JPH11312111A - Method for restoring data base and data base management system thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the volume of transfer data and processing load by checking unstored data by the message ID of small data at the time of restoring data stored in a stand-by system data base device at the occurrence of a communication fault and transferring the checked data. SOLUTION: Each of a current system monitoring device 3 and a stand-by system monitoring device 4 applies one numeral of small data or character message ID to processing data (information message) from a client/data processing terminal 1 and stores the ID. The information message is stored in a current system data base device 34 and a stand-by system data base device 44. At the occurrence of a communication fault, the message ID stored in the device 4 is transmitted to the device 3. The device 3 determines its stored message ID other than the received message ID, reads out the information message (stored data), corresponding to the message ID from the device 34 and transfers the read message to the data base device 44 in the device 4 to restore unstored data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a database recovery method for transferring data stored in a database device in an active system and a standby system duplicated in a local area network or the like to a standby system database device for recovery when a communication failure occurs. More particularly, the present invention relates to a database recovery method and a database management system that reduce the amount of transfer data in a recovery sequence to reduce a network load.

[0002]

2. Description of the Related Art Conventionally, a database apparatus organizes and stores a large amount of data (files) that can be processed by a general-purpose small computer or the like. In particular, a database management system (DBMS: D) having a control function for efficiently executing data search, addition, and update by executing a program
ata Base Management System) is a structured query language (SQL), as well as a hierarchical type and a net type.
ge) is well known for relational data management.

[0003] Such a database management system includes:
Along with the server / client system and the like, they are often arranged in Ethernet, FDDI LAN, or the like by duplication taking into account system maintenance consisting of an active system and a standby system. As an actual configuration of such a database management system, a configuration in which a database device is provided in an active system and a standby system monitoring device is often used. The small general-purpose computer (data processing terminal) in the server / client system changes (searches,
When adding or updating), first, the data stored in the database device provided in the active system monitoring device is updated.

Next, data stored in a database device provided in the standby monitoring device is updated so that data stored in the active and standby database devices are always the same. In this case, if a communication failure occurs after updating the data stored in the database device provided in the active monitoring device, the data cannot be normally updated in the database device provided in the standby monitoring device. Therefore, the data stored in the active system and the data stored in the standby system are inconsistent.

In this case, by controlling the monitoring device, the database device provided in the standby monitoring device cannot be processed and is separated from the LAN communication path in a controlled manner, so that the stored data cannot be changed thereafter. As the recovery procedure, the operator performs an input operation from a data processing terminal or a maintenance device on the LAN accommodating the active system monitoring device and the standby system monitoring device, so that the data stored in the database device provided in the active system monitoring device is restored. The data is transferred to a database device provided in the standby system monitoring device to recover the data.

In this recovery procedure, all the stored data of the database device provided in the active monitoring device is transferred to the database device provided in the standby monitoring device, so that the transfer data amount is large and the However, there is a problem that the processing load is increased.

As a technique for solving such a problem, a conventional example of Japanese Patent Laid-Open Publication No. 1-128142, "copying method of duplicated file" is well known. In this conventional example, data of a primary file in a duplicated file is updated. Further, in order to make the sub-files have the same contents, only the update information management table and the updated block data are copied so that the copying time can be reduced.

[0008]

However, in the above conventional example, only the update information management table and updated block data are copied in order to make the primary file and the secondary file of the duplicated file have the same contents, and the copy time is reduced. Although it can be shortened, the update information management table and the update block data may have a relatively large data amount.
Therefore, there is room for improvement from the viewpoint of reducing the amount of transfer data and reducing the processing load on the system.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art. In a duplicated database apparatus comprising an active system and a standby system, when a communication failure occurs, a standby system is set up based on an identification code of a small amount of data. It is an object of the present invention to provide a database recovery method and a database management system that can confirm and transfer unstored data in a system database, reduce the amount of transferred data, and reduce the processing load on a network.

[0010]

In order to achieve the above object, the present invention provides a database restoration method according to the present invention, wherein a redundant database apparatus comprising an active system and a standby system is connected to a communication network, and a standby system is used when a communication failure occurs. A method for restoring data stored in a database device, in which an identification code of a small amount of data is added to processing data in a communication network and held in active and standby database devices,
In addition, the processing data is stored in the active and standby database devices, and further, when a communication failure occurs, the identification code stored in the standby database device is transmitted to the active database device. Then, the stored identification code other than the received identification code is determined, and the processing data corresponding to the identification code determined by this determination is transferred to the standby database device to restore the stored data.

