JPH02280250A - Method for switching control system - Google Patents

Abstract

PURPOSE:To properly execute a system switching operation by providing a system switching control means to switch a control system based on a first instruction from a first or second controller in a standby. CONSTITUTION:A high order device 1 issues a second instruction to a second or first controller 4 or 2 in the standby by the chance of the reception of error generation information from the first or second controller 2 or 4 in the middle of operation or an instruction from an external part. The first or second controller 2 or 4 issues a first instruction to a system switching control means 3 by the chance of the second instruction, and it starts the system switching operation. Thus, the execution of the system switching operation to be mistaken due to the malfunction of the first or second controller 2 or 4 can be surely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control system switching technique, and particularly to a technique that is effective when applied to a technique for switching multiplexed control systems in an information processing system.

[Conventional technology]

For example, in an information processing system such as a general-purpose computer system, an external storage device is connected to a central processing unit and a channel device that controls the exchange of information between the main memory and the outside on behalf of the central processing unit. and its control devices, etc., so that if a failure occurs in one system, the operation is switched to another system to avoid the entire external storage device from stopping in the event of a failure. It is known.

By the way, such technology has been developed in Japanese Unexamined Patent Publication No. 1983
A technique disclosed in Japanese Patent No. 166644 is known.

The outline is that a communication means is provided between multiple control systems that are loosely coupled via a group of file memories, and a control system that detects an error in a specific file memory communicates with other control systems about the error in that file memory. By notifying the disconnection and reconfiguration of the connection state, it is possible to dynamically change the system configuration using multiple control systems and file memory groups.

[Problem to be solved by the invention]

However, in the case of the above-mentioned conventional technology, if the error detection information in a specific file memory is caused by an error in the control system itself, the input/output operation in the file memory is normal and input/output from other systems is not detected. A problem in which input/output processing to file memory that is deemed to have caused an error is forcibly aborted even though the processing is being performed normally, resulting in a decrease in the efficiency of use of the hardware resources that make up the system. There is.

In addition, when an error is detected in a specific file memory, the input/output processing to the file memory is immediately terminated and the system is disconnected as described above, so data cannot be written to the file memory from other systems. If it is inside, there are various problems such as destruction or loss of data.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a control system switching technique that enables accurate system switching operations in multiplexed control systems.

Another object of the present invention is to provide a control system switching technique that allows easy maintenance and management of multiplexed control systems.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in Ho is as follows.

That is, the control system switching method according to the present invention includes first and second control devices that are interposed between a higher-level device and a lower-level device and perform control operations for the lower-level devices independently of each other based on commands from the higher-level device. and first and second memories that are shared by the first and second control devices and whose storage contents are maintained the same, and when one of the first and second control devices is in an operating state. In a control system that is multiplexed so that the other is placed in a standby state and the two are switched between an operating state and a standby state at any time, one
Alternatively, system switching control means for switching the control system based on the first command from the second control device is provided.

[Effect]

According to the control system switching method of the present invention described above, for example, the lower-level device waits for the second command upon receiving error occurrence information from the operating first or second control device or an instruction from the outside. The first or second control device in standby issues the first command to the system switching control means using this second command as a trigger, and performs system switching. Starting the operation reliably prevents an erroneous system switching operation from being performed due to a malfunction of the first or second control device.

Further, by the operation of a switching request receiving circuit, a timer circuit, etc. provided in the system switching control means, a system switching notice signal is issued to the second or first control device in operation, and the first and second control devices are activated. Since the actual system switching operation is executed after the rewrite operation for the second memory is completed, destruction of information stored in the first and second memories is reliably prevented.

Thereby, system switching operations in multiplexed control systems can be performed accurately.

