Abstract: A control method which is used in a RAID1 storage subsystem including a plurality of storage devices, and processes an access request from a host computer with the cooperation of the plurality of storage devices of the storage subsystem is provided. In the storage subsystem, each storage device of the RAID1 storage subsystem includes a unit for sharing an access request from the host computer, and a unit for determining if the storage device should process the shared access request. The storage device further includes a unit for transferring write data, which is transmitted from the host computer to the storage subsystem, to at least a storage device that should process it.

Abstract: Error detection in a fiber-channel arbitrated loop (FC-AL) is facilitated by incorporating certain error detection circuitry in FC-AL adapted electronic devices. Transmission circuitry is provided to transmit diagnostic frames during periods when the electronic device has no pending output transactions. Receiver circuitry is provided to perform CRC checking of each received frame.

Abstract: A control method which is used in a RAID1 storage subsystem including a plurality of storage devices, and processes an access request from a host computer with the cooperation of the plurality of storage devices of the storage subsystem is provided. In the storage subsystem, each storage device of the RAID1 storage subsystem includes a unit for sharing an access request from the host computer, and a unit for determining if the storage device should process the shared access request. The storage device further includes a unit for transferring write data, which is transmitted from the host computer to the storage subsystem, to at least a storage device that should process it.

Abstract: A magnetic disk drive has magnetic disks having tracks and a number of sectors forming each track. The tracks have an ID few track format and the drive is divided into a plurality of notches. The drive also includes a memory and a defect sector list, sector replacement list, defect track list and replacement track list, each of which is stored in the memory. Defective sectors and tracks in each notch are slipped during formatting, and further defective sectors and tracks detected subsequent to the formatting are skipped. Spare sectors in the notch are provided in a spare region to accommodate the slipped and skipped sectors and tracks, respectively. The defective sector list is supervised as a two stage table to reduce the required memory size for maintaining the list and to decrease the time required for searching the list.

Abstract: A data transfer control apparatus for communicating data between a host device and an input/output device through a main buffer memory for temporarily holding the data, wherein a sub-buffer memory is disposed at least either between the main buffer memory and the host device or between the main buffer memory and the input/output device for temporarily storing the data, the amount of data stored in the sub-buffer memory is detected, access requests to the main buffer memory on the side of the host device or the input/output device are outputted in accordance with the detected data amount, and one of the access requests to the main buffer memory is selected in accordance with the priority order to access the main buffer memory on the basis of the selected access request.