JP4193754B2 - Data duplication method and program - Google Patents

Description

The present invention relates to a redundant configuration system composed of an active system device and a standby system device that stands by as a backup when a failure occurs in the active system device, and in particular, is stored in a main storage device of the active system device. The present invention relates to a data duplication method for transferring data to a main storage device of a standby system device.

  In recent years, systems composed of various devices have been used for various purposes, but depending on the system, high reliability may be required. In a system used for such an application, not only an active system device performing a normal operation but also a standby system device having exactly the same configuration as the active system device is kept on standby as a standby system. When a failure occurs, high reliability is realized by using a hot standby configuration that prevents the system from going down by switching the standby system device as an active system device and continues operation.

  For example, if a call control server that manages call information in a mobile communication system or the like goes down, the entire communication system will not function, and the call control server is required to have high reliability. Therefore, a call control server with the same configuration is prepared as a standby device separately from the call control server that functions as an active device, and if any failure occurs in the active device, switch to the standby device. The operation is being continued.

  When such a configuration is used, call information must be shared between the active device and the standby device so that switching can be performed at any time. Therefore, when a device in which a failure has occurred recovers from the failure, it is necessary to incorporate the device into the system as a standby device. When a device recovered from a failure is incorporated into the system, it is necessary to copy all call information on the main memory of the active device to the main memory of the device to be incorporated as a standby device.

Various methods have been proposed as a method of copying the contents on the main memory of the active system device to the main memory of the standby system device (see, for example, Patent Documents 1, 2, and 3). However, in any prior art, while the call information of the active device is being copied to the device to be incorporated as a standby device, the call information update process is interrupted in the active device, or the update processing of the active device is There was a method of copying call information little by little in between. The former has a problem that if the amount of call information to be copied is large, the interruption time becomes long, which adversely affects the operation. In the latter prior art, since it takes a long time to transfer the data on the main storage device of the active system device to the main storage device of the standby system device, it is necessary to incorporate the standby system device into the system. There is a problem that it takes a long time and cannot be switched even if a failure occurs in the active system during that time.
JP 2001-177446 A JP 2001-195202 A JP 2002-41345 A

  In the above-described prior art, when all the data on the main storage of the active device is to be transferred to the main storage device of the standby device in order to incorporate the standby device into the system, the data update processing in the active device There has been a problem that it has been impossible to quickly incorporate the standby system into the system due to the interruption of data transfer or a long time for data transfer.

  An object of the present invention is to incorporate all the data on the main memory of the active device quickly without interrupting the data update process in the active device when incorporating the standby device into the system. To provide a data duplication method and a redundant configuration system capable of transferring data to a main storage device of a standby system device.

To achieve the above object, the present invention provides a redundant configuration system comprising an active device and a standby device that stands by as a backup when a failure occurs in the active device . the data stored in the main memory, a data duplication methods for transferring the main storage device of the standby system device,
When the standby device is incorporated into a redundant configuration system, the data management unit of the active device transmits all data stored in the main storage device of the active device to the main storage device of the standby device. Performing a synchronization instruction for performing an instruction to perform,
Data transmission means of the operating system device that has received the synchronization instruction, a flag indicating that a current synchronization process in after setting the main memory of the operating system device, on the main memory of the operating system device All the data is sequentially transmitted to the standby system device, and the address information indicating the data that has been transmitted is stored in the main storage device of the active system device ;
When the data management unit of the active device updates data stored in the main storage device of the active device , an update instruction is issued to instruct transmission of the updated data to the standby device. Outputting to the data transmission means;
The data transmission means of the active device that has received the update instruction determines the flag of the main storage device of the active device , and if the flag is not set to indicate that synchronization processing is being performed, The update instruction is registered in the waiting queue, and when the flag is set to indicate that synchronization processing is in progress , the address is indicated by comparing the address indicated by the update instruction with the address information. the standby device already determined whether sent to only if the data has already been determined to be transferred to the standby system, and registering the update instruction to the queue,
A step of canceling the setting of the flag indicating that synchronization processing is being performed when transmission of all data stored in the main storage device of the active device is completed;
The data transmission means of the active system device monitors the status of the interface between the active system device and the standby system device, and when it is in a transmittable state and a flag indicating that synchronization processing is in progress is not set, it is placed in the wait queue. Sequentially transmitting update data indicated by a registered update instruction to the standby device;
Data receiving means of the standby system device, and writing to the specified area on the sequential main memory data sent from said operating system device,
That it has a.

