JPH096638A - Dual computer system and its switching device - Google Patents

Abstract

PURPOSE: To minimize the system reorganization to easily change the connection by simplifying the connection at the time of connecting another computer to two computers directly connected for communication. CONSTITUTION: Terminals of first and second connection parts having two terminals are internally cross-connected, and first switches 15, 25, and 35 and a second short-circuit switch connected from respective terminals of first and second connection parts are provided, and first switches connect the computers to terminals when online signals of computers are inputted. Three alternative computers 11, 21, and 31 are provided with switching circuits 12 to 32 consisting of these switches, and switching circuits are connected by external cables 40 and 50 and are linearly arranged, and the computer arranged in the center is used as a standby computer; and if one of computers on both sides is faulty, the computer arranged in the center is operated instead of the faulty computer by switching of switches.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual computer system having a communication function for backing up each other in the event of a failure, and more particularly to a dual computer system and its switching device in which a communication connection system between dual computers is improved. .

[0002]

2. Description of the Related Art In a computer system such as an ATM system of a bank which needs to perform business processing online, two computers which perform business processing are connected to each other so that they can back up each other.

FIG. 6 is a diagram showing a duplicated computer system configured by connecting two computers in a one-to-one correspondence. Figure 6
In this system, two systems of business operation system are computer 6
1 and the computer 62, and these 2
The computers 61 and 62 are connected by a common communication medium 63, and communication by Ethernet is performed.

By providing such a communication path, when one of the computers has a trouble, the other computer can perform the work substitution. If Ethernet is used, the connection between the computers is relatively simple, but it may be difficult to secure sufficient communication capacity for performing the business agent only with Ethernet.

Therefore, in order to further secure the reliability of communication, in the system of FIG. 6, computers are directly connected by one communication medium, and a direct communication path 64 different from the communication by Ethernet is provided.

[0006]

However, in such a redundant computer system in which a normal computer takes over the work that is being processed by each computer in the event of a failure, an abnormal computer stops. As a result, the work load on the normal computer side is significantly increased, and the processing capacity of the entire system is reduced, which causes a problem of congestion of processing.

Further, at this time, if a double failure occurs in which the computer which has taken over the work fails, there is a possibility of causing a fatal situation of stopping the system. In order to prevent such a system stop, as shown in FIG. 7, in addition to simply duplicating the computers, a computer 65 of a standby system that is not used during normal business processing may be provided.

However, when the highly reliable direct connection communication path 64 as shown in FIG. 6 is provided, since the connection of the path 64 is complicated, it is necessary to connect the computers one to one. is there. It is impossible to connect another computer to this direct connection communication path 64. Also, if the connection is forcibly made, it may cause a malfunction, which may affect the operation of the system.

Therefore, when the standby system is used by using the direct connection communication, two communication lines are further used as shown in FIG.
It is necessary to secure one directly connected communication path 66, 67, which causes a problem that the connection relationship of the entire system becomes complicated. Moreover, since the connection path is complicated, the processing on the computer side increases.

Further, when a redundant computer system without a standby system is remodeled into a system with a standby system, it is necessary to drastically change the connection of the communication system, and the cost is high due to the remodeling. In addition, there is a problem that connection mistakes are likely to occur during modification.

The present invention has been made in consideration of such a situation, and when one computer is directly connected to two computers connected by a direct communication path, the connection path is simply connected. It is an object of the present invention to provide a duplicated computer system and a switching device for the same, which enables easy connection change while minimizing system modification.