[0011] The present invention also provides a database management system in which a duplexed database device comprising an active system and a standby system is connected to a communication network, and which restores data stored in the standby database device when a communication failure occurs. The communication monitoring and control means of each of the active system and the standby system attaches and retains the processing data to the identification code of the small amount of data, and stores the processed data in the respective database devices of the active system and the standby system,
When the communication failure occurs, the identification code is transmitted from the standby communication monitoring control means to the active communication monitoring control means, and the active communication monitoring control means determines the identification code held in addition to the received identification code, and The active communication monitoring control means reads out the processing data corresponding to the identification code from the determination from the active database apparatus, executes a recovery sequence for transmitting the processing data to the standby communication monitoring control means, and It is configured to recover the stored data.

A communication control unit for executing a communication protocol for performing transmission and reception according to a predetermined access method, and a main control unit for executing a recovery sequence when a communication failure occurs, as the active and standby communication monitoring control means. A notification message area unit for assigning and holding a message ID as an identification code for executing a recovery sequence to data stored in the active and standby database devices when a communication failure occurs, and a main control unit. A data processing unit that processes data transmission / reception with the notification message area unit.

The communication network is a local area network accommodating a server data processing device and a client data processing terminal in a server / client system that sends out processing data, wherein the identification code of the small amount of data is at least one numeral or character. Data. Further, the active communication monitoring and control means and the active database device, and the standby communication monitoring and controlling means and the standby database device are individually configured or integrated. Further, a plurality of the standby system communication monitoring control means and the standby system database device are arranged, and the communication network is connected to another communication network through a public line or a dedicated line, so that the active system and the standby system communication monitoring control unit are connected. The configuration is such that the means and the active and standby database devices are shared.

The data processing device on the communication network which has received the communication failure occurrence notification from the standby communication monitoring / controlling means transmits the manual recovery instruction command here to the active communication monitoring / controlling means and / or the standby communication monitoring means. The data processing device on the communication network that has received the communication failure occurrence notification from the standby communication monitoring control unit transmits the recovery instruction command to the active communication monitoring control unit. The automatic transmission to the communication means and / or the standby communication monitoring control means executes the restoration sequence.

When the standby communication monitoring control means recognizes the occurrence of a communication failure, the standby communication monitoring control means notifies the active communication monitoring control means and a recovery sequence between the active communication monitoring control means and the standby communication monitoring control means. Is executed.

A database recovery method and a database management system according to the present invention having such a configuration are provided in a redundant database apparatus comprising an active system and a standby system connected to a communication network at the time of executing a recovery sequence. The non-stored data in the standby database is confirmed based on the identification code of the above, and the data is transferred. As a result, the amount of transfer data in a communication network such as a local area network is reduced, and the processing load on the network can be reduced.

Further, in the database management system of the present invention, the redundant active communication monitoring and control means and the active database device, and the standby communication monitoring and controlling means and the standby database device are individually configured, or
It is configured as an integral, ie, conventional, database management system. Also, a plurality of standby communication monitoring / control means and standby database devices are arranged. Further, the communication network is connected to another communication network through a public line or a dedicated line, and the active and standby communication monitoring control means and the active and standby database devices are shared.

As a result, the communication network, ie,
The degree of freedom in the configuration of a closed area, for example, a local area network built in a company or the like is improved.

Further, the database management system of the present invention executes a recovery sequence in response to a recovery instruction command by manual operation or automatic transmission in the data processing apparatus which has received the notification of the occurrence of a failure, and executes a standby communication when a communication failure occurs. When the monitoring control unit recognizes, the recovery sequence is executed.

As a result, various communication controls in a communication network, for example, a local area network can be performed.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a database recovery method and a database management system according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a database management system according to an embodiment of the present invention. This database management system, for example,
NFS (Net
It is provided on a LAN such as Ethernet or FDDI that accommodates a server / client system of a work file system. The example of FIG. 1 shows a client / data processing terminal 1 which performs data processing as a client, and a server / server which executes a program and performs data processing as a server.
And a data processing device 2.

