Abstract: Read parameter estimation techniques are provided that obtain information from multiple read operations to customize read parameters for data recovery. One method comprises performing the following steps, in response to a decoding failure of a page of a memory or a codeword of the memory: obtaining at least three read values of the page or codeword; and processing the at least three read values to determine read parameters comprising: (i) a log likelihood ratio, and/or (ii) a center read reference voltage, wherein the determination is based on a signal count of a number of bits falling in particular regions of multiple regions of the memory and wherein the determined read parameters are used for a decoding of the page or codeword following the decoding failure and/or a subsequent read operation following a successful decoding of the page or codeword.

Abstract: In one implementation, the disclosure provides a decoding system that concurrently executes a read sample combining recovery process and an iterative outer code (IOC) recovery process. Performing the read sample combining recovery process entails executing multiple rounds of logic that each provide for combining together different data samples read from a data block. The IOC recovery process is performed at least partially concurrent with the read sample combining recovery process and each round of the IOC recovery process is based on newly-updated data samples generated by the read sample combining recovery process.

Abstract: Read parameter estimation techniques are provided that obtain information from multiple read operations to customize read parameters for data recovery. One method comprises performing the following steps, in response to a decoding failure of a page of a memory or a codeword of the memory: obtaining at least three read values of the page or codeword; and processing the at least three read values to determine read parameters comprising: (i) a log likelihood ratio, and/or (ii) a center read reference voltage, wherein the determination is based on a signal count of a number of bits falling in particular regions of multiple regions of the memory and wherein the determined read parameters are used for a decoding of the page or codeword following the decoding failure and/or a subsequent read operation following a successful decoding of the page or codeword.

Abstract: An error recovery process provides for selecting a first recovery scheme for a decoding attempt on a first subset of a set of failed data blocks read from a data track; selecting a second different recovery scheme for a decoding attempt on a second subset of the set of failed data blocks read from the data track; and during a single revolution of the data track, performing operations to decode a first subset of the failed data blocks according to the first recovery scheme operations to decode the second subset of the failed data blocks according to the second different recovery scheme.

Abstract: A low-density parity check (LDPC) decoder includes a variable node unit (VNU) comprising a plurality of variable nodes configured to perform sums. A first message mapper of the LDPC decoder receives first n1-bit indices from likelihood ratio (LLR) input and maps the first n1-bit indices to first numerical values that are input to the variable nodes of the VNU. A second message mapper of the LDPC decoder receives second n2-bit indices from a check node unit (CNU) and maps the second n2-bit indices to second numerical values that are input to the variable nodes of the VNU. The CNU includes a plurality of check nodes that perform parity check operations. The first and second numerical values having ranges that are larger than what can be represented in n1-bit and n2-bit binary, respectively.

Abstract: In one implementation, the disclosure provides a decoding system that concurrently executes a read sample combining recovery process and an iterative outer code (IOC) recovery process. Performing the read sample combining recovery process entails executing multiple rounds of logic that each provide for combining together different data samples read from a data block. The IOC recovery process is performed at least partially concurrent with the read sample combining recovery process and each round of the IOC recovery process is based on newly-updated data samples generated by the read sample combining recovery process.

Abstract: An error recovery process provides for identifying a set of failed data blocks read from a storage medium during execution of a read command, populating sample buffers in a read channel with data of a first subset of the set of failed data blocks, and initiating an error recovery process on the data in the sample buffers. Responsive to successful recovery of one or more data blocks in the first subset, recovered data is released from the sample buffers and sample buffers locations previously-storing the recovered data are repopulated with data of a second subset of the set of failed data blocks. The error recovery process is then initiated on the data of the second subset of the failed data blocks while the error recovery process is ongoing with respect to data of the first subset of failed data blocks remaining in the sample buffers.

Abstract: Method and apparatus for managing data in a non-volatile memory (NVM) of a storage device, such as a solid-state drive (SSD). In some embodiments, flash memory cells are arranged along word lines to which read voltages are applied to sense programmed states of the memory cells, with the flash memory cells along each word line being configured to concurrently store multiple pages of data. An encoder circuit is configured to apply error correction encoding to input data to form code words having user data bits and code bits, where an integral number of the code words are written to each page. A reference voltage calibration circuit is configured to randomly select a single selected code word from each page and to use the code bits from the single selected code word to generate a set of calibrated read voltages for the associated page.

Abstract: An apparatus may include a circuit configured to initialize a read operation to read one or more requested data segments of a respective data unit having a plurality of data segments. Based on a number of failed data segments of the requested data segments and an erasure capability of an outer code error correction scheme, the circuit may perform erasure recovery to recover the failed data segments. Based on the number of failed data segments, the erasure capability of the outer code error correction scheme, and a threshold value, the circuit may perform iterative outer code recovery to recover the failed data segments.

Abstract: Method and apparatus for managing data in a non-volatile memory (NVM) of a storage device, such as a solid-state drive (SSD). In some embodiments, flash memory cells are arranged along word lines to which read voltages are applied to sense programmed states of the memory cells, with the flash memory cells along each word line being configured to concurrently store multiple pages of data. An encoder circuit is configured to apply error correction encoding to input data to form code words having user data bits and code bits, where an integral number of the code words are written to each page. A reference voltage calibration circuit is configured to randomly select a single selected code word from each page and to use the code bits from the single selected code word to generate a set of calibrated read voltages for the associated page.

Abstract: Embodiments herein provide for a controller that is operable to soft read a data bit a plurality of times, to generate a bit set for the data bit from the soft reads, to logically operate on the bit set, and to generate a Hamming weight for the data bit based on the logical operation. The Hamming weight has fewer bits than the bit set and is operable to correct the data bit.

Abstract: Read parameter estimation techniques are provided that obtain information from multiple read operations to customize read parameters for data recovery. One method comprises performing the following steps, in response to a decoding failure of a page of a memory or a codeword of the memory: obtaining at least three read values of the page or codeword; and processing the at least three read values to determine read parameters comprising: (i) a log likelihood ratio, and/or (ii) a center read reference voltage, wherein the determination is based on a signal count of a number of bits falling in particular regions of multiple regions of the memory and wherein the determined read parameters are used for a decoding of the page or codeword following the decoding failure and/or a subsequent read operation following a successful decoding of the page or codeword.

Abstract: In one implementation, the disclosure provides a system including a detector configured to generate an output of a first log-likelihood ratio for each bit in an input data stream. The system also includes at least one look-up table providing a mapping of the first log-likelihood ratio to a second log-likelihood ratio. The mapping between the first log-likelihood ratio and the second log-likelihood ratio is non-linear. The system also includes a decoder configured to generate an output data stream using the second log-likelihood ratio to generate a value for each bit in the input data stream.

Abstract: Systems and methods are disclosed for error correction with multiple log likelihood ratio (LLR) lookup tables (LUTs) for a single read, which allows for adaptation to asymmetry in the number of 0 or 1 bit errors without re-read operations. In certain embodiments, an apparatus may comprise a circuit configured to receive a sequence of bit value estimates for data read from a solid state memory during a single read operation, generate a first sequence of LLR values by applying the sequence of bit value estimates to a first LUT, and perform a decoding operation on the first sequence of LLR values. When the first sequence of LLR values fails to decode, the circuit may be configured to generate a second sequence of LLR values by applying the bit value estimates to a second LUT, and perform the decoding operation on the second sequence of LLR values to generate decoded data.

Abstract: Read parameter estimation techniques are provided that obtain information from multiple read operations to customize read parameters for data recovery. One method comprises performing the following steps, in response to a decoding failure of a page of a memory or a codeword of the memory: obtaining at least three read values of the page or codeword; and processing the at least three read values to determine read parameters comprising: (i) a log likelihood ratio, and/or (ii) a center read reference voltage, wherein the determination is based on a signal count of a number of bits falling in particular regions of multiple regions of the memory and wherein the determined read parameters are used for a decoding of the page or codeword following the decoding failure and/or a subsequent read operation following a successful decoding of the page or codeword.

Abstract: Method and apparatus for decoding error correction code (ECC) code words. Reference voltages are used to extract a selected code word from a communication channel. The selected code word is processed by an ECC decoder, and an initial syndrome weight is determined indicative of unresolved parity errors. A coarse search operates to concurrently adjust, over a first succession of iterations, each of the reference voltages. A subsequent fine search operates, over a second succession of iterations, to individually adjust the reference voltages. Decoding and syndrome weight determination continues over each iteration until a minimum syndrome weight is obtained, after which a user data content of the code word is decoded. The coarse search may transition the decoder from a saturated operational region to a linear operational region. The decoder may be a low density parity check (LDPC) decoder.

Abstract: In one implementation, the disclosure provides a system including a detector configured to generate an output of a first log-likelihood ratio for each bit in an input data stream. The system also includes at least one look-up table providing a mapping of the first log-likelihood ratio to a second log-likelihood ratio. The mapping between the first log-likelihood ratio and the second log-likelihood ratio is non-linear. The system also includes a decoder configured to generate an output data stream using the second log-likelihood ratio to generate a value for each bit in the input data stream.

Abstract: Method and apparatus for decoding error correction code (ECC) code words. Reference voltages are used to extract a selected code word from a communication channel. The selected code word is processed by an ECC decoder, and an initial syndrome weight is determined indicative of unresolved parity errors. A coarse search operates to concurrently adjust, over a first succession of iterations, each of the reference voltages. A subsequent fine search operates, over a second succession of iterations, to individually adjust the reference voltages. Decoding and syndrome weight determination continues over each iteration until a minimum syndrome weight is obtained, after which a user data content of the code word is decoded. The coarse search may transition the decoder from a saturated operational region to a linear operational region. The decoder may be a low density parity check (LDPC) decoder.

Abstract: Read parameter estimation techniques are provided that obtain information from multiple read operations to customize read parameters for data recovery. One method comprises performing the following steps, in response to a decoding failure of a page of a memory or a codeword of the memory: obtaining at least three read values of the page or codeword; and processing the at least three read values to determine read parameters comprising: (i) a log likelihood ratio, and/or (ii) a center read reference voltage, wherein the determination is based on a signal count of a number of bits falling in particular regions of multiple regions of the memory and wherein the determined read parameters are used for a decoding of the page or codeword following the decoding failure and/or a subsequent read operation following a successful decoding of the page or codeword.

Abstract: Systems and methods are disclosed for error recovery in a digital data channel. In an error recovery approach when the hardware fails to recover a sector, the sample for that sector can be saved along with a metric measure that indicates the quality of the sample. This process can begin from a first on-the-fly receiving and decoding of data. During each step of error recovery, a retry attempt may either use samples obtained during a new decoding attempt or may use a sample, or a combination of samples, having the best metric from an earlier attempt, or a combination of earlier attempts, to perform the recovery during a current retry recovery attempt.