[0012]

In order to solve the above problems, the invention according to claim 1 provides a dual computer system in which at least two computers that execute online processing are connected so that their respective processing can be replaced. In the switching device, the first and second connecting portions each having the terminal a and the terminal b are provided, and the terminal a of the first connecting portion and the terminal b of the second connecting portion are connected by an internal cable. And a short-circuit terminal to which the terminal a of the second connecting portion and the terminal b of the first connecting portion are connected by an internal cable, and the terminal a of the first connecting portion is connected. And a common terminal to which the terminal a of the second connection section is connected and a connection terminal to which a communication path from the corresponding computer is connected, and an online signal indicating the online processing state of the corresponding computer is input. If you The first switch that closes the terminals and the connection terminals and closes the common terminals and the short-circuited terminals when the online signal is not input, and the terminal b of the first connection portion and the terminal b of the second connection portion. A switching circuit having a second switch that can be opened and closed is provided in the same number as at least two computers, and the first connection portion of a certain switching circuit and the second connection portion of another switching circuit are connected to the outside. This is a switching device of a dual computer system in which each switching circuit computer is linearly arranged by sequentially connecting the terminals a to each other and the terminals b to each other by using a cable and opening the connection portions located at both ends. .

Next, the invention corresponding to claim 2 is a dual computer system in which first, second and third computers capable of executing online processing are connected so that their respective processing can be replaced with each other. First and second connection parts respectively provided with b are provided, the terminal a of the first connection part and the terminal b of the second connection part are connected by an internal cable, and the second connection part An internal-external connection means in which the terminal a of the first connection part and the terminal b of the first connection part are connected by an internal cable;
And a common terminal to which the terminal a of the second connection portion is connected, and a connection terminal to which a communication path from the corresponding computer is connected are provided. A switching circuit having a switch that closes the common terminal and the connection terminal when an online signal indicating the online processing state of the computer is input and a switch that closes the common terminal and the short-circuited terminal when the online signal is not input is first. 1, each of the second and third computers is provided, and each computer corresponding to each switching circuit is connected via a switch,
From the respective switching circuits corresponding to the first, second and third computers, the first connecting portion and the second connecting portion in the other switching circuit are connected to each other by using an external cable, and the terminals a and b are connected to each other. The first computer, the second computer, and the third computer are arranged in a line, and the second computer serves as a standby computer, and the first or third computer is connected. When a failure occurs in any of the above computers, the standby computer replaces the failed computer with the redundant computer system.

According to a third aspect of the present invention, in a duplicated computer system in which first, second and third computers capable of executing online processing are connected so that their respective processing can be replaced, terminal a and terminal b are provided. First and second connection portions respectively provided with are connected, the terminal a of the first connection portion and the terminal b of the second connection portion are connected by an internal cable, and An internal / external connecting means in which the terminal a and the terminal b of the first connecting portion are connected by an internal cable;
And a common terminal to which the terminal a of the second connection portion is connected, and a connection terminal to which a communication path from the corresponding computer is connected are provided. When an online signal indicating the online processing state of the computer is input, the common terminal and the connection terminal are closed, and when the online signal is not input, the common terminal and the short-circuit terminal are closed. A switching circuit having a normally open second switch that can be opened and closed between the terminal b of the connection portion and the terminal b of the second connection portion is provided for each of the first, second and third computers, Each computer corresponding to each switching circuit is connected via the first switch, and each switching circuit corresponding to the first, second and third computers is connected to the first computer.
By connecting the connection part of No. 2 and the second connection part of the other switching circuit sequentially with the terminals a and the terminals b using an external cable, and by opening the connection parts located at both ends, When the first, second and third computers are arranged in a line and the second computer is a standby computer and one of the first or third computers fails, the standby computer causes a failure. It is a redundant computer system that replaces the computer that has occurred.

[0015]

Therefore, first, in the switching device of the dual computer system according to the first aspect of the present invention, at least two computers that execute online processing are connected to each other so that their processing can be replaced.

This connection is realized by connecting a switching circuit provided for each computer with an external cable. In other words, in this switching device, by connecting the same unit consisting of a switching circuit with an external cable and arranging each computer linearly,
It is possible to realize a dual computer system whose connection path is simple.

Further, the first and second connecting portions are connected by the internal / external connecting means provided with the cross-connected internal cables in the first connecting portion and the second connecting portion, and the first and second switches connected to these. It is possible to construct a duplicated computer system by selecting two of the two or more computers.

