Utilizing locally decodable redundancy data in a vast storage network

Abstract

A network storage system operates by: sending, to at least one storage unit of a storage network, at least one read request corresponding to at least a read threshold number of a set of encoded data slices to be retrieved, wherein the set of encoded data slices correspond to a data segment, wherein the data segment is codable in accordance with dispersed error coding parameters that include a write threshold number and the read threshold number, wherein the write threshold number is a number of encoded data slices in the set of encoded data slices and wherein the read threshold number is a number of the set of slices that is required to decode the data segment; receiving from the at least one storage unit, a first subset of encoded data slices of the set of encoded data slices, wherein the first subset of encoded data slices is missing at least one missing encoded data slice from the number of the set of slices that is required to decode the data segment and that was not received from the at least one storage unit in response to the at least one read request; generating at least one rebuilt encoded data slice corresponding to the at least one missing encoded data slice utilizing locally decodable redundancy data, wherein the locally decodable redundancy data includes a plurality of local redundancy slices generated from a second subset of the set of encoded data slices that includes the at least one missing encoded data slice; and recovering the data segment based on the at least one rebuilt encoded data slice and the first subset of encoded data slices.