Further, the database management system includes:
It has an active system monitoring device 3 which incorporates active and standby database devices. That is, it is a duplicated database device. The active monitoring device 3 stores the data processed by the client / data processing terminal 1 and the server / data processing device 2 in the internal database device during normal operation, and the standby monitoring device 4 stores the data when the communication failure occurs. Client / data processing terminal 1
And data processed by the server / data processing device 2. Also, devices from the client / data processing terminal 1 to the standby monitoring device 4 are connected to the LAN communication path 5 in a bus format (multidrop connection system).

The client / data processing terminal 1
Are actually arranged in large numbers. The active system monitoring device 3 and the standby system monitoring device 4 are so-called database management systems each including a database device and a communication control processing device.

The active system monitoring device 3 is a CSMA / C
A communication control unit 31 that controls transmission and reception between the client / data processing terminal 1, the server / data processing device 2, and the standby monitoring device 4 by a LAN access method such as D
And a main control unit 32 that controls each unit of the active monitoring device 3 and executes a recovery sequence when a communication failure occurs in the standby monitoring device 4 with respect to the standby database device 44.

Further, in the active system monitoring device 3, a data processing unit 33 for processing data exchange with the main control unit 32, and various processing data (notification messages) are updated and stored. An active database device 34 capable of efficient processing of searching, adding, and updating by processing, and a message ID for executing a recovery sequence when a communication failure occurs with respect to data stored in the active database device 34, And a notification message area 35 to be added and held. The message ID is an identification code for a small amount of data.
3 or data of characters A, B, and C.

The standby system monitoring device 4 also has a communication control unit 41, a main control unit 42, a data processing unit 43, a standby system database device 44, and a notification message area unit 45 similar to the active system monitoring device 3.

Next, the operation of this embodiment will be described. In this operation, the active database device 3
4 and the standby database device 44 are, for example, a relational data management form for searching using a structured query language (SQL). Further, a client / data processing terminal 1 and a server / data processing device 2
Calls a remote procedure call (RPC: Remote Procedure Cal)
l) through the process.

Further, the LAN communication path 5 has a network topology of a bus type (multi-drop connection system). As a LAN access method, CSMA for a bus format is used.
/ CD, which executes a retransmission algorithm when a data collision occurs on the network or a communication failure occurs.
The active database device 3 in the active monitoring device 3
4 and the standby database device 44 in the standby monitoring device 4
Whether or not the respective stored data is the same is recognized by the confirmation algorithm (communication sequence) between the communication control units 31 and 41. This communication sequence may be developed and used for exclusive use, or may be an existing Y-MODE.
A transfer sequence such as M may be used.

In this confirmation, for example, the confirmation is performed by exchanging bits indicating the memory area. In addition, the client /
The data processing terminal 1, the server / data processing device 2, the active system monitoring device 3, and the standby system monitoring device 4 specify an address at the time of data transmission, and mutually authenticate the address by executing negotiation (training algorithm) between the communication control units. Then, the data is transmitted and received.

The active-system monitoring device 3 and the standby-system monitoring device 4 based on the duplication capture packets of the processing data in the client / data processing terminal 1 through the LAN communication path 5 and respectively use the active-system database device 34 and the standby-system database. It is stored in the device 44. In this process, the client / data processing terminal 1 first transmits a notification message packet to the active system monitoring device 3 by specifying its address each time the data processing is completed.

In the active system monitoring device 3, the communication control unit 31 receives the notification message by the communication control. The communication control of the transmission and reception of the packet is performed by CSMA / CD, that is, the multi-random access method by carrier detection. The notification message is sent to the notification message area unit 35 through the main control unit 32 and the data processing unit 33.
Captures the message ID for each notification message
And hold it. This notification message is transferred to the active database device 34 through the data processing unit 33 and stored.

After storage by transfer to the active database device 34, the active monitoring device 3 sends this notification message to the standby monitoring device 4. The standby system monitoring device 4 includes a communication control unit 41, a main control unit 42, and a data processing unit 4.
3, the notification message area 45 takes in and writes. Then, the data is transferred to and stored in the standby database device 44 through the data processing unit 43. As a result, the data (storage data) processed by the client / data processing terminal 1 must match between the active database device 34 in the active monitoring device 3 and the standby database device 44 in the standby monitoring device 4. become.