For example, when two computers are connected, the first switch is closed between the common terminal and the connection terminal, and the second switch of one switching circuit is opened.
A duplicated computer system can be realized by closing the second switch of the other switching circuit.

Further, for example, by expanding the above system,
When connecting two computers and using one as a standby system, it is sufficient to connect the same switching circuit to the above system via an external cable.

In this case, for example, if the computer at the right end is to be used as a standby system, all the second switches are opened, and the first switch of the switching circuit at the left end and the center is connected to the common terminal,
The connection terminals may be closed, and the first switch of the switching circuit at the right end may be closed between the common terminal and the short-circuit terminal.

As another method for making the computer at the right end part a standby system, for example, the switch state of the switching circuit at the left end part and the center may be set to the same state as when connecting only the two computers. . In this case, the computer at the right end is completely separated from the communication system of the redundant computer.

On the other hand, the method of setting the computer on the left end side to the standby system is the same as the case of setting the computer on the right end side to the standby system. Furthermore, if you want to use the computer in the center as a standby system,
All the second switches may be opened, and the first switches of the switching circuits at the left end and the right end may be closed between the common terminal and the connection terminal.

By adjusting the switching of each switch in the switching circuit in this manner, it is possible to easily change the system while minimizing system modifications. In addition, claim 2
In the redundant computer system of the invention corresponding to, in the invention corresponding to claim 1, the number of computers is three,
In addition to the same operation as in the case where the second switch in the invention of claim 1 is normally open, each computer is used as a standby system with the computer in the central portion.

In this case, each computer is connected via a switch, and the switch is closed between the common terminal and the connection terminal when an online signal is input, so the computers at the left end and the right end are online. If the processing is being executed, these computers will be in the directly communicable state, and the duplicated computer system will be realized.

Here, the computer at the central portion is not connected to the computers at the left end portion and the right end portion regardless of whether the switch is in the online state or in the offline state.

In such a duplicated computer system, when a failure occurs in the computer at the left end or the right end, the switch connection in the computer is closed between the common terminal and the short-circuited terminal, so that the computer in the central part is in the online state. In the case of, the computer in which no failure occurs and the central standby computer are connected, so that it is possible to easily realize the continuation of the processing of the failure computer.

Further, in the redundant computer system of the invention corresponding to claim 3, the second computer system operates in the same manner as the invention corresponding to claim 2 and is the same as the invention corresponding to claim 1 and is normally open. A switch is provided.

Therefore, it is possible to disconnect the computer at the right end or the left end from the communication system of the duplicated computer system by using the second switch as in the case of the invention according to claim 1, and it is possible to disconnect the computer. It is also possible to separate the computer in which the error occurred and perform maintenance.

[0029]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing an embodiment of a duplicated computer system according to the present invention. The duplicated computer is duplicated by a first operating system 10 and a second operating system 20 that perform online business processing. Furthermore, one of the operating systems 10 and 20 is duplicated.
There is provided a standby system 30 that operates when there is an abnormality.

Each of the operating systems 10 and 20 and the standby system 30 comprises computers 11, 21 and 31 and switching circuits 12, 22 and 32 having the same configuration, and the switching circuit 1
A direct connection cable 40 as an external cable connects between 2 and 32. Similarly, the switching circuits 32 and 22 are connected by a direct connection cable 50 as an external cable.

The direct connection cable 40 is composed of two sets of cables 40a and 40b, which are sufficient for direct connection communication between computers, and these two sets of cables are integrated as one direct connection cable 40. The direct connection cable 50 is also composed of two sets of cables 50a and 50b.

On the other hand, the computers 11, 21, 31 are configured to perform online business processing and communication with other computers. During normal operation, the computers 11, 21 are used and the computer 31 is on standby. ing.

The switching circuit 12 includes direct connection cable connecting portions 13X and 13Y as first and second connecting portions, internal cables 14a and 14b, a changeover switch 15 as a first switch, and a first switch. And a short-circuit switch 16 as a second switch.

