JPS6381538A - Duplicated information processing system with backup file and its operating method - Google Patents

Abstract

PURPOSE:To always assure the coincidence between contents of an active equipment file and a standby equipment file by providing a file and a file version table recording the update history of the file to both two controllers acting like alternately the active and standby equipments. CONSTITUTION:An active controller 3 controls terminal equipments 5a-5m via its communication control section 32, transmits/receives input/output information, sends the received input information to the standby controller 4, and the standby controller 4 cannot control the terminal equipment via its communication control section 42 but can receive the information sent from the active controller 3. The file 33 of the active controller 3 is updated based on the input information from the terminal equipment and its update history is stored in the file version table 34. The input information to the active controller 3 is sent to the standby controller 4 and the file 43 of the standby controller 4 is revised based thereupon, its update history is stored in the file version table 44 of the standby controller 4 and the coincidence of contents of both the files are always kept.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a redundant information processing system having a working machine and a standby machine, and particularly to file backup in such a system.

[Conventional technology]

In a so-called duplex or stand-by system, the main equipment is duplicated, and one of them is usually used as the active machine to perform the main task, while the other is on standby as a standby machine or is used to handle non-urgent tasks. If a failure occurs in the active aircraft, the backup aircraft will take over the functions of the active aircraft. This type of system is often employed to increase the reliability of online real-time processing systems.

In such a standby system, unlike a parallel (dual) system in which two sets or groups of devices perform the same processing in parallel, the file is often single, and this is the file that is assigned to the active machine at each point in time. Connected and processed. For example, the duplex system described in Japanese Patent Application Laid-Open No. 53-12243 has two processing devices and a single file, and input information is sent to the image processing device by a distribution device.

Although each processing device holds the file as an input queue, the file is managed only by one of the processing devices. Loss of input information due to an error in the processing device that is managing the file can be detected and rescued by the input queue of the other processing device.

In such a standby system that does not have a single file, file reliability must be maintained sufficiently high by performing a single system backup, such as periodic file dumps (transferring file contents to auxiliary storage). Requires file backup similar to . Even in the duplex system described in the above-mentioned publication, periodic file dumps are still necessary in order to deal with file destruction caused by errors during file updates in the processing device that manages the files.

A system is possible in which a pair of files are prepared and the current processing device updates these files in parallel. However, although this type of system can prevent file contents from being destroyed due to a failure in the file itself, it cannot cope with file contents being destroyed due to a failure in a processing device.

[The interlayer point that the invention attempts to solve]

As mentioned above, traditional waiting systems do little to improve file reliability. Even if you make the preprocessor wait for its own files.

That alone is meaningless. This is because the preprocessor does not receive input information necessary for updating files, unlike in parallel systems.

If the file in the preliminary processing device is updated to the current processing bag ml, the same result as the above-mentioned system provided with a pair of files can only be obtained. It is necessary not only for the preprocessor to have its own file, but also to take special measures to keep its contents consistent with the contents of the file of the active processor.

In addition, switching files between two processing units or updating a pair of files in parallel requires additional hardware and reinforcement of the O8, so systems using small computers such as microcontrollers are required. It is not suitable for this, and changing to a higher-end model will result in a sharp increase in costs.

The purpose of the present invention is to improve the reliability of files in a standby system at low cost. The goal is to provide a means for

[Means for solving problems]

According to the present invention, two control devices that alternately function as an active device and a backup device are provided with a file version table for recording files and file update history. Furthermore, the communication control unit of each control device communicates with both the terminal device and the control device operating as a standby device when it is operating as an active device, and communicates with the control device that is operating as a standby device without communicating with the terminal device. The controller is configured to communicate only with a controller operating as a controller.

As a method of operating the system configured as described above, when the active control device receives input information from the terminal device, it updates the file and file version table of the active control device, and sends this input information to the standby control device. When the backup controller receives this information, it updates the backup controller's file and file version table.

At the start of operation and other necessary times, the file versions of the two control devices are compared, and if they do not match, the contents of the file with the older update history are replaced with the contents of the file with the newer update history.

