A rack server system for a map/reduce data processing is disclosed. The method can include a plurality of servers arranged in a rack, and a plurality of offload processor modules supported on at least two of the servers, each offload processor module having an input-output (IO) port and multiple offload processors, a first offload processor module configured to execute map steps of the map/reduce data processing, and being connected directly to a second offload processor through their respective IO ports to define a midplane switch, wherein the second offload processor module is configured to execute reduce steps of on data provided from the first offload processor module.