A method begins by a processing module receiving a large data file for storage in a dispersed storage network (DSN) and determining initial dispersed storage error encoding parameters. The method continues with the processing module encoding, during a first time interval of receiving the large data file, first data segments of the large data file using the initial dispersed storage error encoding parameters to produce a first plurality of sets of encoded data slices. The method continues with the processing module writing the first plurality of sets of encoded data slices to the DSN and monitoring processing of the writing to produce first write processing performance information. When the first write processing performance information compares unfavorably to a desired write performance range, the method continues with the processing module adjusting, for a second time interval, the initial dispersed storage error encoding parameters to produce adjusted dispersed storage error encoding parameters.