Storage node processing of data functions using overlapping symbols

Example storage systems, storage nodes, and methods provide storage node processing of data functions, such as map-reduce functions, using overlapping symbols. Storage nodes are configured to partition data units into symbols that include an overlap data portion of an adjacent symbol and erasure encode the symbols. The storage nodes may then decode erasure encoded symbols, identify subunits of a data unit from the decoded symbols, and process the subunits using map-functions to generate intermediate contexts. A reduce-function may be used to determine a function result using the intermediate contexts.