Patent Publication Number: US-2017366413-A1

Title: Network evaluation program, network evaluation method, and network evaluation device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2016-122473, filed on Jun. 21, 2016, the entire contents of which are incorporated herein by reference. 
     FIELD 
     The present invention relates to a network evaluation program, a network evaluation method, and a network evaluation device. 
     BACKGROUND 
     There are information processing systems in which a plurality of physical machines (hereinafter also referred to as physical servers) and a plurality of physical storage devices are connected over a network. In such information processing systems, a virtual storage or a virtual machine is deployed with respect to the physical machine. A virtual storage is associated with the physical area of the physical storage device. 
     In the case where the virtual machine accesses the virtual storage, the virtual machine accesses the physical area of the physical storage device over a physical path, such as a local area network (LAN) cable. In the case where a plurality of the virtual machines access the physical storage device over the same physical path, the bandwidth of the physical path is shared. 
     In each virtual machine, the bandwidth demanded for communication with the physical storage device is set. Therefore, upon deployment of the virtual machine, an administrator of the information processing system deploys the virtual machine in the physical server that is able to reliably provide the demanded bandwidth. 
     A technique relating to the evaluation of the physical server is described in, for example, Japanese Laid-open Patent Publication No. 2014-139845. 
     SUMMARY 
     However, there are cases where the physical path over which the virtual machine accesses the physical storage device is not detectable. For the administrator, in such cases, communications for which the bandwidth of the physical path is shared are not identifiable, and the physical server that is able to reliably provide the bandwidth demanded for the virtual machine is not determinable. Therefore, cases occur where the virtual machine is deployed beyond the bandwidth of the physical path, and there are cases where the service level agreement (SLA) is not able to be met. 
     A non-transitory computer-readable storage medium storing therein a network evaluation program for causing a computer to execute a process comprising: 
     deploying, in each physical machine of a system in which one or more physical machines and one or more physical storage devices are connected via a physical path, a first virtual machine to execute software of applying a steady access load with respect to the physical storage device or a second virtual machine to execute software of applying a fluctuating access load with respect to the physical storage device; and 
     identifying a plurality of the virtual machines that share a same physical path, based on a measurement result of throughput for a case where at least one or more of the second virtual machines and one or more of the first virtual machines have been executed in a same time period. 
     In one aspect, a physical path over which the communication of a virtual machine with respect to a physical storage device is made is able to be managed. 
     The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram illustrating an example of an information processing system of this embodiment. 
         FIG. 2  is a flowchart diagram illustrating the processing flow of the network evaluation program  120  in this embodiment. 
         FIG. 3  is a diagram illustrating a deployment example of the steady-load virtual machine VM and the fluctuating-load virtual machine VM. 
         FIG. 4  is a diagram illustrating an example of the measurement results of a case where the fluctuating-load virtual machine VM and the steady-load virtual machine VM do not share the same LAN cable  200 . 
         FIG. 5  is a diagram illustrating an example of the measurement results of a case where the fluctuating-load virtual machine VM and the steady-load virtual machine VM share the same LAN cable  200 . 
         FIG. 6  is a diagram illustrating an example of the measurement results of a case where the fluctuating-load virtual machine VM and a plurality of the steady-load virtual machines VM share the same LAN cable  200 . 
         FIG. 7  is a hardware configuration diagram of a network evaluation device  100  in a second embodiment. 
         FIG. 8  is a diagram illustrating the functions of software of the network evaluation device  100  illustrated in  FIG. 7 . 
         FIG. 9  is a flowchart diagram illustrating the processing flow of the network evaluation program  120  in the second embodiment. 
         FIG. 10  is a flowchart diagram illustrating the processing of step S 21  in  FIG. 9 . 
         FIG. 11  is a diagram illustrating an example of the physical server PM selected in accordance with the method  1 . 
         FIG. 12  is a diagram illustrating an example of the physical server PM selected in accordance with the method  2 . 
         FIG. 13  is a flowchart diagram illustrating the processing of step S 33  in  FIG. 10  in accordance with the method  1 . 
         FIG. 14  is a flowchart diagram illustrating the processing of step S 43  in  FIG. 13 . 
         FIG. 15  is a diagram illustrating an example of the measured-load-value table  122 - 1 . 
         FIG. 16  is a diagram illustrating a calculation example for the similarity. 
         FIG. 17  is a diagram illustrating an example of a shared-bandwidth management table  121 - 1  created in step S 46  of  FIG. 13 . 
         FIG. 18  is a flowchart diagram illustrating the processing of step S 33  in  FIG. 10  in accordance with the method  2 . 
         FIG. 19  is a diagram illustrating an example of a measured-load-value table  122 - 2  created in step S 55 . 
         FIG. 20  is a diagram illustrating a calculation example for the similarity. 
         FIG. 21  is a diagram illustrating an example of a shared-bandwidth management table  121 - 2  created in step S 56  of  FIG. 18 . 
         FIG. 22  is a flowchart diagram illustrating the processing of step S 22  in  FIG. 9 . 
         FIG. 23  is a diagram illustrating an example of the processing in step S 64 . 
         FIG. 24  is a diagram illustrating an example of the processing in step S 65 . 
         FIG. 25  is a flowchart diagram illustrating the processing of step S 23  in  FIG. 9 . 
         FIG. 26  is a diagram schematically illustrating the processing of step S 23 , described with the flowchart diagram in  FIG. 25 . 
         FIG. 27  is a flowchart diagram illustrating the processing of step S 24  in  FIG. 9 . 
         FIG. 28  is a diagram schematically illustrating the processing of step S 24 , described with the flowchart diagram in  FIG. 27 . 
         FIG. 29  is a flowchart diagram illustrating the details of the processing of step S 25  in  FIG. 9 . 
         FIG. 30  is a diagram schematically illustrating the processing of step S 25 . 
         FIG. 31  is a diagram illustrating the number of actions taken for the identification of the sharing relationship. 
         FIG. 32  is a diagram illustrating an example of the access loads and the measurement results of the first and second fluctuating-load virtual machines VM. 
         FIG. 33  is a diagram illustrating an example of the access load and the measurement result of the steady-load virtual machine VM. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments will be described hereinafter according to the drawings. However, it is noted that the technical scope is not limited to the embodiments described below, but covers the matters described in the claims and the equivalents thereof. 
     Information Processing System 
       FIG. 1  is a diagram illustrating an example of an information processing system of this embodiment. The information processing system is, for example, a system in a data center.  FIG. 1  illustrates an example of a case where the information processing system includes three physical machines PM 1 - 1 , PM 2 - 1 , and PM 3 - 1  (hereinafter also referred to as physical servers PM) and three physical storage devices  300   a,    300   b,  and  300   c  (hereinafter also referred to as storage devices  300 ). The example of  FIG. 1  is not limiting, and the information processing system may include a large number of the physical servers PM and a large number of the storage devices  300 . 
     The storage device  300  includes a large number of physical storage devices aligned in an array, for example. The storage device  300  is a storage device such as, for example, a network attached storage (NAS) or a storage area network (SAN). In the storage device  300 , files f 11  to f 15  (also referred to as file f 1 ) are stored. 
     The physical server PM is, for example, a computer including a server function. Although not illustrated in the drawing, the physical server PM includes a central processing unit (CPU), a memory, and the like. In the respective physical servers PM, one or a plurality of virtual machines vma to vme (hereinafter also referred to as virtual machine vm) are deployed, for example. 
     On each virtual machine vm, a program of an operation system or various types of application programs are run. The virtual machine vm performs, for example, application processing or the like in accordance with an application program. Specifically, on the physical server PM 1 - 1  illustrated in  FIG. 1 , the two virtual machines vma and vmb are run. On the physical server PM 2 - 1 , the two virtual machines vmc and vmd are run. On the physical server PM 3 - 1 , one virtual machine vme is run. 
     In the physical server PM, storage pools SP 11   a,  SP 11   b,  SP 21   a,  SP 21   b,  and SP 31  (hereinafter also referred to as storage pools SP) are deployed as virtual storage. Specifically, in the physical server PM 1 - 1 , the storage pools SP 11   a  and SP 11   b  are deployed. In the physical server PM 2 - 1 , the storage pools SP 21   a  and SP 21   b  are deployed. In the physical server PM 3 - 1 , the storage pool SP 31  is deployed. 
     The storage pool SP is a virtual volume associated with the storage device  300 . In the storage pool SP, an allocatable area out of a physical storage area of the storage device  300  is registered in units of logical storage areas (hereinafter referred to as logical volumes). With the logical volume, the physical storage area storing the file f 1  is associated. 
     The virtual machine vm accesses the storage pool SP as storage. In the case of accessing the file f 1 , the virtual machine vm accesses the storage device  300  storing the file f 1 , via the storage pool SP. 
     The storage pool SP and the storage device  300  are connected via a network. In this embodiment, the network includes a path that is a signal line (physical path), such as a local area network (LAN) cable or an optical cable. In this embodiment, a case is illustrated as an example where LAN cables  200   a  and  200   b  (hereinafter also referred to as LAN cables  200 ) are used for the communication path of the storage pool SP and the storage device  300 . 
     In this manner, upon the virtual machine vm accessing the storage pool SP, the virtual machine vm connects with the storage device  300  over the LAN cable  200  to perform an access (reading, writing, or the like) with respect to the physical storage area. 
     (Sharing of LAN Cable  200 ) 
     According to the example of  FIG. 1 , one LAN cable  200  is shared for the communications by the plurality of virtual machines vm. Specifically, the LAN cable  200   a  is shared for the communications by the three virtual machines vma, vmb, and vmc. Therefore, the bandwidth of the LAN cable  200   a  is shared for the communications by the three virtual machines vma, vmb, and vmc. In the case where one LAN cable  200  is shared by the plurality of virtual machines vm, the bandwidth that one virtual machine vm is able to use is reduced. 
     The LAN cable  200   b  is shared for the communications by the two virtual machines vmd and vme. Therefore, the bandwidth of the LAN cable  200 B is shared for the communications by the two virtual machines vmd and vme. 
