Abstract: A plurality of commands which may be sent sequentially from a host computer are interpreted by a host command interpreter to generate a disk command for each disk unit. When these commands make up an access demand for a single continuous area, they are grouped into a single command, which is executed substantially at the same time at each disk unit. Also, a plurality of RMW processing systems having different command issued to disk units are available. A selection condition is detected from the I/O demand information supplied by a host computer, and an optimum one of a plurality of RMW processing systems is selected and executed on the basis of the selection condition.

Abstract: A disc storage apparatus includes a disc having at least one recording surface, a head associated with the recording surface for recording data on the recording surface during a data write operation, and for reproducing data from the recording surface during a data read operation, a disc control unit for receiving data and outputting parallel data during the data write operation, and for receiving parallel data and outputting data during the data read operation, and an encoder/decoder circuit for receiving the parallel data from the disc control unit and outputting data to the head to be recorded on the recording surface during the data write operation, and for receiving from the head data reproduced from the recording surface and outputting parallel data to the disc control unit during the data read operation.

Abstract: In a computer system utilizing an array disk for an external storage device, an array controller arranged between a host computer and disk unit group has a main controller for controlling the array disk; a buffer for temporarily buffering data transferred between the host computer and the disk units; a parity data generator for generating parity data; and an interface controller for controlling interfaces connecting the host computer with the disk units. The buffer has memories for storing transfer requested data and parity data as previous data and previous parity data, respectively. The array controller also has memory management information for managing the memories.

Abstract: A recording apparatus includes a plurality of ECC units operating selectively and independently. A medium access unit reads data from a recording medium in a read mode, and writes data from a host device to the recording medium in a write mode. The data read out from the recording medium contains a reproduction data and a medium reproduction check symbol added to the reproduction data, and data written contains a recording data and a medium recording check symbol added to the recording data. The reproduction data or the recording data is stored in a buffer. In a read mode, the reproduction data from the medium access unit is transferred to the host device through the buffer and in the write mode, the recording data from the host device is transferred to the medium access unit through the buffer.

Abstract: A host computer is connected with a magnetic disk storage device by an SCSI bus. In the magnetic disk storage device, a plurality of partitions are set in a disk drive unit and have device identifiers (ID's) respectively allocated thereto as SCSI ID's=1, 2 and 3, which are supported by a disk controller. When the host computer has acquired the control of the SCSI bus through arbitration and has selected, for example, the partition with the device identifier SCSI ID=1, the disk controller permits the host computer to access the partition in response to the selection. Since the partitions are different in attributes, properties etc., they appear as magnetic disk storage devices that are separate from one another when viewed from the host computer. Thus, the single magnetic disk storage device can be managed as a plurality of storage devices of different nature.

Abstract: A disk array system in which the disk array control mode can be switched to a higher-performance mode easily by exchanging extension boards. An IF board is parallel-connected to disk devices through signal lines. Several types of extension boards each having a controller in accordance with the access control mode are prepared so that one of the extension boards is connected to the IF board through a connector formed as a set of one internal bus connector, a plurality of SCSI connectors and extension board type identification pins. As a result, it is not necessary for a user to alter the connection of disk drives and to switch control software on the host computer, so that the disk array control mode can be changed to a higher-performance mode easily only by exchanging the board.