If the active system database device 34 in the active system monitoring device 3 is not updated by the standby system database device 44 in the standby system monitoring device 4 due to the occurrence of a failure in the LAN communication path 5 after the active system database device 34 is updated, Due to a mismatch between the data stored in the active database device 34 and the stored data in the standby database device 44, the standby database device 44 provided in the standby monitoring device 4 cannot be used.

When the standby database device 44 provided in the standby monitoring device 4 becomes unavailable, the client /
A recovery instruction from the data processing terminal 1 is issued to the standby monitoring device 4. In the standby monitoring device 4, the main control unit 42 searches the message ID corresponding to the last received notification message via the data processing unit 43. The message ID obtained by this search is transmitted from the data processing unit 43, the main control unit 42, and the communication control unit 41 to the active system monitoring device 3 via the LAN communication path 5.

In the active system monitoring device 3, the standby system monitoring device 4
The main control unit 42 fetches the message ID from the communication control unit 31 through the communication control unit 31 and searches the notification message area unit 45 through the data processing unit 43. A notification message corresponding to a message ID other than the message ID sent from the standby monitoring device 4 in this search is read out from the active database device 34 and sent to the active monitoring device 3 via the LAN.
The data is transferred through the communication path 5. The active monitoring device 3 transmits the notification message from the standby monitoring device 4 to the notification message area 45 through the communication control unit 41, the main control unit 42, and the data processing unit 43 in the same manner as the notification message from the client / data processing terminal 1. Captures, writes, and holds a message ID.

In the active system monitoring device 3 and the standby system monitoring device 4, the respective notification message areas 35,
45 cyclically updates the message ID. That is, when the maximum storage number is reached, the message ID corresponding to the notification message stored first is deleted, and the message ID corresponding to the new notification message is held. The maximum number corresponds to the storage capacity of the active database device 34 and the standby database device 44, that is, the throughput.

Then, the notification message is transferred from the notification message area section 45 to the standby database device 44 through the data processing section 43 and stored therein. As a result, the data (storage data) processed by the client / data processing terminal 1 matches the active database device 34 in the active monitoring device 3 and the standby database device 44 in the standby monitoring device 4. become. That is, the recovery of the unstored data in the standby database device 44 is completed.

Next, the main part of this operation will be described in detail.
FIG. 2 is a transmission sequence diagram in the main part operation described above. In FIG. 2, a client / data processing terminal 1
Instructs the active monitoring device 3 and the standby monitoring device 4 to update the data to be stored every time the data processing is completed. In the case of sequentially registering a notification message in this case, for example, new path registrations 1, 2, and 3, input of setting information necessary for the path registration 1 is performed. A notification message corresponding to the input setting information is transmitted by designating the address of the active system monitoring device 3.

In the active system monitoring device 3, the communication control unit 31 identifies its own address, receives the notification message (path registration 1), and sets the main control unit 32 and the data processing unit 33.
The notification message area unit 35 fetches the data of the path registration 1 through. Next, the data is transferred to the active database device 34 through the data processing unit 33 and updated. In this case, the notification message area unit 35 stores a small amount of data for the path registration 1, for example, numerals 1, 2, 3,.
The message ID 1 of C ... is assigned and held. After this,
An acknowledgment notification (ACK) indicating the completion of storage from the notification message area 35 specifies the address of the client / data processing terminal 1 from the data processing unit 33, the main control unit 32, and the communication control unit 31 through the LAN communication path 5. Sent.

When the path registration 1 is registered and updated in the active database device 34 of the active system monitoring device 3, the data of the path registration 1 is transferred to the data processing unit 33 and the main control unit 3.
2 and the communication control unit 31 to transfer the data from the LAN communication path 5 to the standby monitoring device 4. The standby system monitoring device 4 registers and updates the path registration 1 in the standby system database device 44 in the same manner as the active system monitoring device 3.