     (Deployment of Virtual Machine) 
     An administrator of a data center deploys the virtual machine vm in accordance with the state of deployment of the storage pool SP, upon construction of the information processing system. The bandwidth demanded for the communication with the storage device  300  is set for the virtual machine vm, and the administrator deploys the virtual machine vm in the physical server PM that is able to reliably provide the demanded bandwidth. 
     The LAN cable  200  over which the communication by the virtual machine vm with the storage device  300  is made is set for each storage pool SP. Thus, the administrator deploys the virtual machine vm in the physical server PM with the deployed storage pool SP for which a path is set such that the total of bandwidths of the virtual machines vm sharing the LAN cable  200  does not exceed the bandwidth of the LAN cable  200 . 
     Note that, in the case where the information processing system employs a cloud network, information inside the network is hidden, and only inputs and outputs are indicated. A cloud network is constructed using a network device, such as a switch or a router, but the topology and communication paths are hidden. Thus, the administrator is not able to detect the physical path over which the communication of the storage pool SP and the storage device  300  is made. 
     Thus, for the administrator, the virtual machines vm that share the bandwidth of the LAN cable  200  are not identifiable, and the physical server PM that is able to reliably provide the bandwidth demanded for the virtual machine vm is not determinable. Accordingly, cases occur where the virtual machine vm is deployed beyond the bandwidth of the LAN cable  200 , and the demanded bandwidth is not able to be met. As a result, there are cases where the SLA of the information processing system is not able to be met. 
     As such, it is desired that the shared state of the LAN cable  200  be identified, in order to guarantee the performance demanded for the communication by the virtual machine vm with respect to the storage device  300 . 
     First Embodiment 
     Thus, a network evaluation program  120  of this embodiment deploys a first virtual machine or a second virtual machine, in each physical machine of a system in which one or more physical machines and one or more physical storage devices are connected via a physical path. 
     The first virtual machine is a virtual machine to execute software with which a steady access load is applied with respect to the physical storage device. The second virtual machine is a virtual machine to execute software with which a fluctuating access load is applied with respect to the physical storage device. The access load is an access with respect to the physical storage device and is writing or reading of data. 
     The network evaluation program  120  identifies a plurality of virtual machines that share the same physical path, on the basis of the measurement results of the throughput for a case where at least one or more of the second virtual machines and one or more of the first virtual machines have been executed in the same time period. 
     The physical machine corresponds to the physical server PM illustrated in  FIG. 1 , and the physical storage device corresponds to the storage device  300  illustrated in  FIG. 1 . The physical path is a physical path as a unit for sharing the bandwidth and is a LAN cable, an optical cable, or the like. 
     Accordingly, the network evaluation program  120  is able to identify the combination of communications of the virtual machines with respect to the physical storage device in which the same physical path is shared. That is, the network evaluation program  120  is able to identify the combination of the virtual machines that share the same physical path for an access to the physical storage device. 
     Thus, an administrator is able to calculate the total of bandwidths demanded for the communications, with respect to the physical storage device, of the virtual machines that share the physical path. Accordingly, the administrator is able to determine, out of the plurality of physical machines, the physical machine with which the total bandwidth demanded for the plurality of virtual machines sharing the physical path connected with the deployed virtual machines falls within the bandwidth of the physical path. Thus, the administrator is able to determine the physical machine that meets the demanded bandwidth for the virtual machine intended to be deployed. Accordingly, it is possible to guarantee the performance demanded for the virtual storage. 
     In this manner, the network evaluation program  120  in this embodiment is able to detect the shared state of the physical path, even in the information processing system of which the communication path of the virtual machine and the physical storage device is not disclosed. Thus, on the basis of information of the virtual machines that share the bandwidth, it is possible to manage the physical path over which the communication of the virtual machine with respect to the physical storage device is made. Accordingly, it is possible to meet the SLA demanded for the system. 
     (Processing Flow of Network Evaluation Program  120 ) 
       FIG. 2  is a flowchart diagram illustrating the processing flow of the network evaluation program  120  in this embodiment. 
     S 11 : The network evaluation program  120  deploys the first virtual machine (hereinafter referred to as steady-load virtual machine VM) or the second virtual machine (hereinafter referred to as fluctuating-load virtual machine VM), in each physical server PM of the system. Hereinafter, the steady-load virtual machine VM and the fluctuating-load virtual machine VM are also referred to as measurement virtual machine VM. The deployed measurement virtual machine VM includes at least one fluctuating-load virtual machine VM. 
     S 12 : The network evaluation program  120  executes at least one or more of the steady-load virtual machines VM and one or more of the fluctuating-load virtual machines VM in the same time period. 
     The network evaluation program  120  executes each measurement virtual machine VM for 20 to 30 minutes, for example. During this time, the throughput of the access processing is measured in each measurement virtual machine VM. The throughput indicates the amount of access processing per second (in megabytes per second (MB/s)) that is executed with respect to the storage device  300 . 
     S 13 : The network evaluation program  120  collects the measurement results of the throughput of the access processing from each of the measurement virtual machines VM. The measurement result includes information of the amounts of access processing over a time of, for example, 20 to 30 minutes. 
     S 14 : On the basis of the measurement results, the network evaluation program  120  identifies a plurality of the measurement virtual machines VM that share the same physical path. The network evaluation program  120  identifies, for example, the combination of the steady-load virtual machine VM and the fluctuating-load virtual machine VM having a correlation in the measurement results, as a plurality of the measurement virtual machines VM that share the same physical path. 
     Deployment Example of Measurement Virtual Machine VM 
       FIG. 3  is a diagram illustrating a deployment example of the steady-load virtual machine VM and the fluctuating-load virtual machine VM. In  FIG. 3 , those that are the same as those illustrated in  FIG. 1  are indicated by the same reference signs. Although not illustrated in  FIG. 3 , a network evaluation device in this embodiment is connected with each physical server PM. 
     In the example of  FIG. 3 , the network evaluation program  120  deploys a fluctuating-load virtual machine VM 1 - 1 A and a steady-load virtual machine VM 1 - 1 B with respect to the physical server PM 1 - 1 , upon construction of the system. The communication path to and from the storage device  300  is set for each storage pool SP. Thus, the network evaluation program  120  deploys the measurement virtual machine VM for each storage pool SP. 
     In the example of  FIG. 3 , the network evaluation program  120  deploys two steady-load virtual machines VM 2 - 1 A and VM 2 - 1 B in the physical server PM 2 - 1  and one steady-load virtual machine VM 3 - 1  in the physical server PM 3 - 1 . As illustrated in  FIG. 3 , at least one out of the deployed measurement virtual machines VM is the fluctuating-load virtual machine VM. Note that this example is not limiting, and a plurality of the fluctuating-load virtual machines VM may be deployed. 
     The network evaluation program  120  collects the measurement results of the throughput for a case where the measurement virtual machines VM have been executed in the same time period. On the basis of the correlation of the measurement results, the network evaluation program  120  identifies the combination of the fluctuating-load virtual machine VM and the steady-load virtual machine VM that share the same LAN cable  200 . 
     Example of Measurement Result 
     With reference to  FIGS. 4 to 6 , an example of the measurement results of the throughput of the fluctuating-load virtual machine VM and the steady-load virtual machine VM will be described. 
     (Case where Sharing Relationship is Absent) 
       FIG. 4  is a diagram illustrating an example of the measurement results of a case where the fluctuating-load virtual machine VM and the steady-load virtual machine VM do not share the same LAN cable  200 . Two graphs g 1   a  and g 1   b  in the upper part in  FIG. 4  indicate graphs of the fluctuating-load virtual machine VM, and two graphs g 2   a  and g 2   b  in the lower part indicate graphs of the steady-load virtual machine VM. 
     The graph g 1   a  illustrates the change in the access load applied by the fluctuating-load virtual machine VM. The access load indicates the amount of access processing such as reading or writing executed with respect to the storage device  300  and is represented as an I/O control value. The abscissa of the graph g 1   a  indicates the time, and the ordinate the I/O control value. 
     As illustrated in the graph g 1   a,  the amount of access processing applied by the fluctuating-load virtual machine VM fluctuates. The amount of access processing applied by the fluctuating-load virtual machine VM fluctuates cyclically between the maximum value and the minimum value of the access processing. Note that this example is not limiting, and it is not that the change in the access load applied by a fluctuating-load tool has to have a cycle. 
     The graph g 2   a  illustrates the change in the access load applied by the steady-load virtual machine VM. The abscissa of the graph g 2   a  indicates the time, and the ordinate the I/O control value. As illustrated in the graph g 2   a,  the amount of access processing applied by the steady-load virtual machine VM is steady (constant) and is at the maximum value of the access processing. 
     The graph g 1   b  illustrates the change in the throughput of the access processing measured by the fluctuating-load virtual machine VM, and the graph g 2   b  illustrates the change in the throughput of the access processing measured by the steady-load virtual machine VM. The abscissas of the graphs g 1   b  and g 2   b  are the time, and the ordinates are the measured value of the throughput (in megabits per second (Mbps)). 
       FIG. 4  illustrates a case where the same LAN cable  200  is not shared between the fluctuating-load virtual machine VM and the steady-load virtual machine VM. Thus, the measured value of the fluctuating-load virtual machine VM (in the graph g 1   b ) is not subject to the influence of the access load applied by the steady-load virtual machine VM (in the graph g 2   a ) and changes in a similar manner to the applied access load (in the graph g 1   a ). The measured value of the steady-load virtual machine VM (in the graph g 2   b ) is not subject to the influence of the access load applied by the fluctuating-load virtual machine VM (in the graph g 1   a ) and remains constant. 
     In this manner, in the case where the fluctuating-load virtual machine VM and the steady-load virtual machine VM do not share the same LAN cable  200 , the measured value of the fluctuating-load virtual machine VM (in the graph g 1   b ) and the measured value of the steady-load virtual machine VM (in the graph g 2   b ) do not have a correlation. 
     (Case where Sharing Relationship is Present) 
       FIG. 5  is a diagram illustrating an example of the measurement results of a case where the fluctuating-load virtual machine VM and the steady-load virtual machine VM share the same LAN cable  200 . Two graphs g 3   a  and g 3   b  in the upper left in  FIG. 5  indicate graphs of the fluctuating-load virtual machine VM, and two graphs g 4   a  and g 4   b  in the lower left indicate graphs of the steady-load virtual machine VM. 