According to the present invention, when an update instruction is sent to the data transmission unit by the data management unit before the synchronization process is completed, the data transmission unit determines whether the current synchronization process is in progress due to the flag of the main storage device of the active device. If the synchronization processing is in progress, it is determined whether the data for which the update instruction has been made based on the address information has already been transferred to the standby device, and if the data has already been transferred to the standby device, The update instruction is registered in the wait queue and the update process is performed after the synchronization process is completed.

Therefore, the data management unit can update the data stored in the main storage device of the active device even during the synchronization process, and issue an update instruction, and can also wait from the main storage device of the active device. Since the synchronization process itself for transferring data to the main storage device of the system unit is also performed continuously, it does not take a long time. Therefore, the standby system apparatus can be quickly incorporated into the system without interrupting the data update process in the active system apparatus and without requiring a long time.

  As described above, according to the present invention, it is possible to obtain an effect that it is not necessary for the call information management unit that manages call information to stop updating the call information even when the standby device is installed.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of a call control server according to an embodiment of the redundant configuration system of the present invention. Referring to FIG. 1, the call control server according to the present embodiment includes an active device 1 and a standby device 2, and the active device 1 and the standby device 2 are connected to each other via an inter-device interface 3. .

  The active device 1 includes a call information management unit 11 that manages call information, a data transmission unit 12, a data reception unit 13, and a main storage device 14. Further, the standby system device 2 includes a call information management unit 21, a data transmission unit 22, a data reception unit 23, and a main storage device 24.

  The main storage device 14 of the active device 1 includes a call information area 141 for storing managed call information, a waiting queue area 142 for temporarily registering an update instruction, and a flag indicating that synchronization processing is in progress And a synchronization processing area 143 including an address indicating how far the copy of the call information has been completed. Similarly, the main storage device 24 of the standby system device 2 includes a call information area 241, a waiting queue area 242, and a synchronization processing area 243.

  Here, the active system device 1 and the standby system device 2 have the same configuration and can perform the same operation even when they are interchanged with each other. Therefore, only the configuration necessary when transferring call information from the main storage device 14 of the active system device 1 to the main storage device 24 of the standby system device 2 will be mainly described.

  The call information management unit 11 of the active system device 1 functions as a data management unit, and when the standby system device 2 is incorporated into the system, all call information stored in the call information area 141 is stored in the standby system device. A synchronization instruction for giving an instruction to transmit to the second main storage device 24 is output to the data transmitting means 12. Further, when the call information management unit 11 updates the call information stored in the call information area 141, the call information management unit 11 transmits an update instruction for instructing to transmit the updated call information to the standby apparatus 2. Output to means 12.

  When receiving the synchronization instruction from the call information management unit 11, the data transmission unit 12 of the active device 1 sets a flag indicating that synchronization processing is being performed in the synchronization processing area 143, and then uses the inter-device interface 3. All the call information in the call information area 141 is sequentially transferred to the standby system device 2 and the address information indicating the transferred data is stored in the synchronization processing area 143. When the transfer of all the call information is completed, the synchronization process is in progress. Cancel the flag setting that indicates that there is.

  Further, when receiving an update instruction from the call information management unit 11, the data transmission unit 12 determines the flag of the synchronization processing area 143 of the main storage device 14, and when the flag indicating that synchronization processing is in progress is not set. Registers the received update instruction in the wait queue of the wait queue area 142, and when the flag indicating that the synchronization process is in progress is set, by comparing the address indicated by the update instruction with the address information, It is determined whether or not the data has already been transmitted to the standby system device 2. Then, only when it is determined that the data has already been transferred to the standby system device 2, the data transmission unit 12 registers the update instruction in the waiting queue.

  That is, when the data transmission unit 12 receives the update instruction, the data transmission unit 12 sets the flag indicating that the synchronization process is being performed and the update data indicated by the update instruction is not yet transferred to the standby system device 2 by the synchronization process. If it is included, it is not registered in the waiting queue. This is because, in such a case, the update data indicated by the update instruction is transmitted to the standby apparatus 2 by the subsequent synchronization process, and thus it is not necessary to perform the update process individually.

