A backup processing method for backing up data to be used by a data-processing computer system comprises selecting resources in a usable state from a plurality of resources necessary for the data to be used by the data-processing computer system, selecting switches in a usable state from a plurality of switches needed to form routes among said selected resources, and executing backup processing by using the secured resources and routes when the resources and routes necessary for backing up data to be used by the data processing computer system are secured to form multiple backup subsystems.