JPH0775001B2 - System switching method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a system switching method in a duplex system, and is particularly suitable for performing system switching regularly when the system is in a normal state. The present invention relates to a system switching method.

[Conventional technology]

In the existing redundant system, when an error occurs in the active system, how quickly the standby system that was in the standby state until then is started up as a new active system Whether or not the system can be put into operation is one of the important issues when switching systems. Generally, in the past, in the system switching, each of the duplicated control devices for ensuring the continuity of the control processing is independently system switching controlled without the system switching circuit,
In reality, the system switching control is performed under the intervening control by the system switching circuit.

In addition to the above, Japanese Patent Laid-Open No. 59-200531 discloses that control data is incorporated in a control device, so that a system stoppage during system switching is avoided as much as possible. ing. However, due to the occurrence of an abnormality in the active system, when system switching (system switching at the time of abnormality) is performed under the intervening control by the system switching circuit, it is impossible to avoid a temporary stoppage of function on the system. The reality is that

[Problems to be solved by the invention]

By the way, these days, the system is actually switched (system switching at normal time) even when the system is in a normal state. This is to ensure and maintain the reliability of the standby system at all times.Even if the active system does not have any abnormality, the active system and the standby system are regularly used as the standby system and the active system, respectively. It is in the system. In this way, not only is system switching performed when an error occurs in the active system (system switchover in the event of an abnormality), but system switching (normal The time system is switched). However, until now, the normal time system switching is performed in the same way as the abnormal time system switching, so even when the normal time system switching is performed, the system temporarily stops functioning. Is that it cannot be avoided. The occurrence frequency of abnormal time system switching due to the occurrence of an abnormality in the active system is extremely low. However, considering that the normal time system switching is performed at a high occurrence frequency, it is accompanied by the normal time system switching. Temporary outages on the system can no longer be ignored.

The object of the present invention is, even when the system switching is performed at a high frequency during normal operation, when the system switching is performed, in the state where the temporary functional stop on the system is suppressed as much as possible,
An object of the present invention is to provide a system switching method in which the system switching can be performed in a good state.

[Means for solving problems]

The above-mentioned object is that when the active subordinate apparatus and the standby subordinate apparatus are accommodated so that both the active subordinate apparatus and the standby subordinate apparatus are put into the operating state via the system switching circuit, the active subordinate apparatus is connected to the active system processing control apparatus. While the information is bidirectionally transferred between the two, the standby subordinate device is received as the information can be received from the active process control device and the information cannot be transferred to the active process control device. While
Every time the system switching in the system normal state is regularly performed by the active system processing control device, prior to the system switching, the active system subordinate device and the standby system subordinate device are in the use prohibited state, Waiting for the active system processing control device itself to shift to an idle state, the active system subordinate device and the standby subordinate device are accommodated in the standby system process control device via the system switching circuit, and at the same time,
The active system process control device and the standby system process control device are newly placed in the standby system process control device and the active system process control device, respectively, by a system switching interrupt to the standby system process control device, and then a new active system This is achieved by restarting the system operation under the control of the processing control device in a state in which the use prohibited state for each of the active subordinate device and the standby subordinate device is released.

[Action]

When both the active system subordinate device and the standby subordinate device are accommodated in the active system process control device via the system switching circuit so that both are in the operating state, the active system subordinate device is bidirectional with the active system process control device. While the information is stored in the active system processing control device as being transferable, the standby subordinate device is in a state in which it is receiving the information from the active system processing control device and is incapable of transferring information to the active system process control device. The normal system switching is performed. That is, each time the system switching in the system normal state is regularly performed by the active system process control device, the active system subordinate device, prior to the system switching,
Each backup subordinate device is in a state where it is prohibited to use,
Waiting for the active system process control device itself to shift to an idle state, the active system subordinate device and the standby system subordinate device are accommodated in the standby system process control device via the system switching circuit, and at the same time, the standby system process control device. The active system processing control device and the standby system processing control device are newly placed in the standby system processing control device and the active system processing control device, respectively, by the system switching interruption to the new active system processing control device. In addition, when the system operation is restarted in the state where the use prohibited state for the active subordinate device and the standby subordinate device is released, the system temporarily stops functioning when the normal system switching is performed. The system switching can be performed in the state where is avoided as much as possible.

〔Example〕

 Hereinafter, the present invention will be described with reference to FIGS. 1 to 4.

