JP4677482B2 - Access distribution system, server device, common management device, access distribution device, access distribution method, and computer program - Google Patents

Description

  The present invention relates to an access distribution system, a server device, a common management device, an access distribution device, an access distribution method, and a computer program.

  Conventionally, when a server provides an application to a plurality of terminals accessed via a network, the server is prepared for each application based on the access expectation. However, in this case, when the actual access deviates from the access prediction, or when sudden demand occurs, the server is overloaded and may not be able to respond to the request from the terminal. In recent years, physical servers having a plurality of CPU resources have appeared. Therefore, it is conceivable to provide an application using virtual server technology that allows one physical server to be used as a plurality of virtual servers. Since virtual servers dynamically allocate resources according to load conditions, it is possible to improve resource efficiency. In recent years, products that realize such virtual server technology have become widespread.

  FIG. 10 is a diagram illustrating allocation of CPU resources by the virtual server technology. For example, from the initial state shown in FIG. 10A, when the access of the virtual server # 1 increases as shown in FIG. 10B and the CPU resources of the virtual server # 1 are insufficient, the virtual servers # 2 and # 2 3 allocates a part of the CPU resources used by the virtual server # 1 to increase the processing capacity.

On the other hand, Patent Document 1 describes a load distribution method in which a load distribution apparatus and a control server dynamically change processing distribution destinations according to the number of requests to a web server. Patent Document 2 describes a wide area load distribution apparatus that realizes load distribution between servers belonging to different networks. In Patent Document 3, a router connected to a plurality of networks is prepared on the distribution server side, a router installed on the client side, a cost value of the network is measured, and a router with a low cost value is used. Thus, a load distribution method in which a distribution server communicates with a client is described.
JP 2002-259354 A JP 2000-132524 A JP 2007-184969 A

For example, assuming that the application provided by the virtual server is file download, when transmitting a large file (for example, about 200 megabytes) to the end user terminal, the load on the CPU is small, but the network interface When a small file (for example, about 1 kilobyte) is transmitted, the load on the CPU is large, but the load on the network interface is small. Therefore, when there are multiple virtual servers that provide the same file download site, the virtual server CPU status and network interface status are combined to determine which virtual server the access from the end user terminal is distributed to. There is a need. However, in the conventional technology, resources used in individual virtual servers are dynamically changed, while an operator can monitor the system state only in units of physical servers. Therefore, it has been desired to grasp the load status in real time for each virtual server in each physical server.
Further, in the technique of Patent Document 1 described above, since it is necessary to set a load balancer in front of a plurality of installed web servers, there is a case where the performance of this load balancer becomes a bottleneck and cannot be load balanced properly. is there. Similarly, in the technique of Patent Document 2, traffic concentrates on a wide area load distribution apparatus installed between networks, and the performance of the wide area load distribution apparatus becomes a bottleneck. In the technique of Patent Document 3, it is necessary to monitor the cost of each network, and the operation load becomes very high.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to reduce the load on the network and operation without the processing capability of a device other than the virtual server receiving access from the end user terminal becoming a bottleneck. An object of the present invention is to provide an access distribution system, a server device, an access distribution device, a common management device, an access distribution method, and a computer program that can appropriately distribute loads among virtual servers while suppressing the load.

In order to solve the above-described problems, the present invention operates as a plurality of virtual servers and includes a server device provided with a communication unit for each virtual server that performs communication with the end user terminal , and the access of the end user terminal . Using the access distribution device that identifies the virtual server that is the distribution destination and notifies the IP address of the virtual server, and the IP address of the virtual server that is the distribution destination notified from the access distribution device, the virtual server An access distribution system in which an end user terminal that accesses a server is connected via a network, wherein the server device includes a status of a CPU assigned to a virtual server operating in the server device, and Obtained by the resource state monitoring unit for obtaining the state of the communication means of the virtual server, and for each virtual server by the resource state monitoring unit Further, for each of the state of the CPU allocated to the virtual server and the state of the communication means of the virtual server, it is determined whether or not a predetermined condition for determining that a load is applied, and the determination result is referred to as the access A status notification unit that notifies the distribution device, and the access distribution device stores a information that associates the domain name, the IP address of the virtual server, and whether or not distribution to the virtual server is possible, and When the determination result is received from the server device, and the determination result indicates that the CPU assigned to the virtual server and the communication means of the virtual server are not under load, Information that can be distributed to the virtual server is written in the storage unit, and the determination result is the CPU assigned to the virtual server, or the If it indicates that the communication means of the virtual server is under load, the update unit that writes information that cannot be distributed to the virtual server to the storage unit, and the access destination of the end user terminal receiving information of a domain name, corresponding to the domain name, and a notification unit which distribution notifies reads the IP address of the virtual server is allowed from the storage unit, the status notification unit, the virtual When a CPU to be used exclusively by the server is allocated, the CPU determines whether the load is applied based on the usage status of the CPU occupied by the virtual server, and the virtual server assigns the CPU to another virtual server. When sharing with the server, the CPU status indicating whether the load is applied based on the usage status of the CPU by all the virtual servers sharing the CPU It is an access distribution system characterized by judging .

  Further, the present invention is the access distribution system described above, wherein the update unit is such that the virtual server shares a CPU with another virtual server, and the determination result is a load on the CPU. Indicates that information that cannot be distributed to all virtual servers operating in the server device to which the virtual server belongs is written in the storage unit.

Further, the present invention is the access distribution system described above, wherein the status notification unit determines whether the virtual server is activated or whether the communication unit of the virtual server is activated. Notifying the access distribution device of the result, and if it is determined that the virtual server is not started , the maintenance monitoring device notifying the maintenance person that the operation state is not normal in response to receiving the warning. , Sending a warning .

  Moreover, the present invention is the above-described access distribution system, wherein the state notification unit notifies the determination result by a code commonly used for the virtual server.

  Further, the present invention is the access distribution system described above, wherein the update unit periodically transmits a virtual server status inquiry to the server device, and the status notification unit receives a virtual request from the access distribution device. Receiving a server status inquiry, acquiring the status of the CPU assigned to the virtual server and the status of the communication means of the virtual server from the resource status monitoring unit, and returning the determination result .

Further, the present invention discloses an access sorting system described above, the server apparatus, from the master server that stores the master data file to be provided to the end user terminal as connected to the web service via the network, receiving the file, and stores the received file in the storage means of the common management area, if the command to read the file to the virtual server is input, it is stored in the storage means of the common management area The file stored in the storage means assigned to the virtual server is distributed to the reading unit that stores the file in the storage means assigned to the virtual server and the end user terminal that has accessed the virtual server. And a distribution unit.

  Further, the present invention is the access distribution system described above, wherein the server device notifies a log server connected via the network of an access log to a virtual server operating in the server device. A notification unit is provided.

In addition, the present invention operates as a plurality of virtual servers and serves as a distribution destination of a plurality of server devices each provided with a communication unit that communicates with end user terminals for each virtual server. An access distribution device that identifies a virtual server and notifies the IP address of the virtual server, a common management device that manages the states of the plurality of server devices, and a virtual of the distribution destination notified from the access distribution device An access distribution system in which an end user terminal that accesses the virtual server is connected via a network using an IP address of a server, wherein the common management device operates in the plurality of server devices A resource state monitoring unit that acquires a state of a CPU assigned to each virtual server and a state of communication means of the virtual server, and the virtual server For each server, a predetermined condition acquired by the resource state monitoring unit for each of the state of the CPU assigned to the virtual server and the state of the communication means of the virtual server is determined to be loaded. A status notification unit that determines whether or not they match, and notifies the access distribution device of the determination result, and the access distribution device includes a domain name, an IP address of a virtual server, and whether or not distribution to the virtual server is possible And a storage unit that stores information associated with the CPU, the determination result is received from the common management device, and the determination result is a load on the CPU assigned to the virtual server and the communication unit of the virtual server. If it indicates that it is not in the state, the information that can be distributed to the virtual server is written in the storage unit, and the determination result is Update that writes information that cannot be allocated to the virtual server to the storage unit when the CPU allocated to the virtual server or the communication means of the virtual server is in a load state And a notification unit that receives information on the domain name of the access destination of the end user terminal, reads the IP address of the virtual server corresponding to the domain name and that can be distributed, and notifies the storage unit And when the CPU to be used exclusively is allocated to the virtual server, the status notification unit determines the CPU status as to whether a load is applied based on the usage status of the CPU occupied by the virtual server. When the virtual server uses the CPU in common with other virtual servers, the usage status of the CPU by all the virtual servers sharing the CPU An access distribution system that determines a state of a CPU as to whether a load is applied based on a situation .

  The present invention is the access distribution system described above, wherein the common management device determines a priority of access to the virtual server from a load state of the virtual server operating in the plurality of server devices. And a priority notification means for notifying to the access distribution device, wherein the notification unit of the access distribution device is a priority order among virtual servers corresponding to the domain name and capable of distribution. An IP address of a virtual server having a high value is read from the storage unit and notified.

  The present invention is the above-described access distribution system, further comprising a domain name system server connected to the end user terminal via another network, and the access distribution device reads from the storage unit In addition, the update information in which the domain name corresponding to the virtual server whose allocation availability information has been changed, the IP address of the virtual server corresponding to the domain name, and the content of the allocation allocation change is set as the update information. An update notification unit for notifying a domain name system server, wherein the domain name system stores a domain name and information that associates an IP address of a virtual server that can be allocated; The update information is received from the access distribution device, and is associated with the domain name set in the update information. A domain name system update unit that updates the IP address information of a virtual server that can be distributed, which is stored in the domain name system storage unit, on the basis of a change in whether or not the distribution is set in the update information; An address resolution unit that receives information on a domain name of an access destination of the end user terminal, reads an IP address of a virtual server corresponding to the domain name from the domain name system storage unit, and notifies the information. And

  Further, the present invention is the access distribution system described above, wherein the update notification unit of the access distribution device corresponds to the virtual server that has been read from the storage unit and whose distribution availability information has been changed. The domain name system update unit of the domain name system notifies the domain name system server of update information in which a domain name and IP addresses of all the virtual servers that can be allocated corresponding to the domain name are set. Rewriting the IP address information stored in the domain name system storage unit in association with the domain name set in the received update information to the IP address information set in the update information; It is characterized by.