  Then, after the synchronization process is completed, the data transmission unit 12 monitors the state of the inter-device interface 3, confirms that the flag is in a transmittable state and the synchronization process is not set, and enters the wait queue. One update data indicated by the registered update instruction is taken out from the head of the waiting queue and transferred to the standby system device 2 using the inter-device interface 3.

  The data receiving means 23 of the standby system device 2 sequentially writes the data sent from the active system device 1 to the address specified in the call information area 231.

  The format of the synchronization instruction and update instruction transmitted from the call information management unit 11 to the data transmission means 12 is shown in FIG. FIG. 2A is a diagram showing the format of the synchronization instruction, and FIG. 2B is a diagram showing the format of the update instruction. As shown in FIG. 2A, the update instruction is composed of an identifier indicating that this data is an update instruction, an address of the update data, and information indicating the size of the update data. Further, as shown in FIG. 2B, the synchronization instruction includes an identifier indicating that this data is a synchronization instruction.

  Further, data transferred to the standby system device 2 via the inter-device interface 3 has a format as shown in FIG. As shown in FIG. 3, this data is composed of information indicating stored addresses, the size of transferred data, and transferred data (call information).

  Next, the operation of the call control server of this embodiment will be described in detail with reference to FIGS.

  FIG. 4 is a flowchart showing an operation when the data transmission unit 12 receives an update instruction from the call information management unit 11. Referring to FIG. 4, first, the data transmission means 12 determines whether or not the flag of the synchronization processing area 143 of the main storage device 14 is set (steps A1 and A2). When the flag is set, that is, when it indicates that synchronization processing is being performed, the data transmission unit 12 next checks the address of the synchronization processing area 143, and the address of the update data indicated by the update instruction is Then, it is determined whether or not it is included in the address of the call information that has already been transmitted (steps A3 and A4). If the address of the update data indicated by the update instruction is not included, the update data is transmitted to the active system device 2 by the subsequent synchronization process, and the data transmission unit 12 ends the process. On the other hand, if it is determined in step A4 that the address of the update data indicated by the update instruction is included, and if it is determined in step A2 that the flag is not set, the data transmission means 12 The instruction is registered at the end of the wait queue in the wait queue area 142, a wait queue processing routine to be described later is called, and then the process ends (steps A5 and A6).

  FIG. 5 is a flowchart showing the operation when the data transmission means 12 receives a synchronization instruction from the call information management unit 11. Referring to FIG. 5, the data transmission means 12 first sets a flag in the synchronization processing area 143 of the main storage device 14 (step B1). Next, the address of the synchronization processing area 143 is checked, and the data for the maximum size that can be transferred at one time by the inter-device interface 3 is read from the address in the call information area 141, Transfer (steps B2, B3 and B4). Then, after adding the transferred size to the address of the synchronization processing area 143, the data transmitting unit 12 checks whether or not all the call information has been transferred (steps B5, B6 and B7). If untransferred data remains, the data transmission means 12 returns to step B2 and repeats the process. On the other hand, when the transfer is completed, the data transmission unit 12 cancels the setting of the flag of the synchronization processing area 143, resets the head address of the call information area 141 to the address of the synchronization processing area 143, and will be described later. After calling the waiting queue processing routine, the processing ends (steps B8, B9 and B10).

  FIG. 6 is a flowchart showing the operation of a wait queue processing routine in which the data transmission means 12 processes an update instruction registered in the wait queue in the wait queue area 142 of the main storage device 14. Referring to FIG. 6, the data transmission unit 12 monitors the state of the inter-device interface 3 (steps C1 and C2). If it is busy, continue monitoring. On the other hand, if it is in the free state, the data transmission means 12h and then the flag in the synchronization processing area 143 is examined (steps C3 and C4). When the flag state is set, that is, when the synchronization process is being performed, the data transmission unit 12 finishes the process. If it is determined in step C4 that the flag is not set, the data transmission means 12 next checks whether there is an update instruction in the wait queue in the wait queue area 142 (steps C5 and C6). When there is no update instruction, the data transmission unit 12 finishes the process. When there is an update instruction, the data transmission unit 12 extracts one update instruction from the head of the waiting queue, and reads the call information data to be updated from the call information area 141 using the address and size indicated by the extracted update instruction. Then, the data is transferred to the standby system device 2 via the inter-device interface 3 (steps C7, C8 and C9). Then, the data transmission unit 12 returns to Step C1.

