Hitachi, Ltd.

Hitachi Computer Engineering Co., Ltd.

Toshifumi Nishimura

Hiroyuki Kitajima

Katsuharu Kakuse

Akira Yamamoto

Kazuo Takaragi

Akinobu Shimada

Masafumi Nozawa

Mikito Ogata

Minoru Kosuge

Takashi Doi

Yasuhiro Ishii

Tokuhiro Tsukiyama

Fujio Fujita

Kiyoshi Yata

Sadasaburoh Kanai

Takahiko Nakamura

Miho Motoyama

Yasushi Kuba

A magnetic tape data management method and apparatus is described that reduces the access time for updating and referring to directory data. At the time of accessing data on a magnetic tape loaded in a magnetic tape subsystem, directory data for the magnetic tape is, in response to the completion of the processing of data, recorded in a region located near the place at which the magnetic tape head is positioned at that time, said region constituting a directory data region (DDR). Further, a directory data memory for recording directory data from the magnetic tape is provided in the magnetic tape subsystem, remote from the tape. At the time of accessing data on the magnetic tape loaded in the magnetic tape subsystem, directory data for the magnetic tape processing is, in response to completion of the processing of data, recorded in the directory data memory in the magnetic tape subsystem.

Magnetic tape data management method and apparatus

A magnetic recording control apparatus includes conventional magnetic recording media, a large capacity type magnetic recording medium having a memory capacity corresponding to the sum of the capacities of a plurality of conventional magnetic recording media, recording unit for recording data of a plurality of conventional magnetic recording media to the large capacity type magnetic recording medium using a virtual volume corresponding to the recording capacity of one conventional magnetic recording medium and control data relating to the virtual volume as one recording unit, and/or division unit for dividing a data buffer for temporarily storing the data of the large capacity type magnetic recording medium into logical devices corresponding to the conventional magnetic recording media.

Magnetic recording control apparatus

In an information processing system having an upper rank apparatus and an external storage device which performs transmission and reception of data between the storage device and the upper rank apparatus, at least one of encryption and decryption of the data by use of an algorithm controlled by a desired data key is performed in the external storage device, while generation, encryption and decryption of the data key are performed on the upper rank apparatus side. By this configuration, the burden of the upper rank apparatus is largely reduced and the secrecy of data stored in the external storage device can be surely kept without spoiling the throughput of the whole system.

File encryption method and file cryptographic system

When invormation is recorded on a magnetic tape, a plurality of first data blocks which have been separately transferred from a higher rank apparatus are combined with each other while adding thereto control information for identifying each of the first data blocks, and are recorded on the magnetic tape as a continuous second data block. During a reproducing operation, either the first data blocks which have been separated based upon the control information, or the second data block containing the control information, are transferred to the higher rank apparatus.

Information recording/reproducing method and magnetic tape subsystem

An I/O control system includes an I/O control unit, a plurality of I/O devices, the start process prior to a data transfer process of the I/O device being off-line processed from the I/O control unit, and a data transfer path for data transferring to the I/O device, the data transfer being performed for one I/O device at a time. The I/O control unit controls an I/O device in such a way that the start process of the I/O device completes at the time when another I/O device under data transfer completes its data transfer, thus improving the utilization of a data transfer path.

I/O control system and method

A plurality of sequentially occuring information signals are stored in a memory by considering past record of the information signals. The number of times the same information occurs is counted, and when the information changes, the current count and the newly generated information are stored in the memory. The method of the invention thus enables much information to be stored in a small-capacity memory.

Data compaction system with contiguous storage of non-redundant

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Minami-ashigara, Japan

Toshifumi Nishimura