First, the duplex system according to the present invention will be described.
FIG. 1 shows an outline of the system configuration in that example. In this case, the memory device MM0, the external storage device DK0, the switch device SW0, the input / output control device IOC0, and the system control device SC0 are subordinate devices actively controlled by the process control device CP0, and by the process control device CP1. Process control device CP as a subordinate device that is passively controlled
0, the processing control device CP1 is selectively accommodated in the system control circuit SEL. Also a memory device
MM1, external storage device DK1, switch device SW1, input / output control device IOC1 and system control device SC1 are processing control device CP1.
As a subordinate device actively controlled by the process control device CP0, as a subordinate device passively controlled by the process control device CP0, either the process control device CP0 or the process control device CP1 is connected to the system switching circuit SE.
It is selectively accommodated via L. The system switching circuit SEL is provided to allow the system control devices SC0 and SC1 to selectively store the active system subordinate device and the standby system subordinate device in either of the process control devices CP0 and CP1.

Now, the processing control devices CP0 and CP1 are provided for controlling the entire system. First, when the processing control device CP0 is in the active system, the processing control device CP0 has a memory device MM0 and an external storage. Device DK0, switch device SW0, I / O controller IOC0 and system controller SC0, as well as memory device MM1, external storage device DK1, switch device SW
1, the input / output control device IOC1 and the system control device SC1 are also accommodated via the system switching circuit SEL so as to be placed in the operating state. In this case, the processing control device CP1 is placed in the standby system and in the standby state from the active system due to the normal system switching until the system switching interrupt occurs. In this state, the processing control device CP0 and the memory device MM0,
External storage device DK0, switch device SW0, input / output control device IO
Although data can be transferred bidirectionally to and from C0, processing control device CP0, memory device MM1, and external storage device DK
Data can be transferred from the processing control device CP0 to the memory device MM1, the external storage device DK1, the switch device SW1, and the input / output control device IOC1 between the switch device SW1 and the input / output control device IOC1. However, the transfer in the opposite direction is prohibited. As a result, for example, although data writing to each of the memory devices MM0 and MM1 by the processing control device CP0 is permitted, when reading data from each of the memory devices MM0 and MM1 to the processing control device CP0, reading from the memory device MM0 is performed. Only what is allowed.

By the way, process (= program) control units CP0, CP1 are provided inside each of the processing control devices CP0, CP0, and a start process and an end process of the processing process are performed in response to a request from each of the process control devices CP0, CP0. The control of the waiting process is performed as follows.

That is, FIG. 2 shows the process control flow by the process control unit together with the process control table.
When an interrupt from the subordinate device (data I / O request interrupt), a clock interrupt (including a periodic normal time system switching interrupt), or a request from the typewriter TTY command occurs, the processing control unit sends the process control unit to the process control unit. On the other hand, a process start request, a process standby request, a process stop request, or a normal time system switch request is issued. Based on these requests, the process control unit refers to the process control table and controls the process to start / stop / standby.
Here, the process control table will be described. This consists of a process start table and a process WAIT table, and each process is controlled and managed on the process control table. More specifically, when there is a process activation request, the process is registered in the process activation table and the process is activated. If the process is in a wait (WAIT) state, when the process is registered in the process start table, the process is deleted from the process WAIT table and then started. Further, when there is a standby request for a process in the activated state, the registration of the process is moved from the process activation table to the process WAIT table, and the process is placed in the standby state.
Furthermore, if the process is in the active state when the process is requested to be stopped, it is placed in the inactive state by deleting the process from the process activation table, but if the process is in the standby state. If it is, the process is placed in the terminated state by deleting the process from the process WAIT table.

FIG. 3 also shows a process control flow relating to the system switching method according to the present invention. When an interrupt from a subordinate device, an interrupt from a clock, or a request from a command occurs, the process controller sends a request to the process controller.
A process start request, process standby request, process stop request, or normal time system switch request is issued.
Based on these requests, the process control unit refers to the process control table and controls the process to start / stop / standby. By the way, when there is a system switching request (during normal operation) from the processing control device,
In this case, the process control unit first puts the subordinate devices (external storage devices DK0, DK1, switch devices SW0, SW1, input / output control devices IOC0, IOC1) in a prohibited state. As a result, thereafter, the process that performs input / output with the subordinate device remains in the standby state until the subordinate device is put in the usable state again after being put in the unusable state. is there. After that, it is checked whether or not the processing control device is in the idle state, but after waiting for the processing control device to become in the idle state, the system switching is performed by issuing a system switching request to the system switching circuit SEL. The processing control device CP1 that was in the standby state until then was placed in the new active system, and the memory device MM1 and the external storage device D
Not only K1, switch device SW1, input / output control device IOC1 and system control device SC1, but also memory device MM0, external storage device DK0, switch device SW0, input / output control device IOC0 and system control device SC0 are also in the operating state. Therefore, it is accommodated via the system switching circuit SEL. A system switching interrupt is generated in the processing control device CP1 in response to the system switching request, but based on this interrupt, the processing control device CP1 causes the subordinate device (external storage device DK0, The DK1, the switch devices SW0 and SW1, and the input / output control devices IOC0 and IOC1) are returned to the usable state again. Since the subordinate device has been temporarily disabled, the process control device CP1 issues a start request to each process in the standby state to the process control unit PC1, thereby controlling the process. The processes are sequentially started by the unit PC1, and thereafter the system operation is restarted under the control of the processing control device CP1 to put the system in a normal operating state.

