International Business Machines Corporation

Shmuel Winograd

Barry Marshall Trager

Martin Aureliano Hassner

Luis Alfonso Lastras-Montano

Charles Edwin Cox

Eric Eugene Retter

Steven Robert Hetzler

Timothy Jay Dell

Kenneth Lee Wright

Piyush Chunilal Patel

Michael Raymond Trombley

Tetsuya Tamura

Paul William Coteus

Warren Edward Maule

Myron Dale Flickner

James Lee Hafner

Daniel Felix Smith

William John Kabelac

Uwe Schwiegelshohn

Dong Chen

Alan G Gara

Viresh Paruthi

Todd Edward Takken

Marc Avery Gollub

James Anthony Marcella

Alexey Y Lvov

William Thomas Flynn

Ali S El-Zein

Irving G Baysah

Robert J Shadowen

Gradus (Geert) Janssen

A system to improve error code decoding with retries may include a processing unit that requests data packets, and a queue to hold the data packets for the processing unit. The system may also include a decoder to determine a processing time for each data packet in the queue based upon any errors in each data packet, and if the processing time for a particular data packet is greater than a threshold, then to renew any requests for the data packets that are in the queue.

System for error decoding with retries and associated methods

An error correction method and system includes an Encoder and Syndrome-generator that operate in parallel to reduce the amount of circuitry used to compute check symbols and syndromes for error correcting codes. The system and method computes the contributions to the syndromes and check symbols 1 bit at a time instead of 1 symbol at a time. As a result, the even syndromes can be computed as powers of the odd syndromes. Further, the system assigns symbol addresses so that there are, for an example GF(2) which has 72 symbols, three (3) blocks of addresses which differ by a cube root of unity to allow the data symbols to be combined for reducing size and complexity of odd syndrome circuits. Further, the implementation circuit for generating check symbols is derived from syndrome circuit using the inverse of the part of the syndrome matrix for check locations.

Reduced circuit implementation of encoder and syndrome generator

In one exemplary embodiment of the invention, a method includes: receiving a first description for a circuit whose operation over a plurality of inputs is to be verified; receiving a second description for expected behavior of the circuit, where the expected behavior in the second description is expressed as a set of algebraic systems of multivariable polynomials over at least one Galois field; applying at least one computational algebraic geometry technique to a combination of the first description and the second description to determine whether the circuit is verified, where verification of the circuit confirms that at least one output obtained based on the first description corresponds to at least one expected value based on the expected behavior expressed in the second description; and outputting an indication as to whether the circuit is verified.

Circuit verification using computational algebraic geometry

A method for longitudinal position (LPOS) detection in a magnetic tape storage system for storing data upon linear tape open (LTO) magnetic storage tape, which data includes odd and even 36-bit LPOS words with error correcting ability. The method includes first encoding positional information onto the tape within the 36-bit LPOS words using each LPOS word's 8-bit sync mark field, and six of each LPOS word's 4-bit symbol fields, wherein 6 of 24 total bits comprise the encoded 8-bit sync mark field: Sy, and six 4-bit symbol fields are utilized as parity bits. The magnetic tape storage system passes the LTO magnetic storage tape encoded with the odd and even LPOS words with error correcting ability longitudinally across a servo reader/writer at a known speed, decoding the encoded positional information and detecting and correcting both ambiguous bits and single erroneous bit errors.

Correcting errors in longitudinal position (LPOS) words

A system to improve memory failure management may include memory, and an error control decoder to determine failures in the memory. The system may also include an agent that may monitor failures in the memory. The system may further include a table where the error control decoder may record the failures, and where the agent can read and write to.

System to improve memory failure management and associated methods

The invention includes a method for longitudinal position (LPOS) detection in a magnetic tape storage system for storing data upon linear tape open (LTO) magnetic storage tape, which data includes odd and even 36-bit LPOS words with error correcting ability. The method includes steps of encoding positional information onto the magnetic storage tape within the odd and even 36-bit LPOS words using each LPOS word's 8-bit sync mark field, Sy, and six of each LPOS word's 4-bit symbol fields, L, L, LL, L, and L, wherein 6 of 24 total bits comprising the encoded 8-bit sync mark field: Sy, and six 4-bit symbol fields: L, L, LL, L, and Lare utilized as parity bits, operating the magnetic tape storage system by passing the LTO magnetic storage tape encoded with the odd and even LPOS words with error correcting ability longitudinally across a servo reader/writer at a known speed, decoding the encoded positional information by reading either two words sequentially or two words simultaneously, the simultaneous reading requiring that the LPOS words include servo band numbers and detecting and correcting both ambiguous bits and single erroneous bit errors.

