Update method, update device, and program

Abstract

To provide an update method suitable for an information processing system configured to execute mirroring, an update apparatus and a program.SOLUTION: An update method of an information processing system configured to execute mirroring of data includes: a first update step (S3) of updating data stored in a second server, while stopping the second server, the data stored in a first server and the second server of the information processing system being stored so that first data not to be mirrored is separated from second data to be mirrored; and a second update step (S4) of updating the second data in the second server by mirroring the second data stored in the first server, while starting the stopped second server.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an update method, an update device, and a program. [Background technology]

[0002] Conventionally, techniques for monitoring plants such as water purification plants have been known. A monitoring and control system (an example of an information processing system) used for such monitoring must constantly perform monitoring and control. To prevent the information processing system from stopping, for example, multiple servers constituting the system may be assigned as a primary system (operating system) and a secondary system (standby system), and data may be mirrored. In an information processing system configured to perform mirroring, data is constantly shared so that even if the primary system goes down, the secondary system can immediately start operating in place of the primary system.

[0003] Here, data used in the information processing system is stored in a server and updated through version upgrades (upgrading of the version number). Data updated through version upgrades includes, for example, monitoring and control applications (programs, software) and their definition data. In the following, data refers to data in a broad sense, including applications.

[0004] To prevent the information processing system from stopping due to such an upgrade, for example, the technology of Patent Document 1 stops the server with the lowest operating rate when it receives an upgrade command and then performs the upgrade. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-250427 Summary of the Invention [Problem to be solved by the invention]

[0006] Here, in an information processing system configured to perform mirroring, when a stopped server is restarted, mirroring of data between servers may cause the data to revert to the state before the update, or may result in a mismatch between the versions of the application and the definition data.

[0007] In view of the above circumstances, an object of the present disclosure is to provide an update method, an update device, and a program suitable for an information processing system configured to perform data mirroring. [Means for solving the problem]

[0008] An update method according to an embodiment of the present disclosure includes: 1. A method for updating an information processing system configured to perform data mirroring, comprising: The data stored in the first server and the second server of the information processing system are stored such that the first data that is not a target of mirroring is stored separately from the second data that is a target of mirroring; a first updating step of stopping the second server and updating data stored in the second server; and a second update step of running the stopped second server and updating the second data of the second server by mirroring the second data stored in the first server.

[0009] An update device according to an embodiment of the present disclosure includes: An update device provided in an information processing system configured to perform data mirroring, The data stored in the first server and the second server of the information processing system are stored such that the first data that is not a target of mirroring is stored separately from the second data that is a target of mirroring; and an update means for updating the second data of the second server by stopping the second server, updating the data stored in the second server, and running the stopped second server to mirror the second data stored in the first server.

[0010] A program according to an embodiment of the present disclosure includes: An update device provided in an information processing system configured to perform data mirroring, The data stored in the first server and the second server of the information processing system are stored such that the first data that is not a target of mirroring is stored separately from the second data that is a target of mirroring; a first updating step of stopping the second server and updating data stored in the second server; and a second update step of running the stopped second server and updating the second data of the second server by mirroring the second data stored in the first server. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide an update method, an update device, and a program suitable for an information processing system configured to perform data mirroring. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of an information processing system including an update device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of data updates in the first server and the second server. [Figure 3] FIG. 3 is a sequence diagram illustrating an update method according to an embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of an information processing system of the comparative example. [Figure 5]FIG. 5 is a diagram illustrating an example of data updates in the first server and the second server according to the update method of the comparative example. [Figure 6] FIG. 6 is a diagram illustrating an example of data updates in the first server and the second server according to another update method of the comparative example. [Figure 7] FIG. 7 is a diagram illustrating an example of data updates in the first server and the second server according to yet another update method of the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an update method, an update device, and a program according to an embodiment of the present disclosure will be described with reference to the drawings.

[0014] (Information Processing System) FIG. 1 is a diagram showing an example of the configuration of an information processing system 1 including an update device 30 according to this embodiment. The information processing system 1 is configured to include at least a first server 10 and a second server 20 in addition to the update device 30. In this embodiment, the first server 10 and the second server 20 are devices that monitor and control a plant such as a water purification plant. One of the first server 10 and the second server 20 operates as a main system (operating system) and the other operates as a secondary system (standby system) so that the monitoring and control function in the information processing system 1 does not stop. In other words, the first server 10 and the second server 20 mirror data in the information processing system 1. The updating device 30 performs updating. When there is a version upgrade (version number upgrade), the updating device 30 updates the data stored in the first server 10 and the second server 20 according to an updating method described below. The first server 10, the second server 20, and the updating device 30 may each be a computer in terms of hardware configuration. The first server 10, the second server 20, and the updating device 30 are connected to each other via a network 40 so that they can communicate with each other. The network 40 is, for example, a local area network (LAN). The network 40 may also be connected to sensors that measure measurement data of the plant for monitoring and control. Here, from the viewpoint of security of information related to the plant, it is preferable that the network 40 is a LAN that is not connected to an external network (for example, the Internet).