  In the call control server of the present embodiment, when an update instruction is sent to the data transmission unit 12 by the call control management unit 11 before the synchronization process is completed, the data transmission unit 12 performs the synchronization process of the main storage device 14. It is determined whether or not the synchronization process is currently being performed based on the flag in the area 143. If the update instruction has already been transferred to the standby system device 2, the update instruction is registered in the wait queue in the wait queue area 142, and the update process is performed after the synchronization process is completed. .

  Therefore, the call information management unit 11 can update the call information stored in the main storage device 14 and issue an update instruction even during the synchronization process, and the main storage device 14 of the active device 1. Since the synchronization processing itself for transferring data from the standby device 2 to the main storage device 24 is continuously performed, it does not take a long time. Therefore, it is possible to quickly incorporate the standby system device 2 into the system without interrupting the call information update process in the active system device 1 and without requiring a long time.

  Next, the operation of the call control server of this embodiment will be described using a specific example.

  As illustrated in FIG. 7, for example, it is assumed that the processing proceeds in the following order ((1) to (7)) during operation only by the active system device 1. The call information area 141 divided into the maximum size that can be transferred at once is defined as areas A, B, C, and D from the top.

(1) The call information management unit 11 updates the call information a. (2) The call information management unit 11 recognizes the rising edge of the standby system device 2 and transmits a synchronization instruction. (3) The data transfer means 12 is in the areas A and B. (4) The call information management unit 11 updates the call information b. (5) The call information management unit 11 updates the call information c. (6) The data transfer means 12 completes the transfer of the entire area. The information management unit 11 updates the call information d. Operations in the call control server according to the present embodiment when the processing proceeds in (1) to (7) as described above will be sequentially described below.

  (1) The call information management unit 11 updates the call information a. However, since the standby system device 2 is not yet incorporated in the system, the call information management unit 11 does not instruct the data transmission means 12 to update the call information a.

  (2) When the call information management unit 11 recognizes that the standby system device 2 has risen, it issues a synchronization instruction to the data transmission unit 12.

  (3) Upon receiving the synchronization instruction, the data transmission unit 12 sets the flag in the synchronization processing area 143 to a state in which synchronization processing is being performed. Next, the data transmission unit 12 checks the address of the synchronization processing area 143. The address in the synchronization processing area 143 is the start address of the call information area 141 in the initial state, that is, the start address of the area A. Therefore, the data transmission unit 12 reads the data in the area A and transfers it to the standby system device 2 via the inter-device interface 3. Then, the transferred size is added to the address of the synchronization processing area 143. Thereby, the address of the synchronization processing area 143 indicates the head address of the area B. At this point, since there is still an untransferred area, the data transmission unit 12 returns to step B2 and repeats the process. Then, the data transmission unit 12 similarly transfers the data in the area B.

  (4) The call information management unit 11 updates the call information b. Since the synchronization instruction is executed this time, the call information management unit 11 instructs the data transmission unit 12 to update the call information b. The data transmission unit 12 that has received the update instruction checks the flag in the synchronization processing area 143. Here, since the flag is set, the data transmission means 12 checks the address of the synchronization processing area 143 this time, and checks whether the address of the update data indicated by the update instruction is included. At this point, since transmission to area B including call information b has been completed, an update instruction is registered at the end of the wait queue in wait queue area 142, and a wait queue processing routine described later is called. In the processing routine of the wait queue that has been called, the data transmission means 12 checks the state of the inter-device interface 3. At this time, if the state of the inter-device interface 3 is a free state, the data transmission unit 12 next checks the flag in the synchronization processing area 143. Here, since the flag is set, the data transmission unit 12 ends the process.

  (5) The call information management unit 11 updates the call information c. Since the synchronization instruction is also executed this time, the call information management unit 11 instructs the data transmission unit 12 to update the call information c. The data transmission unit 12 that has received the update instruction checks the flag in the synchronization processing area 143. Since the flag is set, the data transmission means 12 checks the address of the synchronization processing area 143 this time and checks whether the address of the update data indicated by the update instruction is included. At this time, since the transmission of the area C including the call information c is not completed, the data transmission unit 12 ends the process without registering the update instruction.