Each switching circuit 12, 22, 32
Have the same configuration, and the portions to which the reference numerals in the respective switching circuits correspond respectively. Figure 1
In, the internal cable 14a, the internal cable 24a, and the internal cable 34a correspond to each other.

In the switching circuit 12, the internal cable 14a is connected between the direct connection cable connection terminal 13Xa and the direct connection cable connection terminal 13Yb.
The internal cable 14b is a direct connection cable connection terminal 13X
It is connected between b and the direct connection cable connection terminal 13Ya. Therefore, the internal cables 14a and 14b are cross-connected between the direct connection cable connection portions 13X and 13Y.

Further, on the internal cables 14a and 14b, the direct connection cable connecting portion 13 is provided before and after the cable cross.
Terminals 14a1 and 14a2 and terminals 14b1 and 14b2 are provided in order from the X side.

The changeover switch 15 is for changing over the direct connection of the computer, the common terminal C is connected to the terminal 14b2, and the short-circuit terminal 15a is the terminal 14a1.
It is connected to the. Also, the connection terminal 15b is the computer 11
When the common terminal C and the connection terminal 15b are connected to each other, the computer 11 is in a state capable of direct connection communication with another computer via a direct connection cable.

With the changeover switch 15, the computer 1
The computer 11 indicating that 1 is normally performing business processing
The common terminal C and the connection terminal 15b are connected to each other when the online signal 17 is input, and the common terminal C and the short-circuit terminal 1 are connected when the online signal 17 is not input.
5a are connected.

The short-circuit switch 16 has terminals 14a2, 14
It is a switch that can short-circuit between b1. It is open during normal business processing in the duplicated computer shown in FIG. 1, and closed during cable disconnection and the like.

Each operating system 10, 20 configured as described above
Also, with respect to the standby system 30, one end of the cable 40a of the direct connection cable 40 has a direct connection cable connection terminal 1 of the operation system 10.
3Xa, and the other end is connected to the direct connection cable connection terminal 33Ya of the standby system 30. Also, the cable 40
One end of b is a direct connection cable connection terminal 13X of the operation system 10
b, and the other end is connected to the direct connection cable connection terminal 33Yb of the standby system 30.

Furthermore, the cable 50 of the direct connection cable 50
One end of a is a direct connection cable connection terminal 23Y of the operation system 20
The other end is connected to the direct connection cable connection terminal 33Xa of the standby system 30. Further, one end of the cable 50b is connected to the direct connection cable connection terminal 23Yb of the operation system 20, and the other end is connected to the direct connection cable connection terminal 3 of the standby system 30.
It is connected to 3Xb.

The direct connection cable connection parts 13X and 13
An example of the internal / external connecting means is realized by Y and the internal cables 14a and 14b. Next, the operation of the redundant computer of this embodiment configured as described above will be explained.

First, the operation when there is no abnormality in each computer and normal business processing is performed will be described with reference to FIG. When the computers of the operating systems 10 and 20 shown in FIG. 2 are respectively processing jobs, the online signals 17 and 27 are output, and the common terminals C of the changeover switches 15 and 25,
The connection terminals 15b and 25b are connected. At this time, the short circuit switches 16, 26 and 36 are all open.

Therefore, in this state, the computer 1
The communication signal between 1 and 21 is a direct communication path A, that is,
Changeover switch 15, internal cable 14b, cable 40b of direct connection cable 40, internal cable 34a, cable 50a of direct connection cable 50, internal cable 24b,
The configuration is such that direct input / output is performed via the changeover switch 25, and direct connection communication between the active systems 10 and 20 is possible.

In the above-mentioned normal operation state, the operation of the standby system changeover switch 35, that is, the operation of the computer 31 of the standby system 30 does not affect the direct connection communication path A. That is, even if the common terminal C and the connection terminal 35b of the changeover switch 35 are connected, the computer 31 is not connected to the direct communication path A, and when the common terminal C and the short-circuit terminal 35a are connected, the computer 31 is , And is disconnected from the switching circuit 32.