[0015] (First server) The first server 10 has the following hardware configuration: The first server 10 includes a communication unit 11, a storage unit 12, and a control unit 13.

[0016] The communication unit 11 is one or more communication interfaces that communicate with the second server 20 and the update device 30 via the network 40. For example, if the network 40 is a wired LAN, the communication unit 11 may be configured with a communication module that complies with the wired LAN standard (1000BASE-T as an example). Also, for example, if the network 40 is a wireless LAN, the communication unit 11 may be configured with a communication module that complies with the wireless LAN standard (IEEE802.11 as an example).

[0017] The storage unit 12 is one or more memories. The memory may be, for example, a semiconductor memory, a magnetic memory, an optical memory, or the like, but is not limited to these, and may be any memory. The storage unit 12 functions as, for example, a primary storage device or a secondary storage device. The storage unit 12 is, for example, built into the first server 10, but may also be configured to be externally connected to the first server 10 via any interface.

[0018] The control unit 13 is one or more processors. The processor may be, for example, a general-purpose processor or a dedicated processor specialized for a specific process, but is not limited to these and may be any processor. The control unit 13 controls the overall operation of the first server 10.

[0019] The first server 10 stores the following data: The storage unit 12 stores a monitoring and control application 121 as program data. The storage unit 12 also stores local data 122 and share data 123. In this embodiment, the local data 122 and the share data 123 are stored separately. For example, the local data 122 and the share data 123 may be stored in different memory areas so as not to be mixed. Furthermore, for example, the local data 122 and the share data 123 may be stored in physically different storage devices.

[0020] The local data 122 is data that is not shared (mirrored) with the second server 20, and includes at least a definition file for correctly executing processing by the monitoring control application 121. The definition file is updated simultaneously with the monitoring control application 121 through version upgrades. For example, if the version of the monitoring control application 121 is "a," then when the monitoring control application 121 is executed, a definition file of the same version "a" must be loaded by the processor. In other words, the definition file is closely related to the monitoring control application 121, and if there is a version mismatch, processing by the monitoring control application 121 will not be performed correctly.

[0021] The shared data 123 is data that is shared (mirrored) with the second server 20. The data includes at least measurement data of the plant measured by sensors or the like for monitoring and control. The measurement data is acquired by a primary server (e.g., first server 10) in operation, and is mirrored by the primary server to a secondary server (e.g., second server 20) on standby.

[0022] The first server 10 has the following software configuration: When the monitoring and control application 121 in the storage unit 12 is read by the control unit 13, the control unit 13 is made to function as a monitoring and control means 131 and a data management means 132.

[0023] The monitoring and control means 131 acquires measurement data of a plant such as a water purification plant and determines the state of the plant based on the measurement data. If an abnormality is detected, the monitoring and control means 131 may notify the plant manager via the communication unit 11. The data management means 132 stores the data in the storage unit 12, and when the first server 10 is the primary server, mirrors the shared data 123 to the secondary server 20. The data management means 132 may store the measurement data and the determination results in the storage unit 12. The data management means 132 also manages the storage unit 12 so that the monitoring and control application 121, local data 122, and shared data 123 are appropriately arranged in their respective storage areas without being mixed together.

[0024] (Second server) The second server 20 has the following hardware configuration. The second server 20 includes a communication unit 21, a storage unit 22, and a control unit 23. The communication unit 21 has the same configuration as the communication unit 11 of the first server 10. The storage unit 22 has the same configuration as the storage unit 12 of the first server 10. Furthermore, the control unit 23 has the same configuration as the control unit 13 of the first server 10.

[0025] The second server 20 stores the following data: The storage unit 22 stores a monitoring and control application 221 as program data. The storage unit 22 also stores local data 222 and share data 223. In this embodiment, the local data 222 and the share data 223 are distinguished without being mixed in storage areas, similar to the first server 10. The monitoring and control application 221 is data similar to the monitoring and control application 121 of the first server 10. The local data 222 is data similar to the local data 122 of the first server 10. The share data 223 is data similar to the share data 123 of the first server 10.

