Thus, in order to synchronize a down time of the tool in step 1{HEAD ~ , i.e., a down time} of {TAIL ~ the chamber 211A}, the processing of the 6000 substrates has to be redistributed so as to process 4000 substrates in the chamber 211A and process 2000 substrates in the chamber 211B. Thus, a corresponding percentage for supplying substrates to step 1 will be two thirds for the chamber 211A and one third for the chamber 211B 