A system to improve error control coding. An example system includes memory chips of at least two different kinds. The system also includes error control encoder circuitry to substantially encode data for storage in any memory rank. The system further includes error control decoder circuitry to substantially decode encoded data received from any memory rank. The error decoder circuitry is comprised of a slow decoder and a fast decoder.

System for error control coding for memories of different types and associated methods

A system to improve error code decoding using historical information. An example system includes storage partitioned into memory ranks, and a table to record symbols having failures for each memory rank. The system generates a memory rank score for each memory rank. The system also includes an error control decoder that uses the memory rank score when each memory rank is accessed in order to determine whether an error should be corrected or not.

System to improve error code decoding using historical information and associated methods

A system to improve error correction includes a fast decoder to process data packets until the fast decoder finds an uncorrectable error in a data packet at which point a request for at least two data packets is generated. The system also includes a slow decoder to correct the uncorrectable error in a data packet based upon the at least two data packets.

System to improve error correction using variable latency and associated methods

A system to improve miscorrection rates in error control code may include an error control decoder with a safe decoding mode that processes at least two data packets. The system may also include a buffer to receive the processed at least two data packets from the error control decoder. The error control decoder may apply a logic OR operation to the uncorrectable error signal related to the processing of the at least two data packets to produce a global uncorrectable error signal. The system may further include a recipient to receive the at least two data packets and the global uncorrectable error signal.

System to improve miscorrection rates in error control code through buffering and associated methods

A system to improve memory reliability in computer systems that may include memory chips, and may rely on a error control encoder to send codeword symbols for storage in each of the memory chips. At least two symbols from a codeword are assigned to each memory chip and therefore failure of any of the memory chips could affect two symbols or more. The system may also include a table to record failures and partial failures of the codeword symbols for each of the memory chips so the error control encoder can correct subsequent partial failures based upon the previous partial failures. The error control coder is capable of correcting and/or detecting more errors if only a fraction of a chip is noted in the table as having a failure as opposed to a full chip noted as having a failure.

System to improve memory reliability and associated methods

A data storage subsystem that includes three data storage units, three check storage units, and an array controller coupled to the three data and three check storage units can tolerate failure of any three data and check storage units failures can be occur before data stored on the data storage subsystem is lost. Information is stored on the data storage subsystem as a symmetric Maximum Distance Separation code, such as a Winograd code, a Reed Solomon code, an EVENODD code or a derivative of an EVENODD code. The array controller determines the contents of the check storage units so that any three erasures of the data storage units and the check storage units can be corrected by the array controller. The array controller updates a block of data contained in any one of the data storage units and the check storage units using only six IO operations.

RAID 3+3

A method and system are disclosed for detecting memory chip failure in a computer memory system. The method comprises the steps of accessing user data from a set of user data chips, and testing the user data for errors using data from a set of system data chips. This testing is done by generating a sequence of check symbols from the user data, grouping the user data into a sequence of data symbols, and computing a specified sequence of syndromes. If all the syndromes are zero, the user data has no errors. If one of the syndromes is non-zero, then a set of discriminator expressions are computed, and used to determine whether a single or double symbol error has occurred. In the preferred embodiment, less than two full system data chips are used for testing and correcting the user data.

Error correcting code with chip kill capability and power saving enhancement

Error correcting codes of any distance (including codes of distance greater than four) use only exclusive OR (XOR) operations. Any code over a finite field of characteristic two are converted into a code whose encoding and correcting algorithms involve only XORs of words (and loading and storing of the data). Thus, the implementation of the encoding and correcting algorithms is more efficient, since it uses only XORs of words&#x2014;an operation which is available on almost all microprocessors. An important code, the (3, 3) code of distance four, is also described.

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Scarsdale, NY, United States of America

Shmuel Winograd