[0026] The second server 20 has the following software configuration. When the monitoring and control application 221 in the storage unit 22 is read by the control unit 23, the control unit 23 is made to function as a monitoring and control means 231 and a data management means 232. The monitoring and control means 231 has the same configuration as the monitoring and control means 131 of the first server 10. The data management means 232 has the same configuration as the data management means 132 of the first server 10.

[0027] (update device) The update device 30 has the following hardware configuration. The update device 30 includes a communication unit 31, a storage unit 32, and a control unit 33. The communication unit 31 has the same configuration as the communication unit 11 of the first server 10. The storage unit 32 has the same configuration as the storage unit 12 of the first server 10. Furthermore, the control unit 33 has the same configuration as the control unit 13 of the first server 10.

[0028] The update device 30 stores the following data: The storage unit 32 stores one or more programs, and data such as upgraded applications and definition files. The upgraded applications are stored in the monitoring and control application 121 stored in the storage unit 12 of the first server 10 and the storage unit 22 of the second server 20. The definition file is an application in which the version number of the monitoring and control application 221 stored in the storage unit 12 of the first server 10 has been upgraded. The upgraded definition file is a definition file in which the version number of the definition file included in the local data 122 stored in the storage unit 12 of the first server 10 and the definition file included in the local data 222 stored in the storage unit 22 of the second server 20 has been upgraded.

[0029] The update device 30 has the following software configuration: When one or more programs in the storage unit 32 used to control the operation of the update device 30 are read by the control unit 33, the programs cause the control unit 33 to function as update means 331, primary / secondary system setting means 332, and classification means 333.

[0030] The update means 331 updates the data stored in the first server 10 and the data stored in the second server 20 in the case of a version upgrade or the like. Furthermore, the update means 331 controls the stopping and running of the first server 10 and the second server 20 in order to process the data updates. Here, stopping a server means isolating the server from the supervisory control process (putting the server in a state where it is not allowed to execute supervisory control). Stopping a server does not mean not supplying power to the server. Furthermore, operating a server means executing supervisory control process as a primary or secondary system.

[0031] Although details will be described later, in this embodiment, the update means 331 executes the following steps (update steps). The update means 331 executes a first update step of stopping the second server 20 and updating the data stored in the second server 20. In the first update step, the update means 331 also updates the second data stored in the first server 10 as necessary. The update means 331 executes a second update step of operating the stopped second server 20 and updating the second data stored in the first server 10 by mirroring the second data. After the second update step, the update means 331 executes a third update step of stopping the first server 10 and updating the first data stored in the first server 10. Here, the first data is data stored in the first server 10 and the second server 20 that is not subject to mirroring. The second data is data stored in the first server 10 and the second server 20 that is subject to mirroring.

[0032] The update means 331 updates the second data in the first update step, for example, when it is necessary to expand or add to the data area of ​​the second data (a database table that stores the share data 123). In other words, updating the second data in the first update step is, for example, expanding or adding to the data area (database table). Such expansion or addition of the data area can be performed in parallel with the acquisition of the share data 123 while the first server 10 is operating (without stopping the first server 10).

[0033] The primary / secondary setting means 332 sets the first server 10 and the second server 20 as the primary and secondary systems. When the primary / secondary setting means 332 sets the first server 10 as the primary system, it sets the second server 20 as the secondary system. When the primary / secondary setting means 332 sets the first server 10 as the secondary system, it sets the second server 20 as the primary system. The primary server mirrors the data to be mirrored (the above-mentioned second data) to the secondary server. Mirroring is automatically performed between the servers regardless of the processing of the update device 30 as long as the first server 10 and the second server 20 are operating, but is not performed if one of the servers is stopped.

[0034] The classification unit 333 classifies the data stored in the first server 10 and the second server 20 into first data that is not the target of mirroring and second data that is the target of mirroring. Specifically, the first data corresponds to the monitoring control application 121, the local data 122, the monitoring control application 221, and the local data 222. Specifically, the second data corresponds to the shared data 123 and the shared data 223. The classification unit 333 may classify the data stored in the first server 10 into the first data and the second data based on data management information acquired from the first server 10, the data management information including information on the storage areas of the monitoring control application 121, the local data 122, and the shared data 123. The classification unit 333 may classify the data stored in the second server 20 into the first data and the second data based on data management information acquired from the second server 20, the data management information including information on the storage areas of the monitoring control application 221, the local data 222, and the shared data 223.

