A recovery method that uses log takes a long time to recover, and another recovery method that uses backup has the difficulties that if a computer abnormally stops its conversion process due to a failure, the result of the conversion performed up to the time of that abnormal stop couldn't be reflected on the later process for recovery. In a computer system, a system recovery management unit produces backup as the initial status of volume and snapshot taken when the system is operating, by use of a backup restore processing unit of a storage apparatus, and manages the situations of the process by use of a recovery point list/table. When a trouble occurs, it determines a point of recovery from the recovery point list/table, and makes the volume be recovered from the produced backup and the overwriting of meta data in order to keep the data consistency.