Mitsubishi Denki Kabushiki Kaisha

Shiro Ogura

Hiroshi Baba

Toshio Matsumoto

Masahiro Mizuno

Kazuhiko Itoh

Hitoshi Yamamoto

Kazuhiko Ito

Akira Ogawa

Kazuo Ito

A multi-value logic device in which a unique bus level is allocated beforehand to each binary logic signal outputted by a function of the multi-value logic device. Upon receipt of the binary logic signal via a bus level selection circuit, a driver converts the binary logic signal to an analog signal with a voltage having an amplitude of e&middot;2,, in which n is the bus level of the binary logic signal and e is a reference voltage. When a plurality of binary logic signals are simultaneously inputted, the driver superimposes analog signals in accordance with the bus level of each binary logic signal to generate a multi-value logic signal, so that multiplex communication is realized. A receiver performs an operation reverse to the operation of the driver, and encodes a multi-value logic signal received via a bus to convert the signal to a binary logic signal and transmit the signal to each function. In this manner, the multi-value logic device suppresses an increase in the number of bus signal conductors, and enhances throughput by realizing multiplex communication.

Multi-value logic device, bus system of multi-value logic devices connected with shared bus, and network system of information processors loaded with multi-value logic devices and connected with shared network

A bus bridge which can prevent invalid data from being transferred from a secondary PCI bus to a primary PCI bus even when an SCSI controller or another device provided with a memory the content of which is cleared after a read, is connected to the secondary PCI bus. In a controller, a transaction is processed as a delayed transaction. A combination circuit generates a switching logic signal in accordance with a command or an address included in the transaction. In accordance with the memory content, a bus release controller restricts transmission by a transaction forward controller of a control signal for stopping the transaction issued on the primary PCI bus. Instead of restricting the transmission of the control signal, the time-out period of the buffer memory may be prolonged.

PCI bus bridge with transaction forwarding controller for avoiding data

For the high-speed data access machine, data is distributed in a plurality of hard disk drives coupled to slave processors to achieve ever-higher data reliability and maintenance. One master processor is provided with a plurality of slave processors, each of which is coupled to two hard disk drives containing the same data. A synchronous signal permits two hard disk drives to operate in synchronous rotation in half-a-turn phase difference from each other. The hard disk controller writes the same data in both hard disk drives but reads data from whichever hard disk drive requires less access time to obtain the data. A plurality of hard disk drives holding exactly the same data improves data reliability. Also, by rotating a plurality of hard disk drives in different phase, the rotational delay in data access is cut by half.

Data access from the one of multiple redundant out-of-sync disks with

A data storage managing system and method in which a HOST system obtains operation information of a storage device from a system connected to a network without the need for a specific device driver are disclosed. When disks shared between systems connected to the network are managed by a disk manager, monitoring and control information for the shared disks may be accessed by a file access command of the operating system on the HOST system. An operation information storage device is formed in a file format which can be accessed by a file access command of the operating system on the HOST system and the HOST system reads the operation information of the storage devices stored in the operation information file according to the file access command. The information to control the operation of the storage devices is written in the operation information file according to the file access command. The disk manager controls the operation of the storage devices according to the operation information of the operation information file.

Method and system including operation information accessible by a system

Embodiments of the present invention provide a data storage system that reduces a load of a data bus for connecting a HOST system with the data storage system. The data storage system includes a disk manager connected to the HOST system by a SCSI BUS, connected to a disk control unit by an RS PORT and connected to disk enclosures and a fan unit by a Serial BUS. The disk manager monitors operation of the disk control unit and disk enclosures and transmits results to the HOST system. In addition, control commands of the HOST system to the disk enclosures are executed via the disk manager.

Data storage system and storage managing method

Distributed database system having master and member sub-systems

In case of consecutive transmission of a large amount of data such as dynamic image data, a multi-media storage system of the invention generates and transmits data stored in a faulty disk drive when one of a plurality of disk drives being faulty caused by an internal calibration or an error of the disk drive and the faulty disk drive does not respond within a predetermined length of time set in a timeout table. The multi-media storage system cancels an access to the faulty disk drive, generates data to be read from the faulty disk drive based on data stored in the other disk drives of the plurality of disk drives and the redundant data and continues to transmit data.

Multi-media storage system

In a redundant array of disks, the disks are divided into areas of different sizes, so that small amounts of data can be stored in an area of an appropriate size on a single disk, instead of being spread over multiple disks. A usage status table indicates which areas are in use. Check information is generated and stored only for areas indicated to be in use. When new check information is generated, it is therefore possible to omit the reading of unnecessary old data and old check information. When a disk fails and is replaced with a standby disk, only the data in areas indicated to be in use are reconstructed. Check information can be stored on a solid-state disk.

Redundant array of disks with host notification process for improved

Redundant array of disks with improved data reconstruction

Redundant array of disks with improved storage and recovery speed

A read unit 400 which governs reading of data and a write unit 500 which governs writing of data are located separately in a RAID unit 300 which controls array type magnetic disk units. To read data from magnetic disk units 800, a control circuit 600 uses the read unit 400 to read data through an HDD control unit 700. To write data, the control circuit 600 uses the write unit 500 to write data into the magnetic disk units 800. Since the read unit and write unit are provided separately, processing performance improves.

Recording system having a redundant array of storage devices and having

In a redundant array of disks, the disks are divided into areas of different sizes, so that small amounts of data can be stored in an area of an appropriate size on a single disk, instead of being spread over multiple disks. A usage status table indicates which areas are in use. Check information is generated and stored only for areas indicated to be in use. When new check information is generated, it is therefore possible to omit the reading of unnecessary old data and old check information.

The present invention relates to an arrayed recording apparatus with reduced writing time. Various devices are used to write data without redundant data and to update the redundant data more efficiently during idle time. In one embodiment, a temporary write track is provided for each cylinder. When data are read, updated and re-written, the data are re-written to the temporary write track. Since the re-writing does not require a full disk rotation, the writing occurs quickly. Data in the temporary write track are relocated into the disk during an idle state, without being synchronized. Additionally, corresponding blocks in data areas can be used for writing data rather than a specified temporary write track. In order to improve re-writing time, the rotation of the disk drives can be synchronized to avoid full rotations between reads and writes, or cache memories for each disk can be used. When data is accessed from a host computer in a first unit size and from the memory devices in a second unit size, a buffer and cache can be used to limit the written data to those portions of the second unit size which have been changed. Each of these devices reduces the total access time for writing to arrayed recording devices.

Recording apparatus and method for an arrayed recording apparatus

In the magnetic disk apparatus according to the invention, the latch circuit latches the content of the logic signal provided from the comparative operational circuit at the end of the seek operation and holds the latched content during a track trace operation, and the linear position signal selected to constitute a closed loop positioning system is fixed to that at the end of seek operation for controlling the head position, so that recoverable allowance of the deviation from the center of the desired track (i.e., off-track amount) of the head at the time of the track trace operation can be increased to increase the reliability of seek operation.

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Kamakura, Japan

Shiro Ogura