Hitachi, Ltd.

Hitachi Computer Peripherals Co., Ltd.

Tokuhiro Tsukiyama

Katsuharu Kakuse

Takashi Oeda

Kazuo Takaragi

Akinobu Shimada

Masafumi Nozawa

Shigeo Honma

Hiroshi Yashiki

Yasuhiro Ishii

Hiroshi Morishima

Fujio Fujita

Toshifumi Nishimura

Kiyoshi Yata

Yoji Tomono

Hiroyuki Matsushima

Yasushi Kuba

Kunihiro Itoh

Syoji Ozaki

Shinpei Saba

Yoshie Kondo

Osamu Hirose

Kazumi Miyazawa

Tadashi Haga

Yasunori Sagara

Shouichi Serizawa

In order to construct an integrated storage system by reinforcing collaboration of components or functions of a storage system in which a storage area network (SAN) is used, in a computer system having multiple client computers, multiple various servers, multiple various storages which keep data, and a local area network (LAN) which connects the computers and the servers, a storage area network (SAN) which lies between the servers and storages forms a switched circuit network which is capable of connecting any server and any storage through fiber channel FC switches. The computer system further includes a terminal which is equipped with operation and management software which performs storage management including management of logical volumes in the various storages, data arrangement, error monitoring, management of setting up the FC switches, and backup for data in the storages.

Computer system having a storage area network and method of handling data in the computer system

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

A fast calculation circuit for a cyclic redundancy check code of compressed data having a compressed area and an uncompressed area, the compressed area containing at least a data byte representative of the content of consecutive same data bytes and a data byte representative of the number of consecutive same data bytes. The fast calculation circuit includes a cyclic redundancy check code calculation unit for calculating a cyclic redundancy check code of data in the uncompressed area by using a generating polynominal; a fast calculation matrix unit for storing beforehand a plurality of cyclic redundancy check code calculation results of data contents and consecutive data byte numbers; and a detection unit for detecting the compressed area; wherein when the detection unit detects the compressed area, a cyclic redundancy check code of data in the detected compressed area is calculated by the fast calculation matrix unit, and when the detection unit does not detect the compressed area, a cyclic redundancy check code of data in the uncompressed area is calculated by the cyclic redundancy check code calculation unit.

Fast calculation circuit for cyclic redundancy check code

A method of data compression for recording data on a recording medium such as a magentic tape, a method of data restoration for data which has been compressed for recording, and an apparatus of data compression and restoration prescribe the data to be compressed based on type or value and encode the compression object data, thereby reducing the number of bits necessary to indicate the compression object data. Compression is implemented only for consecutive data fewer in number of repeating consecutive bytes than a certain number, thereby reducing the number of bits necessary to indicate the number of bytes of the consecutive data. A compression mark indicative of compression is appended to the compressed data, consisting of data made by encoding the compression object consecutive data and data indicating the number of bytes of the data, either at the front or rear of the compressed data, whereby an input data string can be compressed drastically and compressed data, even including errors, can be restored.

Method and apparatus for data compression and restoration

A data compression and restoration method and an apparatus for realizing same, by which, when identical data patterns appear successively in data information, which may be recorded in a magnetic tape, etc., the data patterns are subjected to a compression operation, the data thus compressed is recorded, and it is restored at the reproduction. When the data patterns appear successively, they are compressed, and the data patterns generated by the compression are subjected to a second compression, after they have been rearranged for the purpose of the second compression. In this way it is possible to record data significantly compressed.

Method for compressing and restoring data series and apparatus for

A control device has a data compression control circuit for compressing data and a data buffer for temporarily storing the data to be written on a recording medium. The data transferred from a CPU is compressed and then recorded on the recording medium. Further provided is a buffer discriminating circuit for discriminating the quantity of data stored in the data buffer to control the data compression control circuit so that the data compressing operation and the operation of recording the data on the recording medium may be conducted in parallel while the amount of transferred data in the data buffer is prevented from becoming less than a predetermined quantity.

Data compression control device

In an optical disc apparatus using an optical disc which has a number of sectors for recording coded information therein, a sector mark formed of a special pattern is previously recorded in each sector at the starting position thereof, to correctly read-out information recorded in each sector. In the case where the optical disc is normally operated, a normal sector mark signal corresponding to each sector mark is detected at a fixed time interval. However, the normal sector mark signal may not be detected for some reasons. A circuit is herein disclosed which generates a pseudo sector mark signal synchronized with the normal sector mark signal. When the normal sector mark signal is not detected, the psuedo sector mark signal is generated, and information recorded in a sector is appropriately processed on the basis of the pseudo sector mark signal. Further, this circuit is provided with circuit means for inhibiting the normal sector mark signal and psuedo sector mark signal from being delivered when the pseudo sector mark signal has been generated a predetermined number of times continuously. However, such inhibition is released when the repetition period of the normal sector mark signal is judged to lie within a predetermined range.

Sector mark signal control circuit for disc apparatus

Method of data compression and restoration wherein an input data string including repetitive data more in number than the specified value is transformed into a data string having a format including the first region where non-compressed data are placed, the second region including a datum representative of a data string section which has undergone the compression process and information indicative of the number of repetitive data, i.e., the length of the data string section, and control information inserted at the front and back of the first region indicative of the number of data included in the first region, said transformed data string being recorded on the recording medium, and, for data reproduction, the first and second regions are identified on the basis of the control information read out on the recording medium so that the compressed data string section is transformed back to the original data string in the form of repetitive data.

Method and system for data compression and restoration

Growing community of inventors

Kanagawa, Japan

Tokuhiro Tsukiyama