[0035] FIG. 2 is a diagram illustrating an example of data updates in the first server 10 and the second server 20. When a version upgrade is performed, the update device 30 updates the data stored in the first server 10 and the second server 20 according to the procedure shown in FIG. 2. In FIG. 2, the monitoring and control application 121, local data 122, and shared data 123 of the first server 10 are each indicated as V0 before the update and V1 after the update. Similarly, the update status of the monitoring and control application 221, local data 222, and shared data 223 of the second server 20 is indicated as V0 or V1. α indicates plant measurement data acquired by an operating server while one server is stopped. Furthermore, each of the first server 10 and the second server 20 is indicated as (primary system) if it is operating and set as a primary system, (secondary system) if it is operating and set as a secondary system, or (stopped) if it is stopped. Here, times t0 to t7 are assigned for the following explanation in correspondence with changes in data stored in the server, and are not spaced at equal intervals.

[0036] As shown in FIG. 2, at time t0, the data of the first server 10 and the second server 20 are in a pre-update state (V0). The update device 30 stops the second server 20 at time t1 and updates the data of the second server 20 at time t2. Here, the update device 30 updates the first data (monitoring control application 221, local data 222) stored in the second server 20, but may not update the second data (shared data 223). In other words, the update device 30 may or may not update the second data (shared data 223) (shown as V0 / V1 in FIG. 2). Furthermore, at time t2, the update device 30 updates the second data (shared data 123) stored in the first server 10 while the first server 10 is operating. Here, the update of the second data is, for example, expanding or adding to a data area (database table) that stores the second data (shared data 123), as described above. Therefore, the first server 10 can acquire the measurement data while updating the second data. Even while the second server 20 is stopped, the first server 10 continues to operate as the primary system, and at time t3, acquires the measurement data α and stores it in the share data 123. At time t4, when the update device 30 starts the stopped second server 20 as the secondary system, the share data 123 of the first server 10 is mirrored to the share data 223 of the second server 20.

[0037] At time t5, the update device 30 sets the first server 10 as the secondary system and the second server 20 as the primary system. At time t6, the update device 30 stops the first server 10, and updates the first data (monitoring control application 121, local data 122) of the first server 10 at time t7.

[0038] As shown in Fig. 2, even during the update process by the update device 30, at least one of the first server 10 and the second server 20 monitors and controls the plant, and the measurement data α is acquired without loss. The versions of the application and definition file (stored in local data 122 and local data 222) of the first server 121 and the second server 20 always match. In other words, even during the update process, the match in version (V0 or V1) between the monitoring control application 121 and the local data 122, and the match in version between the monitoring control application 221 and the local data 222 are always maintained. Here, in the case of a version upgrade, etc., it may not be necessary to update the second data. In this case, the update process of the second data is appropriately omitted, but the measurement data α is acquired by at least one of the running servers without loss.

[0039] (Update method) FIG. 3 is a sequence diagram illustrating an update method executed in the information processing system 1 including the update device 30 according to this embodiment.

[0040] The update device 30 acquires data management information from the first server 10 and classifies the data stored in the first server 10 into first data and second data (step S1). For example, when the update device 30 is set not to update the second data, the process of step S1 enables the update device 30 to appropriately update only the first data.

[0041] As in step S1, the update device 30 acquires data management information from the second server 20 and classifies the data stored in the second server 20 into first data and second data (step S2).

[0042] The update device 30 stops the slave second server 20 using a stop signal, downloads the upgraded data (update data) to the second server 20, and executes the update (step S3). Step S3 corresponds to the first update step described above. Here, in the first update step, the update device 30 updates the second data stored in the first server 10 as necessary.

[0043] The update device 30 operates the stopped second server 20 as a secondary server by the operation signal, and updates the second data of the second server 20 by mirroring the second data stored in the first server 10 (step S4). Step S4 corresponds to the above-mentioned second update step.

[0044] The update device 30 switches the settings of the primary system and the secondary system. The update device 30 stops the secondary first server 10 using a stop signal, downloads the upgraded data (update data) to the first server 10, and executes the update of the first data (step S5). Step S5 corresponds to the third update step described above.

[0045] (Comparative Example) Here, an information processing system 101 of a comparative example will be described for comparison with the information processing system 1 including the update device 30 according to this embodiment. The information processing system 101 is an example of the prior art. FIG. 4 is a diagram showing an example of the configuration of the information processing system 101 of the comparative example. The same elements as those in the information processing system 1 (FIG. 1) are assigned the same reference numerals, and to avoid redundant explanation, these elements will not be described in detail.

