Abstract: A memory device sharing system includes M (M represents an integer of 2 or greater) access control apparatus for sharing N (N represents an integer of 2 or greater) memory devices which store data, and a managing apparatus for managing access to the memory devices via the access control apparatus. The managing apparatus checks data stored in the N memory devices, generates data position information representative of the storage positions of data stored in any one of the N memory devices, and sends the data position information to the M access control apparatus. Each of the M access control apparatuses receives the data position information sent from the manager, and accesses the storage position indicated by the data position information if each of the M access control apparatuses receives an access request to access the data from an access request source.

Abstract: A storage device 110 includes: a data writing part 111 configured to store data to be written into a storage device 120 and also, when storing other data of the same content as the data already stored in the storage device into the storage device, refer to the data already stored in the storage device as the other data; and a data separating part 112 configured to separate data to be written into a user data portion and a management data portion that are classified in accordance with a previously set criterion. The data writing part 111 is configured to store the user data portion into a user data file 121, store the management data portion into a management data file 122, and store the user data portion and the management data portion separated by the data separating part 112 into the storage device 120.

Abstract: A system includes: a copy processing means 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 means is configured to copy the update data stored within the copy source file system into the copy destination file system.