An object of the present invention is to provide a redundant information processing system that can continue its operation without stopping as much as possible. To achieve this, the information processing system includes multiple storage nodes including processors, memories, and storage devices, as well as a network for connecting the storage nodes. The processor of at least one storage node performs the steps of: obtaining the configuration information of the information processing system; obtaining first failure information related to a first failure occurred in the information processing system; calculating the availability level of the information processing system when a second failure further occurs, based on the configuration information and the first failure information; and controlling the operation of the system based on the availability level. Then, the processor outputs a notification.