Next, the switching operation when a failure occurs in the active system 20 will be described with reference to FIG. First, when the standby system 30 outputs the online signal 37 in the standby state, the common terminal C of the standby system changeover switch 35 and the connection terminals 15b and 25b are connected.

In the present embodiment, it is assumed that the standby system 30 always outputs an online signal so that the work can be taken over even when a failure occurs in the active system 10 or 20.

Here, when a failure occurs in the computer 21 of the active system 20, the output of the online signal 27 of the active system 20 is stopped, so that the changeover switch 25 of the active system 20 is connected between the common terminal C and the short-circuit terminal 25a. Switch to. At this time, the short circuit switches 16, 26 and 36 are all open.

In this state, the communication signal of the operating system 10 is
Directly connected communication path B, that is, the switch 40, the internal cable 14b, and the cable 40 of the directly connected cable 40.
b, the internal cable 34a, the cable 50a of the direct connection cable 50, the internal cable 24b, the changeover switch 25,
Internal cable 24a, cable 50 of direct connection cable 50
b, the internal cable 34b, and the changeover switch 35 to directly input / output to / from the standby system 30.

Therefore, when a failure occurs in the active system 20 and the online signal 27 is stopped, the active system 10 and the standby system 30 are immediately connected directly, and the active system 20 is directly connected.
The computer 31 of the standby system
By taking over, the work can be continued with the same processing capacity as before the failure.

Further, even when a failure occurs in the active system 10, the same direct communication path is used for the active system 20 and the standby system 3.
It is formed between zero. Further, a switching operation for disconnecting the active system 20 during the work processing between the active system 10 and the standby system 30 after a failure occurs in the active system 20 will be described with reference to FIG.

A failure occurs in the active system 20 and the computer 2
When it is desired to disconnect the active system 20 for repairing No. 1, the short-circuit switch 36 of the standby system is connected. In this state, the communication signal between the computers 11 and 31 is the direct connection communication path C, that is, the changeover switch 15 and the internal cable 1.
4b, the cable 40b of the direct connection cable 40, the internal cable 34a, the short-circuit switch 36, the internal cable 34b, and the changeover switch 35 to directly input and output,
Direct communication between the active system 10 and the standby system 30 is maintained as it is.

Therefore, since the direct connection state is continuously switched from the direct connection communication path B to the direct connection communication path C, it is possible to disconnect the active system 20 while continuing the work while maintaining the direct connection communication path.

As described above, in the redundant computer system and its switching device according to the present embodiment, the direct connection cable connecting portions 13X and 13Y are cross-connected by the internal cables 14a and 14b, and their respective terminals 13Xa and 13X are connected.
b, 13Ya, 13Yb, the changeover switch 15 and the changeover circuit 12 connected to the short-circuiting switch 16, and the changeover circuits 22 and 32 similar to this are connected to the computers, and between the respective computers depending on the output state of the online signal from each computer. Since the direct connection communication path can be switched, even if a computer under online business processing fails, the business processing of the computer can be immediately continued in the standby system.

Therefore, backup support when a failure occurs by adding a computer to the standby system can be continued without reducing the processing capacity. Further, in such a redundant computer system that is switched when a failure occurs, the short-circuiting switch 36 can be used to disconnect the failed computer from the communication system. Therefore, it is necessary to take measures such as disconnecting the computer for maintenance. Can be taken.

Furthermore, in the redundant computer system and its switching device according to the present embodiment, each operating system and standby system can be freely configured in the unit of the above-mentioned switching circuit, and switching between them and change of connection relationship (direct connection communication path) Setting) is free, so when one computer is provided with a direct connection communication path to two computers connected with a direct connection communication path,
It is possible to construct a system in which the connection path can be simplified and the system can be easily changed by minimizing the system modification.

