Abstract: A multi-chip device and method for storing input data. The multi-chip device includes: a plurality of memory chips being adapted to store encoded input data, wherein each of the plurality of memory chips includes a detection unit that outputs detection information; an evaluation unit being adapted to perform an evaluation of the detection information from each of the plurality of memory chips, and to adapt the detection algorithm of any of the detection units depending on the performed evaluation; a combination unit being adapted to receive the detected bits and to combine the detected bits; and a decoding unit being adapted to output decoded data by decoding the combined detected bits. The present invention also provides a method and a computer program product for storing input data.

Abstract: In one embodiment, a tape drive system includes a soft detector having logic configured to execute a first forward loop of a detection algorithm on a first block of signal samples during a first time interval, execute a first reverse loop of the detection algorithm on the first block of signal samples during a second time interval, execute a second reverse loop of the detection algorithm on the first block of signal samples during a fifth time interval, and execute a second forward loop of the detection algorithm on the first block of signal samples during a fourth time interval using second soft information. Other tape drive systems and computer program products for decoding data are presented in more embodiments.

Abstract: A method and apparatus for detecting N-symbol codewords.

Abstract: A computer-implemented method for performing remote data storage includes providing, by at least one client, files to be stored on a remote server, evaluating popularity of the files, and storing the files on the server in a form that depends on the popularity of the files. Files with a first level of popularity are stored in a deduplicated form and files with a second level of popularity are stored in an encrypted form, the first level of popularity being higher than the second level of popularity.

Abstract: A device for storing data in a plurality of multi-level cell memory chips. The device includes a scrambling unit to generate a plurality of candidate scrambled sequences of data by performing a plurality of scrambling operations on a sequence of data to be stored, a calculation unit to calculate a cost function for each of the plurality of candidate scrambled sequences of data, the result of each cost function being indicative of a balancing degree of subsequences of a candidate scrambled sequence, when the subsequences of the candidate scrambled sequence are written to the plurality of multi-level cell memory chips, a selection unit to select one of the candidate scrambled sequences of data based on the results of the cost functions, and a storing unit to store the selected candidate scrambled sequence of data in the multi-level cell memory chips by storing the subsequences across the multi-level memory chips.

Abstract: In one embodiment, a system for cycle-slip resilient iterative read channel operation includes a processor and logic integrated with and/or executable by the processor. The logic is configured to, in an iterative process until a maximum number of iterations has been reached or a valid codeword is produced, execute cycle-slip detection on signal samples to detect one or more cycle-slip events. Also, the logic is configured to selectively alter a timing estimate driving a phase-locked loop (PLL) during any time interval determined to experience a cycle slip in a first pass as indicated by one or more cycle-slip pointers. Additionally, the logic is configured to generate a set of decisions provided by a detector and generate a set of decisions provided by a decoder. Moreover, the logic is configured to output decoding information relating to the signal samples in response to a decoding algorithm producing a valid codeword.

Abstract: 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.

Abstract: An aspect is a method that includes receiving (k0?1)k1+k2 write data symbols, where k2<k1. The write data symbols are arranged in an array that includes k0?1 rows of length k1 followed by a row of length k2. The first k2 columns are encoded to form a partially encoded array using a vertical error correcting code of length m, m>k0, resulting in k2 columns of length m including the write data symbols and vertical parity values. The k0?1 rows of the write data symbols of length k1 and the m?k0+1 rows from the partially encoded array are encoded into an encoded array of m rows of length n columns, n>k1 including at least one parity value in each of the m rows, thereby enabling correction of up to (n?k1)/2 errors in any row and up to (n?k2)/2 errors in up to m?k0+1 rows of the encoded array.

Abstract: According to one embodiment, a computer program product for dropout detection in a read channel includes a computer readable storage medium having program code embodied therewith, the embedded program code being readable and/or executable by a processor to execute dropout detection on a block of signal samples to detect one or more dropout events employing a set of decisions provided by a detector executing a detection algorithm, determine an approximate location for each of the one or more detected dropout events, statistically characterize the one or more detected dropout events to calculate one or more dropout profiles, and selectively filter the block of signal samples during a duration of each of the detected dropout events. Other computer program products, systems, and methods for detecting dropouts are presented in more embodiments.

Abstract: In one embodiment, a system for integrating data and header protection includes a processor and logic integrated with and/or executable by the processor, the logic being configured to receive a data array organized in rows and columns, each row of the data array comprising two or more interleaved C1 codewords (CWI), and modify one or more rows of the data array to include a header and error correction code (ECC) parity to form one or more modified rows, wherein each modified row includes two or more interleaved codewords, at least one codeword being a C1? codeword which includes ECC parity, wherein each header comprises a CWI Designation (CWID) which indicates a location of the CWI within the data array, and wherein none of the CWIDs are split across multiple C1? codewords in a single modified row. Other systems, methods, and computer program products are presented in additional embodiments.

Abstract: In one embodiment, a method for combination error and erasure decoding for product codes includes receiving, using a hardware processor, captured data. The method also includes generating, using the hardware processor, erasure flags for the captured data and providing the erasure flags to a C2 decoder. Moreover, the method includes setting a stop parameter to be equal to a length of C1 codewords in a codeword interleave used to encode the captured data. In addition, the method includes selectively performing, in an iterative process, error or erasure C1 decoding followed by error or erasure C2 decoding until decoding is successful or unsuccessful. Other methods and computer program products are described in more embodiments.