Here, a method of checking whether or not the processing control device is in the idle state will be described with a delay, and FIG. 4 shows the flow thereof. When the process control unit requests a process start from the process control unit, the process is registered in the process start table and then started. This means that the process is actually in the operating state. Therefore, it means that the processing control device is also in use (non-empty state). When the process uses the subordinate device, for example, the external storage device DK0, the external storage device DK0 is enabled only when the external storage device DK0 is in the usable state. However, when it is in the use prohibited state, the process control unit issues a standby request to the process control unit, so that the process is moved from the process activation table to the process WAIT table. At the end of the process execution, the process control unit issues a process stop request to the process control unit, so that the process is deleted from the process start table and then stopped.

Therefore, as can be seen from the above, if the process is registered in the process activation table, the processing control device is in the in-use state (non-empty state), and if it is not registered, the processing control device is Can be determined to be empty.

Finally, referring to the case where the present invention is applied to an electronic exchange, in the electronic exchange, the usage rate of the processing control device itself in the exchange processing control is generally about 60%. The probability that the device is in the idle state is high, and it is easy to perform the normal time system switching when the process control device is in the idle state. In system switching in the idle state, it is not necessary to maintain continuity in processing control, and the system switching time can be greatly shortened, and software control can be simplified at the same time.

〔The invention's effect〕

As described above, according to the present invention, system switching is performed while the process control device is in the idle state, and therefore it is not necessary to maintain continuity in process control with respect to the standby system. Not only that, software control can be greatly simplified. In addition to this, the system switching can be performed without considering the system state, and the system switching is performed in a state in which the temporary function stop on the system is avoided as much as possible.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a system configuration in an example of the duplex system according to the present invention, FIG. 2 is a diagram showing a process control flow by a process control unit together with a process control table, and FIG. FIG. 4 is a diagram showing a process control flow according to the system switching method according to the present invention, and FIG. 4 is a diagram showing a flow for checking whether or not the processing control device is in an idle state. CP0, CP1 …… Processing control device, MM0, MM1 …… Memory device, DK
0, DK1 …… External storage device, SW0, SW1 …… Switch device, IO
C0, IOC1 …… I / O controller, SC0, SC1 …… System controller, TTY …… Typewriter, SEL …… System switching circuit, PC0,
PC1 ... Process control unit

Claims (1)

[Claims] 1. When an active subordinate apparatus and a standby subordinate apparatus are accommodated so that both the active subordinate apparatus and the standby subordinate apparatus are placed in an operating state via a system switching circuit, the active subordinate apparatus is connected to the active system processing control apparatus. Information is bidirectionally transferred between the two, while the backup subordinate device is allowed to receive information from the active system processing control device and is not transferable to the active system process control device. Is being
Each time the active system processing controller periodically switches the system in a normal system state, prior to the system switchover, the active subordinate device and the standby subordinate device that are currently in operation are prohibited from use. Placed in a state, the active subordinate device,
The process control for each standby subordinate device is sequentially placed in the standby state, and when the active subordinate device and the standby subordinate device have completed the transition to the standby state, the active system process control device itself is determined to be in the idle state. After that, the active system control device and the standby system control device are accommodated in the standby system process control device via the system switching circuit, and at the same time, the active system process control device, the active system process control device, and the standby system process control device The standby system process control device is newly placed in the standby system process control device and the active system process control device, respectively, and under the control of the new active system process control device, the active system subordinate device and the standby system subordinate device are respectively controlled. A system switching method in which the system operation is restarted while the use-disabled state and the standby state for processing control are released.