The communication control unit 31 of the active system monitoring device 3
The communication control unit 41 of the standby system monitoring device 4 and the active system database device 34 and the standby system database device 4 respectively.
A confirmation algorithm for mutually recognizing the coincidence of the update data with the update data No. 4 is executed. This confirmation algorithm is executed every time a notification message (path registration 1, 2, 3) is updated, or at regular intervals.

When transferring a path registration 1 from the active system monitoring device 3 to the standby system monitoring device 4, if a communication failure occurs and the standby system monitoring device 4 cannot update data, the active system monitoring device 3 The communication control unit 31 recognizes that the data cannot be updated in the standby monitoring device 4 and is controllably disconnected from the LAN communication path 5. In this state, the message ID 1 is held in the notification message area 35 of the active system monitoring device 3, and
The message ID 1 is not stored in the notification message area 45 of the standby monitoring device 4.

Here, the communication control unit 31 of the active system monitoring device 3
Sends a packet storing the data to the client / data processing terminal 1 via the LAN communication path 5 to notify the client / data processing terminal 1 that the standby system monitoring device 4 cannot update the data. In response to this notification, the client / data processing terminal 1
The user performs an input operation for the recovery work. The packet of the restoration instruction command is transmitted via the LAN communication path 5 while specifying the address of the standby monitoring device 4. In the standby monitoring device 4, the main control unit 42 receives the packet of the restoration instruction command through the communication control unit 41.

The transmission of the restoration instruction command is performed in place of the manual operation of the client / data processing terminal 1,
It is also possible to recover by automatically sending out from the server / data processing device 2. In this case, the server / data processing device 2 fetches a packet storing data that cannot be updated by the standby monitoring device 4 through the LAN communication path 5 and, after recognizing that the update cannot be performed, issues a recovery instruction command to the standby monitoring device. Automatic transmission to the device 4. Thereafter, the communication control unit 31 of the active system monitoring device 3 and the communication control unit 41 of the standby system monitoring device 4 execute a recovery sequence to recover the data stored in the standby system database device 44. Also, the recovery instruction command is not transmitted to the standby system monitoring device 4 but is transmitted to the active system monitoring device 3 so that the recovery sequence is executed between the active system monitoring device 3 and the standby system monitoring device 4. May be.

Further, self-recovery processing in the active system monitoring device 3 and the standby system monitoring device 4 is also possible. In this case, the standby-system monitoring device 4 transmits a notification of the communication failure by designating the address of the active-system monitoring device 3, and thereafter transmits the recovery sequence to the communication control unit 31 and the standby-system monitoring device of the active-system monitoring device 3. 4
Executed by the communication control unit 41 of the standby database device 4
4 is restored.

After the standby control unit 4 receives the packet of the restoration instruction command from the communication control unit 41 by the main control unit 42, it searches the notification message area unit 45 for the message ID through the data processing unit 43. Here, the message ID 1 corresponding to the path registration 1 is not held, and the “no message ID” is recognized by the main control unit 42, and the address of the active system monitoring device 3 is specified through the communication control unit 41 and the LAN communication path 5. In addition, a packet storing data indicating “execution of a recovery sequence when a communication failure occurs” and “no message ID” is transmitted.

The communication control unit 31 of the active monitoring device 3 receives the “execution sequence of failure occurrence confirmation sequence” and “no message ID” packets from the standby monitoring device 4,
The main control unit 32 takes in the data. The main control unit 32 searches the notification message area unit 35 through the data processing unit 33. In this search, "message ID1" is obtained,
Further, the notification message of the path registration 1 corresponding to the “message ID 1” stored in the active database device 34 is read through the data processing unit 33. This notification message is transferred to the standby monitoring device 4 via the LAN communication path 5.

In the standby system monitoring device 4, the communication control unit 41,
The notification message area unit 45 takes in the notification message of the path registration 1 through the main control unit 42 and the data processing unit 43, and attaches and retains the message ID1. Furthermore,
The notification message of the path registration 1 is updated and stored by the standby database device 44 through the data processing unit 43.
In this way, the recovery sequence when a communication failure occurs is executed, and the data (stored data) processed by the client / data processing terminal 1 is stored in the active database device 34 and the standby monitoring device 4 in the active monitoring device 3. And the standby system database device 44 in the system.