Furthermore, by intentionally issuing a second command to the host device from the outside to the second or first control device in standby, it becomes possible to put any control system into a standby state at any time. Maintenance and management of multiplexed control systems can be easily performed.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of a circuit configuration for realizing a control system switching method according to an embodiment of the present invention, and FIG. 2 is a block diagram showing an information processing system to which the control system switching method according to the present embodiment is applied. FIG. 3 is a block diagram showing an example of the main parts of the system, and FIG. 3 is a timing chart showing an example of the operation of the control system switching method of this embodiment. FIG. FIG. 2 is a conceptual diagram showing an example of the configuration of a cartridge type magnetic tape library device.

First, with reference to FIG. 4, the outline of the configuration of the cartridge type magnetic tape library device will be explained.

Cartridge type magnetic tape library device of this embodiment (
The lower device) includes a plurality of cells 13 in which a plurality of cartridge-type magnetic tapes (not shown), which are storage media, are individually housed.
A library shelf 13 equipped with a cartridge-type magnetic tape, and a tape drive device 14 that actually drives a cartridge-type magnetic tape to record and reproduce information. The library includes a transport robot 12 that performs transport operations such as loading a used cartridge-type magnetic tape into a tape drive device 14 and returning a used cartridge-type magnetic tape to its original storage position on a library shelf 13.

The operation of the transport robot 12 is controlled by a plurality of library control devices 2 and a library control bag ff14, each of which is composed of, for example, a microprocessor and performs mutually equivalent control operations.

Further, the plurality of library control devices 2 and 4 are connected via an interface line 7 to a central processing unit such as a general-purpose computer, and a channel that controls the exchange of information between the main memory and the outside on behalf of the central processing unit. It is connected to a host device 1 consisting of devices, etc., and the operations of the transport port 12 and the like are appropriately controlled based on the commands thereof.

Library controllers t2 and 4 have access lines 10
A plurality of mutually independent library management memories 5 and 6, which are shared by the library control devices 2 and 4 and updated simultaneously so that their stored contents match, are connected via an access line 11.

The library management memories 5 and 6 contain cells that are given in advance from the host device 1 at the time of system initialization, and that indicate the identification number V S N of each cartridge-type magnetic tape and its storage position on the library shelf 13 . Management information such as correspondence with addresses and the current position and operating state of the transfer robot 12 is stored.

The library control devices 2 and 4 are connected to the host device 1.
Based on commands from the controller, the transport operation of the transport robot 12 is controlled as appropriate while referring to such management information from time to time, and the loading operation of the target car (not shown) + J-type magnetic tape into the tape drive device 14 is performed. Alternatively, you can store used cartridge-type magnetic tapes in their original cell 1 on the library shelf.
In addition to performing control operations such as storage in the library shelves 13 and the constantly changing status of the library shelves 13 and the transfer robot 1
It performs operations such as updating the storage contents of the library management memories 5 and 6 in response to changes in management information such as the location of the library management memories 5 and 6.

Note that among the plurality of library control devices 2 and 4 that perform mutually equivalent control operations, one library control device 2
or 4 is put into an active state to perform the control operation as described above, and the other library control device f4 or 2 is put into a standby state where it can immediately start a control operation. Alternatively, if a failure occurs in the library control device 4 or 2, the control operation is switched to the library control device 4 or 2 in a standby state, thereby allowing the normal control operation to continue.

For this reason, it is necessary to appropriately switch the states of both, but in the case of this embodiment, a control line 8 and a System switching control means 3 via control line 9
is provided, and this system switching control means 3 is triggered by receiving a system switching command issued from the standby library control device 2 or 4 via the control line 8 or 9.
The switching operation is performed by a system switching notice signal and a system switching execution signal that are issued to the library control device 4 or 2 in operation.

That is, as shown in FIG. 1, the system switching control means 3 receives the switch strobe signal ASWSTB-P, which is a system switching command from each of the library control devices 2 and 4, and the switch enable signal ASWEN, for example.
-P and switch strobe signal BSWSTB-P,
A switching request detection circuit 3a and a switching request detection circuit 3b are provided, to which a switch enable signal BSWEN-P is inputted via logic gates 3h and 3j, respectively.

