The invention backups job data, and detects and predicts the occurrence of trouble in a storage device. A gateway registers job data registered in a HDD and vibration-detection information of a vibration-detection sensor received from a user terminal in a memory, and then transmits the job data to a MFP. The MFP registers the job data in a HDD, and according to a request from the gateway, transmits the job data registered in the HDD and vibration-detection information of a vibration-detection sensor to the gateway. The gateway compares the data amount of when the job data is registered in the memory and the data amount of the job data from the gateway, and when there is a difference, registers trouble information related to the HDD in the memory.