     The graph g 3   a  illustrates the change in the access load applied by the fluctuating-load virtual machine VM, in a similar to the graph g 1   a  in  FIG. 4 . The graph g 4   a  illustrates the change in the access load applied by the steady-load virtual machine VM, in a similar to the graph g 2   a  in  FIG. 4 . The graph g 3   b  illustrates the measured value of the fluctuating-load virtual machine VM, and the graph g 4   b  illustrates the measured value of the steady-load virtual machine VM. 
       FIG. 5  illustrates a case where the same LAN cable  200  is shared between the fluctuating-load virtual machine VM and the steady-load virtual machine VM. Thus, the measured value of the fluctuating-load virtual machine VM (in the graph g 3   b ) is subject to the influence of the access load applied by the steady-load virtual machine VM (in the graph g 4   a ) and becomes half the value of the measured value of the case where sharing is absent. The measured value of the steady-load virtual machine VM (in the graph g 4   b ) fluctuates in accordance with the access load applied by the fluctuating-load virtual machine VM (in the graph g 3   a ). 
     Specifically, as illustrated in the graph g 4   b,  the measured value of the steady-load virtual machine VM drops when the access load applied by the fluctuating-load virtual machine VM rises. The measured value of the steady-load virtual machine VM rises when the access load applied by the fluctuating-load virtual machine VM drops. In this manner, in the case where the fluctuating-load virtual machine VM and the steady-load virtual machine VM share the same LAN cable  200 , the measurement result of the fluctuating-load virtual machine VM and the measurement result of the steady-load virtual machine VM have a correlation. 
     A graph gc illustrates the state of use of the bandwidth of the LAN cable  200 , for the communication by each measurement virtual machine VM. As illustrated in the graph gc, the total of the measured values coincides with the maximum bandwidth of the LAN cable  200 , in the case where only the fluctuating-load virtual machine VM and the steady-load virtual machine VM share the same LAN cable  200 . 
       FIG. 6  is a diagram illustrating an example of the measurement results of a case where the fluctuating-load virtual machine VM and a plurality of the steady-load virtual machines VM share the same LAN cable  200 . Two graphs g 5   a  and g 5   b  in the upper left in  FIG. 6  indicate graphs of the fluctuating-load virtual machine VM. Two graphs g 61   b  and g 62   b  in the lower left indicate graphs of the measured values of first and second steady-load virtual machines VM. 
     The graph g 5   a  illustrates the change in the access load applied by the fluctuating-load virtual machine VM, in a similar to the graphs g 1   a  and g 3   a  in  FIGS. 4 and 5 . The graph g 5   b  illustrates the measured value of the fluctuating-load virtual machine VM. The graph g 61   b  illustrates the measured value of the first steady-load virtual machine VM, and the graph g 62   b  illustrates the measured value of the second steady-load virtual machine VM. 
       FIG. 6  illustrates a case where the same LAN cable  200  is shared between the fluctuating-load virtual machine VM and the first and second steady-load virtual machines VM. Thus, the measured value of the fluctuating-load virtual machine VM (in the graph g 5   b ) is subject to the influence of the access load applied by the first and second steady-load virtual machines VM and becomes ⅓ the value of the measured value of the case where sharing is absent. 
     The measured values of the first and second steady-load virtual machines VM (in the graphs g 61   b  and g 62   b ) fluctuate in accordance with the access load applied by the fluctuating-load virtual machine VM (in the graph g 5   a ). Therefore, the measurement result of the fluctuating-load virtual machine VM and each of the measurement results of the first and second steady-load virtual machines VM have a correlation. 
     A graph gd illustrates the state of use of the bandwidth of the LAN cable  200 , for the communication by each measurement virtual machine VM. As illustrated in the graph gd, the total of the measured values coincides with the maximum bandwidth of the LAN cable  200 , in the case where the fluctuating-load virtual machine VM and the first and second steady-load virtual machines VM share the same LAN cable  200 . 
     As illustrated in  FIGS. 4 to 6 , the measured values of the steady-load virtual machine VM and the fluctuating-load virtual machine VM have a correlation regardless of the number of the steady-load virtual machines VM, in the case where the steady-load virtual machine VM and the fluctuating-load virtual machine VM share the same LAN cable  200 . Thus, the network evaluation program  120  is able to appropriately determine the sharing relationship for the LAN cable  200 , on the basis of the correlation of the measured values. 
     Returning to  FIG. 3 , the network evaluation program  120  identifies, for example, the fluctuating-load virtual machine VM 1 - 1 A and the steady-load virtual machine VM 1 - 1 B as the virtual machines VM that share the same LAN cable  200 . The network evaluation program  120  identifies the fluctuating-load virtual machine VM 1 - 1 A and the steady-load virtual machine VM 2 - 1 A as the virtual machines VM that share the same LAN cable  200 . 
     Thus, the network evaluation program  120  identifies the combination of the three measurement virtual machines VM 1 - 1 A, VM 1 - 1 B, and VM 2 - 1 A as the virtual machines VM that share the same LAN cable  200 . 
     The sharing relationship is not determined for the combination of the steady-load virtual machines. Thus, the network evaluation program  120  further deploys a fluctuating-load virtual machine (not illustrated) in the physical server PM 2 - 1  and the steady-load virtual machine VM 3 - 1  in the physical server PM 3 - 1 . The network evaluation program  120  determines the sharing relationship of the measurement virtual machines VM 2 - 1 B and VM 3 - 1  on the basis of the measurement results. 
     In this manner, the network evaluation program  120  repeats the deployment and identification while changing the physical server PM in which the measurement virtual machine VM is intended to be deployed. Accordingly, the network evaluation program  120  is able to identify the shared state of the LAN cable  200  for the communication of each storage pool SP and the storage device  300 . 
     Second Embodiment 
       FIG. 7  is a hardware configuration diagram of a network evaluation device  100  in a second embodiment. The network evaluation device  100  includes, for example, a CPU  101 , a memory  102  including a main memory  110 , an auxiliary storage device  111 , and the like, and a communication interface unit  103 . The respective units are mutually connected via a bus  106 . 
     The CPU  101  connects with the memory  102  and the like via the bus  106  and performs control of the entire network evaluation device  100 . The communication interface unit  103  connects with the physical server PM via a wired communication and performs an exchange of information. The communication interface unit  103  is, for example, a network interface card (NIC). 
     The main memory  110  indicating a random access memory (RAM) or the like stores data or the like for the CPU  101  to perform processing. The auxiliary storage device  111  includes an area (not illustrated) storing a program of an operation system executed by the CPU  101  and the network evaluation program storage area  120 . The auxiliary storage device  111  includes a shared-bandwidth management table storage area  121  and a measured-load-value table storage area  122 . The auxiliary storage device  111  indicates a hard disk drive (HDD), a non-volatile semiconductor memory, or the like. 
     A network evaluation program (hereinafter referred to as network evaluation program  120 ) in the network evaluation program storage area  120  is loaded to the main memory  110 . By the CPU  101  executing the network evaluation program  120  loaded into the main memory  110 , the evaluation processing for a network in this embodiment is realized. 
     A shared-bandwidth management table (hereinafter referred to as shared-bandwidth management table  121 ) of the shared-bandwidth management table storage area  121  is a table including information of the sharing relationship identified by the network evaluation program  120 . An example of the shared-bandwidth management table  121  will be described later with reference to  FIGS. 17 and 21 . 
     A measured-load-value table (hereinafter referred to as measured-load-value table  122 ) of the measured-load-value table storage area  122  includes the measurement result of the throughput measured by each measurement virtual machine VM. An example of the measured-load-value table  122  will be described later with reference to  FIGS. 15 and 19 . 
     Function of Software of Network Evaluation Device  100   
       FIG. 8  is a diagram illustrating the functions of software of the network evaluation device  100  illustrated in  FIG. 7 . In  FIG. 8 , those that are the same as those illustrated in  FIG. 7  are indicated by the same reference signs. 
     As illustrated in  FIG. 8 , the network evaluation program  120  includes a measured-value collection module  131 , a method execution module  132 , a load setting module  133 , and a measurement virtual machine deployment module  134 . 
     In accordance with a method, the method execution module  132  selects the physical server PM in which the measurement virtual machine VM is intended to be deployed and instructs the measurement virtual machine deployment module  134  to deploy the measurement virtual machine VM. 
     The method execution module  132  identifies the measurement virtual machines VM that share the same communication path, on the basis of the measured-load-value table  122  created by the measured-value collection module  131 . The method execution module  132  stores the identified sharing relationship in the shared-bandwidth management table  121 . 
     The measurement virtual machine deployment module  134  deploys the measurement virtual machine VM in the physical server PM selected by the method execution module  132 . Accordingly, in the physical server PM 1 - 1  in which the storage pools SP 11   a  and SP 11   b  have been deployed, the fluctuating-load virtual machine VM 1 - 1 A and the steady-load virtual machine VM 1 - 1 B are deployed, for example.  FIG. 8  illustrates the physical server PM 1 - 1  as an example, but it is similar for other physical servers PM as well. 
     On the fluctuating-load virtual machine VM 1 - 1 A, a fluctuating-load tool  150   a  is run. The fluctuating-load tool  150   a  is, for example, a program that applies an access load fluctuating cyclically in a range between the minimum and maximum access loads, with respect to the storage pool SP. On the steady-load virtual machine VM 1 - 1 B, a steady-load tool  150   b  is run. The steady-load tool  150   b  is, for example, a program that applies the maximum access load in a steady state, with respect to the storage pool SP. 
     The fluctuating-load tool  150   a  and the steady-load tool  150   b  include load measurement modules  151   a  and  151   b.  The load measurement modules  151   a  and  151   b  measure and store the throughput of the access processing performed with respect to the storage pool SP. 
