Abstract: A computer system comprises a primary volume 22P having a plurality of storage blocks P, and a differential volume 22D having a plurality of storage blocks D. Differential data corresponding to one among the plurality of storage blocks P is stored in at least one among the plurality of storage blocks D. A control device 210 identifies differential data which is unnecessary for a host device 100, based on a snapshot management table S or C indicating whether data has been read by the host device 100 from any one of storage blocks P, and on a differential management table 400 indicating to which storage block P differential data corresponds and in which storage block D the data is stored, and performs at least one among removal of the identified differential data from the differential volume 22D, and removal of an unnecessary information element from the differential management table 400.

Abstract: An redundant array of independent disks (RAID) storage device is provided. The RAID comprises M number of storage devices, and the storage blocks of the same J-column in each storage device comprises complete stripe blocks and at least a plurality of partially complete stripe blocks. Inside the same stripe block, the total number of the storage blocks (L) is smaller than the number of the storage device (M), and the quantity of the storage blocks (M) is not multiple of storage blocks (L).

Abstract: It is an object to eliminate possibilities in which newest backup data cannot be created owing to overwriting of data update records when performing backup using a duplicating system. The data backup system, including an active system as a computer system of a backup source and a standby system as a computer system of a backup destination, is provided in such that a communication settings judging section is provided in the standby system for actively changing settings of a data communicating section for transferring data update records to thereby prevent overwriting of portions among data update records that are necessary for creating newest backup data.

Abstract: A compound associative memory for use with a data-parallel computer, and a method of storing/retrieving data in the compound associative memory is disclosed. The memory comprises a bit-parallel word-organized associative memory having an array of associative memory cells arranged to be capable of bit-parallel search and write operations. A bit-serial associative memory having an array of memory cells arranged to be capable of bit-serial search and write operations, but not word bit-parallel search and write operations, is also included. The bit-serial memory is operatively connected to the bit-parallel memory and arranged to operate as an extension of the same. The method comprises searching the bit-parallel word-organized associative memory and/or the bit-serial associative memory coupled to the bit-parallel memory for data matching search data, and marking the memory cells having stored data matching the search data.

Abstract: A method and apparatus for managing a migration of a data set from at least one first storage location to at least one second storage location, wherein read requests to the data set from at least one application program executing on a computer system initially are serviced from the at least one first storage location. The data set is copied from the at least one first storage location to the at least one second storage location, and then at least one aspect of the computer system is modified so that read requests to the data set are serviced from the at least one second storage location to achieve the migration. In one embodiment, the migration is subsequently undone by modifying the at least one aspect of the computer system so that read requests to the data set are again serviced from the at least one first storage location. In another embodiment, after the migration is performed, a determination is made as to whether to finalize the migration.

Abstract: A method for efficiently maintaining snapshot instances. To maintain the state of snapshot instances, the snapshot copies the data needed to be protected into free space on the same volume. In order to identify whether a block is free, a snapshot record is created for each block on a volume to record write operations on the block. With these snapshot records, the allocation status of blocks on a volume can quickly be identified. Free space allocation is then accomplished by allocating free space via the file-system provided interface and identifying it with snapshot records. With this mechanism, snapshot software can allocate free space to store snapshot metadata and “copy-to-write” data dynamically.

Abstract: The present invention provides an optical disk drive, optical disk recording method, optical disk recording program and a recording medium having the optical disk recording method recorded therein, applicable to a DVD drive, for example, to permit recording of also a file of still pictures other than moving pictures with a sufficient extension of the recording ability of the optical disk. To this end, individual management information can be accessed via guide information for an extended file in consideration and an identification code CAT ID indicative of the type of the extended file and recording format CAT INFO TYPE of the management information are allocated to the extension-file guide information.

Abstract: The present invention provides an optical disk drive, optical disk recording method, optical disk recording program and a recording medium having the optical disk recording method recorded therein, applicable to a DVD drive, for example, to permit recording of also a file of still pictures other than moving pictures, thereby enabling more effective use of the information recording area of the optical disk and more quick search for desired data. To this end, the address of management information (DK) is identified with reference to a management table (TV) recorded in a fixed area on the optical disk, and a recording format is selected for the management information (DK) to be recorded in combination with an extension file (EF).