[0046] In the first server 10 and the second server 20 of the information processing system 101 of the comparative example, local data and shared data are not separated into different storage areas, and are stored together as local data and shared data 124 and local data and shared data 224. Furthermore, the update device 30 of the information processing system 101 of the comparative example does not include the sorting means 333 (see FIG. 1).

[0047] Fig. 5 is a diagram illustrating an example of data updates in the first server 10 and the second server 20 according to an update method executed by an information processing system 101 of a comparative example. The reference numerals in Fig. 5 and Figs. 6 and 7 described later are the same as those in Fig. 2. However, times t0 to t6 in Fig. 5 and times t0 to t4 in Figs. 6 and 7 are uniquely assigned in each figure, and are not related to Fig. 2 or other figures unless otherwise stated.

[0048] As shown in FIG. 5, at time t0, the data of the first server 10 and the second server 20 are in a state before the update (V0). The update device 30 stops the second server 20 at time t1 and updates the data of the second server 20 at time t2. When the second server 20 is restarted, the contents of the local data and share data 124 (V0) are overwritten with the updated local data and share data 224 (V1) due to mirroring. To prevent such mirroring, the update device 30 stops the first server 10 at time t3. Then, at time t4, the update device 30 sets the second server 20 as the primary system and updates the data of the first server 10. While the first server 10 is stopped, the second server 20 continues to operate as the primary system, and at time t5, it acquires measurement data β and stores it in the local data and share data 224. At time t6, when the update device 30 starts the stopped first server 10 as a secondary system, the local data and shared data 224 of the second server 20 are mirrored to the local data and shared data 124 of the first server 10.

[0049] 5, in the update method executed by the information processing system 101 of the comparative example, both servers are stopped at time t3, and the measurement data α (see FIG. 2) is lost. In other words, the information processing system 101 of the comparative example cannot constantly monitor the plant.

[0050] FIG. 6 is a diagram illustrating an example of data update in the first server 10 and the second server 20 according to another update method executed by the information processing system 101 of the comparative example.

[0051] As shown in Fig. 6, at time t0, the data of the first server 10 and the second server 20 are in a state before the update (V0). The update device 30 stops the second server 20 at time t1 and updates the data of the second server 20 at time t2. While the second server 20 is stopped, the first server 10 continues to operate as the primary system, and at time t3, it acquires measurement data α and stores it in the local data and shared data 124. At time t4, the update device 30 starts the stopped second server 20 as the secondary system, and the local data and shared data 124 of the first server 10 are mirrored to the local data and shared data 224 of the second server 20.

[0052] 6, in the other update method executed by the information processing system 101 of the comparative example, at time t4, a mismatch occurs between the version (V1) of the monitoring control application 221 and the version (V0) of the local data and shared data 224. In other words, in the information processing system 101 of the comparative example, processing of the monitoring control application 221 is not performed correctly.

[0053] FIG. 7 is a diagram illustrating an example of data updating in the first server 10 and the second server 20 according to yet another update method executed by the information processing system 101 of the comparative example.

[0054] 7, the changes in data of the first server 10 and the second server 20 from time t0 to t3 are the same as those from time t0 to t3 in FIG. 6. In the example of FIG. 7, at time t4, the update device 30 sets the first server 10 as a secondary server and starts up the second server 20, which had been stopped. The local data and shared data 224 of the second server 20 are mirrored to the local data and shared data 124 of the first server 10.

[0055] 7, the information processing system 101 of the comparative example executes another update method, in which the measurement data α is lost at time t4. In other words, the information processing system 101 of the comparative example cannot constantly monitor the plant.

[0056] As is clear from the comparison with the comparative example, the update method, update device 30, and program according to this embodiment do not cause a mismatch between the application and the definition file, and do not lose measurement data while the update process is being executed due to a version upgrade. In other words, the update method, update device 30, and program according to this embodiment are suitable for an information processing system configured to perform mirroring.

[0057] Although the present disclosure has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included in the scope of the present disclosure. For example, the functions included in each means, step, etc. can be rearranged so as not to be logically inconsistent, and multiple means or steps can be combined or divided into one.

