A storage device according to an embodiment of the present invention has a plurality of storage nodes, each of which has a plurality of logical ports having send and receive queues for a communication request and an identification number, and an internal network for connecting the plurality of storage nodes with one another. The storage nodes each have, as the logical ports, a data communication logical port used for data communication with other storage nodes and an error communication logical port used to notify the other storage nodes of a state of the data communication logical port. When detecting an occurrence of transition of the data communication logical port to an error state, the storage node uses the error communication logical port to notify the other storage nodes of the identification number and the state of the data communication logical port.

A storage unit according to one aspect of the present invention comprises a storage controller and a plurality of storage devices. Each storage device has nonvolatile semiconductor memories serving as storage media. The controller of each storage device diagnoses the state of degradation of the nonvolatile semiconductor memories, and if one of the nonvolatile semiconductor memories is expected to be nearing end of life, then the controller copies the data stored in that degraded nonvolatile semiconductor memory to another nonvolatile semiconductor memory, and then performs shutdown processing for the degraded nonvolatile semiconductor memory, as well as storage capacity reduction processing.

Disclosed embodiments include an electronic device having a write-once memory (WOM) and a memory controller. The memory controller includes a host interface receiving a data word including first and second symbols, each having at least two bits, a WOM controller that encodes the first and second symbols and outputs a WOM-encoded word including first and second WOM codes corresponding to the first and second symbols, respectively, an error correction code (ECC) controller that encodes the WOM-encoded word and outputs an ECC-encoded word including the first and second WOM codes and a first set of ECC bits corresponding to a first write operation, and a memory device interface that writes the ECC-encoded word the WOM device in the first write operation. Each of the first and second WOM codes include at least three bits with at least two of the at least three bits having the same logic value.

Sensing in non-volatile memory is performed using bias conditions that are dependent on the position of a selected memory cell within a group of non-volatile memory cells. During sensing, a selected memory cell receives a reference voltage while the remaining memory cells receive a read or verify pass voltage. For at least a subset of the unselected memory cells, the pass voltage that is applied is dependent upon the position of the selected memory cell in the group. As programming progresses from a memory cell at a first end of a NAND string toward a memory cell at a second end of the NAND string, for example, the pass voltage for at least a subset of the unselected memory cells that have already been subjected to programming may be increased. This technique may reduce the effects of an increased channel resistance that occurs as more memory cells are programmed.

A technique for storage management involves: determining multiple source disk slices from a storage array that provides redundant storage, a current disk group where each of the multiple source disk slices is located being different from a target disk group where the source disk slice is specified to be located; determining multiple destination disk slices from the target disk group based on the multiple source disk slices, the multiple destination disk slices being used to replace the multiple source disk slices; and causing data to be moved to the multiple destination disk slices from the multiple source disk slices. Accordingly, such a technique may improve the reliability of a storage system.

Data to be stored at a memory sub-system can be received from a host system. A portion of the host data that includes user data and another portion of the host data that includes system metadata can be determined. A mapping for a data structure can be received that identifies locations of the data structure that are fixed with respect to an encoding operation and locations of the data structure that are not fixed with respect to the encoding operation. The data structure can be generated for the user data and system metadata based on the mapping, and an encoding operation can be performed on the data structure to generate a codeword.

Methods, systems, and apparatus for error correction with syndrome computation in a memory device are described. A first syndrome for first encoded data is generated in a memory device. The first syndrome and the first encoded data are transmitted to a controller that is coupled with the memory device. A second syndrome for first and second encoded data is generated. The first encoded data and the second encoded data are interrelated according to an error correction code. The second syndrome is transmitted to the controller without the second encoded data and the controller is to decode the first encoded data based on at least one of the first syndrome, the second syndrome, or a combination thereof.

A storage network processing system includes a processor, a network interface and memory that stores operational instructions. The operation instructions enable the processor to receive a data object for storage and dispersed error encode the data object in accordance with dispersed error encoding parameters to produce a plurality of encoded data slices. The operation instructions further enable the processor to generate to determine a plurality of site slice sets from the plurality of encoded data slices, where each site slice set of the plurality of site slice sets includes a number of unique encoded data slices of the plurality of encoded data slices that is greater than or equal to a site write threshold value. The operation instructions further enable the processor to a designate one of a plurality of storage sites for each of the plurality of site slice sets and transmit each of the plurality of site slice sets to a corresponding designated one of the plurality of storage sites via the network.

Described are a system, method, and computer program product for generating a data storage server distribution pattern. The method includes determining a set of servers and raw data to be stored. The method also includes transforming the raw data according to an error-correcting code scheme to produce distributable data. The method further includes determining a server reliability of each server in the set of servers. The method further includes generating the data storage server distribution pattern based on maximizing a system reliability relative to maximizing a system entropy. System reliability may be based on a minimum reliability of the set of servers, and system entropy may be based on a cumulated information entropy of each server of the set of servers. The method further includes distributing the distributable data to be stored across at least two servers of the set of servers according to the data storage server distribution pattern.

A storage unit includes an interface configured to interface and communicate with a dispersed storage network (DSN), a memory that stores operational instructions, and processing circuitry. The storage unit receives a set of read slice requests for a set of encoded data slices (EDSs) associated with a data object stored within a first set of storage units, where the storage the first set of storage units includes the storage unit. When at least a read threshold number of EDSs and fewer than all of the set of EDSs can be successfully retrieved from the first set of storage units, the storage unit identifies at least one EDS associated with a data object that is stored in a second set of storage units, obtains the at least one EDS and stores the at least one EDS in the storage unit.