[Effect]

The active control device can control the terminal device, send and receive input/output information, and send the received input information to the backup control device via its communication control unit, and the backup control device can control the communication. Although the terminal device cannot be controlled through the control unit, it is possible to receive information sent by the current control device. The file of the current control device is updated based on input information from the terminal device, and the update history is recorded in the file version table. The input information to the active control unit is sent from there to the standby control unit, and the file of the standby control unit is updated based on the input information, and the update history is recorded in the file version table of the standby control unit, so that both files content consistency is always maintained. When files need to be synchronized, the contents of the file version table are exchanged and compared, and if they do not match,
The contents of the file with the older update history are replaced with the contents of the file with the newer update history, and the contents of both files are matched.

〔Example〕

FIG. 1 shows an embodiment of a duplex information processing system according to the present invention. The host computer is connected to a pair of terminal control devices 3 and 4 through a communication path 2, and the terminal control devices 3 and 4
is connected by a communication path 6 to a plurality of terminal devices 5a to 5m. For example, the terminal devices 5a to 5m are PO8 terminal devices.

The terminal control devices 3 and 4 are either a mask PO8 having both a PO8 terminal function and a terminal control function, or a mask controller exclusively for control. Either one of the terminal control bags Wx3 or 4 functions as a current control device (hereinafter referred to as a pressure control device), and the other functions as a backup control device. 4 devices (hereinafter referred to as side control devices). The main control device is in charge of communication with the host computer 1 and management of the terminal devices 5a to 5m,
Furthermore, it communicates with the sub-control device. Although the sub-control device does not communicate with the host computer or manage the terminal device,
It communicates with the primary control device to update files as described later. The opening control devices also perform mutual monitoring, as described below.

The terminal control bag W3 is essentially a small computer (for example, a microcomputer), and only one element necessary for the present invention is conceptually shown in FIG. The indicator 31 is a type of well-known status indicator (or register),
It indicates whether this terminal control device is operating as a primary control device or a sub-control device, thereby regulating the operation of the device. The communication control unit (CCU) 32 is essentially the same as a normal communication control unit, but it has a control function including a communication control program so that it can communicate with the other terminal control device 4 even in the sub-control device state. It is characterized by the structure of the mechanism. Furthermore.

File 33 and file version table (FVT)
34 is provided. The file version table 34 can be formed in an appropriate area of the main storage device, and
As shown in the figure, it consists of an overall version 341, a file number 342 and a file version 343 for each file. The overall version 341 indicates the number of updates for the entire file, and each file version 343
indicates the number of updates of the file with the corresponding number.

The terminal control device 4 has the same configuration as the terminal control device 3 and includes an indicator 41, a communication control unit 42, a file 43, and a file version table 44.

Next, the operation of the information processing system shown in FIG. 1 will be explained. Figures 3 and 4 schematically illustrate the file update process, and in these figures, the sub-control device has been moved to a position alongside the terminal device so that it can be easily distinguished from the main control device. Illustrated. In the following, it is assumed that the terminal control device 3 is operating as a primary control device and that the terminal control device 4 is operating as a sub-control device.

First, in FIG. 3, a message sent from the terminal device 5a is received by the main control device 3.

The main control device 3 transmits the received message to the sub control device 4 as an output message 8. The primary control device 3 and the sub-control device 4 independently execute file update processes 9 and 10 based on the messages received by each.

FIG. 5 shows communications performed in the process of FIG. 3,
In response to the polling 51 from the primary control device 3, the terminal device it5a transmits a message 52 (7 in FIG. 3), and the primary control device 3 that received this message 52 returns an acknowledgment 53. Next, the main control device 3 sends a transmission request 54 to the sub control device W4, and in response to this, the sub control device 4 returns an access request 55. The primary control device 3 that has received this acknowledgment 55 sends a message 56 (8 in FIG. 3) having the same content as the previously received message 52 to the sub-control device 4, and the sub-control device 4 that received this message 56
returns an acknowledgment of 57.

FIG. 4 shows the processing of messages sent from the host computer. Message 2 sent from host computer 1
1 is received by the primary control device 3 via the communication path 2. The main control device 3 transmits this received message to the sub control device 4 as an output message 22. The primary control device 3 and the sub-control device 4 independently execute file update processes 23 and 24 based on messages received by each.