  Further, the present invention is the access distribution system described above, wherein the update notification unit of the access distribution device corresponds to the virtual server that has been read from the storage unit and that has been updated with information about whether distribution is possible. An update notification unit for notifying the domain name system server of update information in which a domain name and IP addresses of all the virtual servers corresponding to the domain name and information indicating whether or not the virtual server can be distributed are set; The domain name system storage unit stores information associating domain names with IP addresses of all virtual servers using the domain name, and the domain name system update unit includes: Write the update information received from the access distribution device to the domain name system storage unit, The address resolution unit receives the information of the domain name of the access destination of the end user terminal, indicates that it corresponds to the domain name from the domain name system storage unit and can be distributed by the update information. The IP address of the virtual server to be read is read and notified.

Further, the present invention distributes access from an end user terminal to the virtual server, and a server device that operates as a plurality of virtual servers and includes communication means for communicating with the end user terminal for each virtual server. Access distribution formed by connecting an access distribution device and an end user terminal that accesses the virtual server using the IP address of the virtual server of the distribution destination notified from the access distribution device via a network A resource status monitoring unit that acquires a status of a CPU assigned to a virtual server operating in the server device and a status of a communication unit of the virtual server, the server device in the system; The CPU status assigned to the virtual server and the virtual server acquired by the resource status monitoring unit. For each state of the communication means of bus, to determine matches the predetermined condition is judged that the load is applied, includes a state notification portion for notifying the determination result to the access sorting device, the said When a CPU to be used exclusively by the virtual server is allocated, the state notification unit determines a state of the CPU as to whether a load is applied based on a usage state of the CPU occupied by the virtual server, and When the server uses the CPU in common with other virtual servers, the CPU determines whether the load is applied based on the usage status of the CPU by all the virtual servers sharing the CPU. it is a server device that.

In addition, the present invention provides a plurality of server devices that operate as a plurality of virtual servers and have communication means for communicating with end user terminals for each virtual server, and access from the end user terminals to the virtual servers. Access to the virtual server using the IP address of the allocation destination virtual server notified from the access allocation device, the common management device that manages the status of the plurality of server devices, and the access allocation device A common management device in an access distribution system in which an end user terminal is connected via a network, the state of a CPU assigned to each virtual server operating in the plurality of server devices, and The resource status monitoring unit for acquiring the status of the communication means of the virtual server, and the resource status monitoring unit for each virtual server. For each of the acquired CPU state assigned to the virtual server and the communication means state of the virtual server, it is determined whether or not a predetermined condition for determining that a load is applied, and the determination result is A status notification unit for notifying the access distribution device, and when the CPU to be used exclusively by the virtual server is allocated, the status notification unit is based on the usage status of the CPU occupied by the virtual server. When the virtual server uses the CPU in common with other virtual servers, the CPU status is determined based on the usage status of the CPU by all the virtual servers sharing the CPU. It is a common management apparatus characterized by determining a state of a CPU as to whether a load is applied .

Further, the present invention distributes access from an end user terminal to the virtual server, and a server device that operates as a plurality of virtual servers and includes communication means for communicating with the end user terminal for each virtual server. Access distribution formed by connecting an access distribution device and an end user terminal that accesses the virtual server using the IP address of the virtual server of the distribution destination notified from the access distribution device via a network A storage unit that stores information in which a domain name is associated with an IP address of a virtual server and whether or not distribution to the virtual server is possible; and the server device, Operates in the server device from a common management device connected to the network for managing the state of the server device That for each of the states of the state and the communication means of the virtual server's CPU allocated to the virtual server, when said CPU used to occupy the virtual server is assigned, use of the CPU the virtual server occupies This is a determination result based on the situation. When the virtual server uses the CPU in common with another virtual server, the determination result is based on the usage situation of the CPU by all virtual servers sharing the CPU. A determination result as to whether or not a predetermined condition for determining that the load is applied is received, and the determination result is a load on both the CPU assigned to the virtual server and the communication means of the virtual server. If it indicates that it is not applied, information that can be distributed to the virtual server is written in the storage unit, and the determination result is Indicates that the CPU allocated to the virtual server or the communication means of the virtual server is in a state of being loaded, information that cannot be distributed to the virtual server is stored in the storage unit. The update unit to be written in and information on the domain name of the access destination of the end user terminal are received, and the IP address of the virtual server corresponding to the domain name and available for distribution is read from the storage unit and notified. An access distribution device comprising: a notification unit.

Further, the present invention distributes access from an end user terminal to the virtual server, and a server device that operates as a plurality of virtual servers and includes communication means for communicating with the end user terminal for each virtual server. Access distribution formed by connecting an access distribution device and an end user terminal that accesses the virtual server using the IP address of the virtual server of the distribution destination notified from the access distribution device via a network An access distribution method used in a system, wherein in the server device, a resource state monitoring unit assigns a state of a CPU assigned to a virtual server operating in the server device, and a state of communication means of the virtual server And the status notification unit acquires the virtual server acquired by the resource status monitoring unit for each virtual server. For each of the state of the CPU assigned to the state of the virtual server and the state of the communication means of the virtual server, it is determined whether or not a predetermined condition for determining that a load is applied, and the determination result is notified to the access distribution device In the access distribution device, the update unit receives the determination result from the server device, and the determination result places a load on the CPU assigned to the virtual server and the communication means of the virtual server. In the storage unit that stores information that associates the domain name, the IP address of the virtual server, and whether or not allocation to the virtual server is possible. The information that is acceptable is written, and the determination result places a load on the CPU assigned to the virtual server or the communication means of the virtual server. Information indicating that allocation to the virtual server is impossible is written in the storage unit, the notification unit receives information on the domain name of the access destination of the end user terminal, and When the IP address of a virtual server that corresponds to a domain name and can be distributed is read from the storage unit and notified, and the status notification unit is assigned a CPU to be used exclusively by the virtual server The CPU status is determined based on the usage status of the CPU occupied by the virtual server, and when the virtual server shares the CPU with another virtual server, the CPU is shared. An access distribution method characterized by determining a state of a CPU as to whether a load is applied based on a usage state of the CPU by all virtual servers. .

In addition, the present invention provides a plurality of server devices that operate as a plurality of virtual servers and have communication means for communicating with end user terminals for each virtual server, and access from the end user terminals to the virtual servers. Access to the virtual server using the IP address of the allocation destination virtual server notified from the access allocation device, the common management device that manages the status of the plurality of server devices, and the access allocation device An access distribution method used in an access distribution system in which end user terminals are connected via a network, wherein, in the common management device, a resource state monitoring unit operates in the plurality of server devices. CPU status assigned to each virtual server and the status of the communication means of the virtual server, and the status notification unit For each virtual server, a predetermined condition obtained by the resource status monitoring unit, for each of the state of the CPU assigned to the virtual server and the state of the communication means of the virtual server, determined to be loaded, and Judgment is made, the judgment result is notified to the access distribution device, and in the access distribution device, the update unit receives the judgment result from the common management device, and the judgment result is the virtual server. If the CPU assigned to the virtual server and the communication means of the virtual server indicate that there is no load, the domain name, the IP address of the virtual server, and whether or not the virtual server can be distributed Information that can be distributed to the virtual server is written in the storage unit that stores the associated information, and the determination result is the virtual server. When the allocated CPU or the communication means of the virtual server indicates that the load is applied, information indicating that the allocation to the virtual server cannot be performed is written in the storage unit, and the notification unit Receiving the information of the domain name of the access destination of the end user terminal, reading out the IP address of the virtual server corresponding to the domain name and available for distribution from the storage unit, and notifying the state notification unit However, if a CPU that is used exclusively by the virtual server is assigned, the CPU determines whether the load is applied based on the usage status of the CPU occupied by the virtual server, and the virtual server Is shared with other virtual servers, a load is applied based on the usage status of the CPU by all virtual servers sharing the CPU. The access distribution method is characterized in that the CPU status is determined .

Further, the present invention distributes access from an end user terminal to the virtual server, and a server device that operates as a plurality of virtual servers and includes communication means for communicating with the end user terminal for each virtual server. Access distribution formed by connecting an access distribution device and an end user terminal that accesses the virtual server using the IP address of the virtual server of the distribution destination notified from the access distribution device via a network A computer program used for the server device of a system, the step of acquiring a state of a CPU assigned to a virtual server operating in the server device and a state of communication means of the virtual server; For each server, the state of the CPU assigned to the virtual server and the state of the communication means of the virtual server For each, the case of CPU used to occupy the virtual server is assigned based on the usage of CPU in which the virtual servers occupy the virtual server share the CPU with other virtual servers using If it is determined , based on the usage status of the CPU by all the virtual servers that share the CPU, it is determined whether or not a predetermined condition for determining that a load is applied, and the determination result is assigned to the access distribution. A computer program characterized by causing a computer to execute the step of notifying the apparatus.

In addition, the present invention provides a plurality of server devices that operate as a plurality of virtual servers and have communication means for communicating with end user terminals for each virtual server, and access from the end user terminals to the virtual servers. Access to the virtual server using the IP address of the allocation destination virtual server notified from the access allocation device, the common management device that manages the status of the plurality of server devices, and the access allocation device A computer program used in the common management device of an access distribution system in which an end user terminal is connected via a network, and assigned to each virtual server operating in the plurality of server devices And acquiring the status of the communication means of the virtual server, and for each virtual server, the resource Obtained by scan state monitoring unit for each of the states of the state and the communication means of the virtual server's CPU allocated to the virtual server, when said CPU used to occupy the virtual server is assigned, the When the virtual server shares the CPU with another virtual server based on the usage status of the CPU occupied by the virtual server, it is based on the usage status of the CPU by all the virtual servers sharing the CPU. , it is determined whether to match the predetermined condition is judged that the load is applied, a computer program, characterized in that to execute the step of notifying the determination result to the access sorting device, to the computer.

Further, the present invention distributes access from an end user terminal to the virtual server, and a server device that operates as a plurality of virtual servers and includes communication means for communicating with the end user terminal for each virtual server. Access distribution formed by connecting an access distribution device and an end user terminal that accesses the virtual server using the IP address of the virtual server of the distribution destination notified from the access distribution device via a network A computer program used for the access distribution device of a system, which operates on the server device from a common management device connected to the network that manages the state of the server device or a plurality of the server devices. Of the CPU assigned to the virtual server and the communication means of the virtual server For Les, the case of CPU used to occupy the virtual server is assigned a determination result the virtual server based on the usage of CPU occupying, the virtual server CPU and other virtual servers When sharing and using, it is a determination result based on the usage status of the CPU by all virtual servers sharing the CPU, and a determination is made as to whether or not a predetermined condition is determined to be loaded When receiving the result and the received determination result indicates that the CPU assigned to the virtual server and the communication means of the virtual server are not under load, the domain name, Allocation to the virtual server is possible in the storage unit that stores information that associates the IP address of the virtual server and whether or not allocation to the virtual server is possible. When certain information is written and the determination result indicates that the CPU assigned to the virtual server or the communication means of the virtual server is under load, the distribution to the virtual server is Writing the information that is impossible to the storage unit, receiving the information of the domain name of the access destination of the end user terminal, the IP address of the virtual server that corresponds to the domain name and can be distributed, A computer program that causes a computer to execute a step of reading from a storage unit and notifying.

According to the present invention, the access distribution device receives the status of the CPU and communication means of the virtual server, updates the information indicating whether the distribution to the virtual server is possible, and uses the information. Thus, before the end user terminal accesses the web, the IP address of the virtual server that provides the web and can be distributed is notified. Therefore, it is not necessary for another device to relay and distribute the access data of the virtual server from the end user terminal, and the load on the access distribution device and the network and the load on maintenance are light. In this way, load distribution between virtual servers can be appropriately distributed while suppressing the load on the entire system and the load on operations, without the processing capacity of devices other than the virtual server that actually provides the web service becoming a bottleneck. Can be done.
In addition, by changing the information update interval for whether or not the virtual server can be allocated by the access distribution device according to the user's access interval, even if the virtual server is stopped due to a failure or periodic maintenance of the virtual server, for example, It is possible to minimize the influence.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an overall configuration diagram of an access distribution system according to an embodiment of the present invention. In the figure, an access distribution device 1 and a cache server 2 are connected to a maintenance network 7 and an end user network 8. Furthermore, a maintenance monitoring device 3, a master server 5 and a log server 6 are connected to the maintenance network 7, and an end user terminal 4 is connected to the end user network 8. The maintenance network 7 and the end user network 8 are, for example, IP networks. In the figure, only one cache server 2 and one end user terminal 4 are shown, but a plurality of cache servers 2 and end user terminals 4 may exist.

  The cache server 2 is a hardware main body of the real server and operates as a plurality of virtual server computers. The common management unit 27 of the cache server 2 manages the entire cache server 2 and uses a virtual server computer realized in the cache server 2 as a virtual server 28.

  The resource pool 23 is a virtual space in which various resources such as an OS (Operating System) in the common management area 20, a CPU (Central Processing Unit) used by the virtual OS environment 24, and a memory are secured. The resource allocation to each virtual OS environment 24 is dynamically performed by the OS in the common management area 20 according to the CPU load or the like, but may be fixedly allocated.

The virtual OS environment 24 is an execution environment of the virtual server 28 and operates using various resources such as CPU and memory in the resource pool 23 assigned by the OS in the common management area 20. The virtual OS executed in the virtual OS environment 24 occupies resources in advance in addition to resource sharing means for sharing resources with other virtual OSs (for example, virtual OS # 1 has 50% of the CPU operation rate). It is also possible to have resource occupying means that can be set to be exclusively and exclusively reserved and not used by other virtual OSs # 2 to #n. Each virtual OS environment 24 executes a process 25, but can access only its own process 25 and cannot access processes 25 of other virtual OS environments 24. The process 25 includes, for example, web access for downloading a file to the end user terminal 4, Disk I / O, and the like. The NIC 26 is hardware for performing communication with the end user terminal 4 via the end user network 8, and is provided for each virtual server 28. Each NIC 26 has a different IP address, and various settings such as a routing table and a filtering rule and reference of the information can be performed for each NIC 26. As a result, the network can be virtualized. Compared with the case where a plurality of virtual servers 28 share the IP layer and use one NIC, each virtual server 28 has the performance of the NIC 26 provided by itself. It can be fully utilized.
Here, the cache server 2 realizes virtual servers 28-1 to 28-3 as a plurality of virtual servers 28, and the virtual OS environment 24 corresponding to the virtual servers 28-i (i = 1 to 3), The process 25 and the NIC 26 are described as a virtual OS environment 24-i, a process 25-i, and a NIC 26-i, respectively.

  The common management area 20 provides an execution environment for the status response program and the resource status monitoring program. That is, by operating these programs on the OS of the common management area 20, the state response unit 21 and the resource state monitoring unit 22 in the common management unit 27 are realized. The status response unit 21 receives the status inquiry of the virtual server from the access distribution device 1, and returns a response according to the status of the virtual OS environment 24, the resource pool 23, and the NIC 26. The resource state monitoring unit 22 periodically collects the state of the CPU and NIC 26 of each virtual OS environment 24 and notifies the collected data in response to a request from the state response unit 21.

  As described above, in the cache server 2, the common management unit 27 is realized by the common management area 20 and the resources in the resource pool 23 provided for the common management area 20, and the virtual server 28-i This is realized by the environment 24-i, the NIC 26-i, and resources in the resource pool 23 allocated to the virtual OS environment 24-i.

  The access distribution device 1 includes an update unit 11, a storage unit 12, and a notification unit 13. The storage unit 12 has a fully qualified domain name (FQDN), an IP address of the virtual server 28 that provides the web service of the FQDN, and the virtual server 28 having the IP address can provide the current web service. The distribution information indicating the information associating with the state of whether or not is stored. The update unit 11 inquires of the cache server 2 about the status of the virtual server 28 and updates the information in the storage unit 12 according to the response. Further, the update unit 11 transmits a failure notification message to the maintenance monitoring device 3 as necessary. The notification unit 13 receives a DNS (Domain Name System) query from the end user terminal 4 and returns the IP address of the accessible virtual server 28 obtained by referring to the information in the storage unit 12.

  The maintenance monitoring device 3 is a device for maintaining and monitoring the entire system including the access distribution device 1 and the cache server 2. The end user terminal 4 is a computer terminal such as a personal computer or a mobile phone, for example, and transmits the access destination FQDN to the cache server 2 and accesses the virtual server 28 of the cache server 2 using the returned IP address. . The master server 5 stores download file master data provided as a web service by the virtual server 28 of the cache server 2, and distributes the download file to the cache server 2. The log server 6 receives and stores an access log from the end user terminal 4 in each virtual server 28 of the cache server 2 and totals the access logs.

  FIG. 2 is a diagram showing an outline of the operation of the access distribution system shown in FIG. First, the update unit 11 of the access distribution device 1 transmits a status inquiry of the virtual server 28 to the cache server 2 via the maintenance network 7 by SNMP (Simple Network Management Protocol) (step S101). When the status response unit 21 of the cache server 2 receives the status query, the status response unit 21 acquires the CPU resource status of the virtual server 28 and the throughput of the NIC 26 from the resource status monitoring unit 22 (step S102), and the virtual server 28 is acquired from the acquired data. Is determined (step S103). When the operation state of the virtual server 28 is not normal and the alarm needs to be transferred, the state response unit 21 transfers the alarm to the maintenance monitoring device 3 (step S104). The maintenance monitoring device 3 notifies the maintenance person that the operation state is not normal, for example, by displaying the received alarm on the screen. The state response unit 21 returns the determination result of the state of the virtual server 28 to the access distribution device 1 (step S105). The update unit 11 of the access distribution device 1 receives the response from the status response unit 21 of the cache server 2 and receives the determination result of the status of the virtual server 28 to determine whether the virtual server 28 can provide the web service. Based on the determination, the web service provision availability information in the distribution information stored in the storage unit 12 is updated. The access distribution device 1 and the cache server 2 periodically repeat steps S101 to S105 for all virtual servers 28.

  When the end user terminal 4 accesses the web, the end user terminal 4 notifies the access sorting apparatus 1 of the access destination FQDN (step S201). The notification unit 13 of the access distribution device 1 refers to the distribution information in the storage unit 12, reads the IP address of the accessible virtual server 28 corresponding to the received FQDN, and returns it to the end user terminal 4. (Step S202). The end user terminal 4 transmits a web service request to the virtual server 28 of the cache server 2 with the received IP address as the destination. The virtual server 28 of the cache server 2 that has received the access provides the web service such as the requested file download to the end user terminal 4.

  FIG. 3 is a diagram showing a detailed processing procedure of the status inquiry shown in steps S101 to S105 of the access distribution system shown in FIG.

  The update unit 11 of the access distribution device 1 transmits a status inquiry of the virtual server 28 by SNMP to the cache server 2 via the maintenance network 7 every predetermined time (steps S301 and S302). Here, the state of one virtual server 28 is inquired by a single inquiry, but the state of a plurality or all of the virtual servers 28 may be inquired by a single inquiry.

  When the status response unit 21 of the cache server 2 receives the status inquiry about the virtual server 28-i, it first determines whether or not the virtual OS environment 24-i is activated (step S303). When it is determined that the virtual OS environment 24-i is activated (step S303: YES), the state response unit 21 determines whether the NIC 26-i included in the virtual server 28-i is activated (step S303: YES). Step S304). When it is determined that the NIC 26-i is activated (step S306: YES), the status response unit 21 subsequently determines whether the resource status monitoring program is activated (step S305). If it is determined that the resource status monitoring program is activated (step S305: YES), the status response unit 21 notifies the resource status monitoring unit 22 of information specifying the virtual server 28-i and a data request (step S30). S306). The resource status monitoring unit 22 of the cache server 2 periodically acquires data on the CPU resource status and the throughput of the NIC 26 for each of the virtual servers 28 and stores the data in a storage unit such as a memory. The CPU 28 returns the CPU resource status of the virtual server 28-i and the throughput of the NIC 26-i acquired in step S307.

  The state response unit 21 determines whether the acquired throughput of the NIC 26-i is equal to or less than a predetermined threshold value for determining that the load is high (step S308). When it is determined that the throughput of the NIC 26-i is equal to or less than the threshold (step S308: YES), the state response unit 21 then has a high load on the usage rate of the CPU resources allocated to the virtual OS environment 24-i. It is determined whether it is below a predetermined threshold for determining (step S309). When it is determined that the usage rate of the CPU resource allocated to the virtual OS environment 24-i is equal to or less than a predetermined threshold (step S309: YES), the state response unit 21 sets return code 0 to state response transmission. It is set (step S310) and returned to the access distribution device 1 (steps S311 and S312).

  When it is determined that the throughput of the NIC 26-i is greater than the threshold (step S308: NO), the state response unit 21 sets the return code 1 as a state response (step S313) and returns it to the access distribution device 1. (Steps S311, S312). If it is determined that the usage rate of the CPU resource is larger than a predetermined threshold (step S309: NO), the state response unit 21 sets the return code 2 as the state response (step S314), and the access distribution is performed. It returns to the apparatus 1 (steps S311 and S312).

If it is determined that the virtual OS environment 24-i has not been activated (step S303: NO), the state response unit 21 sends information specifying the virtual OS environment 24-i to the maintenance monitoring device 3 and the virtual OS The return code 4 indicating that it is not activated is transferred as an alarm (steps S315 and S316), and the status response in which the return code 4 is set is returned to the access distribution device 1 (steps S311 and S312).
When it is determined that the NIC 26-i has not been activated (step S304: NO), the state response unit 21 determines that the NIC is not activated and information for identifying the virtual server 28-i to the maintenance monitoring device 3. Is returned as an alarm (steps S317 and S318), and a status response in which the return code 3 is set is returned to the access distribution device 1 (steps S311 and S312).
When it is determined that the resource status monitoring unit 22 has not been activated (step S305: NO), the status response unit 21 determines that the information that identifies the virtual server 28-i to the maintenance monitoring device 3 and the resource status monitoring program A return code 5 indicating that it has not been activated is transferred as an alarm (steps S319 and S329). A status response in which the return code 4 is set is returned to the access distribution device 1 (steps S311 and S312).

  When receiving the status of the virtual server 28-i by the response from the status response unit 21 of the cache server 2, the update unit 11 of the access distribution device 1 determines whether the return code is 0 (step S321). If the return code is 0 (step S321: “0”), it is determined that continuous operation is possible as a distribution target, and the distribution information in the storage unit 12 is associated with the address of the virtual server 28-i. The information indicating that allocation is possible is written (step S322). On the other hand, if the return code is other than 0 (step S321: “other than 0”), it is determined that the virtual server 28-i should be excluded from the distribution target, and the virtual server 28 is included in the distribution information in the storage unit 12. Information indicating that distribution is impossible is written in association with the address of -i (step S323).

  The access distribution device 1 and the cache server 2 periodically repeat the process of FIG. 3 for all the virtual servers 28.

When the virtual OS executed in the virtual OS environment 24 of the cache server 2 has resource sharing means, if all resources are used up in one virtual OS environment 24 in the cache server 2, the cache server 2 Another virtual OS environment 24 has a problem that a new resource cannot be acquired. Therefore, access is not distributed to the cache server 2 that has used up resources in this way, and access is distributed to other cache servers 2.
Therefore, in step S309 of FIG. 3 described above, the state response unit 21 determines whether the OS used in the virtual OS environment has resource sharing means or resource occupying means, and has resource occupying means. In such a case, the process shown in FIG. 3 is performed.

On the other hand, when the resource sharing means is included, even if the resource load of the virtual OS in the virtual server 28-i inquired from the access distribution device 1 is low, the other virtual OS sharing the same resource When the resource load at is high, it is determined that the load is applied. That is, when the CPU load in the entire cache server 2 is larger than a predetermined threshold, a return code indicating that fact is set in the status response and returned to the access distribution device 1.
The access distribution device 1 stores information on the virtual server 28 realized by each cache server 2 in the storage unit 12 and receives a return code indicating that the entire cache server 2 is under load. Then, all the virtual servers 28 in the cache server 2 to which the status inquiry target virtual server 28-i belongs are specified, and information indicating that distribution is not possible for the specified virtual server 28 is written in the distribution information.

In the above description, it is determined whether the load is applied to the virtual server 28-i based on the state of the CPU and the NIC 26. However, the load on the virtual server 28-i may be determined as follows.
(1) In the virtual OS environment 24-i, the number of requests from the end user terminal 4 and the number of sessions are periodically monitored every second or the like, and the load is determined based on whether the number exceeds a predetermined threshold.
(2) The Disk I / O included in the virtual OS environment 24-i is monitored, and the load is determined based on the monitoring result.
(3) The number of processes in the virtual OS environment 24-i is monitored, and the load is determined based on the monitoring result.
If it is determined that the load is high as described above, a return code (other than 0) indicating that fact is set and returned to the access distribution device 1 so that access is not distributed to the virtual server 28-i. Limit connections.

FIG. 5 is a diagram showing distribution information held by the storage unit 12 of the access distribution device 1 shown in FIG.
As shown in the figure, the distribution information includes the FQDN, the IP address of the virtual server 28 having the FQDN, whether the virtual server 28 is activated, whether the CPU state is OK, NIC Information indicating whether or not the state is OK is held.
When the update unit 11 of the access distribution device 1 receives a return code 0 as a result of a status inquiry of a certain virtual server 28-i, the update unit 11 turns ON the distribution information corresponding to the virtual server 28-i. When the CPU state and the NIC state are set to OK and the return code 1 is received, the activation state is set to ON. When the return code 2 is received, the activation state is set to ON. When the return code 2 is received, the activation state is set to ON. Is set to OK in the NIC state, and when the return code 3 or 4 is received, the activation state is set to OFF.
As described above, the distribution information can be easily updated by using a common return code in which the same value is set for all the virtual servers 28 in the same state.

FIG. 4 is a diagram showing a detailed processing procedure of the status inquiry shown in steps S106 to S107 of the access distribution system shown in FIG.
The end user terminal 4 transmits an FQDN inquiry in which the FQDN of the web service to be accessed is set to the access distribution device 1 (steps S401 and S402). The notification unit 13 of the access distribution device 1 refers to the distribution information in the storage unit 12 and corresponds to the received FQDN, the activation state is ON, and the CPU state and the NIC state are OK. Identify possible virtual servers 28. The notification unit 13 acquires the IP address of the identified virtual server 28 from the distribution information when there is one identified accessible virtual server 28, and when there are a plurality of identified accessible virtual servers 28, from among them One is selected according to a predetermined standard, and the IP address of the selected virtual server 28 is acquired from the distribution information (step S403). When one is selected from the accessible virtual servers 28, for example, the server with the oldest time selected as the last access destination can be selected, or can be selected randomly.

  The notification unit 13 of the access distribution device 1 notifies the end user terminal 4 of the acquired IP address of the virtual server 28 (steps S404 and S405). When receiving the IP address from the access distribution device 1 (step S406), the end user terminal 4 accesses the virtual server 28 using the IP address as a destination (step S407). When the virtual server 28 of the cache server 2 receives an access from the end user terminal 4 via the end user network 8 by the NIC 26, the virtual server 28 provides a web service such as file download by the process 25.

  The data downloaded to the end user terminal 4 by the process 25 is distributed from the master server 5. Specifically, the master server 5 distributes the download target file to the cache server 2. The common management unit 27 of the cache server 2 temporarily stores the file distributed to the memory of the common management area 20. When a command for reading this file is input to the virtual OS environment 24, the virtual OS environment 24 reads the instructed file stored in the memory of the common management area 20, and the virtual OS environment 24 Write to the memory allocated to. Thereafter, a file distributed from the master server 5 can be downloaded to the end user terminal 4 by the process 25 executed by the virtual OS environment 24. A command for reading a file into the virtual OS environment 24 may be input by a maintenance person using an input unit, and the file distributed from the master server 5 is stored in the memory of the common management area 20 in the common management unit 27. When this is detected, the command may be executed.

  Access log data from the end user terminal 4 in each virtual server 28 of the cache server 2 is periodically transmitted to the log server 6 by the common management unit 27. The access log data includes information such as the identification information of the virtual server 28, the time when the virtual server 28 received access from the end user terminal 4, the address of the end user terminal 4, the process 25 executed by the access, and the like. It is. The log server 6 stores the received access log data in its own storage unit, and creates various statistical data using the access log data.

  In the above, the access distribution device 1 directly receives the FQDN inquiry from the end user terminal 4, but a DNS server is installed on the end user network 8, and the end user terminal 4 receives the IP of the access destination web service. In order to inquire about the address, the FQDN may be transmitted to the DNS server, and the DNS server may acquire the IP address corresponding to the FQDN of the access destination from the access distribution apparatus 1 and notify the end user terminal 4 of the IP address.

  Here, a case where the end user terminal 4 transmits an FQDN inquiry to a DNS server installed on a different network from the end user network, and the end user terminal 4 and the access distribution device 1 do not directly communicate with each other will be described. To do. For example, although the access distribution device 1 performs communication by IPv6, when the end user terminal 4 accesses the DNS server for name resolution, only the communication by IPv4 can be performed, or the end user terminal 4 It is assumed that the user must first connect to the external network before connecting to the end user network 8.

  FIG. 6 shows the overall configuration of the access distribution system when the end user terminal 4 performs name resolution by a DNS server installed in an external network. The same components as those in FIG. Is omitted. In FIG. 6, the end user terminal 4 is connected to the end user network 8 and the network 9, and a DNS (Domain Name System) server 100 connected to the network 9 is the primary DNS of the end user terminal 4. Here, the end user network 8 is described as an IPv6 network, and the network 9 is described as an IPv4 network. However, the present invention is also applicable to the case where the end user network 8 and the network 9 use the same communication protocol.

  In the configuration shown in FIG. 6, the end user terminal 4 transmits an FQDN query to the DNS server 100 to perform name resolution. The DNS server 100 has a general DNS function that has been used for general purposes. The status of each virtual server 28 that the access distribution apparatus 1 manages cannot be managed. For this reason, the cache server 2 is also allocated to the virtual server 28 that cannot be used due to a high load or that has failed. In order to solve this, for example, delegation and zone transfer can be considered, but in the case of delegation, since it is necessary to assign an IPv4 global address to the access distribution device 1 as well, the scale of the system increases. It will be difficult to realize. On the other hand, zone transfer is to transfer zone information of a corresponding domain, that is, information in which a domain and an IP address are associated with each other. In the access distribution device 1, a function realized by a conventional general DNS is provided. Therefore, the state of the virtual server 28 cannot be reflected even if the conventional zone transfer is applied as it is. Therefore, the access distribution device 1 requests the update of the zone information held by the DNS server 100 according to the state of the virtual server 28.

  The access distribution device 1 shown in FIG. 6 shows the configuration of the access distribution device 1 shown in FIG. 1 in more detail, and an update notification unit 15 is added. The update notification unit 15 notifies the DNS server 100 of the update contents of the zone information. The communication unit 16 is also provided in the access distribution device 1 shown in FIG. 1 and transmits and receives data via the maintenance network 7 and the end user network 8. 9 may be used to transmit and receive data via a dedicated line. The name resolution unit 14 included in the notification unit 13 has the same function as the name resolution function realized in the conventional DNS server.

  The DNS server 100 includes a storage unit 101, a communication unit 102, an update unit 103, and a name resolution unit 104. The storage unit 101 stores zone information. The communication unit 102 performs data transmission / reception via the network 9, but the access distribution device 1 may perform data transmission / reception via a dedicated line. The update unit 103 updates the zone information stored in the storage unit 101 based on the update contents of the zone information received from the access distribution device 1. The name resolution unit 104 has the same function as the name resolution unit 14 of the access distribution device 1 and refers to the zone information to notify the end user terminal 4 of the IP address of the virtual server 28.

  FIG. 7 is a diagram illustrating an example of distribution information stored in the storage unit 12 of the access distribution device 1 illustrated in FIG. The distribution information of this embodiment shown in the figure has the same data configuration as the distribution information shown in FIG. 5, but an IPv6 IP address is set as the IP address.

  FIG. 8 is a diagram illustrating examples of zone information stored in the storage unit 12 of the access distribution device 1 and the storage unit 101 of the DNS server 100 illustrated in FIG. 6. In the figure, zone information stores a domain name and information of one or more IP addresses corresponding to the domain name, and is described by, for example, a text file. In this zone information, only the IP address of the virtual server 28 that can be currently distributed is set.

FIG. 9 is a diagram showing a processing flow of the access distribution system shown in FIG.
When the name resolution unit 104 of the DNS server 100 receives from the end user terminal 4 an FQDN query in which the FQDN of the web service to be accessed is set, the IP address corresponding to the domain name included in the received FQDN is obtained from the zone information. Reading and returning. When a plurality of IP addresses are registered corresponding to the identified domain name, one of the plurality of IP addresses having the oldest time selected as the last access destination is selected, or 1 is randomly selected. Or select one according to a predetermined rule such as round robin and send it back. For example, in the case of the zone information shown in FIG. 7, since the domain name included in the FQDN is “xxxxx.xxx.jp”, the IP address “XXXX: XXXX :: XXX2” of the virtual server virtual server # 2 One of the IP addresses “XXXX: XXXX :: XXX3” of the server # 3 is selected and returned.

  In the figure, the update unit 11 of the access distribution device 1 performs the same processing as steps S301 and S302 in FIG. 3, and sends the virtual server 28-i to the cache server 2 via the maintenance network 7 every predetermined time. Is sent (steps S501 and S502). The cache server 2 that has received the status inquiry performs the same processing as steps S303 to S312 of FIG. 3 (steps S503 and S504). As a result, the cache server 2 performs the virtual OS activation, NIC activation, resource state management program activation, NIC bandwidth, and CPU resource check, and returns indicating the state of the virtual server 28-i obtained as a result of these checks. The code is set in the status response and returned to the access distribution device 1. The update unit 11 of the access distribution device 1 determines whether or not the received return code is 0, similarly to step S321 in FIG. 3 (step S505).

  When the received return code is 0 (step S505: “0”), the update unit 11 refers to the distribution information in the storage unit 12 and the status of the virtual server 28-i indicates that distribution is possible. That is, it is determined whether activation “OK”, CPU “OK”, and NIC “OK” are set. Then, when distribution permission is not currently set, the updating unit 11 reads the domain name and IP address corresponding to the virtual server 28-i from the distribution information, and stores them in association with the read domain name. The information on the IP address of the virtual server 28-i is added to the zone information in the unit 12. Further, the update unit 11 associates with the virtual server 28-i and indicates information indicating that the distribution information in the storage unit 12 can be distributed, that is, activation “OK”, CPU “OK”, and NIC “OK”. Is written (step S506).

  On the other hand, when the received return code is other than 0 (step S505: “other than 0”), the update unit 11 refers to the distribution information in the storage unit 12 and the status of the virtual server 28-i indicates It is determined whether or not the division is indicated, that is, whether the activation “OK”, the CPU “OK”, and the NIC “OK” are set. Then, when distribution is possible, the update unit 11 reads the domain name and IP address corresponding to the virtual server 28-i from the distribution information, and stores the domain name and the IP address corresponding to the read domain name. 12, the IP address information of the virtual server 28-i is deleted from the IP address information of the virtual server 28 set in the zone information in 12. Further, the updating unit 11 writes information on the state corresponding to the received return code in the distribution information in the storage unit 12 in association with the virtual server 28-i (step S507).

  When the zone information is updated in step S506 or S507 (step S508: YES), the update notification unit 15 sets the updated zone information, that is, the domain name that is the update target from the zone information, and the domain name. Information of all the associated IP addresses is read and notified to the DNS server 100 as update information (steps S509 and S510). For example, DNS Notify can be used for notification of update information. In the update unit 103 of the DNS server 100, the IP address information set in the zone information in the storage unit 101 corresponding to the domain name set in the received update information is set in the update information. The IP address information is rewritten (step S511).

For example, the zone information stored in the storage unit 12 of the access distribution device 1 and the zone information stored in the storage unit 101 of the DNS server 100 include the domain name “xxxxx.xxx.jp” as shown in FIG. Corresponding to the IP addresses “XXXX: XXXX :: XXX2” and “XXXX: XXXX :: XXX3” of the virtual servers 28-2 and 28-3 are set, and the storage unit 12 of the access distribution device 1 stores them. As shown in FIG. 7, it is assumed that the virtual server 28-1 is unassignable and the virtual servers 28-2 and 28-3 are in a state where assignment is possible, as shown in FIG.
At this time, since the virtual server 28-1 that cannot be distributed has returned to the normal state, in step S504, in response to the status inquiry of the virtual server 28-1, the return code from the cache server 2 to the access distribution device 1 is returned. Assume that 0 is returned. Since it is currently set in the distribution information that the virtual server 28-1 cannot be distributed, the update unit 11 of the access distribution device 1 determines the IP address of the virtual server 28-1 from the distribution information. “XXXX: XXXX :: XXX1” and the domain name “xxxxx.xxx.jp” are read out, and the zone information in the storage unit 12 is associated with the domain name “xxxxx.xxx.jp” and the virtual server 28-1. Add the IP address “XXXX: XXXX :: XXX1”. That is, the zone information in the storage unit 12 corresponds to the domain name “xxxxx.xxx.jp”, the IP addresses “XXXX: XXXX :: XXX1” of the virtual servers 28-1, 28-2, 28-3, “XXXX: XXXX :: XXX2” and “XXXX: XXXX :: XXX3” are described. Further, the update unit 11 rewrites the distribution information to the effect that the virtual server 28-1 can be distributed.

  The update notification unit 15 of the access distribution device 1 uses the domain information “xxxxx.xxx.jp” to be updated from the zone information in the storage unit 12 and all virtual servers associated with the domain name. The IP address information of 28-1, 28-2 and 28-3 is read out and notified to the DNS server 100 as update information. When the update unit 103 of the DNS server 100 receives the update information from the access distribution device 1, the update unit 103 sets the zone information in the storage unit 101 in association with the domain name “xxxxx.xxx.jp” notified by the update information. The IP addresses of the virtual servers 28-1, 28-2 that have been notified of the virtual servers 28-1, 28-2, 28-3 notified by the update information “XXXX: XXXX :: XXX1”, “ Rewrite to "XXXX: XXXX :: XXX2", "XXXX: XXXX :: XXX3". Thereafter, when the name resolution unit 104 of the DNS server 100 receives the FQDN from the end user terminal 4 and the domain name included in the FQDN is “xxxxx.xxx.jp”, it is associated with the domain name. One of the IP addresses of the virtual servers 28-1, 28-2, 28-3 set in the zone information is selected and returned.

  Thereafter, it is assumed that the virtual server 28-2 that can be distributed is overloaded, and therefore a return code other than 0 is returned from the cache server 2 in response to the status inquiry of the virtual server 28-2. Since it is currently set in the distribution information that the virtual server 28-2 can be distributed, the update unit 11 of the access distribution device 1 determines the IP address of the virtual server 28-2 from the distribution information. Read “XXXX: XXXX :: XXX2” and domain name “xxxxx.xxx.jp”. The update unit 11 uses the zone information stored in the storage unit 12 and the IP addresses of the virtual servers 28-1, 28-2, and 28-3 that are currently set in association with the domain name “xxxxx.xxx.jp”. Among them, the IP address of the virtual server 28-2 is deleted. That is, the zone information stored in the storage unit 12 corresponds to the domain name “xxxxx.xxx.jp” and the IP addresses “XXXX: XXXX :: XXX1”, “XXXX” of the virtual servers 28-1 and 28-3. : XXXX :: XXX3 ”is described. Further, the update unit 11 rewrites the distribution information to the effect that the virtual server 28-2 cannot distribute.

  The update notification unit 15 of the access distribution device 1 uses the domain information “xxxxx.xxx.jp” to be updated from the zone information in the storage unit 12 and all virtual servers associated with the domain name. The IP address information of 28-1 and 28-3 is read out and notified to the DNS server 100 as update information. When the update unit 103 of the DNS server 100 receives the update information from the access distribution device 1, it is described in the zone information in the storage unit 101 in association with the domain name “xxxxx.xxx.jp” notified by the update information. The IP addresses of the virtual servers 28-1, 28-2, and 28-3 that have been notified of the IP addresses “XXXX: XXXX :: XXX1”, “ To "XXXX: XXXX :: XXX3". Thereafter, when the name resolution unit 104 of the DNS server 100 receives the FQDN from the end user terminal 4 and the domain name included in the FQDN is “xxxxx.xxx.jp”, it is associated with the domain name. One of the IP addresses of the virtual servers 28-1 and 28-3 set in the zone information is selected and returned.

  In the above, the update information includes the domain name to be updated and all the IP addresses read from the zone information in the storage unit 12 of the access distribution device 1 corresponding to the domain name, that is, The information of the IP address that can be allocated is set, but the domain name that has been updated and the virtual server 28-i that has been added corresponding to the domain name, that is, that has been allocated. And the IP address of the virtual server 28-i that has been deleted corresponding to the domain name to be updated, that is, the virtual server 28-i that has become unallocated, and Information indicating that distribution is impossible may be set. When the update unit 103 of the DNS server 100 receives the update information from the access distribution device 1 and the distribution information is set to allow distribution, the storage unit 101 associates it with the domain name notified by the update information. The IP address of the virtual server 28-i notified by the update information is added to the IP address of the virtual server 28 described in the zone information. Alternatively, when the distribution information is set to “unassignable”, the IP address of the virtual server 28 described in the zone information in the storage unit 101 is associated with the domain name notified by the update information. The IP address of the virtual server 28-i notified by the update information is deleted.

  In addition, in the update information, the domain name to be updated, the IP addresses of all virtual servers 28 corresponding to the domain name read from the updated distribution information, and the virtual server 28 can be distributed. It is also possible to set information on whether or not there is. The update unit 103 of the DNS server 100 associates the domain name notified by the update information with the IP address of the virtual server 28 in which distribution is set in the received update information in the zone information in the storage unit 101. Is added to the update information received from the IP address of the virtual server 28 set in the zone information in the storage unit 101 in association with the domain name notified by the update information. The IP address of the existing virtual server 28 is deleted.

  In addition, in the update information, the domain name to be updated, the IP addresses of all virtual servers 28 corresponding to the domain name read from the updated distribution information, and the virtual server 28 can be distributed. When information indicating whether or not there is set is set, the update unit 103 of the DNS server 100 may register the update information in the storage unit 101. When the name resolution unit 104 of the DNS server 100 receives the FQDN from the end user terminal 4, the name resolution unit 104 reads the IP address of the virtual server 28 corresponding to the received FQDN from the zone information in the storage unit 101. Information on whether or not the read IP address can be distributed is read from the update information stored in 101. Then, the name resolution unit 104 selects one of the IP addresses that can be assigned from the IP addresses of the virtual servers read from the zone information corresponding to the received FQDN, and returns the selected IP address to the end user terminal 4.

  As described above, when the end user terminal 4 cannot communicate directly with the access distribution device 1, for example, when the access distribution device 1 and the end user terminal 4 use different protocols, The state of the CPU and NIC of the virtual server acquired from the cache server 2 by the access distribution device 1 even if it must first connect to the DNS of the external network before connecting to the end user network 8 It is possible to appropriately distribute the load among the virtual servers by reflecting the distribution enabled / disabled state based on the. In addition, by notifying the update information from the access distribution device to the DNS server by an existing message such as DNS Notify, it can be realized without changing the existing domain server.

In addition, according to the said embodiment, although each cache server 2 has the common management part 27 provided with the state response part 21 and the resource state monitoring part 22, the state response part 21 and resource state are provided in each cache server 2. A common management server provided with a common management server that is connected to the plurality of cache servers 2 via the maintenance network 7 without providing the monitoring unit 22, and includes the status response unit 21 and the resource status monitoring unit 22 in the common management server 27 may be provided in a centralized manner, and a plurality of cache servers 2 may be managed in a centralized manner.
In this case, the update unit 11 of the access distribution device 1 transmits a status query of the virtual server 28 via SNMP to the common management server via the maintenance network 7 every predetermined time, and the common management server sends the query. The cache server 2 that implements the received virtual server 28 is accessed, and the above-described processing of FIG. 3 is performed.

  The common management server holds information that centrally lists all the virtual servers 28 (virtual OS environments 24) of the subordinate cache servers 2, and determines the higher priority as the load is lower. The priority distribution information may be added and notified to the access distribution device 1. The load on the virtual server 28 is determined by the usage status of the CPU and NIC in the virtual server 28 (virtual OS environment 24), the number of requests from the end user terminal 4, the number of sessions, the usage status of the Disk I / O, the number of processes, and the like. can do. Note that the load may be statistically determined from these past load conditions. As a result, it is possible to notify the access distribution device 1 of a predetermined number of virtual servers 28 having a high priority, and the notification unit 13 of the access distribution device 1 has a virtual network with a high priority indicated by the received list. Distribution to the server 28 is possible. For example, when there are a plurality of identified accessible virtual servers 28 in step S403 in FIG. 4, the virtual server 28 having a higher priority is selected from among them, and the IP address of the selected virtual server 28 is obtained from the distribution information. Then, the end user terminal 4 is notified.

According to this embodiment, the access distribution device periodically inquires the cache server, receives a return code indicating the status of the CPU and NIC of the virtual server, and can distribute to the virtual server. The information indicating whether or not it is impossible is updated, and before the end user terminal accesses the web, the IP address of the allocable virtual server that provides the web is notified using the information. Therefore, it is not necessary for other devices to relay and distribute access data from the end user terminal to the virtual server, and the load on the access distribution device and the network and the load on maintenance are light. In this way, the processing capacity of devices other than the virtual server that actually provides the web service does not become a bottleneck, and the load on the entire system and the load on the operation are suppressed, while the CPU and NIC of the latest virtual server are suppressed. Reflecting the load state, it is possible to appropriately distribute the load among the virtual servers.
In addition, by changing the information update interval for whether or not the virtual server can be allocated by the access distribution device according to the user's access interval, even if the virtual server is stopped due to a failure or periodic maintenance of the virtual server, for example, It is possible to minimize the influence.

  The access distribution device 1, the cache server 2, the maintenance monitoring device 3, the end user terminal 4, the master server 5, the log server 6, and the common management server have a computer system therein. The operation processes of the access distribution device 1, the cache server 2, the maintenance monitoring device 3, the end user terminal 4, the master server 5, the log server 6, and the common management server described above can be read by a computer in the form of a program. When the computer system reads and executes this program, the above processing is performed. Here, the computer system includes a CPU, various memories, an OS, and hardware such as peripheral devices.

Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory in a computer system serving as a server or a client in that case, and a program that holds a program for a certain period of time are also included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

1 is a diagram showing an overall configuration of an access distribution system according to an embodiment of the present invention. It is a figure which shows the operation | movement outline | summary of the access distribution system by the embodiment. It is a figure which shows the process sequence of the status inquiry of the access distribution system by the embodiment. It is a figure which shows the processing procedure of the DNS inquiry of the access distribution system by the embodiment. It is a figure which shows the structural example of the distribution information by the embodiment. It is a figure which shows the whole structure of an access distribution system in case an end user terminal uses the DNS server installed in the network of another network. It is a figure which shows the structural example of the distribution information used for the access distribution system shown in FIG. It is a figure which shows the structural example of the zone information used for the access distribution system shown in FIG. It is a figure which shows the process sequence of the access distribution system shown in FIG. It is a figure for demonstrating the resource allocation of the virtual server by a prior art.

Explanation of symbols

1 ... Access distribution device 2 ... Cache server (server device)
DESCRIPTION OF SYMBOLS 3 ... Maintenance monitoring apparatus 4 ... End user terminal 5 ... Master server 6 ... Log server 7 ... Maintenance network 8 ... Network for end users 9 ... Network 11 ... Update part 12 ... Memory | storage part 13 ... Notification part 14 ... Name resolution part 15 ... Update notification unit 16 ... communication unit 21 ... state response unit (state notification unit)
22 ... Resource status monitoring unit 23 ... Resource pool 24-1-24-3 ... Virtual server unit 25-1-25-3 ... Process (distribution unit)
26-1 to 26-3... NIC (communication means)
27 ... Common management unit (reading unit, log notification unit)
28-1 to 28-3 ... virtual server 100 ... DNS server (domain name system server)
101 ... storage unit (domain name system storage unit)
102: Communication unit 103 ... Update unit (domain name system update unit)
104 ... Name resolution department

Claims (20)

A server device that operates as a plurality of virtual servers and has communication means for communicating with end user terminals for each virtual server, and a virtual server that is an allocation destination of end user terminals are identified, and the virtual server An access distribution device that notifies the IP address of the server and an end user terminal that accesses the virtual server using the IP address of the virtual server that is the distribution destination notified from the access distribution device via the network An access distribution system that is connected,
The server device
A resource status monitoring unit that acquires the status of the CPU assigned to the virtual server operating in the server device and the status of the communication means of the virtual server;
Predetermined conditions for determining that a load is applied to each of the state of the CPU assigned to the virtual server and the state of the communication means of the virtual server, acquired by the resource state monitoring unit for each virtual server And a state notification unit that notifies the access distribution device of the determination result,
The access distribution device
A storage unit that stores information in which a domain name is associated with an IP address of a virtual server and whether or not distribution to the virtual server is possible;
When the determination result is received from the server device, and the determination result indicates that the CPU allocated to the virtual server and the communication means of the virtual server are not under load, Information that can be distributed to a virtual server is written in the storage unit, and the determination result is a state in which the CPU assigned to the virtual server or the communication means of the virtual server is under load. An update unit that writes information that cannot be distributed to the virtual server to the storage unit,
A notification unit that receives information on a domain name of an access destination of the end user terminal, reads an IP address of a virtual server corresponding to the domain name and that can be distributed from the storage unit, and notifies the information ;
The state notification unit, when a CPU to be used exclusively by the virtual server is assigned, determines a CPU state of whether a load is applied based on a usage state of the CPU occupied by the virtual server, When a virtual server shares a CPU with another virtual server and uses the CPU, the CPU determines whether the load is applied based on the usage status of the CPU by all the virtual servers sharing the CPU. access sorting system that. The update unit operates in the server device to which the virtual server belongs when the virtual server shares the CPU with another virtual server and the determination result indicates that the CPU is loaded. 2. The access distribution system according to claim 1 , wherein information that cannot be distributed to all virtual servers is written in the storage unit. The status notification unit notifies the access distribution device of a determination result of whether or not the virtual server is activated or whether or not the communication unit of the virtual server is activated, and the virtual server When it is determined that the virtual server communication unit is not started, or when it is determined that the communication unit of the virtual server is not started , a maintenance monitoring device that notifies the maintenance person that the operation state is not normal upon reception of the warning. against, the access sorting system according to any one of claims 1 or 2, characterized in that transmitting the alert. The access distribution system according to any one of claims 1 to 3 , wherein the status notification unit notifies the determination result by a code commonly used for the virtual server. The update unit periodically transmits a virtual server status query to the server device,
The status notification unit receives a status inquiry of the virtual server from the access distribution device, and acquires the status of the CPU assigned to the virtual server and the status of the communication means of the virtual server from the resource status monitoring unit. , Return the judgment result,
The access distribution system according to any one of claims 1 to 4 , wherein the access distribution system is provided. The server device
From the master server that stores the master data file to be provided to the end user terminal as a web service are connected via the network, receiving the file, and stores the received file in the storage means of the Common management area, A reading unit that stores the file stored in the storage unit of the common management area in the storage unit assigned to the virtual server when a command for reading the file into the virtual server is input;
A distribution unit that distributes the file stored in the storage unit allocated to the virtual server to an end user terminal that has accessed the virtual server;
The access distribution system according to any one of claims 1 to 5 , wherein The server apparatus claims 1 to 6, characterized in that it comprises a log notification unit for notifying an access log to the virtual servers running in the server device to the log server connected via the network The access distribution system according to any one of the items. A plurality of server devices that operate as a plurality of virtual servers and communicate with end user terminals for each virtual server, and identify a virtual server that is an allocation destination of end user terminals , Using the access distribution device that notifies the IP address of the virtual server, the common management device that manages the states of the plurality of server devices, and the IP address of the virtual server that is the distribution destination notified from the access distribution device An access distribution system in which an end user terminal that accesses the virtual server is connected via a network,
The common management device is:
A resource state monitoring unit that acquires a state of a CPU assigned to each virtual server operating in the plurality of server devices and a state of communication means of the virtual server;
Predetermined conditions for determining that a load is applied to each of the state of the CPU assigned to the virtual server and the state of the communication means of the virtual server, acquired by the resource state monitoring unit for each virtual server And a state notification unit for notifying the access distribution device of the determination result,
The access distribution device
A storage unit that stores information in which a domain name is associated with an IP address of a virtual server and whether or not distribution to the virtual server is possible;
When the determination result is received from the common management device, and the determination result indicates that the CPU assigned to the virtual server and the communication means of the virtual server are not under load, Information that can be distributed to the virtual server is written in the storage unit, and the determination result is in a state where a load is applied to the CPU assigned to the virtual server or the communication means of the virtual server. Indicates an update unit that writes information that cannot be distributed to the virtual server to the storage unit,
A notification unit that receives information on a domain name of an access destination of the end user terminal, reads an IP address of a virtual server corresponding to the domain name and that can be distributed from the storage unit, and notifies the information ;
The state notification unit, when a CPU to be used exclusively by the virtual server is assigned, determines a CPU state of whether a load is applied based on a usage state of the CPU occupied by the virtual server, When a virtual server shares a CPU with another virtual server and uses the CPU, the CPU determines whether the load is applied based on the usage status of the CPU by all the virtual servers sharing the CPU. access sorting system that. The common management device further includes priority notification means for determining a priority of access to the virtual server from a load state of the virtual server operating in the plurality of server devices and notifying the access distribution device. Have
The notification unit of the access distribution device reads out and notifies the IP address of a virtual server having a high priority among virtual servers corresponding to the domain name and capable of distribution,
The access distribution system according to claim 8 . A domain name system server connected to the end user terminal via another network;
The access distribution device
Set the domain name corresponding to the virtual server whose allocation information has been read, read from the storage unit, the IP address of the virtual server corresponding to the domain name, and the allocation change contents An update notification unit for notifying the domain name system server of the updated information,
The domain name system is:
A domain name system storage unit that stores information in which a domain name is associated with an IP address of a virtual server that can be distributed;
Information on the IP address of the virtual server that can be distributed, stored in the domain name system storage unit in association with the domain name set in the update information, received from the access distribution device A domain name system update unit that updates the content based on the change in availability of distribution set in the update information,
An address resolution unit that receives information on a domain name of an access destination of the end user terminal, and reads and notifies an IP address of a virtual server corresponding to the domain name from the domain name system storage unit;
The access distribution system according to any one of claims 1 to 9 , wherein The update notification unit of the access distribution device
The domain name corresponding to the virtual server that has been read from the storage unit and whose allocation permission information has been changed, and the IP addresses of all the virtual servers that can be allocated corresponding to the domain name are set. Notifying the domain name system server of update information,
The domain name system update unit of the domain name system includes:
Rewriting the IP address information stored in the domain name system storage unit in association with the domain name set in the received update information with the IP address information set in the update information,
The access distribution system according to claim 10 . The update notification unit of the access distribution device
The domain name corresponding to the virtual server that has been read from the storage unit and whose allocation permission information has been updated, the IP addresses of all the virtual servers corresponding to the domain name, and whether or not to distribute to the virtual server An update notification unit for notifying the domain name system server of update information in which information indicating
In the domain name system,
The domain name system storage unit stores information in which a domain name is associated with IP addresses of all virtual servers that use the domain name;
The domain name system update unit writes the update information received from the access distribution device to the domain name system storage unit,
The address resolution unit receives information on the domain name of the access destination of the end user terminal, corresponds to the domain name from the domain name system storage unit, and can be distributed according to the update information Read and notify the IP address of the indicated virtual server,
The access distribution system according to claim 10 . A server device that operates as a plurality of virtual servers and has communication means for communicating with end user terminals for each virtual server; an access distribution device that distributes access from end user terminals to the virtual servers; The server apparatus in the access distribution system in which an IP address of a virtual server that is a distribution destination notified from the access distribution apparatus is connected to an end user terminal that accesses the virtual server via a network. There,
A resource status monitoring unit that acquires the status of the CPU assigned to the virtual server operating in the server device and the status of the communication means of the virtual server;
Predetermined conditions for determining that a load is applied to each of the state of the CPU assigned to the virtual server and the state of the communication means of the virtual server, acquired by the resource state monitoring unit for each virtual server And a state notification unit for notifying the access distribution device of the determination result;
Equipped with a,
The state notification unit, when a CPU to be used exclusively by the virtual server is assigned, determines a CPU state of whether a load is applied based on a usage state of the CPU occupied by the virtual server, When a virtual server shares a CPU with another virtual server and uses the CPU, the CPU determines whether the load is applied based on the usage status of the CPU by all the virtual servers sharing the CPU. A server device characterized by that. A plurality of server devices that operate as a plurality of virtual servers and communicate with each virtual server for communicating with end user terminals, and an access distribution device that distributes access from the end user terminals to the virtual servers A common management device that manages the states of the plurality of server devices, and an end user terminal that accesses the virtual server using the IP address of the virtual server that is the distribution destination notified from the access distribution device. The common management device in an access distribution system connected via a network,
A resource state monitoring unit that acquires a state of a CPU assigned to each virtual server operating in the plurality of server devices and a state of communication means of the virtual server;
Predetermined conditions for determining that a load is applied to each of the state of the CPU assigned to the virtual server and the state of the communication means of the virtual server, acquired by the resource state monitoring unit for each virtual server And a state notification unit for notifying the access distribution device of the determination result;
Equipped with a,
The state notification unit, when a CPU to be used exclusively by the virtual server is assigned, determines a CPU state of whether a load is applied based on a usage state of the CPU occupied by the virtual server, When a virtual server shares a CPU with another virtual server and uses the CPU, the CPU determines whether the load is applied based on the usage status of the CPU by all the virtual servers sharing the CPU. A common management device characterized by that. A server device that operates as a plurality of virtual servers and has communication means for communicating with end user terminals for each virtual server; an access distribution device that distributes access from end user terminals to the virtual servers; The access distribution in an access distribution system in which an IP address of a distribution destination virtual server notified from the access distribution device is connected to an end user terminal that accesses the virtual server via a network. A device,
A storage unit that stores information in which a domain name is associated with an IP address of a virtual server and whether or not distribution to the virtual server is possible;
The state of the CPU assigned to the virtual server operating in the server device from the common management device connected to the network, which manages the state of the server device or the plurality of server devices, and the status of the virtual server For each state of the communication means, when a CPU dedicated to the virtual server is assigned, it is a determination result based on the usage status of the CPU occupied by the virtual server, and the virtual server uses the CPU. In the case of sharing with other virtual servers, the determination result is based on the usage status of the CPU by all the virtual servers sharing the CPU, and a predetermined condition for determining that a load is applied. A determination result indicating whether or not the CPU matches the CPU assigned to the virtual server, and the virtual server When the communication means indicates that the load is not applied, information that can be distributed to the virtual server is written in the storage unit, and the determination result is assigned to the CPU assigned to the virtual server, Alternatively, when it indicates that the communication means of the virtual server is in a state of being loaded, an update unit that writes information that cannot be distributed to the virtual server to the storage unit;
A notification unit that receives information on a domain name of an access destination of the end user terminal, reads the IP address of a virtual server corresponding to the domain name and that can be distributed, and notifies the IP address;
An access distribution device comprising: A server device that operates as a plurality of virtual servers and has communication means for communicating with end user terminals for each virtual server; an access distribution device that distributes access from end user terminals to the virtual servers; Using the IP address of the virtual server of the distribution destination notified from the access distribution device, an access distribution used in an access distribution system in which an end user terminal accessing the virtual server is connected via a network. A minute method,
In the server device,
The resource status monitoring unit acquires the status of the CPU assigned to the virtual server operating in the server device and the status of the communication means of the virtual server,
The state notification unit determines that for each virtual server, a load is applied to each of the state of the CPU allocated to the virtual server and the state of the communication unit of the virtual server acquired by the resource state monitoring unit. To determine whether the predetermined condition is satisfied, and notify the access distribution device of the determination result,
In the access distribution device,
The update unit receives the determination result from the server device, and the determination result indicates that the CPU assigned to the virtual server and the communication means of the virtual server are not under load. If there is, information that can be distributed to the virtual server is written in a storage unit that stores information in which the domain name is associated with the IP address of the virtual server and whether or not the virtual server can be distributed. If the result indicates that the CPU assigned to the virtual server or the communication means of the virtual server is under load, information that cannot be distributed to the virtual server is stored in the memory Write to the department,
The notification unit receives the information of the domain name of the access destination of the end user terminal, reads the IP address of the virtual server corresponding to the domain name and can be distributed, and notifies the storage unit ,
When the status notification unit is assigned a CPU to be used exclusively by the virtual server, the CPU determines whether the load is applied based on the usage status of the CPU occupied by the virtual server, When a virtual server shares a CPU with another virtual server and uses the CPU, the CPU determines whether the load is applied based on the usage status of the CPU by all the virtual servers sharing the CPU. Access distribution method. A plurality of server devices that operate as a plurality of virtual servers and communicate with each virtual server for communicating with end user terminals, and an access distribution device that distributes access from the end user terminals to the virtual servers A common management device that manages the states of the plurality of server devices, and an end user terminal that accesses the virtual server using the IP address of the virtual server that is the distribution destination notified from the access distribution device. An access distribution method used in an access distribution system connected via a network,
In the common management device,
The resource status monitoring unit acquires the status of the CPU assigned to each virtual server operating in the plurality of server devices and the status of the communication means of the virtual server,
The state notification unit determines that for each virtual server, a load is applied to each of the state of the CPU allocated to the virtual server and the state of the communication unit of the virtual server acquired by the resource state monitoring unit. To determine whether the predetermined condition is satisfied, and notify the access distribution device of the determination result,
In the access distribution device,
The update unit receives the determination result from the common management device, and the determination result indicates that the CPU assigned to the virtual server and the communication means of the virtual server are not under load. If there is a domain name, the IP address of the virtual server, and the information that can be distributed to the virtual server are stored in the storage unit that stores the information that can be distributed to the virtual server. When the determination result indicates that the CPU assigned to the virtual server or the communication means of the virtual server is under load, information indicating that the distribution to the virtual server is impossible is performed. Write to memory,
The notification unit receives the information of the domain name of the access destination of the end user terminal, reads the IP address of the virtual server corresponding to the domain name and can be distributed, and notifies the storage unit ,
When the status notification unit is assigned a CPU to be used exclusively by the virtual server, the CPU determines whether the load is applied based on the usage status of the CPU occupied by the virtual server, When a virtual server shares a CPU with another virtual server and uses the CPU, the CPU determines whether the load is applied based on the usage status of the CPU by all the virtual servers sharing the CPU. Access distribution method. A server device that operates as a plurality of virtual servers and has communication means for communicating with end user terminals for each virtual server; an access distribution device that distributes access from end user terminals to the virtual servers; Using the IP address of the virtual server of the distribution destination notified from the access distribution device, the server device of the access distribution system formed by connecting an end user terminal that accesses the virtual server via a network A computer program used,
Acquiring the state of the CPU assigned to the virtual server operating in the server device and the state of the communication means of the virtual server;
For each of the virtual servers, if a CPU dedicated to the virtual server is assigned to each of the state of the CPU assigned to the virtual server and the state of the communication means of the virtual server, the virtual server When the virtual server shares the CPU with another virtual server based on the usage status of the CPU occupied by the CPU, the load is determined based on the usage status of the CPU by all the virtual servers sharing the CPU. Determining whether a predetermined condition determined to be applied is met, and notifying the determination result to the access distribution device;
A computer program for causing a computer to execute. A plurality of server devices that operate as a plurality of virtual servers and communicate with each virtual server for communicating with end user terminals, and an access distribution device that distributes access from the end user terminals to the virtual servers A common management device that manages the states of the plurality of server devices, and an end user terminal that accesses the virtual server using the IP address of the virtual server that is the distribution destination notified from the access distribution device. A computer program used for the common management device of an access distribution system connected via a network,
Obtaining the state of the CPU assigned to each virtual server operating in the plurality of server devices and the state of the communication means of the virtual server;
Wherein for each virtual server, acquired by the resource status monitoring unit, for each of the states of the state and the communication means of the virtual server's CPU allocated to the virtual server, CPU used to occupy the virtual server allocated If the virtual server shares the CPU with another virtual server based on the usage status of the CPU occupied by the virtual server, the virtual server sharing the CPU Determining whether or not a predetermined condition determined to be under load is met based on a usage state of the CPU, and notifying the access distribution device of the determination result;
A computer program for causing a computer to execute. A server device that operates as a plurality of virtual servers and has communication means for communicating with end user terminals for each virtual server; an access distribution device that distributes access from end user terminals to the virtual servers; The access distribution of an access distribution system in which an IP address of a virtual server of a distribution destination notified from the access distribution device is connected to an end user terminal that accesses the virtual server via a network A computer program used in an apparatus,
The state of the CPU assigned to the virtual server operating in the server device from the common management device connected to the network, which manages the state of the server device or the plurality of server devices, and the status of the virtual server For each state of the communication means, when a CPU dedicated to the virtual server is assigned, it is a determination result based on the usage status of the CPU occupied by the virtual server, and the virtual server uses the CPU. In the case of sharing with other virtual servers, the determination result is based on the usage status of the CPU by all the virtual servers sharing the CPU, and a predetermined condition for determining that a load is applied. Receiving a determination result of whether it matches,
When the received determination result indicates that the CPU assigned to the virtual server and the communication means of the virtual server are not loaded, the domain name, the IP address of the virtual server, and the In a storage unit that stores information that associates whether or not allocation to a virtual server is possible, information that can be allocated to the virtual server is written, and the determination result is a CPU assigned to the virtual server, or If it indicates that the communication means of the virtual server is in a state of being loaded, writing information that cannot be distributed to the virtual server to the storage unit;
Receiving information on a domain name of an access destination of the end user terminal, reading out the IP address of a virtual server corresponding to the domain name and capable of being distributed from the storage unit, and notifying;
A computer program for causing a computer to execute.

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