Further, the logic signals output from each of the switching request detection circuits 3a and 3b are inputted to the subsequent switching request receiving circuit 3C via the logic gate 3k, and this switching request receiving circuit 3C is connected to the switching request detecting circuit 3a or 3b. Triggered by the input of the logic signal from
-N and a system changeover notice signal BMATEREQ-N to the library control device 4.

The logical states of the system changeover notice signal AMATEREQ-N and the system changeover notice signal BMATEREQ-N are made to be opposite to each other by an inverter 3f interposed on the side of the system changeover notice signal AMATEREQ-N.

Furthermore, a switching control circuit 3d is connected to the subsequent stage of the switching request receiving circuit 3C, and the logic signals that become the system switching notice signal AMATEREQ-N and the system switching notice signal BMATEREQ-N are simultaneously input manually.
Furthermore, this switching control circuit 3d includes a timer circuit 3e.
The system is configured so that the logic signals from the system can be input manually.

Then, the switching control circuit 3d receives a system switching notice signal AMATERE from the switching request receiving circuit 3C at the previous stage.
After a predetermined set time T set in the timer circuit 3e has elapsed from the time of input of the logic signal outputted simultaneously with Q-N and BMATEREQ-N, a system switching execution signal is sent to the library control devices 2 and 4. AMATES
EL-N and system switching execution signal BMATESELN
It performs the operation of outputting.

In addition, this system switching execution signal ΔMATE S EL-
N and system switching execution signal BMATESEL-N are:
The inverter 3g causes the logic states to be opposite to each other.

Furthermore, this system switching execution signal A M A T E
Each of 5EL-N and BMATESEL-N provides a RESET signal to the switching request receiving circuit 3C, as well as a reset input to the switching request detecting circuits 3a and 3b via the logic gates 3Il and 3m, as well as the logic gates 3h and 3J. It becomes.

The operation of this embodiment will be explained below.

First, in a normal state, the library control device 2 is in an operating state in which it performs control operations for the transfer robot 12, etc., and the other library control device 4 is in a standby state in which it can start control operations at any time. .

At this time, the system switching control means 3 informs the library control device which is in the operating state! [System switchover notice signal AMATEREQ-N and system switchover execution signal AM output to [2]
ATESEL-N is at the "L" level, and the system switching advance signal BMATEREQ-N and the system switching execution signal BMATESEL-N output to the library control device 4 in the standby state are at the "H" level.

In this state, when the host device ff issues a command to the library control device 2 to load a cartridge-type magnetic tape, the library control device 2 that receives the command refers to the library management memories 5 and 6 and receives the instruction. knowing in which of the plurality of cells 13a of the library shelf 13 the identification number VSN of the cartridge type magnetic tape is stored;
The transport robot 12 is instructed to take out the target cartridge-type magnetic tape from the cell 13a and load it into the tape drive device 14.

Upon receiving this, the transport port box 12 performs an appropriate movement operation and loads the cartridge type magnetic tape having the designated identification number VSN into the tape drive device 14 .

Thereafter, data is exchanged between the cartridge type magnetic tape loaded in the tape drive device 14 and the host device 1 as appropriate.

When an error occurs in the control operations in a series of library control bags [2], the library control device 2 notifies the higher-level device 1 of the occurrence of the error, and the higher-level device 1 that detects this goes into a standby state. A system switchover command is issued to the library control device 4 located at

Upon receiving this, the library control device 4 outputs a switch enable signal BSWEN of "H" level at the timing shown in FIG. 3 via the control line 9 as a system switching command.
-P and a switch strobe signal B that changes in a pulsed manner.
System switching control means 3 in combination with SWSTB-P
The signal is output to the switching request detection circuit 3b.

Here, the reason why the switch enable signal BSWEN-P and the switch strobe signal BSWSTB-P are output in combination as shown in Figure 3 is to prevent erroneous system switching operations from being easily started due to noise or the like. be.

In this way, the switching request detection circuit 3b, which has confirmed the system switching request by the combination of the predetermined pattern of the switch enable signal BSWEN-P and the switch strobe signal BSWSTB-P, sends a predetermined logic signal to the subsequent switching request reception circuit 3C. Output.

