A computing system includes: a data block including a data; a storage engine, coupled to the data block, configured to process data, as hard information or soft information, through channels including a failed channel and a remaining channel, calculate an aggregated output from a hard decision from the remaining channel, calculate a selected magnitude from a magnitude from the remaining channel with an error detected, calculate an extrinsic soft information based on the aggregated output and the selected magnitude, and decode the failed channel with a scaled soft metric based on the extrinsic soft information.