     The load setting module  133  sets the access load value with respect to the fluctuating-load tool  150   a  and the steady-load tool  150   b  and gives an instruction to execute the fluctuating-load tool  150   a  and the steady-load tool  150   b.  The measured-value collection module  131  collects the measured values measured by the load measurement modules  151   a  and  151   b  from each measurement virtual machine VM and stores the collected measured values in the measured-load-value table  122 . 
     Next, with reference to  FIGS. 9 to 30 , the processing of the network evaluation program  120  in this embodiment will be described. First, with reference to a flowchart diagram in  FIG. 9 , the sequence of processing flow of the network evaluation program  120  will be described. 
     Processing Flow of Network Evaluation Program  120   
       FIG. 9  is a flowchart diagram illustrating the processing flow of the network evaluation program  120  in the second embodiment. 
     S 21 : The method execution module  132  determines the execution order of a plurality of methods. The method is a method of selecting the physical server PM in which the measurement virtual machine VM is intended to be deployed, in order to efficiently identify the measurement virtual machines VM that share the same LAN cable  200 . In this embodiment, two methods will be illustrated as an example. The details of each method will be described later with reference to  FIGS. 11 and 12 . 
     In step S 21 , the method execution module  132  tests the deployment and identification intended for a part of the physical servers PM, in accordance with each method. On the basis of the test result, the method execution module  132  determines the effectiveness of the method and determines the execution order of the methods. The step of processing in step S 21  will be described later with reference to  FIGS. 10 to 21 . 
     S 22 : The method execution module  132  performs the deployment and identification thoroughly that are intended for the remaining physical servers PM, in accordance with the method order determined in step S 21 . The step of processing in step S 22  will be described later with reference to  FIGS. 22 to 24 . After the deployment and identification, the method execution module  132  deletes the deployed measurement virtual machine VM. 
     The execution of steps S 21  and S 22  does not promise an exhaustive identification of all of the sharing relationships. Thus, the network evaluation program  120  repeats the re-deployment and identification while changing the physical server PM intended for deployment, in accordance with steps S 23  and S 24 . Accordingly, it is possible to exhaustively identify all of the sharing relationships. 
     S 23 : The method execution module  132  performs the re-deployment and identification intended for the measurement virtual machine VM for which the sharing relationship (hereinafter also referred to as sharing group) is not identified. The step of processing in step S 23  will be described later with reference to  FIGS. 25 and 26 . 
     S 24 : The method execution module  132  identifies the sharing relationship between the identified sharing groups. The step of processing in step S 24  will be described later with reference to  FIGS. 27 and 28 . When all of the sharing relationships are identified, the method execution module  132  deletes each measurement virtual machine VM deployed in the physical server PM. 
     S 25 : On the basis of the identified sharing group, the method execution module  132  determines the destination of the deployment of the virtual machine (hereinafter also referred to as demanded virtual machine) of which the deployment has been demanded by a user. The step of processing in step S 25  will be described later with reference to  FIG. 29 . 
     Step S 21  in FIG.  9   
       FIG. 10  is a flowchart diagram illustrating the processing of step S 21  in  FIG. 9 . As described above, in step S 21 , the deployment and identification intended for a part of the physical servers PM are tested, in accordance with each method. 
     In this embodiment, the plurality of physical servers PM are held in a rack (not illustrated). In this embodiment, a case is illustrated as an example where the information processing system includes  10  racks, and each rack holds  20  physical servers PM. In step S 21 , the physical servers PM are limited to those held in racks R 1  to R 3 , for example, to test the deployment and identification. 
     S 31 : The method execution module  132  calculates the number of load-applying virtual machines. The number of the load-applying virtual machines is the number of the virtual machines VM that are deployed in one round of the deployment and identification. 
     (Number of Load-Applying Virtual Machines) 
     There are cases where an access load greater than or equivalent to the bandwidth of the LAN cable  200  is not able to be applied with one measurement virtual machine VM. In such cases, the influence of another measurement virtual machine VM on the measurement result is not identifiable. Thus, the method execution module  132  deploys the measurement virtual machines VM in correspondence with the number of the load-applying virtual machines. Note that even if the number of the load-applying virtual machines is a value of the bandwidth of the LAN cable divided by the upper limit of the access load that is able to be applied with one measurement virtual machine VM, there are cases where the influence of the measurement result of another measurement virtual machine VM is not appropriately identifiable, due to a measurement error. 
     Thus, the method execution module  132  calculates the number of the load-applying virtual machines, in accordance with an expression 1 below. The “bandwidth of physical path” in the expression 1 is the maximum bandwidth that the LAN cable  200  is able to use, and the “coefficient” in the expression 1 is a value adjusted in accordance with the environment. The “measurement error” in the expression 1 is the difference between the measured value of the access that is measured for a case where one measurement virtual machine VM has applied the maximum access load and the maximum access load. 
       Number of load-applying virtual machines=bandwidth of physical path/(measurement error*coefficient).   Expression 1:
 
     For example, a case is illustrated as an example where the bandwidth of the physical path is 10 gigabits per second (Gbps), the coefficient is 4, and the measurement error is 100 MB. The measurement error of 100 MB indicates that, in the case where the maximum access load of 2 gigabytes (GB) has been applied, for example, there is a fluctuation range of 5% (=100 MB) in the measured amount of access. In this case, the method execution module  132  calculates the number of the load-applying virtual machines as 25 (=10 GB/100 MB*4). 
     In this manner, the method execution module  132  calculates the number of the measurement virtual machines to be deployed, on the basis of the difference between the measured value and the access load for a case where one measurement virtual machine VM has applied the maximum access load and the bandwidth of the physical path  200 . Accordingly, the method execution module  132  is able to acquire the number for the deployment with which the influence of the measurement result of another measurement virtual machine VM is made appropriately identifiable. Therefore, it is possible to appropriately identify the measurement virtual machines VM that share the same LAN cable  200 . 
     S 32 : The method execution module  132  calculates the respective numbers of the steady-load virtual machines VM and the fluctuating-load virtual machines VM. The number of the fluctuating-load virtual machines VM is at least one or more. In this embodiment, a case is illustrated as an example where there is one fluctuating-load virtual machine VM. Thus, in the case where the measurement virtual machines VM are to be deployed in correspondence with  25  as the number of the load-applying virtual machines, for example, the method execution module  132  calculates the number of the fluctuating-load virtual machines VM as 1, and the number of the steady-load virtual machines VM as 24. 
     This example is not limiting, and a plurality of the fluctuating-load virtual machines VM may be deployed. A case where a plurality of the fluctuating-load virtual machines VM are deployed will be described later as a different embodiment. 
     S 33 : The method execution module  132  selects one method from the plurality of methods and, in accordance with the selected method, performs one round of the deployment and identification of the measurement virtual machine VM. The details of the processing of step S 33  will be described later with reference to  FIG. 13 . 
     S 34 : The method execution module  132  determines whether or not the deployment and identification have been performed for all of the physical servers intended to be tested. The method execution module  132  repeats the processing of step S 33 , until the deployment and identification are completed for all of the physical servers intended to be tested (while No in step S 34 ). 
     S 35 : In the case of the deployment and identification having been completed for all of the physical servers intended to be tested (Yes in step S 34 ), the method execution module  132  determines whether or not the processing of steps S 33  and S 34  has been executed, in accordance with all of the methods. In the case of the executions being incomplete (No in step S 35 ), the method execution module  132  selects a different method and performs the processing of steps S 33  and S 34 . 
     S 36 : In the case of the executions having been done in accordance with all of the methods (Yes in step S 35 ), the method execution module  132  determines whether or not there are a plurality of the methods that have identified the sharing relationship. In the case of the sharing relationship having been identified with only one method (No in step S 36 ), the method execution module  132  performs the processing of step S 22  (in  FIG. 9 ) using only the method with which the sharing relationship has been identified. Accordingly, the method execution module  132  selects only the method with effectiveness. 
     S 37 : In the case of the sharing relationship having been identified with a plurality of the methods (Yes in step S 36 ), the method execution module  132  ranks the methods in descending order of the number of the measurement virtual machines VM for which the sharing relationship has been identified. The method execution module  132  performs the processing of step S 22  (in  FIG. 9 ) in the ranked method order. Accordingly, the method execution module  132  allows the deployment and identification to be performed in the method order with which more sharing relationships are identifiable and allows the sharing relationships to be identified efficiently. 
     In this embodiment, the method execution module  132  gives a ranking, such as “1: Method  1 , 2: Method  2 ,” on the basis of the number of the measurement virtual machines VM for which the sharing relationship has been identified with each method as a result of performing the deployment and identification for the physical servers PM held in the racks R 1  to R 3 . 
     Method  1  and Method  2   
     The methods will be described with reference to  FIGS. 11 and 12 . As described above, the method is a measure taken to select the physical server PM in which the measurement virtual machine VM is intended to be deployed, in order to allow an efficient identification of the measurement virtual machines VM that share the same LAN cable  200 . 
     (Method  1 ) 
       FIG. 11  is a diagram illustrating an example of the physical server PM selected in accordance with the method  1 .  FIG. 11  illustrates an example of the list of the physical servers PM held in the racks R 1  and R 2 . As illustrated in  FIG. 11 , the rack R 1  holds physical servers PM 1 - 1  to PM 1 - 20 , and the rack R 2  holds physical servers PM 2 - 1  to PM 2 - 20 . 
     Although not illustrated in the drawing, each physical server PM connects with the LAN cable  200  via a network device, such as a switch or a router. The method execution module  132  assumes that the possibility of the same LAN cable  200  being shared is higher for a plurality of the virtual machines VM connecting with the same network device, relative to a plurality of the virtual machines VM connecting with different network devices. Thus, the method execution module  132  deploys the measurement virtual machine VM preferentially to a plurality of the physical servers PM with the same network devices that the physical servers PM connect to. 
     In the method  1 , the measurement virtual machines VM deployed in the physical servers PM held in the same rack are considered as a plurality of the physical servers PM with the same network device that the physical servers PM connect to. That is, according to the method  1 , the plurality of physical servers PM for which the connecting network device is the same include a plurality of the physical servers PM for which the rack (holding device) holding the physical server PM is the same. 