Therefore, the one-to-one direct connection communication processing performed by each conventional computer can be used as it is, and the reliability of the communication path can be maintained. can do.

Further, since the switching circuit is commonly used, it can be used without regard for cable connection or the like with any computer, and in the case of a redundant computer system which is constructed by connecting one computer to another with a conventional one. In comparison, the number of cables is small and connection mistakes can be prevented. Therefore, the reliability of the entire system is improved.

FIG. 5 is a diagram showing the structure and operation of another embodiment of the duplicated computer system according to the present invention. The same parts as those in FIG. Will be described only.

This duplicated computer system comprises an active system 10
And an active system 20 and no standby system.
The operation system 10 and the operation system 20 are connected by a direct connection cable 45 including a cable 45a and a cable 45b. Here, one end of the cable 45a is connected to the direct connection cable connection terminal 13Xa of the operation system 10 and the other end is connected to the direct connection cable connection terminal 23Ya of the operation system 20. Further, one end of the cable 45b is connected to the direct connection cable connection terminal 13Xb of the operation system 10 and the other end is connected to the direct connection cable connection terminal 23Yb of the operation system 20.

Further, the short circuit switch 16 is open and the short circuit switch 26 is closed. In this state, the communication signal between the computers 11 and 21 is the direct communication path D, that is, the changeover switch 15, the internal cable 14b, the cable 45b of the direct connection cable 45, the internal cable 24a,
Direct input / output is performed via the short-circuit switch 26, the internal cable 24b, and the changeover switch 25.
0, direct communication between the active system 20 is realized.

In this case, by using the short-circuit switch 26, it can be used as a dual computer system having no standby system. As described above, the redundant computer system and its switching device according to this embodiment are the switching circuit in the previous embodiment, the same switching circuit as the external cable, and the redundant computer system using only two computers using the external cable. Since it is realized, it is possible to construct a low-cost redundant computer system according to the budget amount, and to provide versatility that can be easily expanded to the system with the standby system of the previous embodiment. The present invention is not limited to the above embodiments,
Various modifications can be made without departing from the gist of the invention.

[0063]

As described in detail above, according to the present invention, since the switching circuit having high versatility and expandability is used, one computer is added to two computers connected by the direct communication path. It is possible to provide a duplicated computer system and its switching device that make the connection path simple when directly connected by communication and enable easy connection change while minimizing system modification.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a redundant computer system according to the present invention.

FIG. 2 is an explanatory diagram showing a switching operation of the redundant computer system according to the embodiment.

FIG. 3 is an explanatory diagram showing a switching operation of the redundant computer system according to the embodiment.

FIG. 4 is an explanatory diagram showing a switching operation of the redundant computer system according to the embodiment.

FIG. 5 is a diagram showing the configuration and operation of another embodiment of the redundant computer system according to the present invention.

FIG. 6 is a configuration diagram showing a conventional redundant computer system.

FIG. 7 is a configuration diagram showing a redundant computer system having a conventional standby system.

[Explanation of symbols]

11 ... Calculator, 12 ... Switching circuit, 13X, 13Y ...
Direct connection cable connection part, 14a, 14b internal cable, 1
5 ... Changeover switch, 16 ... Short circuit switch, 17 ... Online signal, 21 ... Calculator, 22 ... Changeover circuit, 2
3X, 23Y ... Direct connection cable connection part, 24a, 24b internal cable, 25 ... Changeover switch, 26 ... Short circuit switch, 27 ... Online signal, 31 ... Calculator, 32 ... Switching circuit, 33X, 33Y ... Direct connection cable connection part, 3
4a, 34b internal cable, 35 ... changeover switch,
36 ... Short circuit switch, 37 ... Online signal, 40 ... Direct connection cable, 40a, 40b ... Cable, 45 ... Direct connection cable, 45a, 45b ... Cable, 50 ... Direct connection cable, 50a, 50b ... Cable.