If a communication failure occurs after the client / data processing terminal 1 transmits up to the path registration 3 to the active system monitoring device 3, the notification message area 35 of the active system monitoring device 3 stores the message ID 1, 2 and 3 and the notification message area 4 of the standby monitoring device 4
5 holds the message IDs 1 and 2. Therefore, only the notification message of the path registration 3 corresponding to the message ID 3 is transferred from the active monitoring device 3 to the standby monitoring device 4.

As described above, when a communication failure occurs, a small amount of data (for example, numerals 1, 2, 3,... Or characters A, B, C,...)
Is transferred first, and the standby database device 44 of the standby monitoring device 4 confirms the notification message that has not been stored. Therefore, it is possible to check a notification message that has not been stored with a very small amount of data.

In this embodiment, an example has been described in which the LAN is constituted by CSMA / CD for a bus format, but the present invention is not limited to this. For example, a ring format or a star format may be used. In this case, a token passing method or the like is used as the LAN access method.

Further, in this embodiment, the client /
First, notification data from the data processing terminal 1 is transmitted to the active system monitoring device 3 by specifying an address. And
After being stored here, the data is transferred from the active system monitoring device 3 to the standby system monitoring device 4, but may be transmitted to the active system monitoring device 3 and the standby system monitoring device 4 simultaneously. In this case, the notification data from the client / data processing terminal 1 is first transmitted to the active system monitoring device 3 and stored.

After the client / data processing terminal 1 receives the acknowledgment notification, the client / data processing terminal 1
The same notification data is transmitted from the data processing terminal 1 to the standby monitoring device 4. In this case, the communication algorithm executed between the active monitoring device 3 and the standby monitoring device 4 is simplified. In other words, when the active system monitoring device 3 and the standby system monitoring device 4 are shared by a large number of clients / data processing terminals, the idle time in the active system monitoring device 3 and the standby system monitoring device 4 increases. Database access becomes easier.

In this embodiment, one standby monitoring device 4 has been described, but a plurality of standby monitoring devices may be provided. This number is determined in consideration of system security. In this case, the plurality of standby monitoring apparatuses assign different addresses to each other, and transmit / receive the data transfer (L
AN access).

Further, in this embodiment, the active system monitoring device 3
And a communication control / data processing system (from the communication control units 31 and 41 to the notification message area unit 3).
5, 45) and the active database device 34
Although the configuration is described as a so-called database management system in which the standby database device 44 and the standby database device 44 are provided integrally, a configuration in which the communication control / data processing system, the active database device 34, and the standby database device 44 are separately arranged is also possible. good.

In this case, the communication control / data processing system is LA
N communication path 5 and this communication control / data processing system
For example, a hard disk device is connected as a database device. This configuration may be constructed in consideration of the system scale (throughput) and the like.

In this embodiment, one closed L
Although the AN configuration has been described, it may be configured on a large-scale communication network. For example, the LAN configuration shown in FIG. 1 is connected to a public line network such as ISDN or PSTN or a dedicated line network, and another remote LAN or center device (host computer) is connected to the active monitoring device 3 and the standby monitoring device. 4, the active database device 34 and the standby database device 44 may be used.

In this case, the LAN configuration shown in FIG.
In the case of accommodating N, a terminal adapter (TA) is connected to a T point of a digital line terminal (DSU), and the LAN configuration shown in FIG. 1 is accommodated at an R point on the output side. The packet transfer in this case is performed by executing a transmission sequence on the control (D) channel and the information (B) channel. For example, if the transmission sequence 921 or X. It is executed with 25 protocols or the like.

[0059]

As is apparent from the above description, according to the database recovery method and the database management system of the present invention, at the time of executing the recovery sequence, a duplicated database device comprising an active system and a standby system connected to a communication network. In this case, when a communication failure occurs, unstored data in the standby database is confirmed based on the identification code of the small amount of data, and the data is transferred. As a result, the amount of transfer data in a communication network such as a local area network is reduced, and the processing load on the network can be reduced.