  (6) Receiving the synchronization instruction, the data transmission unit 12 repeats the area transfer following (3). When the transmission of the area D is finally completed, the data transmission means 12 cancels the setting of the flag of the synchronization processing area 143, returns the address of the synchronization processing area 143 to the head address of the call information area, Call processing routine. In the processing routine of the wait queue that has been called, the data transmission means 12 checks the state of the inter-device interface 3. At this time, if the state of the inter-device interface 3 is a free state, the data transmission unit 12 next checks the flag in the synchronization processing area 143. Since the flag is not set this time, the data transmission unit 12 next checks whether or not there is an update instruction for the waiting queue area 142. At this time, an update instruction for the call information b registered in (4) is registered in the waiting queue. Therefore, the data transmission unit 12 takes out this update instruction from the waiting queue, reads the data of the call information b indicated by the taken out update instruction, transfers it to the standby system device 2 via the inter-device interface 3, and goes to Step C1. Return. However, since the next update instruction is not registered, the data transmission unit 12 stays in the state monitoring of the inter-device interface 3.

  (7) The call information management unit 11 updates the call information d. Since this time also after the execution of the synchronization process, the call information management unit 11 instructs the data transmission means 12 to update the call information d. The data transmission unit 12 that has received the update instruction checks the flag in the synchronization processing area 143. Since the flag is not set this time, the data transmission means 12 immediately registers an update instruction at the end of the queue in the waiting queue area 142 and calls a waiting queue processing routine described later. In the processing routine of the wait queue that has been called, the data transmission means 12 checks the state of the inter-device interface 3. At this time, if the state of the inter-device interface 3 is a free state, the data transmission unit 12 next checks the flag in the synchronization processing area 143. Since the flag is not set this time, the data transmission unit 12 next checks whether there is an update instruction for the waiting queue area 143. At this time, an instruction to update call information d is registered in the waiting queue. Therefore, the data transmission means 12 extracts this update instruction from the waiting queue, reads the data of the call information d indicated by the extracted update instruction, transfers it to the standby system apparatus 2 via the inter-device interface 3, and proceeds to Step C1. Return. However, since the next update instruction is not registered, the data transmission unit 12 stays in the state monitoring of the inter-device interface 3.

  According to the call control server of the present embodiment, as shown in FIG. 7, the call information management unit 11 even during the period from when the synchronization instruction is issued until the synchronization process is completed (2) to (6). The call information b and c can be updated without stopping the synchronization process.

  Although not shown in the figure, the call control server of the present embodiment includes a recording medium that records a program for executing the data duplication method described above. This recording medium may be a magnetic disk, a semiconductor memory, or another recording medium. This program is read from the recording medium into the call control server and controls the operation of the call control server. Specifically, the CPU in the call control server instructs the hardware resources of the active system device 1 and the standby system device 2 of the call control server to perform a specific process under the control of this program. Realized.

  Further, in the present embodiment, the redundant configuration system has been described using a call control server including an active device and a standby device, but the present invention is not limited to this, and the active device and In a general redundant configuration system composed of a standby system device, the present invention can be similarly applied even when data is transferred from the active system device to the main storage device of the standby system device.

It is a block diagram which shows the structure of the information structure system of one Embodiment of this invention. It is the figure (FIG.2 (a)) which shows the format of a synchronous instruction | indication output to the data transmission means 12 from the call information management part 11, and the figure (FIG.2 (b)) which shows the format of an update instruction | indication. It is a figure which shows the format of the data transferred to the standby system apparatus 2 via the inter-device interface 3. FIG. 6 is a flowchart showing an operation when the data transmission unit 12 receives an update instruction from the call information management unit 11; 6 is a flowchart showing an operation when the data transmission unit 12 receives a synchronization instruction from the call information management unit 11. 7 is a flowchart showing the operation of a wait queue processing routine in which the data transmission means 12 processes an update instruction registered in the wait queue in the wait queue area 142 of the main storage device 14. It is a figure which shows the specific example for demonstrating operation | movement of the call control server of one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Active system apparatus 2 Standby system apparatus 3 Interface between apparatuses 11 Call information management part 12 Data transmission means 13 Data reception means 14 Main storage device 21 Call information management part 22 Data transmission means 23 Data reception means 24 Main storage apparatus 141 Call information area 142 Waiting queue area 143 Synchronization processing area 241 Call information area 242 Waiting queue area 243 Synchronization processing area A1 to A6 Step B1 to B10 Step C1 to C9 Step

Claims (4)

