A system includes: a copy processing system configured to copy a copy source file system that includes storage data and key data referring to the storage data and being unique depending on the data, from a copy source storage system storing the copy source file system into a copy destination storage system, thereby forming a copy destination file system; and an update data specifying means configured to compare the key data within the copy source file system with the key data within the copy destination file system and specify, as update data, the storage data within the copy source file system referred to by the key data within the copy source file system, the storage data not existing in the copy destination file system. The copy processing system is configured to copy the update data stored within the copy source file system into the copy destination file system.