Hitachi, Ltd.

Hitachi Microcomputer System, Ltd.

Hitachi Microcomputer Engineering, Ltd.

Nippon T&t Corp.

Michio Miyazaki

Akira Yamamoto

Hiroyuki Kitajima

Yoshihiro Asaka

Shigeo Honma

Takashi Doi

Toshiaki Tsuboi

Koji Ozawa

Masahito Mori

Masafumi Nozawa

Mikito Ogata

Takashi Kobayashi

Takao Sato

Akira Kurano

Shigeru Kishiro

Minoru Kosuge

Yoshiaki Kuwahara

Kenzo Kurihara

Kiyoshi Hisano

Takafumi Oka

Kenji Tokumitsu

Yuji Yamane

Akihito Ogino

Nobuyoshi Izawa

Takikazu Takeuchi

Toru Takeda

In allocating an area of a cache memory to each storage unit, proper allocation of the cache memory is made to each storage unit. If the amount of write-after data becomes equal to or more than a threshold value, an allocation limit is set to each disk unit. If CPU issues a data write request requiring the amount of data equal to or more than the allocation limit, the data write request is held in a wait state until the amount of write-after data becomes less than the allocation limit. Therefore, the allocation amount to the disk unit becomes neither too large nor too small. In this manner, proper allocation of the cache memory to each disk unit can be realized.

Controller limiting modification of cache based upon amount of dirty

Limiting modification of cache entries in a write-back cache based upon

Controller for storage unit and method of controlling storage unit

An information medium storage and management system includes storage compartments for storing a plurality of information media; a plurality of recording/reproducing apparatus each capable of accessing each of a plurality of information media, each capable of recording at least one file; handling apparatus for mounting a mount information medium on a mount recording/reproducing apparatus and demounting a demount information medium from a demount recording/reproducing apparatus; and a controller for controlling the handling apparatus to select as the mount information medium one of the plurality of information media in accordance with the use history data of each information medium, to select as the mount recording/reproducing apparatus one of unoccupied recording/reproducing apparatus of the plurality of recording/reproducing apparatus, and to cause the mount information medium to use the mount recording/reproducing apparatus for a predetermined time period.

Method and system for storing and managing a plurality of information

When a positioning operation of a head on a track of a disk including a target record is completed, information is read out from the track of the disk and stored in a buffer memory without waiting a read command from a host side controller. A transfer operation of the target record of the information from the buffer memory to the controller is performed when the controller is not busy and generates the read command. A transfer rate of the record from the buffer memory to the controller is made faster than a read rate of the information from a disk or a write rate into the buffer memory, so that a nominal transfer rate of an entire system is increased without changing the read or write rate.

Information transfer control system having rotary storage unit which

An input/output control apparatus connected to a plurality of input/output units such as disc systems and an input/output control method. A cache memory is divided into a plurality of storage areas for data management. Data stored in the disc systems are stored in the storage areas. In response to an output request from a HOST system to the disc systems, data outputted from the latter are stored in the storage areas of the cache memory. The data stored in the storage areas and outputted therefrom in response to the output request are transferred to the disc systems. The storage areas storing the data requested and not yet stored in the disc systems are grouped correspondingly to the disc systems where the output data are to be stored. The resulting group is managed as a first attribute group. Write-after processing for every disc units can be executed in parallel efficiently without involving high processing overhead.

Input/output control method and system

Buffers are separately provided for a region for non-sequential transfer and for a region for sequential transfer in each one of the disk units. A director sends a message to inform at least one of the disk units whether transfer of data the respective disk units are to make is sequential or non-sequential. When the disk unit receives a non-sequential transfer request, it uses the buffer region for non-sequential transfer to transfer data requested by the director and when it receives a sequential transfer request, it uses a plurality of buffer regions for the sequential transfer. Thus, data transfer is performed between a host device and that disk unit.

Buffered disk unit and method of transferring data therein

Method for controlling information recording in an information recording apparatus which includes a rewritable information record medium containing a data record area having a plurality of data recording blocks and an alternative area in which data to be written into a defective block in the data record area is written, and writing and reading of data to and from the blocks and erasing of data may be carried out, wherein, data is written into the respective blocks in the data record area on the information record medium, and if a data record error is detected, data to be written into the defect block is written into a block of the alternative area. When data is subsequently rewritten, contents of all blocks in the data record area to be rewritten, including the block previously determined to be defective, are erased and the new data is rewritten, and the content of the alternative area is erased. If a data record error is detected after rewriting, the data to be written into the defect block is written into a block in the alternative area.

Information recording control system reusing a defective area

A data recording/reproducing method for a non-rewritable recording medium of a rotating type, each of tracks on the recording medium is divided into a plurality of blocks which are allotted with respective addresses. Each block includes a data recording area and a deletion flag area which is divided into a plurality of sub-areas. One of the sub-areas in a given block is associated with other block which is in a predetermined address relation with the given block. When the content in the data recording area of one block on the recording medium is to be rendered invalid, deletion flag information is also recorded in the sub-area of the other block having the predetermined address relation with the one block. Upon reading, the data of the blocks read out from the recording medium exclusive of the data of the block determined to be invalid on the basis of the flag information is transferred to a high-rank system.

Data recording and reproducing method

An information recording method and system for writing information onto a recording medium. If an error area is detected in a check of the information read out of the medium after writing, the information is rewritten onto an alternative area on the recording medium using a buffer memory while the information in the error area is kept valid. Loss time accessing the alternative area is eliminated until the error checking and correction in the error checking and correction circuit is not available for the information read out of the error area through a reading circuit.

Information recording system and method for using alternative record

In an information storage system including a rotating recording medium having a number of information tracks, a head positioning mechanism for switching access position between adjacent tracks and a plurality of buffer memories each capable of storing one track of data, an alternate record area for storing data in substitution for an error data block is provided at an end of each of the tracks of the recording medium, and if an error data block is detected by a read-after-write check of the data during the rotation of the disc after the data has been written in one of the tracks from one of the buffer memories during the previous rotation of the disc, the data from the other buffer memory is written in the adjacent track or the data is read from the adjacent track and checked during a disc rotation waiting time required before the data write operation to the alternate record area is started.

Method for accessing to a rotating record medium and an access control

Disclosed is a control method for writing or reading sequentially a plurality of blocks of data for a storage device using a recording medium, such as a photo disk, with a number of recording blocks each having a unique address. In writing data, a plurality of data blocks to be written concurrently are given in their pointer fields the first address indicating the same alternative block, and these data are written in consecutive recording blocks on the recording medium. If blocks with write errors are detected, the data blocks corresponding to the error blocks are written sequentially in an alternative area starting from the first address, after replacing the pointer fields with the second address indicating the defective blocks, respectively. This allows the access of the alternative blocks for defective blocks by detecting the pointer address within the pointer fields of normal blocks preceding and following each of the defective blocks during the data reading operation.

Method of controlling storage device

An information transfer apparatus for connecting between plural channels and input/output control devices in a computer system, comprising a bundle of signal lines with which said channels are connected, said bundle of signal lines including plural signal lines provided respectively for said plural channels so as to effect the time-shared connection between said plural channels and input/output control devices therethrough.

Information transfer apparatus

A method of controlling a rotary memory for preventing failure to read a recorded information block during reading of the contents of the memory. In the method, a second marker is provided separately from a first marker representing the starting point of each recorded information block so as to achieve the desired missing-free read control of the rotary memory.

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Odawara, Japan

Michio Miyazaki