CONTROL METHOD FOR INFORMATION PROCESSING APPARATUS, INFORMATION PROCESSING APPARATUS, CONTROL PROGRAM FOR INFORMATION PROCESSING SYSTEM AND REDUNDANT COMPRISAL CONTROL APPARATUS

The present invention provides a control method for an information processing system, which includes a plurality of processing apparatuses performing a mutually equivalent operation, comprising the step of isolating the processing apparatus for which a fluctuation of power source voltage is relatively large, from the information processing system, if an error is not detected in each of the processing apparatuses and respective items of output information from the plurality of processing apparatuses raise a nonidentity.