Taking this as a trigger, the switching request reception circuit 3C outputs a logic signal to the switching control circuit 3d, and at the same time outputs a system switching notice signal A to the library control device 2.
MATEREQ-N is set to “H” level, and the system switching notice signal BMATEREQ- to the library control device 4 is set to “H” level.
Set N to "L" level.

Then, the operating library control device 2 learns that system switching will be performed from now on as the system switching notification signal AMATEREQ-N changes to 'H' level, and writes control information to the library management memories 5 and 6. The processing is completed within a predetermined time T set in the timer circuit 3e, and preparations are made for execution of actual system switching processing.

Further, the switching control circuit 3d is triggered by the input of the logic signal from the timer circuit 3e, and after a predetermined time T has elapsed since the input of the logic signal from the switching request reception circuit 3C, that is, when the library is in operation. Control device 2
After the predetermined write processing to the library management memories 5 and 6 is completed, the system switchover execution signal AMATESEL-N to the operating library control device 2 is
H" level, and the standby system switching execution signal BMATESEL-N of the library control device 4 is set to "L" level.

As a result, the control operation of the transfer robot 12 and the like is switched from the library control device 2 where the error occurred to the library control device 4 that was in the standby state, and the library control device 2 that was in the operating state becomes the standby state.

Thereafter, in order to determine whether or not the management information held by itself matches the management information stored in the library management memories 5 and 6, the host device 1 stores the information stored in one of the library management memories 6. Read and examine the management information.

If the two match, normal input/output processing based on the switched library control device 40 control operation is immediately continued.

If the two do not match, the library control device 4 rewrites the contents of the library management memories 5 and 6 to match the management information held by itself, and then continues normal input/output processing. .

In this way, according to the control system switching method of this embodiment,
Triggered by a command from the host device 1, a switch strobe signal BSWSTB is sent from a healthy library control device 4 or 2 in a standby state to the system switching control means 3.
-P (ASWSTB-P) and switch enable signal BSWEN-P (ASWEN-P) by providing an accurate failover command signal that combines the logical signals of Since the switching is performed, erroneous execution of the switching process is reliably prevented.

In addition, when executing system switching processing, a system switching advance notice signal AMATEREQ-N is sent to the library control device 2 or 4 that will transition from the active state to the standby state in advance.
(BMATEREQ-N) and completes the process of writing management information to the library management memories 5 and 6, etc. that are currently being executed, then the system switchover execution signal AMA
Since actual system switching processing is performed by issuing TESEL-N (BMATESEL-N), destruction or loss of the management information stored in the library management memories 5 and 6 can be prevented.

As a result, control operations are accurately switched between the library control devices 2 and 4 that are in the active state or the standby state.

Note that in the above description, a case has been described in which system switchover processing is started in response to the occurrence of an error in the library control device 2 that is in an operating state; however, the present invention is not limited to this.
An operator intentionally gives an instruction to the host device 1 from the outside, and the host device 1 sends a command to the library control device 2 that is on standby.
Alternatively, a command for system switching processing may be issued to node 4.

This allows, for example, library control device 2 or 4
When carrying out maintenance, etc., it is possible to shift the target library control device 2 or 4 to a standby state where maintenance work can be performed at any time, simplifying the maintenance work of the library control devices 2 and 4. can be converted into

Furthermore, in the above explanation, the system switchover process was first explained when the library control device 2 is in the operating state and the library control device 4 is in the standby state, but it goes without saying that the two states may be reversed. stomach.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the control system is not limited to a library control device in a cartridge type magnetic tape library device, but can be widely applied to a system switching technique for a multiplexed control system that can be applied to a general external storage subsystem.

〔Effect of the invention〕

Among the inventions disclosed in this application, the effects obtained by typical inventions are briefly explained below.