     According to the example of  FIG. 11 , the method execution module  132  deploys the measurement virtual machine VM preferentially to, for example, the physical servers PM 1 - 1  to PM 1 - 20  held in the rack R 1  (as illustrated by an arrow RX). For example, the method execution module  132  deploys the measurement virtual machines VM in the physical servers PM 1 - 1  to PM 1 - 20  in order from the physical server PM 1 - 1  of which the position within the rack is high or in the opposite order from the physical server PM 1 - 20 . 
     Accordingly, the method execution module  132  is able to deploy the measurement virtual machines VM in the physical servers PM with a high possibility of sharing the same LAN cable  200 . Therefore, the method execution module  132  is able to identify the sharing relationship efficiently. 
     For example, in the case of deploying the measurement virtual machines VM in correspondence with  25  as the number of the load-applying virtual machines, the method execution module  132  deploys the measurement virtual machines VM in the physical servers PM 1 - 1  to PM 1 - 14 , as illustrated by a dotted rectangle x 1  in  FIG. 11 . At this time, the method execution module  132  deploys the measurement virtual machine VM for each storage pool. Accordingly, for each storage pool SP, the sharing relationship, for the LAN cable  200 , of the measurement virtual machines VM that access the storage pool SP is made identifiable. 
     In this embodiment, the method execution module  132  deploys one fluctuating-load virtual machine VM. The method execution module  132  deploys the fluctuating-load virtual machine VM in the physical server PM of which the position within the rack is high, for example. The method execution module  132  deploys, for example, the fluctuating-load virtual machine VM 1 - 1 A and the steady-load virtual machine VM 1 - 1 B to VM 1 - 14 . 
     As illustrated by a dotted rectangle x 2 , the method execution module  132  upon the second round of the deployment and identification deploys the measurement virtual machines VM with respect to the physical server PM 1 - 15  to PM 2 - 8 . It is also similar for the third round of the deployment and thereafter. 
     (Method  2 ) 
       FIG. 12  is a diagram illustrating an example of the physical server PM selected in accordance with the method  2 .  FIG. 12  illustrates the list of the physical servers PM held in the racks R 1  to R 3 . The physical servers PM held by the racks R 1  and R 2  are as illustrated in  FIG. 11 , and the rack R 3  holds physical servers PM 3 - 1  to PM 3 - 20 . 
     In the method  2 , the measurement virtual machines VM deployed in the physical servers PM held in adjacent racks are considered as a plurality of the physical servers PM with the same network device that the physical servers PM connect to. That is, according to the method  2 , the plurality of physical servers PM for which the connecting network device is the same include a plurality of the physical servers PM for which the racks (holding devices) holding the physical servers PM are adjacent. 
     Accordingly, the method execution module  132  is able to deploy the measurement virtual machines VM in the physical servers PM with a high possibility of sharing the same LAN cable  200 . Therefore, the method execution module  132  is able to identify the sharing relationship efficiently. 
     According to the example of  FIG. 12 , the method execution module  132  deploys the measurement virtual machine VM preferentially to, for example, the physical servers PM 1 - 1  to PM 3 - 20  held in the adjacent racks R 1  to R 3 . The method execution module  132  deploys the measurement virtual machines VM in order from the physical servers PM in the adjacent racks R 1  to R 3  of which the positions within the rack are close to each other (as illustrated by an arrow RY). 
     The physical servers PM of which the positions within the rack are close are, for example, a combination of the physical servers PM 1 - 1 , PM 2 - 1 , and PM 3 - 1 , a combination of the physical server PM 1 - 2 , PM 2 - 2 , and PM 3 - 2 , and the like. 
     The method execution module  132  deploys the measurement virtual machines VM in the physical servers PM 1 - 1  to PM 1 - 4 , PM 2 - 1  to PM 2 - 4 , and PM 3 - 1  to PM 3 - 4 , as illustrated by a dotted rectangle y 1  in  FIG. 12 . As illustrated in  FIG. 12 , the method execution module  132  deploys the fluctuating-load virtual machine VM 2 - 1 A and the steady-load virtual machines VM 1 - 1 A to VM 3 - 4 . 
     As illustrated by a dotted rectangle y 2 , the method execution module  132  upon the second round of the deployment and identification deploys the measurement virtual machines VM with respect to the physical server PM 1 - 5  to PM 3 - 9 . It is also similar for the third round of the deployment and thereafter. 
     Next, with reference to  FIGS. 13 to 21 , the details of the processing of a case of performing the processing of step S 33  in  FIG. 10  will be described. In step S 33 , the method execution module  132  performs one round of the deployment and identification of the measurement virtual machine VM, in accordance with the selected method. 
     (Step S 33  in  FIG. 10  with Method  1 ) 
       FIG. 13  is a flowchart diagram illustrating the processing of step S 33  in  FIG. 10  in accordance with the method  1 . 
     S 41 : The method execution module  132  creates a plan to deploy the measurement virtual machines VM such that there is a one-to-one relationship between the storage pool SP and the measurement virtual machine VM. That is, in the case where one physical server PM includes two storage pools SP, the method execution module  132  creates a plan to deploy two virtual machines VM in the physical server PM. 
     S 42 : In accordance with the method  1 , the method execution module  132  selects the physical server PM in which the measurement virtual machine VM is intended to be deployed. For example, in the case where the number of the selected measurement virtual machines VM does not reach the number of the load-applying virtual machines, the method execution module  132  selects the physical server PM within a different rack. As described above with  FIG. 11 , the method execution module  132  selects, for example, the physical servers PM 1 - 1  to PM 1 - 14 . 
     S 43 : The method execution module  132  instructs the measurement virtual machine deployment module  134  to deploy the fluctuating-load virtual machine VM and the steady-load virtual machine VM with respect to the selected physical server PM. In response to the instruction, the measurement virtual machine deployment module  134  performs the deployment of the measurement virtual machine VM and the installation of the tool. Accordingly, the fluctuating-load virtual machine VM 1 - 1 A and the steady-load virtual machines VM 1 - 1 B to VM 1 - 14  are deployed. 
     (Step S 43  in  FIG. 13 ) 
       FIG. 14  is a flowchart diagram illustrating the processing of step S 43  in  FIG. 13   
     S 101 : In response to the instruction, the measurement virtual machine deployment module  134  deploys the measurement virtual machine VM in the selected physical server PM. 
     S 102 : The measurement virtual machine deployment module  134  installs the fluctuating-load tool  150   a  with respect to the virtual machine VM 1 - 1 A deployed in the physical server PM in which the fluctuating-load virtual machine VM is to be deployed. 
     S 103 : The measurement virtual machine deployment module  134  installs the steady-load tool  150   b  with respect to the respective virtual machines VM 1 - 1 B to VM 1 - 14  deployed in the physical server PM in which the steady-load virtual machine VM is to be deployed. 
     S 104 : The measurement virtual machine deployment module  134  makes a notification through a deployment complete notification with respect to the method execution module  132 . Return to the flowchart diagram in  FIG. 13 . 
     S 44 : When the deployment of the measurement virtual machine VM (in step S 43 ) is complete, the load setting module  133  sets the value of the access load with respect to the fluctuating-load tool  150   a  or the steady-load tool  150   b  that runs on the measurement virtual machine VM. The load setting module  133  gives an instruction to start the fluctuating-load tool  150   a  or the steady-load tool  150   b  and to start the load measurement modules  151   a  and  151   b.    
     Accordingly, in each measurement virtual machine VM, the throughput of the access processing in the time period of applying the access load is measured in accordance with the load measurement modules  151   a  and  151   b.    
     S 45 : With the measured-value collection module  131 , the measurement results of the throughput are collected from the respective measurement virtual machines VM and stored in a measured-load-value table  122 - 1 . 
     (Measured-Load-Value Table  122 - 1 ) 
       FIG. 15  is a diagram illustrating an example of the measured-load-value table  122 - 1 . In the measured-load-value table  122 - 1  in  FIG. 15 , the measurement results of the fluctuating-load virtual machine VM 1 - 1 A and the steady-load virtual machines VM 1 - 1 B and VM 1 - 2 A are excerpted and represented. 
     As illustrated in  FIG. 15 , the measured-load-value table  122 - 1  includes information of the rack holding the physical server PM in which the measurement virtual machine VM is deployed and the measured values of the throughput (MB/S) over time. In the example of  FIG. 15 , the measured-load-value table  122 - 1  includes the measured values for each minute. That is, times  1  to n are times for each minute. 
     According to the example of  FIG. 15 , the measured value of the fluctuating-load virtual machine VM 1 - 1 A fluctuates between a value of 70 MB and a value of 0 MB, and the measured value of the steady-load virtual machine VM 1 - 1 B fluctuates between a value of 50 MB and a value of 100 MB. The measured value of the steady-load virtual machine VM 1 - 2 A is a steady value of 100 MB. 
     S 46 : The method execution module  132  identifies the fluctuating-load virtual machine VM and the steady-load virtual machine VM that share the same LAN cable  200 , on the basis of the measured-load-value table  122 - 1 . The method execution module  132  stores the identified sharing relationship in the shared-bandwidth management table  121 . 
     (Identification of Sharing Relationship) 
     Specifically, the method execution module  132  identifies the combination of the steady- and fluctuating-load virtual machines VM that share the same LAN cable  200 , on the basis of the correlation of a first measurement result of the steady-load virtual machine VM and a second measurement result of the fluctuating-load virtual machine VM. 
     As described above with  FIGS. 4 to 6 , the measured values of the steady-load virtual machine VM and the fluctuating-load virtual machine VM that share the same LAN cable  200  have a correlation. Thus, the method execution module  132  is able to easily and appropriately identify the measurement virtual machines VM that share the same LAN cable  200 , on the basis of the correlation of the first and second measurement results. 
     More specifically, the method execution module  132  calculates the similarity in accordance with an expression 2 below and determines the presence or absence of a correlation on the basis of the similarity. The “reverse value of measured value of fluctuating-load virtual machine VM” in the expression 2 indicates the opposite result of the measurement result of the fluctuating-load virtual machine VM. For example, the “reverse value of measured value of fluctuating-load virtual machine VM” is the difference between the measured value measured when the maximum access load is applied and the measured value of the fluctuating-load virtual machine VM. 