Abstract: Methods and apparatus 3 are provided for encoding data for storage in multilevel memory cells 2 having q cell-levels. Input data words are encoded into respective codewords, each having N symbols with one of q symbol-values, via an encoding scheme adapted such that the q symbol-values have unequal multiplicities within at least some codewords, and the multiplicity of each of the q symbol-values in every codeword is no less than ?, where ??2 and more preferably ?3. A first type of encoding scheme uses recursive symbol-flipping to enforce the ?-constraint, adding indicator symbols to indicate the flipped symbols. A second type of encoding scheme maps data words to codewords of a union of permutation codes, the initial vectors for these permutation codes being selected to enforce the ?-constraint. The N qary symbols of each codeword are supplied for storage in respective cells of the multilevel memory 2.

Abstract: In one embodiment, a computer program product for iterative read channel operation has program instructions embodied therewith that are executable by a controller to cause the controller to: in an iterative process until a maximum number of iterations has been reached or a valid codeword is produced: execute one or more digital front-end (DFE) functions on a plurality of signal samples employing the set of decisions provided by a decoder; execute a detection algorithm on the signal samples using a detector employing the set of decisions provided by the decoder to regenerate the set of decisions provided by a detector; execute a decoding algorithm of an error correcting code (ECC) using the set of decisions provided by the detector to regenerate the set of decisions provided by the decoder; and output decoding information relating to the signal samples when the decoding algorithm produces a valid codeword.

Abstract: Provided are a computer program product, system, and method for generating a code alphabet for use by a deployed program to determine codewords for words. A first code alphabet has a first number of symbols that provide variable length codings of the words. A second code alphabet is generated having a second number of symbols formed by merging the symbols in the first code alphabet, wherein the second code alphabet comprises the code alphabet used by the deployed program.

Abstract: Methods and apparatus are provided for determining level-thresholds for q-level memory cells. A group of the memory cells are read to obtain respective read signal components. The read signal components are processed in dependence on signal level to produce a signal level vector, comprising a series of elements, indicative of the distribution of read signal components in order of signal level. A plurality of possible sets of q?1 elements corresponding, respectively, to q?1 level-thresholds which partition the signal level vector into q segments, is then defined. The q?1 level-thresholds for the group of memory cells are then determined by selecting from said possible sets that set for which a predetermined difference function, dependent on differences in signal level for elements in each of said q segments for the set, has an optimum value.

Abstract: According to one embodiment, a magnetic medium's readback signal samples are processed iteratively to provide a slip-resistant read channel by feeding the decoder output decisions back to the read channel front end where they are used to drive the decision-aided digital signal processing functions and control loops. Since data decisions provided by the decoder are typically more reliable than those provided by the detector, a significant performance improvement is obtained. A more reliable operation of the digital front-end signal processing functions in turn allows improvements to the reliability of the decoded data. Usage of Error Correcting Code (ECC) schemes that are soft decodable makes the read channel technique, described according to various embodiments herein, particularly efficient.

Abstract: In one embodiment, a method includes executing a first forward loop of a detection algorithm on a block of signal samples during a first time interval, executing a first reverse loop of the detection algorithm on the block during a second time interval to produce first soft information, executing a decoding algorithm on the block during a third time interval using the first soft information to produce second soft information, executing a second forward loop of the detection algorithm on the block during a fourth time interval using the second soft information, executing a second reverse loop of the detection algorithm on the block during a fifth time interval to produce third soft information, executing the decoding algorithm on the block during a sixth time interval using the third soft information to produce a decoded block of signal samples, and outputting the decoded block of signal samples.

Abstract: The memory cells storing a group of codewords are read to obtain respective read signals each comprising N signal components corresponding to respective symbols of a codeword. The components of each read signal are ordered according to signal level to produce an ordered read signal. Correspondingly-positioned components of the ordered read signals are then ordered according to signal level to produce ordered component sets for respective component positions in a said ordered read signal. Each ordered component set is partitioned into subsets corresponding to respective memory cell levels, wherein the subsets of the ordered component sets contain respective numbers of components dependent on predefined probabilities of occurrence of different symbol values at different positions in a said codeword whose symbols are ordered according to symbol value. The reference signal level is determined in dependence on the signal components in the subsets corresponding to that memory cell level.

Abstract: In one embodiment, a tape drive system includes a write channel for writing data to a magnetic tape, the write channel utilizing a rate-(232/234) reverse concatenated modulation code. The write channel includes logic adapted for receiving a data stream comprising one or more data sets, logic adapted for separating each data set into a plurality of sub data sets, logic adapted for encoding each sub data set with a C2 encoding, logic adapted for encoding each C2-encoded sub data set with a modulation code, logic adapted for encoding each modulated sub data set with a C1 encoding, and logic adapted for simultaneously writing the encoded modulated sub data sets to data tracks of the magnetic tape. Other systems for writing data to a magnetic tape utilizing a rate-(232/234) reverse concatenated modulation code are described according to various other embodiments.

Abstract: In one embodiment, a method includes writing data to a storage medium of a data storage system using a partial reverse concatenated modulation code by encoding data sets using a C2 encoding scheme, adding a header to each subunit of the data sets, encoding the headers of the data sets with a first modulation encoding scheme, encoding data portions of the data sets with a second modulation encoding scheme, encoding portions of the one or more C2-encoded data sets using a C1 encoding scheme, combining the C1-encoded portions with the modulation-encoded headers of the C2-encoded data sets using a multiplexer, and writing the one or more combined C1- and C2-encoded data sets to data tracks of the storage medium. Other methods 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.