Abstract: When the management area and the actual data area are separated beforehand in a filesystem and the management area is replicated to perform backup, the maximum number of files to be managed will be limited by the size of the management area because it is necessary to reserve the management area and the backup management area beforehand. In a filesystem in which the management area and the data area are recorded into a common area, it is impossible to use a replicating technique of the entire management area since there is no concept of the management area.

Abstract: When one recording medium is accessed from a multiple number of applications, the medium is usually divided into multiple areas. If this area division is performed and managed by the partitioning, it is difficult to change the partitions in size. Therefore, there has been the problem that the recording medium can not be used effectively. The recording medium is divided into multiple areas, and for each area, a dummy data is written into the blank space in the area so that dummy data can only be overwritten using a particular application or with a file of a particular type. This configuration makes it easy to divide the medium into multiple areas and change the areas in size.