JPS61160150A - Duplex system - Google Patents

Abstract

PURPOSE:To attain the duplicate writing of the same data in disks of both disk control devices even if a single disk control device is failed by forming a means for writing stored data in the other external storage device. CONSTITUTION:A channel program for executing similar seaking, searching and wiring operations from a current CPU1 to disks 16, 16' is sent to a disk control device 10. The device 10 sends such operation indication to the disk 16 through a disk control part 15. When the disk 16 starts the seaking operation, an operation control part 13 of the disk control device 10 sends the same seaking operation command to the other disk 16'. If a recoverable read error is generated in the primary disk 16 at the time of reading, the reading operation command of the secondary disk 16' is sent from the current CPU1 to the device 10, so that the device 10 can read out data from the secondary disk 16'.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a duplex system, and more particularly to a duplex system equipped with active and standby central processing units (hereinafter referred to as CPUs) and active and standby external storage devices.

Prior Art A conventional example of a system employing a duplex configuration is disclosed in Japanese Patent Publication No. 59-31743. FIG. 2 is a block diagram showing a duplication system of such a conventional disk control system.

In the figure, the left side is the active system, and the right side is the backup system. C.P.
Disk controllers 2 and 2' are connected to U1 and 1', respectively, and each disk controller 2 and 2' has a plurality of magnetic disk storage devices (hereinafter referred to as disks) 7 and 7'.
are connected respectively.

The disk control units @2 and 2- consist of interface circuits 3 and 3', operation control units 4 and 4', active system control circuits 5 and 5', and standby system control circuits 6 and 6'. The operation control units 4 and 4' have a dual-system operation control circuit 8 and 8-1 and a dual-system operation reporting circuit 9 and 9', respectively.

In such a duplex system, both disks 7 and 7'
When writing the same data twice to CPU1, first
From there, one operation command is sent to write the same data to the active disk 7 and the standby disk 7' via the active disk controller 2 and interface circuit 3.

Upon receiving the command, the dual-system operation control circuit 8 of the operation control unit 4 included in the active disk control device 2 issues an operation command to the active system control circuit 5 of the active system, and at the same time issues a command to the active system control circuit 5 of the active system. A standby system control circuit 6 included in the disk control device 2
Issue a movement command to. The active control circuit 5 of the active system starts writing to the disk 7 of the active system. The active standby control circuit 6 starts writing to the disk 7' via the standby disk control device 2'.

When the write operation on the active disk 7 and the backup disk 7- is completed, the data is transferred to both active disks via the active control circuit 5 and the backup control circuit 6 included in the active disk controller 2. The operation completion results of the active disk 7 and the standby disk 7' are reported to the operation report circuit 9.

When the dual-system operation reporting circuit 9 receives the report of the operation completion results of the active disk 7 and the standby disk 7', it edits them and reports the completion to the CPU 1 via the interface circuit 3.

In the conventional duplex system described above, when performing dual writing, the disk control devices of both systems are used, so if a failure occurs in the disk control device of one system, dual writing becomes impossible. be. In addition, since the disk controllers of both systems are used during dual writing, there is a drawback that a queue occurs, and in order to communicate the waiting state and release of the queue, a communication means is required between the disk controllers. There are some drawbacks that make it necessary.

Purpose of the Invention The present invention provides that even if a failure occurs in the disk control device (external storage control device) of one system, the disks (external storage devices) of both systems
The purpose of the present invention is to provide a duplication system that can perform dual writing of the same data.

Another object of the present invention is to provide a duplex system that does not require waiting even during dual writing of an external storage device and does not require communication means between external storage control devices.

Structure of the Invention A duplex system according to the present invention includes first and second external storage control devices connected to both active and standby central processing units, respectively. Each of the box 1 and second external storage control devices is characterized in that it is configured to be able to independently control both the current and standby external storage devices. means for controlling the writing of write data from the active central processing unit into either the active or standby external storage device in response to an operation command from the central processing unit;
It is characterized by having means for storing this write data and means for writing this stored data to another external storage device.

EXAMPLES The present invention will be described in detail below using the blocks shown in FIG.

CPLJl is the active system, and CPU1- is the standby system, which are connected to the disk control units W110 and 10', respectively. A plurality of active disks 16 and 16' are commonly connected to each disk control device 10 and 10'.

The disk control units @10 and 10- are respectively composed of interface circuits 12 and 12', operation control units 13 and 13-, data buffers 14 and 14', and disk control units 15 and 15'.

One channel program is sent to the disk controller 10 from the active CPU 1 to the disks 16 and 16- to perform similar seek, search, and write operations. First, the disk control section @10 sends a seek operation instruction to the disk 16 via the disk control section 15. When the disk 16 starts a seek operation, the operation control unit 13 of the disk controller 10 sends the same seek operation instruction to the other disks 16-. The operation control unit 13 sends, via the disk control device 15, a search operation instruction to whichever of the disks 16 and 16- the seek operation was completed first.

Next, the operation control unit 13 starts a write operation from the disk on which the target sector is detected first among the disks 16 and 16'. child! For example, assume that the target sector of the disk 16 is detected first. The operation control unit 13 of the disk control device 10 makes a data transfer request to the active CPU 1 via the interface circuit 12, and
1 through the interface circuit 12 is written to the disk 16. At the same time, the operation control section 13
The data buffer 14 transfers data transferred via the interface circuit 12 to be written to the disk 16'.
Store it in. After writing to the disk 16 is completed, when writing to the disk 16' becomes possible, the operation control unit 13 starts writing to the disk 16' using the data stored in the data buffer 14. When the writing to the disk 16' is completed, the operation control unit 13 releases the disks 16 and 16', and then reports the completion of the operation of both disks to the active CPU 1 via the interface circuit 12.

Typically, disk 16 will be used to read from the disk, and thus disk 16 will be the primary disk. If an unrecoverable read error occurs when reading from this next disk 16, the active CPU
1 to the disk controller 10, the disk controller 10 can read from the secondary disk 16'.

According to the present invention, dual writing is possible with one disk controller, so even if a failure occurs in the active disk controller, the backup disk controller can perform double writing. is possible. Furthermore, since the active and standby disk control devices can operate completely independently of each other, there is no waiting during execution of double writing, and communication means between the disk control devices is not required.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional duplex system. Explanation of symbols of main parts 1... Active system CPU i'... Backup system CPU 1o, io''... Disk control device 1
3.13-...Operation control unit 14.14'...Data buffer 15.15-
...Disk control section 16.16-disk

Claims (2)

[Claims] (1) A redundant system comprising active and standby central processing units and active and standby external storage devices,
comprising first and second external storage control devices connected to both the active and standby central processing units, respectively;
and a second external storage control device, each of which is configured to be able to independently control both the active and standby external storage devices. (2) Each of the first and second external storage control devices:
means for controlling writing of write data from the active central processing unit into either the active or standby external storage device in response to an operation command from the active central processing unit; and storage of the write data. 2. The duplex system according to claim 1, further comprising means for writing the stored data to another external storage device.