Disaster recovery refers to recovery and repair of systems fatally damaged by natural disasters (such as earthquakes and typhoons), fires, and so on. It includes measures against large-scale system damage that threatens continuation of business and data tampering by unlawful entry to systems. To carry out disaster recovery, for example, it is possible to set up a back-up strong point at an adequately separated location (so that it does not feel the effect of disasters), and data is synchronized from there.