[0058] Furthermore, the first server 10, the second server 20, and the update device 30 may have any configuration. For example, in the above embodiment, the processing executed by the first server 10, which is a single computer, may be executed by distributed processing of multiple computers. Similarly, the processing executed by the second server 20, which is a single computer, may be executed by distributed processing of multiple computers. Similarly, the processing executed by the update device 30, which is a single computer, may be executed by distributed processing of multiple computers.

[0059] For example, the first server 10, the second server 20, and the update device 30 may further include an input / output device. The input / output device is an interface for accepting user operations on the first server 10, the second server 20, and the update device 30. The input / output device is also an interface for presenting information to the user from the first server 10, the second server 20, and the update device 30. The input / output device may be configured with an input device and a display device. The input device may be configured with hardware such as a keyboard and a mouse. The input device may be used, for example, by a plant manager to adjust the timing of an update due to a version upgrade. The display device may be configured with hardware such as a liquid crystal display or an OEL (organic electroluminescence) display. The display device may be used to notify the manager of the completion of the update. [Explanation of symbols]

[0060] 1. Information Processing Systems 10 First Server 11 Communications Department 12 Storage section 13 Control Unit 20 Second Server 21 Communications Department 22 Memory section 23 Control Unit 30 Update device 31 Communications Department 32 Storage section 33 Control Unit 40 Network 101 Information Processing Systems 121 Supervisory Control Applications 122 Local Data 123 Share Data 124 Local and Shared Data 131 Monitoring and control means 132 Data Management Measures 221 Supervisory Control Applications 222 Local Data 223 Share Data 224 Local and Shared Data 231 Monitoring and control means 232 Data Management Measures 331 Update method 332 Master system slave system setting means 333 Sorting means

Claims

1. 1. A method for updating an information processing system configured to perform data mirroring, comprising: The data stored in the first server and the second server that perform supervisory control and that are included in the information processing system are stored such that the first data, which is not a target of mirroring and includes a supervisory control application, is stored separately from the second data, which is a target of mirroring and includes measurement data for supervisory control related to a monitored object; a first updating step of, while the first server is operating to execute a monitoring and control process by the monitoring and control application, isolating the second server from the monitoring and control process without stopping the supply of power to the second server, and updating the monitoring and control application of the first data stored in the second server; a second updating step of operating the second server, which is separated from the monitoring and control processing, to execute the monitoring and control processing while the first server is in operation to execute the monitoring and control processing, and mirroring the second data stored in the first server, thereby updating the second data of the second server; An update method, when executing the first update step, expanding or adding a data area for storing the second data stored in the first server, and expanding or adding a data area for storing the second data stored in the second server.

2. 2. The update method according to claim 1, further comprising, after the second update step, a third update step of disconnecting the first server from the monitoring and control processing without stopping the supply of power to the first server, and updating the monitoring and control application of the first data stored in the first server.

3. An update device provided in an information processing system configured to perform data mirroring, The data stored in the first server and the second server that perform supervisory control and that are included in the information processing system are stored such that the first data, which is not a target of mirroring and includes a supervisory control application, is stored separately from the second data, which is a target of mirroring and includes measurement data for supervisory control related to a monitored object; While the first server is operating to execute a monitoring control process using the monitoring control application, the second server is separated from the monitoring control process without stopping the supply of power to the second server, and the monitoring control application of the first data stored in the second server is updated; While the first server is operating to execute the monitoring and control process, the second server, which is separated from the monitoring and control process, is operated to execute the monitoring and control process, and the second data stored in the first server is mirrored, thereby updating the second data in the second server; an update means for expanding or adding a data area for storing the second data stored in the first server when updating the monitoring and control application of the first data stored in the second server, and for expanding or adding a data area for storing the second data stored in the second server.

4. An update device provided in an information processing system configured to perform data mirroring, The data stored in the first server and the second server that perform supervisory control and that are included in the information processing system are stored such that the first data, which is not a target of mirroring and includes a supervisory control application, is stored separately from the second data, which is a target of mirroring and includes measurement data for supervisory control related to a monitored object; a first updating step of, while the first server is operating to execute a monitoring and control process by the monitoring and control application, isolating the second server from the monitoring and control process without stopping the supply of power to the second server, and updating the monitoring and control application of the first data stored in the second server; a second updating step of operating the second server, which is separated from the monitoring and control processing, to execute the monitoring and control processing while the first server is in operation to execute the monitoring and control processing, and mirroring the second data stored in the first server, thereby updating the second data of the second server; A program that, when executing the first update step, causes a data area for storing the second data stored in the first server to be expanded or added, and a data area for storing the second data stored in the second server to be expanded or added.

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