JPH1031608A - Process data backup method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently perform data backup when collecting/recording process data while duplexing a database system. SOLUTION: When collecting/recording the process data from a controller 103 and connecting two database systems 101 and 102 and the controller 103 to a network (LAN) 104, the files of the respective database systems 101 and 102 are provided with recording areas for master/slave information and when recording the process data, the master/slave information is recorded together so that data backup is possible and reliability can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process control system, and more particularly to a data backup method including equalization of process data.

[0002]

2. Description of the Related Art Generally, in a system in which two database devices are prepared and the same process data is held in each of them to perform backup (hereinafter, also referred to as a redundant system), when one of the database devices is stopped, At the time of restoration, equalization is performed using data during the suspension period from the other database device. Also, when reading the stored data in the database, either one of the database devices (usually,
Since the data is exclusively read from the master (the side used as the master), if the data on the side to be read is lost due to a stop etc., the data equalization processing of the data in the missing period from the other database is performed. Data cannot be read unless

FIG. 6 shows a conventional example of this kind of equalization method. FIGS. 6 (a) and 6 (b) show the contents of the master and slave database devices. When the master database device shown in (a) has a stop period as shown in FIG. All the data of, that is, all the data of FIG.
It is common to perform equalization by copying as shown in (c).

[0004]

However, the above data equalization method has the following problems. (1) Since the equalization process is performed off-line, the data collection is stopped during the equalization process, and the data for that period is lost. (2) It takes time because all data are equalized. (3) If data is missing due to suspension, etc.
It is necessary to perform the equalization processing (data restoration) using the other database and then read it. That is, there is a problem in reliability and performance. Therefore, an object of the present invention is to basically eliminate the data equalization processing and reduce the time and burden for the processing.
Another object of the present invention is to improve reliability and performance by enabling data equalization online to prevent data loss.

[0005]

In order to solve such a problem, in the invention of claim 1, in collecting the process data in the process control system and recording it in the duplicated database device, each of the database devices is When a master / slave information area is provided in a file and the collected process data is recorded in a database device,
Master / slave information is recorded together for each collected data. According to the first aspect of the present invention, only the data at the time of mastering can be made readable by the master / slave information (the second aspect of the present invention). The amount of data at that time and the amount of data at that time can be recorded, and the data at the time of master can be combined in time series order and can be transmitted to the data read request source (the invention of claim 3).

According to a fourth aspect of the present invention, in collecting process data in the process control system and recording it in the duplicated database device, a master / slave information area is provided in each file of the database device,
Master / slave information is also recorded for each collected data, and when any of the above database devices is stopped, only the master data is read from the other database device at the time of restoration and data equalization is performed. I do it.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram showing an embodiment of the present invention. In this type of system, database apparatuses 101 and 102 and a controller (data generation source) 103 are connected to a LAN as a network system.
(Local area network) 104. That is, the database devices 101 and 102
Are duplicated, for example, 101 is a master (main device), 102
Is operated as a slave (standby device).

In such a configuration, the database devices 101 and 102 collect and record the same process data from the controller 103 based on, for example, status information on the LAN. Master / slave information is added and recorded for each data. Specifically, the database device 1
The data collected in 01 is always recorded as master data regardless of the operating state of the database device 102 because this device is the master. On the other hand, the data collected by the database device 102 is recorded as slave data when the database device 101 is in operation, and as master data when the database device 101 is stopped, since this device is a slave. FIG. 2 shows an example of a database collected and recorded in this way. The feature is that a recording (storage) area for master / slave information is provided as compared with the conventional one.

FIG. 3 is an explanatory diagram for explaining a second embodiment of the present invention. This is because the process data collected and recorded as described with reference to FIGS. 1 and 2 are stored in the database devices 101 and 102 in response to a request from the computer 2, for example.
When reading from the database, the database devices 101 and 102 that have received the read request judge the master / slave information added to the data as shown in FIG. 2, and add the period information (start time, number of data) to the master data. In this case, the master data D1M, D2M, and D3M are transmitted to the computer 200 as the data request source. By doing so, even if one of the database devices is stopped as in the past, data can be secured and read out even if that database device does not equalize the data during the stop period after restoration. It is.

FIG. 4 is an explanatory diagram for explaining a third embodiment of the present invention. This is because data read out as shown in FIG. 3 is combined with data in chronological order based on period information including the start time and the number of data (amount), and the start time and the number of data are updated. It is designed to be sent. Here, the start time T1, the master data D1M having the data number N1, the start time T2, the master data D3M having the data number N2, and the start time T
3, an example is shown in which master data D2M having the number of data N3 are combined and combined as data having the start time T4 and the number of data N4.

FIG. 5 is an explanatory view for explaining a fourth embodiment of the present invention. Conventionally, it was common to read all the contents of the other side database device and copy it to its own database device for equalization (see FIG. 6). By using this, when there is a suspension period, only the master data is read out from the partner database device and equalized. By doing so, the equalization processing time can be shortened and the burden can be reduced.

[0012]

According to the present invention, the following effects can be expected. (1) Since the master / slave information is added to the data in the database, the master data can be transferred from two database devices at the time of recovery after stopping one of the database devices without performing data equalization processing. The data of the suspension period can be obtained only by reading. (2) Since only master data can be read from one of the database devices and the equalization process can be performed, the amount of data is reduced, the processing time and burden are not only reduced, but also the online state allows arbitrary timing (restoration after restoration). Since the equalization process can be started at the timing, continuous data collection can be performed and data loss can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a structural explanatory view of a database used in the present invention.

FIG. 3 is an explanatory diagram illustrating a second embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a third embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram of a conventional example.

[Explanation of symbols]

101, 102 ... Database device, 103 ... Controller, 104 ... LAN (Local Area Network), 200 ... Computer.

Claims (4)

[Claims] When collecting process data in a process control system and recording it in a duplicated database device, a master / slave information area is provided in each file of the database device, and the collected process data is recorded in the database device. In this case, the process data backup method is characterized in that master / slave information is recorded together for each collected data. 2. The process data backup method according to claim 1, wherein only master data can be read by the master / slave information. 3. The process data is recorded with time data and the amount of data at that time, and the data at the time of master is combined in chronological order so that the data can be transmitted to a data read request source. The process data backup method according to claim 2. 4. When collecting process data in a process control system and recording the data in a duplicated database device, a master / slave information area is provided in each file of the database device, and master / slave information is collected for each collected data. A process data backup method for simultaneously recording and, when one of the database devices is stopped, reading out only the data at the time of the master from the partner database device at the time of recovery, and equalizing the data. Method.