Claims (3)

[Claims] 1. A switching device for a redundant computer system, wherein at least two computers that execute online processing are connected so that their processing can be replaced with each other. First and second connections, each having a terminal a and a terminal b. Is provided, the terminal a of the first connecting portion and the terminal b of the second connecting portion are connected by an internal cable, and the terminal a of the second connecting portion and the terminal b of the first connecting portion are provided. And an internal / external connecting means, which is connected by an internal cable, a short-circuit terminal to which the terminal a of the first connecting portion is connected, and a common terminal to which the terminal a of the second connecting portion is connected. A connection terminal to which a communication path from the computer is connected, and an online signal indicating an online processing state of the corresponding computer is input, the common terminal,
A first switch that closes the connection terminals and closes the common terminal and the short-circuited terminal when the online signal is not input; and a terminal b of the first connection portion and a terminal b of the second connection portion. A switching circuit including a second switch that can be opened and closed is provided in the same number as that of the at least two computers, and the first connection portion in a certain switching circuit and the second connection portion in another switching circuit. By sequentially connecting the terminals a to each other and the terminals b to each other using an external cable, and connecting portions located at both ends are opened to arrange the switching circuits linearly. Switching device for redundant computer system. 2. A dual computer system in which first, second, and third computers capable of executing online processing are connected so that their respective processing can be replaced with each other, first and second terminals each having a terminal a and a terminal b. Is provided, the terminal a of the first connecting part and the terminal b of the second connecting part are connected by an internal cable, and the terminal a of the second connecting part and the first connecting part are connected. An internal / external connecting means in which the terminal b is connected by an internal cable, a short-circuit terminal to which the terminal a of the first connecting portion is connected, and a common terminal to which the terminal a of the second connecting portion is connected. , A connection terminal to which a communication path from a corresponding computer is connected, and an online signal indicating an online processing state of the corresponding computer is input, the common terminal,
A switching circuit including a switch that closes the connection terminals and closes the common terminal and the short-circuited terminal when the online signal is not input is provided for each of the first, second, and third computers, The respective computers corresponding to the respective switching circuits are connected via the switch, and the respective switching circuits corresponding to the first, second and third computers are connected to the first connection unit and the other switching circuits. An external cable is used to sequentially connect the second connecting portion to the terminals a and the terminals b to each other, and the connecting portions located at both ends are opened so that the first, second, and The third computer is arranged in a line, the second computer is a standby computer, and the first or third computer
A redundant computer system characterized in that, when a failure occurs in any of the above computers, this standby computer replaces the failed computer. 3. A dual computer system in which first, second and third computers capable of executing online processing are connected so that their respective processing can be replaced by each other, and first and second terminals each having a terminal a and a terminal b. Is provided, the terminal a of the first connecting part and the terminal b of the second connecting part are connected by an internal cable, and the terminal a of the second connecting part and the first connecting part are connected. An internal / external connecting means in which the terminal b is connected by an internal cable, a short-circuit terminal to which the terminal a of the first connecting portion is connected, and a common terminal to which the terminal a of the second connecting portion is connected. , A connection terminal to which a communication path from a corresponding computer is connected, and an online signal indicating an online processing state of the corresponding computer is input, the common terminal,
A first switch that closes the connection terminals and closes the common terminal and the short-circuited terminal when the online signal is not input; and a terminal b of the first connection portion and a terminal b of the second connection portion. A switching circuit having a second switch that can be opened and closed and is normally open is provided for each of the first, second, and third computers, and each computer corresponding to each of the switching circuits has a first switch. And connecting the first connecting part and the second connecting part in another switching circuit from each switching circuit corresponding to the first, second and third computers by using an external cable. The terminals a, b are sequentially connected to each other, and the connecting portions located at both ends are opened to arrange the first, second, and third computers in a line, The second computer is a standby computer, and the first or second computer Is the third
A redundant computer system characterized in that, when a failure occurs in any of the above computers, this standby computer replaces the failed computer.