Further, according to the database management system of the present invention, the redundant active communication monitoring control means and the active database apparatus, and the standby communication monitoring control means and the standby database apparatus are individually configured,
Alternatively, they are integrally configured. Also, a plurality of standby communication monitoring / control means and standby database devices are arranged.
Further, the communication network is connected to another communication network through a public line or a dedicated line to share the active and standby communication monitoring control means and the active and standby database devices. Thereby, the degree of freedom of the configuration of the local area network, which is the communication network, is improved.

Further, according to the database management system of the present invention, a recovery sequence is executed by a recovery instruction command by manual operation or automatic transmission in the data processing device which has received the notification of the occurrence of a failure, and the occurrence of a communication failure is awaited. When the system communication monitoring control unit recognizes, the recovery sequence is executed. This enables various communication controls in the local area network, which is a communication network.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a database recovery method and a database management system according to an embodiment of the present invention.

FIG. 2 is a transmission sequence diagram in the operation of the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 client / data processing terminal 2 server / data processing device 3 active system monitoring device 4 standby system monitoring device 5 LAN communication path 31, 41 communication control unit 32, 42 main control unit 33, 43 data processing unit 34 active system database device 35 , 45 notification message area 44 standby database device

Claims (11)

[Claims] 1. A database recovery method for connecting a redundant database device comprising an active system and a standby system to a communication network and recovering data stored in a standby database device when a communication failure occurs. An identification code for a small amount of data is added and retained in the active and standby database devices, and processing data is stored in the active and standby database devices. Further, when a communication failure occurs, the standby database device is switched to the active database. Transmits the retained identification code to the device, and then determines the retained identification code other than the received identification code by the active database device, and waits for processing data corresponding to the determined identification code. Transfer data to a system database device to recover stored data Database recovery method to be. 2. A database management system in which a redundant database device including an active system and a standby system is connected to a communication network and recovers data stored in the standby database device when a communication failure occurs. The communication monitoring control means of each of the active system and the standby system assigns and retains an identification code of a small amount of data, and stores the processing data in the respective database devices of the active system and the standby system. While transmitting an identification code from the standby communication monitoring control means to the active communication monitoring control means, the active communication monitoring control means determines an identification code held other than the received identification code, and The working communication monitoring control means converts the processing data corresponding to the identification code by this determination to A database management system for executing a recovery sequence for reading from an active database device and transmitting the read data to the standby communication monitoring control means to recover data stored in the standby database device. 3. A communication control unit for executing a communication protocol for performing transmission and reception according to a predetermined access method as said active and standby communication monitoring control means, and a main control for executing a recovery sequence when a communication failure occurs. A notification message area section for assigning and holding a message ID as an identification code for executing a recovery sequence to data stored in the active and standby database devices when a communication failure occurs; The database management system according to claim 2, further comprising: a data processing unit that processes data transmission and reception between a control unit and the notification message area unit. 4. The database management system according to claim 2, wherein said communication network is a local area network accommodating a server data processing device and a client data processing terminal in a server / client system for transmitting processing data. . 5. The database management system according to claim 2, wherein the identification code of the small amount of data is at least one numeral or character data. 6. The active communication monitoring control unit and the active database device, and the standby communication monitoring control unit and the standby database device are individually configured,
Or a unitary structure.
The database management system described. 7. The database management system according to claim 2, wherein a plurality of said standby system communication monitoring control means and standby database devices are arranged. 8. The communication network, wherein the communication network is connected to another communication network via a public line or a dedicated line to share the active and standby communication monitoring and control means with the active and standby database devices. 3. The database management system according to claim 2, wherein 9. The data processing device on the communication network which has received the communication failure occurrence notification from the standby communication monitoring and control means transmits the manual recovery instruction command to the active communication monitoring and control means and / or the standby. 3. The database management system according to claim 2, wherein the database management system transmits the data to the system communication monitoring control unit and executes a recovery sequence. 10. The data processing device on the communication network, which has received the communication failure notification from the standby communication monitoring control means, sends a recovery instruction command to the active communication monitoring control means and / or the standby communication monitoring control means. 3. The database management system according to claim 2, wherein a recovery sequence is executed by automatic transmission. 11. The standby communication monitoring and control means, when recognizing the occurrence of a communication failure, notifies the active communication monitoring and control means, and the communication between the active communication monitoring and control means and the standby communication monitoring and controlling means. 3. The database management system according to claim 2, wherein a recovery sequence is executed.