized sample values for that transition. In parallel with calculation of the distance values, the sample is compared with a set of thresholds, each defined between a pair of successive hypothesized symbol values arranged in value order, to produce a comparison result. An optimum distance value is selected as a branch metric for the transition in dependence on the comparison result.

Sequence detection

In one embodiment, a method includes writing a data set to a sequential access medium. The method also includes reading the data set after being written in a read-while-write process to identify faulty encoded data blocks, each of the faulty encoded data blocks including at least one faulty codeword. Moreover, the method includes rewriting a correct version of a first of the encoded data blocks in a first encoded data block set to the rewrite area of the sequential access medium selected from a predetermined subset of logical tracks. The predetermined subset of logical tracks includes D1+D2+1 logical tracks. Only one encoded data block from a particular sub data set is rewritten in a single encoded data block set in the rewrite area.

Efficient rewrite using larger codeword sizes

A computer-implemented method according to one embodiment includes sending a data request from a host to a storage drive, where the data request includes quality of service (QoS) information, receiving, in response to the data request, a response from the storage drive at the host, and performing one or more actions at the host, based on the response.

Implementing data requests with quality of service information

A methodology that enables, for example, tape drive operation at lower SNR and/or reduced rewrite area uses a first threshold T and a second threshold r for a rewrite condition. Codeword interleaves (CWIs) in a data set are written onto a plurality of simultaneously-written parallel tracks of a magnetic recording medium, read back and error correction decoded. A determination is made as to whether at least one of the Cor C' codewords in each decoded CWI contains more byte errors than the second threshold r of the rewrite condition. A number of CWIs in a rewrite buffer are according to the following criteria: b&#x2032;=b&#x2212;T when bis greater than the first threshold T, and b&#x2032;=0 when bis less than or equal to the first threshold T.

Magnetic tape device capable of selecting codeword rewrite based on determined threshold

A computer-implemented method according to one embodiment includes receiving at a storage drive, from a host, a data request, implementing the data request at the storage drive, utilizing a streaming mode, and returning, by the storage drive, a confirmation to the host, in response to implementing the data request at the storage drive utilizing the streaming mode.

Implementing a storage drive utilizing a streaming mode

A computer-implemented method according to one embodiment includes sending, from a host to a storage drive, a read request for data, receiving, at the host from the storage drive, a portion of the data as fixed-size two-dimensional units, where the fixed-size two-dimensional units are mapped to fixed-size one-dimensional user data blocks located at the host, and performing one or more actions at the host, utilizing the portion of the data.

Implementing a mapping between data at a storage drive and data blocks at a host

In one general embodiment, a method includes receiving data logically organized into a predetermined number of two-dimensional arrays, each two-dimensional array including a plurality of NS codewords positioned orthogonally to a plurality of WS codewords. The method also includes successively writing each of the NS codewords to a data storage medium. A first NS codeword from a first two-dimensional array is written to the data storage medium prior to starting to write a second NS codeword from the first two-dimensional array. Also, the plurality of NS codewords are protected with a stronger encoding than the plurality of WS codewords.

Logical format utilizing lateral encoding of data for storage on magnetic tape

A computer-implemented method according to one embodiment includes identifying code word interleaved (CWI)-4 entries to be re-written to a data storage cartridge, selecting a subset of the CWI-4 entries to be included within a first CWI-4 set, where a plurality of the CWI-4 entries within the subset are associated with a single sub data set (SDS), and re-writing the first CWI-4 set to the data storage cartridge.

Prioritized sourcing for efficient rewriting

In one embodiment, a computer program product includes a computer readable storage medium having program instructions embodied therewith. The computer readable storage medium is not a transitory signal per se. The embodied program instructions are readable/executable by a processor to cause the processor to write, by the processor, data to a storage medium of a data storage system using a partial reverse concatenated modulation code. The partial reverse concatenated modulation code includes encoding the data by applying a C2 encoding scheme prior to encoding the data by applying one or more modulation encoding schemes, followed by encoding the data by applying a C1 encoding scheme subsequent to the encoding of the data with the one or more modulation encoding schemes. Other computer program products for writing data to a storage medium of a data storage system using a partial reverse concatenated modulation code are presented according to more embodiments.

A system includes, according to one embodiment, a magnetic head having a plurality of write transducers configured to store data to tracks of a sequential access medium and a plurality of read transducers. Each read transducer is configured to read data from the sequential access medium after being written thereto by a corresponding write transducer. A first of the read transducers is aligned with a first of the write transducers, wherein the output of the first read transducer is produced during read-while-write. The system also includes a controller and logic integrated with and/or executable by the controller. The logic is configured to read, using the plurality of read transducers, encoded data from a plurality of tracks of the sequential access medium simultaneously. The logic is configured to determine that one or more tracks of the sequential access medium are dead within a sliding window and rewrite a set of encoded data from the one or more dead tracks to one or more live tracks in a rewrite area of the sequential access medium. Other systems, methods, and computer program products are described according to more embodiments.

Sequential data storage with rewrite using dead-track detection

Sequence detectors and detection methods are provided for detecting symbol values corresponding to a sequence of input samples obtained from an ISI channel. The sequence detector comprises a branch metric unit (BMU) and a path metric unit (PMU). The BMU, which comprises an initial set of pipeline stages, is adapted to calculate, for each input sample, branch metrics for respective possible transitions between states of a trellis. To calculate these branch metrics, the BMU selects hypothesized input values, each dependent on a possible symbol value for the input sample and L&#x3e;0 previous symbol values corresponding to possible transitions between states of the trellis. The BMU then calculates differences between the input sample and each hypothesized input value. The BMU compares these differences and selects, as the branch metric for each possible transition, an optimum difference in dependence on a predetermined state in a survivor path through the trellis.

Sequence detectors

Growing community of inventors

Rueschlikon, Switzerland

Roy Daron Cideciyan