Hitachi, Ltd.

Toshihiko Tamiya

Akira Yamamoto

Akira Kurano

Hisashi Takamatsu

Hirofumi Inomata

Eiju Katsuragi

Naoya Takahashi

Mikito Ogata

A disk array device selects a redundant generation method for reducing the overhead and improving the reliability associated with generating redundant data. The disk array device includes a disk controller connected to and controlling an array of disk drives. The disk controller includes a redundant data generator, a difference data generator, and a redundant data generation method selector. The redundant data generator is able to generate redundant data via a read and modify method and an all stripes method. The disk array device selects a method of generating redundant data from a method of read and modify and all stripes, and a method of generation in a drive and a method of difference, both of which are executed to generate redundant data on a disk drive.

Disk array device with selectable method for generating redundant data

A disk array device selects a redundant generation method for reducing the overhead and improving the reliability associated with generating redundant data. The disk array device includes a disk controller connected to and controlling an array of disk drives. The disk controller includes a redundant data generator, a difference data generator, and a redundant data generation method selector. The redundant data generator is able to generate redundant data via a read and modify method and an all stripes method. The disk array device selects a method of generating redundant data from a method of read and modify and all stripes, and a method of generation in a drive and a method of difference, both of which are executed to generate redundant data on a disk drive. The disk array device selects the method of generating redundant data that will minimize the time required to process, transfer and store both the received host data and the generated redundant data based on the length of write data received from the host, an access pattern specified by the host, by the current load state of the disk drives, and by the existence of a failure state in a disk drive. Divided write data and previous data to be updated may be transferred depending on the write data length.

A disk array stores data records and parity records. The data records are transferred to the disk array through a control unit that is connected to a host processor. The disk array is part of a disk unit having a processor for generating parity records from information sent by the control unit to the disk unit. The parity record is generated and stored in the disk unit to reduce the number of data transfer operations between the control unit and the disk unit for storage systems using disk array disk units.

Parity storage unit, in a disk array system, for generating updated parity data from received data records

A disk array device selects a redundant data generation method for reducing the overhead and improving the reliability associated with generating redundant data. The disk array device includes a disk controller connected to and controlling an array of disk drives. The disk controller includes a redundant data generator, a difference data generator, and a redundant data generation method selector. The redundant data generator is able to generate redundant data via a read and modify method and an all stripes method. The disk array device selects a method of generating redundant data from a method of read and modify and all stripes, and a method of generation in a drive and a method of difference, both of which are executed to generate redundant data on a disk drive. The disk array device selects the method of generating redundant data that will minimize the time required to process, transfer and store both the received host data and the generated redundant data based on the length of write data received from the host, an access pattern specified by the host, by the current load state of the disk drives, and by the existence of a failure state in a disk drives. Divided write data and previous data to be updated may be transferred depending on the write data length.

Parity storage unit, in a disk array system, for generating updated

Parity storage unit, in a disk array system for generating updated

Storage unit with parity generation function and storage systems using

A data recording and reading system includes a recording medium having a plurality of fixed length recording units, recording units for recording data and associated data recording information indicating the record status of the data in the recording medium, and reading units for reading the data recorded in the recording medium. In the data recording and reading system, the data recording information includes a data flag indicating if data has been recorded on the recording medium, and a data length indicating the length of the recorded data.

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Hadano, Japan

Toshihiko Tamiya