     In this embodiment, the measured value measured for a case where the maximum access load has been applied is a value of 100 MB. The measured value is calculated on the basis of, for example, 25 as the number of the load-applying virtual machines, 4 as the coefficient, and 1 Gbps as the bandwidth that the LAN cable  200  is able to use. 
       Similarity=cosine(reverse value of measured value of fluctuating-load virtual machine VM, measured value of steady-load virtual machine VM).   Expression 2:
 
     The similarity indicates the proximity for the angle between the vector “reverse value of measured value of fluctuating-load virtual machine VM” and the vector “measured value of steady-load virtual machine VM.” A higher similarity of the vectors give a value closer to 1. Thus, the method execution module  132  identifies the combination of the fluctuating-load virtual machine VM and the steady-load virtual machine VM with which the calculated similarity is greater than or equal to a predetermined value, as the measurement virtual machines VM that share the same LAN cable  200 . The similarity for the expression 2 may be calculated in accordance with the reverse value of the measured value of the steady-load virtual machine VM and the measured value of the fluctuating-load virtual machine VM. 
     In this manner, the method execution module  132  calculates the correlation value for the difference between the measurement result of a case where the maximum access load has been applied and the first measurement result of the steady-load virtual machine VM and the second measurement result of the fluctuating-load virtual machine VM. Alternatively, the method execution module  132  calculates the correlation value for the difference between the measurement result of a case where the maximum access load has been applied and the second measurement result of the fluctuating-load virtual machine VM and the first measurement result of the fluctuating-load virtual machine VM. The method execution module  132  identifies the combination of the steady-load virtual machine VM and the fluctuating-load virtual machine VM for which the correlation value exceeds a predetermined value. 
     In this manner, it is possible to appropriately determine the presence or absence of a correlation in the measurement results, on the basis of the correlation value indicating the similarity of the reverse value of the measurement result of one and the measurement result of the other of the steady- and fluctuating-load virtual machines VM. Thus, the method execution module  132  is able to appropriately identify the combination of the steady-load virtual machine VM and the fluctuating-load virtual machine VM having a correlation in the measurement results. 
     The method of calculating the correlation value of the measurement results is not limited to the example in the expression 2. For example, the method execution module  132  may calculate the correlation value in accordance with the inverse Fourier transformation or other methods of calculating the similarity. 
     The method execution module  132  may determine that the sharing relationship with another measurement virtual machine VM is not present, in the case where the difference in the measured values for the respective times of the measurement results of the steady-load virtual machine is at a value of 0 or within a predetermined error range. The method execution module  132  may identify the combination of the measurement virtual machines VM for which the total of the measurement results coincides with or is close to the maximum bandwidth of the LAN cable  200 , as the measurement virtual machines VM that share the same LAN cable  200 . 
     (Step S 46  in  FIG. 13 ) 
       FIG. 16  is a diagram illustrating a calculation example for the similarity.  FIG. 16  illustrates the reverse value of the measured value of the fluctuating-load virtual machine VM 1 - 1 A. The method execution module  132  calculates, as the reverse value, the difference between 100 MB as the maximum value of the measured value and the measured value. Thus, the reverse value for a time  1  is a value of 30 MB (=100−70). The reverse values are calculated in a similar manner for other times as well. 
     The method execution module  132  calculates that the similarity is 0.9852117, on the basis of the reverse value of the measurement result of the fluctuating-load virtual machine VM 1 - 1 A and the measurement result of the steady-load virtual machine VM 1 - 1 B, in accordance with the expression 2 described above. In a similar manner, the method execution module  132  calculates that the similarity is 0.8804711, on the basis of the reverse value of the measurement result of the fluctuating-load virtual machine VM 1 - 1 A and the measurement result of the steady-load virtual machine VM 1 - 2 A. 
     The method execution module  132  identifies that a plurality of the measurement virtual machines VM share the same LAN cable  200 , in the case where the similarity exceeds a predetermined value of 0.9, for example. The predetermined value is set in accordance with a test or the like. According to the example of  FIG. 16 , the method execution module  132  identifies the fluctuating-load virtual machine VM 1 - 1 A and the steady-load virtual machine VM 1 - 1 B as the measurement virtual machines VM that share the same LAN cable  200 . 
     (Shared-Bandwidth Management Table  121 - 1 ) 
       FIG. 17  is a diagram illustrating an example of a shared-bandwidth management table  121 - 1  created in step S 46  of  FIG. 13 . As illustrated in  FIG. 17 , the shared-bandwidth management table  121 - 1  includes a sharing identification (ID), a rack ID, a physical server ID, and a virtual machine ID. 
     The sharing ID is an identifier of the sharing group. The rack ID is an identifier of the rack holding the physical server PM, and the physical server ID is an identifier of the physical server PM in which the measurement virtual machine VM is deployed. The virtual machine ID is an identifier of the measurement virtual machine VM. 
     As illustrated in the shared-bandwidth management table  121 - 1 , the sharing group with a sharing ID of 1 includes information of the measurement virtual machines VM 1 - 1 A and VM 1 - 1 B. The shared-bandwidth management table  121 - 1  includes information of the physical servers PM in which the virtual machines VM 1 - 1 A and VM 1 - 1 B are deployed and information of the racks. 
     Next, the details of the processing in the case of performing the processing of step S 33  in  FIG. 10  on the basis of the method  2  will be described. 
     (Step S 33  in  FIG. 10  with Method  2 ) 
       FIG. 18  is a flowchart diagram illustrating the processing of step S 33  in  FIG. 10  in accordance with the method  2 . The processing of steps S 51  and S 53  to S 56  is similar to that of steps S 41  and S 43  to S 46  in  FIG. 13 , and therefore description will be omitted. 
     S 52 : In accordance with the method  2 , the method execution module  132  selects the physical server PM in which the measurement virtual machine VM is intended to be deployed. As described above with  FIG. 12 , the method execution module  132  selects, for example, the physical servers PM 1 - 1  to PM 1 - 4 , PM 2 - 1  to PM 2 - 4 , and PM 3 - 1  to PM 3 - 4 . 
     (Measured-Load-Value Table  122 - 2 ) 
       FIG. 19  is a diagram illustrating an example of a measured-load-value table  122 - 2  created in step S 55 . In the measured-load-value table  122 - 2  in  FIG. 19 , the measurement results of the fluctuating-load virtual machine VM 2 - 1 A and the steady-load virtual machines VM 1 - 1 A and VM 3 - 1  are excerpted and represented. 
     According to the example of  FIG. 19 , the measured value of the fluctuating-load virtual machine VM 2 - 1 A fluctuates between a value of 30 MB and a value of 90 MB, and the measured value of the steady-load virtual machine VM 1 - 1 A fluctuates between a value of 5 MB and a value of 30 MB. The measured value of the steady-load virtual machine VM 3 - 1  is a steady value of 100 MB. 
     (Step S 46  in  FIG. 13 ) 
       FIG. 20  is a diagram illustrating a calculation example for the similarity.  FIG. 19  illustrates the reverse value of the measured value of the fluctuating-load virtual machine VM 2 - 1 A. As described above, the method execution module  132  calculates, as the reverse value, the difference between 100 MB as the maximum value of the measured value and the measured value. Thus, the reverse value for the time  1  is a value of 70 MB (=100−30). The reverse values are calculated in a similar manner for other times as well. 
     The method execution module  132  calculates that the similarity is 0.9970795, on the basis of the reverse value of the measurement result of the fluctuating-load virtual machine VM 2 - 1 A and the measurement result of the steady-load virtual machine VM 1 - 1 A. In a similar manner, the method execution module  132  calculates that the similarity is 0.8834522, on the basis of the reverse value of the measurement result of the fluctuating-load virtual machine VM 2 - 1 A and the measurement result of the steady-load virtual machine VM 3 - 1 . 
     According to the example of  FIG. 20 , the method execution module  132  identifies the fluctuating-load virtual machine VM 2 - 1 A and the steady-load virtual machine VM 1 - 1 A as the measurement virtual machines VM that share the same LAN cable  200 . 
     (Shared-Bandwidth Management Table  121 - 2 ) 
       FIG. 21  is a diagram illustrating an example of a shared-bandwidth management table  121 - 2  created in step S 56  of  FIG. 18 . As illustrated in the shared-bandwidth management table  121 - 2 , the sharing group with the sharing ID of 1 includes information of the measurement virtual machines VM 1 - 1 A and VM 2 - 1 A that share the same LAN cable  200 . 
     The processing of step S 21  in  FIG. 9  has been described with reference to  FIGS. 10 to 21 . Next, the processing of steps S 22  to S 25  in  FIG. 9  will be described with reference to  FIGS. 22 to 30 . 
     Step S 22  in FIG.  9   
       FIG. 22  is a flowchart diagram illustrating the processing of step S 22  in  FIG. 9 . As described above, in step S 22 , the deployment and identification are performed thoroughly with respect to the remaining physical servers PM in accordance with the determined method order. That is, in step S 22 , the deployment and identification intended for the physical servers PM not held in the racks R 1  to R 3  are performed. 
     S 61 : The method execution module  132  selects a method at a higher rank. In this embodiment, the method execution module  132  first selects the method  1  that is at a high rank. 
     S 62 : In accordance with the selected method, the method execution module  132  performs the deployment and identification. The deployment and identification are as described for step S 33  in  FIG. 10 . The method execution module  132  performs the deployment and identification intended for the physical server PM for which the deployment and identification have not been performed in step S 21 . 
     S 63 : In the case where a new sharing relationship has been identified in step S 62 , the method execution module  132  determines whether or not the measurement virtual machine VM for which the sharing relationship is newly identified is included in the sharing group that has been already identified. 
     S 64 : With the method execution module  132 , in the case of the virtual machine VM being included (Yes in step S 63 ), information is added to the existing sharing group and joined with the shared-bandwidth management table  121 . Specifically, the method execution module  132  adds information of the sharing relationship that has been newly identified to the existing sharing group. 
     S 65 : With the method execution module  132 , in the case of the virtual machine VM not being included (No in step S 63 ), a new sharing group is created and joined with the shared-bandwidth management table  121 . Specifically, the method execution module  132  adds information of the new sharing relationship in the new sharing group of the shared-bandwidth management table  121 . 