Thereafter, the primary control device 3 transmits a message 25 to each of the terminal devices 15a to 5b, if necessary.

Following the file update processing shown in FIGS. 3 and 4, the primary control device 3 and the secondary control device 4 update their respective file version tables 34 and 44. In the primary control device 3, first, the entire version 341 is counted up, and then the file version 343 corresponding to the file number 342 of the updated file is counted up. Updating of the file version table 44 in the sub-control device 4 is also performed in the same manner as described above.

When the system starts operating, file synchronization processing is necessary to ensure that the contents of the file 33 of the primary control device 3 and the file 43 of the sub-control device 4 match. FIG. 6 is a flowchart of file synchronization processing performed at the start of operation. In the file synchronization process, the primary control device 3 and the sub-control device 4 use the file version tables 34 and 44.
(61). Each control device compares the contents of its own file version table with the file version table of the other control device.

First, the whole version (341) is compared (62),
If it is -1, the file synchronization process ends and services to terminal devices etc. are started (64). On the other hand, if the overall version does not match, the file version (343)
A file number (342) with a different file number is searched, and for files with the searched numbers, that is, files with different file versions, the content of the corresponding file is transferred from the control device with the larger overall version to the other control device. is transmitted (63).

The file synchronization process may be performed not only at the start of operation but also during operation as needed.

Mutual fault monitoring between the primary control device and the sub control device is performed as follows. The main control device 3 via the communication path 6
Polling of the terminal devices 5a to 5m and the sub-control device 4 is repeated, and the polled devices return some kind of response if they are normal.

If there is no response from the sub-control device 4 after a predetermined number of polling attempts, the main control device 3 determines that a failure has occurred in the sub-control device 4 and stops the service therefor. On the other hand, the sub-control device 4 monitors polling from the main control device, and if it does not receive polling within a predetermined time, it determines that a failure has occurred in the main control device W3 and sets its own indicator 41. Switches to the primary control device state and starts operating as the primary control device.

This mutual monitoring method does not require any special equipment for fault monitoring, and is therefore advantageous in that it is inexpensive.

〔Effect of the invention〕

According to the present invention, sufficient backup of files in the standby system can be easily realized using the communication function between the active machine and the standby machine.

A highly reliable system can be provided at low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a duplex information processing system according to the present invention, FIG. 2 is a diagram showing the contents of a file version table, and FIGS. 3 and 4 are examples of file backup processing according to the present invention. Schematic diagram, 5th
The figure is a time chart of communication performed during the process shown in FIG. 3, and FIG. 6 is a flow chart showing an example of the file synchronization process according to the present invention. 3.4... Control device that can alternately function as a working machine/backup machine, 58-5 rn... Terminal device, 7... Input message to the working control device, 8... Working control device Messages sent from 9, 10, etc. to the standby control unit
-File update processing, 31, 41... Working/standby status indicator, 32.42... Communication control unit, 3
3.43...File, 34.44...File version table, 61-63...File synchronization processing.

Claims (1)

[Scope of Claims] 1. Comprising at least one terminal device and two control devices connected to each other and each connected to the terminal device, each of the control devices is a file updated based on input information; a file version table for recording an update history of the file; communication control means that communicates with both the terminal device and the other control device while the indicator means indicates standby operation, but communicates only with the other control device while the indicator means indicates standby operation. 2. At least one terminal device and two control devices interconnected and each connected to the terminal device; a file that is updated based on input information; a file version table for recording the update history of the file; In a redundant information processing system having communication control means that communicates with both the device and the other control device, but communicates only with the other control device while the indicator means indicates standby device operation, updating the file and file version table of the control device when the control device receives input information from the terminal device, and sending the input information to the other control device; updating the file and file version table of the control device upon receiving information. 3. At least one terminal device and two control devices interconnected and each connected to the terminal device; a file that is updated based on input information; a file version table for recording the update history of the file; and a communication control means that communicates with both the device and the other control device, but communicates only with the other control device while the indicator means indicates standby device operation, wherein the two control devices are controlled a step of exchanging and comparing the file version tables between the devices, and a step of replacing the contents of the file with the older update history with the contents of the file with the newer update history if there is a mismatch between them. A file synchronization method comprising: