In an error detector 4, a symbol mask generation unit 27 generates a mask pattern, an error detection unit 30 detects and counts an error in a portion corresponding to Flit in a PAM4 signal from a device under test W, and a Flit error detection unit 31 detects and counts an FEC symbol error in a portion corresponding to Flit for each ECC group, and determines in which the number of FEC symbol errors exceeds a threshold value to be a Flit error.

A communication device includes a barrel shifter shifting an information sequence according to a code word number; an error correction coding circuit encoding the shifted information sequence to generate a code word; and a transmitter transmitting a frame with N rows and M columns in the order of the row numbers. One code word is disposed in a row of the frame. The row number of the frame corresponds to the code word number. When a code word number is N, the error correction coding circuit encodes an information sequence of a second size smaller than the first size and fixed data of a third size, which is the difference between the first size and the second size, and disposes them in a row of the frame such that the error correction parity follows the information sequence of the second size and the fixed data follows the error correction parity.

A method includes dispersed storage error encoding, by a device of the dispersed storage network (DSN), a data segment of a data object into a set of encoded data slices. The method further includes sending, by the device, a set of write fan out with redundancy sharing requests to a set of storage units of the DSN. The method further includes, in response to the set of write fan out with redundancy sharing requests, storing, by the set of storage units, a number of copies of a decode threshold number of encoded data slices of the set of encoded data slices. The method further includes storing, by the set of storage units, a single copy of a redundancy number of encoded data slices of the set of encoded data slices.

A method includes dispersed storage error encoding, by a device of the dispersed storage network (DSN), a data segment of a data object into a set of encoded data slices. The method further includes sending, by the device, a set of write fan out with redundancy sharing requests to a set of storage units of the DSN. The method further includes, in response to the set of write fan out with redundancy sharing requests, storing, by the set of storage units, a number of copies of a decode threshold number of encoded data slices of the set of encoded data slices. The method further includes storing, by the set of storage units, a single copy of a redundancy number of encoded data slices of the set of encoded data slices.

A method for receiving data frames which consists of determining a reference frame by firm decisions on the value of each bit received and then verifying the reference frame according to an integrity check code used for the transmission. The method may include the following steps: calculating, for each bit of said reference frame, a plausibility value that represents the probability of a transmission error; and, in the event of incompatibility with said integrity check code, identifying in said reference frame a non-empty finite set of the most plausibly erroneous bits in accordance with said plausibility values; listing candidate frames each corresponding respectively to one of the possible combinations of numbers of reversals of the identified most plausibly erroneous bits; and verifying the compatibility of the listed candidate frames with said integrity check code.

Based on a detected data transfer instruction, a computing device within a dispersed storage network (DSN) determines a data transfer synchronization protocol that substantially maintains synchronization of at least the write threshold number of first associated slices (e.g., a first row of encoded data slices) to be transferred from the first set of storage units (SUs) to a second set of SUs based on a substantially same first transfer rate and substantially maintains synchronization of at least the write threshold number of second associated slices (e.g., a second row of encoded data slices) to be transferred from the first set of SUs to the second set of SUs based on a substantially same second transfer rate. The computing device then executes the data transfer synchronization protocol to perform substantially synchronized transfer of respective sets of the plurality of sets of encoded data slices from the first set of SUs to the second set of SUs.

Based on a detected data transfer instruction, a computing device within a dispersed storage network (DSN) determines a data transfer synchronization protocol that substantially maintains synchronization of at least the write threshold number of first associated slices (e.g., a first row of encoded data slices) to be transferred from the first set of storage units (SUs) to a second set of SUs based on a substantially same first transfer rate and substantially maintains synchronization of at least the write threshold number of second associated slices (e.g., a second row of encoded data slices) to be transferred from the first set of SUs to the second set of SUs based on a substantially same second transfer rate. The computing device then executes the data transfer synchronization protocol to perform substantially synchronized transfer of respective sets of the plurality of sets of encoded data slices from the first set of SUs to the second set of SUs.

A method for use by a computing device in a dispersed storage network (DSN) to recover corrupt encoded data slices. In response to a request to storage units of the DSN for encoded data slices corresponding to a data segment, the computing device of a receives less than a decode threshold number of valid encoded data slices and at least one integrity error message that provides an indication of a corrupt encoded data slice. The computing device requests and receives at least one corrupt encoded data slice corresponding to the integrity error message(s). Utilizing at least one correction approach involving stored integrity data, the computing device then corrects the corrupt slice(s) to produce a decode threshold number of encoded data slices in order to decode the corresponding data segment. A variety of correction approaches may be employed, including a multi-stage approach that utilizes data from both valid and invalid slices.

A method for use by a computing device in a dispersed storage network (DSN) to recover corrupt encoded data slices. In response to a request to storage units of the DSN for encoded data slices corresponding to a data segment, the computing device of a receives less than a decode threshold number of valid encoded data slices and at least one integrity error message that provides an indication of a corrupt encoded data slice. The computing device requests and receives at least one corrupt encoded data slice corresponding to the integrity error message(s). Utilizing at least one correction approach involving stored integrity data, the computing device then corrects the corrupt slice(s) to produce a decode threshold number of encoded data slices in order to decode the corresponding data segment. A variety of correction approaches may be employed, including a multi-stage approach that utilizes data from both valid and invalid slices.

An improved approach is provided to identifying the boundary of data encoded using additive cyclic codes. In some embodiment, the process includes determining a first calculated parity of a first bit stream window, and, second, one or more updates to the calculated parity of the bit stream window to determine the parity of the next bit stream window, where after each update to the calculated parity, the calculated parity is compared with the target parity, and matching the calculated parity to the target parity indicates a proper boundary of a bit stream window. In some embodiments, the process supports shortened cyclic codes. In some embodiments, the bit stream boundary can be identified prior to descrambling the bit stream inputs for a given bit stream window. In this way, the process can avoid unnecessarily descrambling of the bit stream windows that are not properly aligned to a bit stream boundary.