     S 66 : In accordance with the selected method, the method execution module  132  determines whether or not the deployment and identification have been performed thoroughly with respect to all of the physical servers PM. In the case of a negative (No in step S 66 ), the method execution module  132  moves on to the processing in step S 62 . 
     S 67 : In the case of the deployment and identification having been performed thoroughly (Yes in step S 66 ), the method execution module  132  determines whether or not the executions have been done in accordance with all of the methods. In the case of the executions having been done in accordance with all of the methods (Yes in step S 67 ), the method execution module  132  terminates the processing in step S 22 . 
     S 68 : In the case of a negative (No in step S 67 ), the method execution module  132  selects a different method and moves on to the processing in step S 62 . 
     (Steps S 64  and S 65 ) 
       FIG. 23  is a diagram illustrating an example of the processing in step S 64 . In  FIG. 23 , the two shared-bandwidth management tables  121 - 1  and  121 - 2  are illustrated an example. 
     The shared-bandwidth management table  121 - 1  includes information of an already-identified first sharing group including the sharing relationship of the measurement virtual machine VM 1 - 1 A and VM 1 - 1 B. The shared-bandwidth management table  121 - 2  includes information of a newly-identified second sharing group including the sharing relationship of the measurement virtual machine VM 1 - 1 A and VM 2 - 1 A. 
     With the example of  FIG. 23  (for Yes in step S 63 ), there is an overlap of the measurement virtual machine VM 1 - 1 A between the first and second sharing groups. That is, the example of  FIG. 23  illustrates a case where the measurement virtual machine VM within the second sharing group for which the sharing relationship is newly identified is included in the first sharing group. Thus, a shared-bandwidth management table  121 - 11  includes information of the sharing group in which the first and second sharing groups are joined. 
       FIG. 24  is a diagram illustrating an example of the processing in step S 65 . In  FIG. 24 , two shared-bandwidth management tables  121 - 1  and  121 - 3  are illustrated an example. 
     The shared-bandwidth management table  121 - 1  includes information of the first sharing group in a similar manner to the shared-bandwidth management table  121 - 1  illustrated in  FIG. 23 . The shared-bandwidth management table  121 - 3  includes information of a newly-identified third sharing group including the sharing relationship of the measurement virtual machine VM 2 - 1 B and VM 3 - 1 . 
     With the example of  FIG. 24  (for No in step S 63 ), the measurement virtual machine VM with an overlap of the sharing relationship between the first and third sharing groups does not exist. Thus, a shared-bandwidth management table  121 - 12  includes information of the first and third sharing groups separately. 
     Step S 23  in FIG.  9   
       FIG. 25  is a flowchart diagram illustrating the processing of step S 23  in  FIG. 9 . As described above, in step S 23 , the re-deployment and identification intended for the measurement virtual machine VM for which the sharing relationship is not identified are performed. That is, the method execution module  132  performs the re-deployment and identification of the measurement virtual machine VM, intended for the measurement virtual machine VM of which the sharing relationship is yet to be identified even with the deployment and identification (in steps S 21  and S 22 ) having been performed in accordance with the method. 
     S 71 : The method execution module  132  selects the sharing groups in correspondence with the number of the load-applying virtual machines from the sharing groups to which a single measurement virtual machine VM belongs. The method execution module  132  selects the measurement virtual machine VM of the selected sharing group and selects the measurement virtual machines VM in correspondence with the number of the load-applying virtual machines. 
     S 72 : The method execution module  132  selects one out of the selected measurement virtual machines VM as the fluctuating-load virtual machine VM and the others as the steady-load virtual machines VM. The method execution module  132  performs the re-deployment and identification. The deployment and identification are as described for steps S 43  to S 46  in  FIG. 13  (and similarly for steps S 53  to S 56  in  FIG. 18 ). 
     S 73 : With the method execution module  132 , in the case where a new sharing relationship has been identified in accordance with step S 72 , the sharing groups are joined and stored in the shared-bandwidth management table  121 . Specifically, the method execution module  132  integrates the sharing relationship into the sharing group with a smaller value of the sharing ID, between the sharing groups for which the sharing relationship is identified. 
     S 74 : The method execution module  132  determines whether or not the processing of steps S 72  and S 73  has been performed for all of the combinations of the sharing groups to which a single measurement virtual machine VM belongs. 
     S 75 : In the case of a negative (No in step S 74 ), the method execution module  132  selects the sharing group to which a single measurement virtual machine VM belongs and for which the determination is yet to be performed and selects the measurement virtual machine VM. The method execution module  132  moves on to the processing of step S 72 . In the case of a positive (Yes in step S 74 ), the method execution module  132  terminates the processing of step S 23 . 
     (Processing Flow of Step S 23 ) 
       FIG. 26  is a diagram schematically illustrating the processing of step S 23 , described with the flowchart diagram in  FIG. 25 .  FIG. 26  illustrates an example of the change over time with sharing group sets T 11  to T 13 . 
     According to the first sharing group set T 11 , sharing groups ID 10  to ID 13  include single measurement virtual machines VM 7 - 1 A, VM 8 - 1 A, and VM 9 - 1 A. Thus, the method execution module  132  selects the measurement virtual machines VM 7 - 1 A, VM 8 - 1 A, and VM 9 - 1 A (in step S 71  of  FIG. 25 ). The method execution module  132  performs the re-deployment and identification (in step S 72 ). 
     In the example of  FIG. 26 , the sharing relationship of the measurement virtual machines VM 7 - 1 A and VM 8 - 1 A is identified. Thus, as illustrated in the second sharing group set T 12 , the method execution module  132  integrates the sharing group ID 11  into the sharing group ID 10  with a smaller value of the sharing ID (in step S 73 ). As illustrated in the third sharing group set T 13 , the method execution module  132  changes the sharing group ID 12  to the sharing group ID 11 . 
     In this manner, with the method execution module  132 , a plurality of the measurement virtual machines VM not included in a plurality of the identified measurement virtual machines VM are selected, and the re-deployment, in each physical server PM in which each selected measurement virtual machine VM has been deployed, and identification of the first or second measurement virtual machine VM are performed. Accordingly, the method execution module  132  is able to efficiently identify the sharing relationship that has not been identifiable with the method. 
     Step S 24  in FIG.  9   
       FIG. 27  is a flowchart diagram illustrating the processing of step S 24  in  FIG. 9 . As described above, in step S 24 , the sharing relationship between the identified sharing groups is identified. 
     S 81 : The method execution module  132  selects the sharing groups in correspondence with the number of the load-applying virtual machines from the sharing groups that include a plurality of the measurement virtual machines VM. The method execution module  132  selects one measurement virtual machine VM from each of the selected sharing groups. Accordingly, the measurement virtual machines VM in correspondence with the number of the load-applying virtual machines are selected. 
     The processing of steps S 82  and S 83  is similar to the processing of steps S 72  and S 73  in  FIG. 25 . 
     S 84 : The method execution module  132  determines whether or not the processing of steps S 82  and S 83  has been performed for all of the combinations of the sharing groups including a plurality of the measurement virtual machines VM. 
     S 85 : In the case of a negative (No in step S 84 ), the method execution module  132  selects the sharing groups that include a plurality of the measurement virtual machines VM and for which the determination is yet to be performed and selects the measurement virtual machine VM. The method execution module  132  moves on to the processing of step S 82 . In the case of a positive (Yes in step S 84 ), the method execution module  132  terminates the processing of step S 24 . 
     (Processing Flow of Step S 24 ) 
       FIG. 28  is a diagram schematically illustrating the processing of step S 24 , described with the flowchart diagram in  FIG. 27 .  FIG. 28  illustrates an example of the change over time with sharing group sets T 21  to T 24 . 
     According to the first sharing group set T 21 , sharing groups ID 1  to ID 3  each include a plurality of the measurement virtual machines. The method execution module  132  selects the sharing groups ID 1  to ID 3 , and selects measurement virtual machines VM 2 - 1 A, VM 3 - 1 A, and VM 4 - 11 A as ones representing the plurality of measurement virtual machines VM included in the sharing groups (in step S 81  of  FIG. 27 ). The method execution module  132  performs the re-deployment and identification (in step S 82 ). 
     In the example of  FIG. 28 , the sharing relationship of the measurement virtual machines VM 2 - 1 A and VM 3 - 1 A is identified. Thus, as illustrated in the second sharing group set T 22 , the method execution module  132  integrates the sharing group ID 2  into the sharing group ID 1  with a smaller value of the sharing ID (in step S 83 ). 
     As illustrated in the third sharing group set T 23 , the method execution module  132  changes sharing groups ID 3  to ID 5  to sharing groups ID 2  to ID 4 . As illustrated in the fourth sharing group set T 24 , the method execution module  132  selects the sharing groups ID 3  and ID 4  that have been yet to be selected, in addition to the sharing group ID 1 , and performs the re-deployment and identification (in steps S 81  and S 82 ). 
     In this manner, the method execution module  132  selects one virtual machine VM from each of respective measurement virtual machine VM sets each including a plurality of the identified measurement virtual machines VM. The method execution module  132  performs the re-deployment, in each physical server PM in which each selected measurement virtual machine VM has been deployed, and identification of the first virtual machine VM or the second measurement virtual machine VM. 
     In this manner, by identifying the sharing relationship between the sharing groups, the method execution module  132  is able to identify the virtual machines VM that share the same LAN cable  200  more efficiently. Since the measurement virtual machines except for one out of the sharing group are able to be excluded from those intended for the next round of the deployment and thereafter, it is possible to reduce the number of rounds of the deployment and identification. 
     Step S 25  in FIG.  9   
       FIG. 29  is a flowchart diagram illustrating the details of the processing of step S 25  in  FIG. 9 . As described above, in step S 25 , the destination of the deployment of the demanded virtual machine for which the deployment has been demanded by the user is determined on the basis of information of the identified sharing group. 
     S 91 : The method execution module  132  references the shared-bandwidth management table  121  and selects the sharing group having an available bandwidth out of the sharing groups. The method execution module  132  calculates the available bandwidth in accordance with an expression 3 below. 