In a redundant configuration system composed of an active device and a standby device that stands by as a backup when a failure occurs in the active device, data stored in the main storage of the active device is stored in the standby system. A data duplication method for transferring to a main storage device of a system device,
When the standby device is incorporated into a redundant configuration system, the data management unit of the active device transmits all data stored in the main storage device of the active device to the main storage device of the standby device. Performing a synchronization instruction for performing an instruction to perform,
The data transmission unit of the active device that has received the synchronization instruction sets a flag indicating that the synchronization processing is currently being performed in the main storage device of the active device, and then on the main storage device of the active device. All the data is sequentially transmitted to the standby system device, and the address information indicating the data that has been transmitted is stored in the main storage device of the active system device;
When the data management unit of the active device updates data stored in the main storage device of the active device, an update instruction is issued to instruct transmission of the updated data to the standby device. Outputting to the data transmission means;
The data transmission means of the active device that has received the update instruction determines the flag of the main storage device of the active device, and if the flag is not set to indicate that synchronization processing is being performed, The update instruction is registered in the waiting queue, and when the flag is set to indicate that synchronization processing is in progress, the address is indicated by comparing the address indicated by the update instruction with the address information. Determining whether it has already been transmitted to the standby device, and only when it is determined that the data has already been transferred to the standby device, the update instruction is registered in the waiting queue;
The flag indicating that synchronization processing is being performed when the data transmission unit of the active device that has received the synchronization instruction has completed transmission of all data stored in the main storage device of the active device A step to cancel the setting of
The data transmission means of the active device receives the update instruction and registers the update instruction in the waiting queue, or receives the synchronization instruction and is stored in the main storage of the active device. When the transmission of all the data being completed is completed and the setting of the flag indicating that the synchronization processing is in progress is released , the status of the interface between the active device and the standby device is monitored, and in a transmittable state, And, when the flag indicating that the synchronization process is in progress is not set, the update data indicated by the update instruction registered in the waiting queue is sequentially transmitted to the standby device;
The data receiving means of the standby system device sequentially writes the data sent from the active system device to a designated area on the main memory; and
A data duplexing method.   The data duplication method according to claim 1, wherein the data transferred from the main storage device of the active device to the main storage device of the standby device is call information for performing call control in the communication system. In a redundant configuration system composed of an active device and a standby device that stands by as a backup when a failure occurs in the active device, data stored in a main storage device of the active device is stored in the standby system. A program for causing a computer to execute a data duplication method for transferring to a main storage device of a system device,
When the standby device is incorporated into a redundant configuration system, the data management unit of the active device transmits all data stored in the main storage device of the active device to the main storage device of the standby device. A process of issuing a synchronization instruction for issuing an instruction to perform,
The data transmission unit of the active device that has received the synchronization instruction sets a flag indicating that the synchronization processing is currently being performed in the main storage device of the active device, and then on the main storage device of the active device. All the data is sequentially transmitted to the standby system device, and the address information indicating the data that has been transmitted is stored in the main storage device of the active system device;
When the data management unit of the active device updates data stored in the main storage device of the active device, an update instruction is issued to instruct transmission of the updated data to the standby device. Processing to output to the data transmission means;
The data transmission means of the active device that has received the update instruction determines the flag of the main storage device of the active device, and if the flag is not set to indicate that synchronization processing is being performed, The update instruction is registered in the waiting queue, and when the flag is set to indicate that synchronization processing is in progress, the address is indicated by comparing the address indicated by the update instruction with the address information. Determining whether or not it has already been transmitted to the standby device, and only when it is determined that the data has already been transferred to the standby device, processing to register the update instruction in the wait queue;
The flag indicating that synchronization processing is being performed when the data transmission unit of the active device that has received the synchronization instruction has completed transmission of all data stored in the main storage device of the active device Processing to cancel the setting of
The data transmission means of the active device receives the update instruction and registers the update instruction in the waiting queue, or receives the synchronization instruction and is stored in the main storage of the active device. When the transmission of all the data being completed is completed and the setting of the flag indicating that the synchronization processing is in progress is released , the status of the interface between the active device and the standby device is monitored, and in a transmittable state, And, when the flag indicating that the synchronization process is in progress is not set, processing for sequentially transmitting update data indicated by the update instruction registered in the waiting queue to the standby system device;
A program for causing the computer to execute a process in which the data receiving means of the standby system apparatus sequentially writes the data sent from the active system apparatus to a specified area on the main memory.   The program according to claim 3, wherein the data transferred from the main storage device of the active device to the main storage device of the standby device is call information for performing call control in the communication system.

Images