That is, according to the control system switching method of the present invention,
first and second control devices that are interposed between a higher-level device and a lower-level device and perform control operations for the lower-level device independently of each other based on commands from the higher-level device; and the first and second control devices It consists of first and second memories that are shared by the device and whose storage contents are maintained the same, and when one of the first and second control devices is in an operating state, the other is in a standby state, and at any time. , in a control system that is multiplexed so as to switch between an operating state and a standby state, the control system is switched based on a first command from the first or second control device that is on standby. Since the control means is provided, for example, upon receiving error occurrence information from the operating first or second control device or an instruction from the outside, the host device can control the second or second control device that is waiting for the second command. The first or second control device, which is on standby, issues the first command to the system switching control means using this second command as a trigger and starts the system switching operation. , it is reliably prevented that an erroneous system switching operation is performed due to a malfunction of the first or second control device.

Further, by the operation of a switching request receiving circuit, a timer circuit, etc. provided in the system switching control means, a system switching notice signal is issued to the second or first control device in operation, and the first and second control devices are activated. Since the actual system switching operation is executed after the rewrite operation for the second memory is completed, destruction of information stored in the first and second memories is reliably prevented.

Thereby, system switching operations in multiplexed control systems can be performed accurately.

Furthermore, by intentionally issuing a second command to the host device from the outside to the second or first control device in standby, it becomes possible to put any control system into a standby state at any time. Maintenance and management of multiplexed control systems can be easily performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a circuit configuration for realizing a control system switching method according to an embodiment of the present invention, and FIG. 2 is a block diagram of an information processing system to which the control system switching method of this embodiment is applied. FIG. 3 is a timing chart showing an example of the operation of the control system switching method of this embodiment. FIG. 4 is a cartridge-type magnetic tape used as an external storage device of an information processing system. FIG. 2 is a conceptual diagram showing an example of the configuration of a library device. 1... Host device, 2... Library control device, 3.
... System switching control means, 3a, 3b... Switching request detection circuit, 3c... Switching request receiving circuit, 3d.
...Switching control circuit, 3e...Timer circuit, 3f,
3g...Inverter, 3h, 3j, 3, 31,3m
. . . logic gate, 4. library control device, 5.
6...Library management memory, 7...Interface line, 8...Control line, 9...Control line, 10°11
...Access line, 12...Transportation robot, 13...
・Library shelf, 13a...Cell, 14...Tape malfunction device, ASWEN-P, BSWEN-P...Switch enable signal, ASWSTB-P, BSWSTB
-P...Switch strobe signal, AMATEREQ
-N, BMATEREQ-N... system switching notice signal, AMATES'EL-N, BMATESEL-N...
- System switching execution signal, T... Time from the system switching notice signal by the timer circuit to the system switching execution signal. Agent Patent Attorney Daiwa Tsutsui Figure 4 3a

Claims (1)

[Scope of Claims] 1. First and second control devices that are interposed between a higher-level device and a lower-level device and independently perform control operations for the lower-level device based on commands from the higher-level device; The first and second memories are shared by the first and second control devices and have the same storage contents, and when one of the first and second control devices is in operation, the other is In a control system that is multiplexed so as to put the device into a standby state and to switch between the operating state and the standby state of both at any time, the control system controls the control system based on a first command from the first or second control device that is on standby. A control system switching method characterized in that a system switching control means for switching control systems is provided. 2. Claim 1, wherein the first or second control device on standby issues the first command to the system switching control means in response to a second command from the host device.
Control system switching method described. 3. The higher-level device receives the error occurrence information from the first or second control device in operation or an instruction from the outside, and controls the second or first control device that is waiting for the second command. 3. The control system switching method according to claim 1, wherein the control system switching method is issued to a control device. 4. The system switching control means includes a switching request detection circuit that confirms the first command from the first or second control device that is on standby, and a switching request detection circuit that confirms the first command from the first or second control device that is in operation; The system is characterized by comprising a switching request receiving circuit that issues a system switching notice signal to a system switch, a switching control circuit that issues a system switching signal, and a timer circuit that sets a time difference between the system switching notice signal and the system switching signal. 4. The control system switching method according to claim 1, 2 or 3.