       Available bandwidth=bandwidth that physical path is able to use−sum of already-allocated guaranteed bandwidth of sharing group.   Expression 3:
 
     For example, the method execution module  132  acquires the “bandwidth that physical path is able to use” corresponding to the sharing group. For example, the method execution module  132  acquires the bandwidth that the physical path is able to use, on the basis of the measurement result. 
     S 92 : The method execution module  132  determines whether or not a sharing group with an available bandwidth to which the demanded bandwidth demanded by the user is allocatable is present for the demanded virtual machine. In the case of the sharing group being absent (No in step S 92 ), the method execution module  132  makes a notification through a message that the demanded bandwidth is not able to be reliably provided and terminates the processing. 
     S 93 : In the case of the sharing group being present (Yes in step S 92 ), the method execution module  132  selects, out of the physical servers PM belonging to the sharing group, the physical server PM with a small number of the deployed demanded virtual machines and with a small bandwidth that has already been allocated to the storage pool SP. 
     S 94 : With the method execution module  132 , information of the ID of the demanded virtual machine and the demanded bandwidth of the demanded virtual machine is registered in the shared-bandwidth management table  121 . 
     (Processing Flow of Step S 25 ) 
       FIG. 30  is a diagram schematically illustrating the processing of step S 25 .  FIG. 30  illustrates an example of shared-bandwidth management tables  121   a  and  121   b  after the processing of step S 25 . Relative to the shared-bandwidth management tables  121 - 1  and  121 - 2  described with  FIGS. 17 and 21 , the shared-bandwidth management tables  121   a  and  121   b  illustrated in  FIG. 30  further include information of the bandwidth of the physical path, the ID of the storage pool SP, and the guaranteed bandwidth of the demanded virtual machine. 
     The shared-bandwidth management table  121   a  in  FIG. 30  illustrates an example of a case where demanded virtual machines VMx 1  to VMx 6  of which the deployment has been demanded by the user have already been deployed and where further a demanded virtual machine VMxx is to be deployed. For this example, an example is illustrated of a case where the guaranteed bandwidth of the demanded virtual machine VMxx is 4 Gbps. 
     According to the shared-bandwidth management table  121   a,  the bandwidth of the LAN cable  200  is 10 Gbps for the sharing group ID 1 , while the total of the bandwidths that have already been allocated is at a value of 6 Gbps (=1+2+3). Thus, the available bandwidth of the sharing group ID 1  is at a value of 4 Gbps (=10−6). The available bandwidth of the sharing group ID 2  is at a value of 3 Gbps, and the available bandwidth of the sharing group ID 3  is at a value of 1 Gbps. 
     Thus, the group that is able to reliably provide the guaranteed bandwidth of 4 Gbps is the sharing group ID 1 . Out of the physical servers PM belonging to the sharing group ID 1 , the physical server PM 1 - 3  is without a demanded virtual machine VM deployed and without a bandwidth that has already been allocated to a storage pool SP 13 . Thus, the method execution module  132  determines that the demanded virtual machine VMxx is to be deployed in the physical server PM 1 - 3 . 
     The method execution module  132  stores information of the ID “VMxx” and the demanded bandwidth of 4 Gbps of the demanded virtual machine in the item for the physical server PM 1 - 3  in the shared-bandwidth management table  121   b.    
     Increasing Efficiency of Identification of Sharing Relationship 
     With the network evaluation program  120  in this embodiment, as described for step S 24 , it is possible to exclude the steady-load virtual machine VM for which the sharing relationship with the fluctuating-load virtual machine VM has been identified, from those intended for the next round of the deployment and thereafter. Accordingly, it is possible to reduce the number of rounds of the deployment and identification, and it is possible to reduce the number of actions taken for the identification of the sharing relationship. 
       FIG. 31  is a diagram illustrating the number of actions taken for the identification of the sharing relationship.  FIG. 31  illustrates an example of a case of identifying the sharing relationship of 10 measurement virtual machines VM, the case being such that four measurement virtual machines VM are deployed in one round of the deployment and identification. For example, in the case of determining the sharing relationships of the 10 measurement virtual machines VM by brute force, for four at a time, there are  210  combinations (=combination (10, 4)) for the determination. In contrast, with the network evaluation program  120  of this embodiment, it is possible to identify the sharing relationships in seven rounds of the deployment and identification. 
     As illustrated in  FIG. 31 , in the first round, the deployment and identification of a fluctuating-load virtual machine  1  and steady-load virtual machines  2  to  4  are performed. In the second round, steady-load virtual machines  5  to  7  that have been yet to be deployed, in addition to the fluctuating-load virtual machine  1 , are deployed. In the third round, steady-load virtual machines  8  to  10  that have been yet to be deployed, in addition to the fluctuating-load virtual machine  1 , are deployed. Accordingly, a sharing group (of 1, 2, 4, 9, and 10) is identified. 
     In the fourth round, a fluctuating-load virtual machine  3  and the steady-load virtual machines  5  to  7  for which the sharing relationship is yet to be identified are deployed, and a sharing group (of 3 and 6) is identified. In a similar manner, in the fifth round, the fluctuating-load virtual machine  3  and the steady-load virtual machine  8  for which the sharing relationship is yet to be identified are deployed, and the identification is performed. In the sixth round, a fluctuating-load virtual machine  5  and the steady-load virtual machines  7  and  8  for which the sharing relationship is yet to be identified are deployed, and the identification is performed. In the seventh round, a fluctuating-load virtual machine  7  and the steady-load virtual machine  8  for which the sharing relationship is yet to be identified are deployed, and the identification is performed. 
     Accordingly, sharing groups of “1, 2, 4, 9, and 10,” “3 and 6,” “5,” “7,” and “8” are identified. In this manner, by executing the seven rounds of the deployment and identification, the network evaluation program  120  is able to reduce the number of rounds of the deployment and identification and reduce the number of actions taken for the identification of the sharing relationship, relative to the  210  combinations of the case where the identification is done through brute force. 
     Different Embodiment 
     In the embodiment described above, a case has been illustrated as an example where one measurement virtual machine VM out of the plurality of measurement virtual machines VM is the fluctuating-load virtual machine VM. Note that the method execution module  132  may deploy two or more of the fluctuating-load virtual machines VM. By increasing the number of the fluctuating-load virtual machines VM, it is possible to identify more sharing relationships in one round of the deployment and identification. 
     In the case of deploying a plurality of the fluctuating-load virtual machines VM, the method execution module  132  causes the fluctuation cycles of the access load of the plurality of fluctuating-load virtual machines VM to be different. That is, the method execution module  132  identifies a plurality of the virtual machines VM that share the same physical path, on the basis of the measurement results for a case where one or more of the first virtual machines VM and a plurality of the second virtual machines VM with the different fluctuation cycles of the access load have been executed. 
     In this manner, with the fluctuation cycles being different, the method execution module  132  is able to identify the fluctuating-load virtual machine VM having a correlation with the steady-load virtual machine VM in the measurement results. Accordingly, in the case where the steady-load virtual machine VM has a sharing relationship with any of the plurality of fluctuating-load virtual machines VM, it is possible to appropriately identify the combination of the steady-load virtual machine VM and the fluctuating-load virtual machine VM having the sharing relationship. 
     With the fluctuation cycles being different, it is possible to appropriately identify the presence or absence of the sharing relationship of the steady-load virtual machine VM with the plurality of fluctuating-load virtual machines VM, also in the case where the steady-load virtual machine VM has a sharing relationship with two of the plurality of fluctuating-load virtual machines VM. 
     Example of Measurement Result 
       FIGS. 32 and 33  are diagrams illustrating an example of the measurement results for a case where two of the fluctuating-load virtual machines VM and the steady-load virtual machine VM share the same LAN cable  200 . 
       FIG. 32  is a diagram illustrating an example of the access loads and the measurement results of the first and second fluctuating-load virtual machines VM. 
     A graph g 7   a  in the upper left in  FIG. 32  illustrates the change in the access load applied by the first fluctuating-load virtual machine VM, and a graph g 7   b  illustrates the measured value of the first fluctuating-load virtual machine VM. A graph g 8   a  in the lower left in  FIG. 32  illustrates the change in the access load applied by the second fluctuating-load virtual machine VM, and a graph g 8   b  illustrates the measured value of the second fluctuating-load virtual machine VM. As illustrated in the graphs g 7   a  and g 8   a,  the fluctuation cycles of the access loads applied by the first and second fluctuating-load virtual machines are different from each other. 
       FIG. 33  is a diagram illustrating an example of the access load and the measurement result of the steady-load virtual machine VM. A graph g 9   a  in the upper left in  FIG. 33  illustrates the change in the access load applied by the steady-load virtual machine VM, and a graph g 9   b  illustrates the measured value of the steady-load virtual machine VM. 
       FIGS. 32 and 33  illustrate a case where the same LAN cable  200  is shared between the first and second fluctuating-load virtual machines VM and the steady-load virtual machine VM. Thus, the measured value of the steady-load virtual machine VM (in the graph g 9   b ), being subject to the influence of the sum total of the access load applied by the first and second fluctuating-load virtual machines VM (in the graphs g 7   a  and g 8   a ), fluctuates. 
     The measured values of the first and second fluctuating-load virtual machines VM (in the graphs g 7   b  and g 8   b ), being subject to the influence of the total sum of the access load applied by the steady-load virtual machine VM and the other fluctuating-load virtual machine VM, fluctuate. As illustrated in a graph ge, the total of the measured values coincides with the maximum bandwidth of the LAN cable  200 . 
     In this manner, the network evaluation program  120  is able to determine the sharing relationship of the steady-load virtual machine VM and a plurality of the fluctuating-load virtual machines VM, on the basis the correlation between the measurement result of the steady-load virtual machine VM and the total of the measurement results or each measurement result of the two fluctuating-load virtual machines VM. 
     While a case is illustrated as an example where each communication is made over one LAN cable  200  in this embodiment, this example is not limiting. It is effective also for a case where each communication is made over a plurality of the LAN cables  200 . 
     All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.