Patent Publication Number: US-2015074251-A1

Title: Computer system, resource management method, and management computer

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a system, a method, and an apparatus that are used in a management subject system where a plurality of computer systems are built to hierarchically present the reliability of the computer systems. 
     It is necessary in resource management and infrastructure management to allocate resources in a manner appropriate for the use. “Appropriate” allocation means providing a quality and agility that match the price paid by an end user. A resource administrator therefore needs to keep information for determining whether a computer system is capable of meeting a user&#39;s request. Grasping this information is difficult in a large-scale system environment where a diversity of IT equipment and middleware is used mixedly. 
     A method of evaluating the qualities of computer systems and classifying the computer systems by their reliability levels, and a method of migrating resources between computer systems of different reliability levels are being sought. 
     SUMMARY OF THE INVENTION 
     Resource administrators have hitherto manually determined whether or not a computer system that satisfies reliability demanded by a user can be built based on configuration information of computer systems and connection information which indicates the coupling relationship between components (see, for example, JP 2011-018198 A). 
     JP 2011-018198 A describes that a management server holds configuration information of functions of heterogeneous resources and configures resource functions to functional requirements, and the management server allocate resources that match a user&#39;s request in a computer system pooled resources are not homogeneous. 
     The technology of JP 2011-018198 A, however, is not capable of optimizing the count of computer systems whose reliability meets the user&#39;s demand by presenting computer system reliability that is demanded by the user and changing the computer system configuration as needed. 
     The present invention can be appreciated by the description which follows in conjunction with the following figures, wherein: a computer system, comprising: at least one computer; at least one network apparatus; at least one storage apparatus; and a plurality of service systems for use in execution of given services. The at least one computer includes at least one first processor, a first memory coupled to the at least one first processor, and a plurality of first I/O devices coupled to the at least one first processor. The at least one storage apparatus includes a second memory, at least one storage medium, and at least one second I/O device for coupled to another apparatus. The at least one network apparatus includes a third memory and at least one port for coupling to another apparatus. The at least one computer further includes a system control part for managing the plurality of service systems. The system control part being configured to: hold system configuration information for managing configurations of the plurality of service systems, and evaluation information for managing evaluation values that indicate reliability of the plurality of service systems in the services; obtain configuration information of the service systems from the system configuration information in a case of evaluating the reliability of the service systems in the services; calculate the evaluation values of the service systems based on the obtained configuration information of the service systems and the evaluation information; and generate information that indicates the reliability of the service systems based on the calculated evaluation values. 
     According to one embodiment of this invention, the reliability of a service system in a service can be evaluated as a numerical value, thereby facilitating the determination of the reliability of a service system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be appreciated by the description which follows in conjunction with the following figures, wherein: 
         FIG. 1  is an explanatory diagram illustrating an example of the configuration of a management subject system according to a first embodiment of this invention, 
         FIG. 2  is a block diagram illustrating the configuration of a management server according to the first embodiment of this invention 
         FIG. 3  is a block diagram illustrating the configuration of a server according to the first embodiment of this invention, 
         FIG. 4  is a block diagram illustrating a configuration example of virtual servers that run on each server according to the first embodiment of this invention, 
         FIGS. 5A and 5B  are explanatory diagrams outlining the first embodiment of this invention, 
         FIG. 6  is an explanatory diagram showing an example of system management information according to the first embodiment of this invention, 
         FIGS. 7A and 7B  are explanatory diagrams showing an example of system configuration information according to the first embodiment of this invention, 
         FIG. 8  is an explanatory diagram showing an example of connection relationship evaluation information according to the first embodiment of this invention, 
         FIG. 9  is an explanatory diagram showing an example of configuration requirement information according to the first embodiment of this invention, 
         FIG. 10  is an explanatory diagram showing an example of service management information according to the first embodiment of this invention, 
         FIG. 11  is a flow chart illustrating processing that is executed by control part according to the first embodiment of this invention, 
         FIG. 12  is a flow chart illustrating processing that is executed by a reliability determining part according to the first embodiment of this invention, 
         FIG. 13  is a flow chart illustrating processing that is executed by a configuration determining part according to the first embodiment of this invention, 
         FIG. 14  is a flow chart illustrating processing that is executed by a configuration changing part according to the first embodiment of this invention, 
         FIG. 15  is a flow chart illustrating processing that is executed by an evaluation value changing part according to the first embodiment of this invention, and 
         FIG. 16  is an explanatory diagram illustrating an example of a resource management screen according to the first embodiment of this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
       FIG. 1  is an explanatory diagram illustrating an example of the configuration of a management subject system according to a first embodiment of this invention. 
     The management subject system according to the first embodiment includes a plurality of computer systems. The computer systems include a management server  101 , servers  102 , a virtual server management server  151 , a storage subsystem  105 , a network switch for management (NW-SW)  103  and a network switch for service (NW-SW)  104 , and a fiber channel switch (FC-SW)  108 . 
     The management server  101  manages the group of computer systems included in the management subject system. The management server  101  is coupled via the NW-SW  103  to a management interface (management I/F)  113  of the NW-SW  103 , and to a management interface  114  of the NW-SW  104 . The management server  101  can set a virtual LAN (VLAN) for each of the NW-SWs  103  and  104 . 
     To the NW-SW  103 , in addition to the management server  101  and the servers  102 , the virtual server management server  151  for managing virtual servers (virtual machines) running on the servers  102  is coupled. 
     The NW-SW  103  constructs a network for management. The network for management is a network used by the management server  101  to manage operations such as distribution of an OS and applications running on the plurality of physical servers  102  and power supply control. 
     The NW-SW  104  constructs a network for service. The network for service is a network used by applications that are executed by virtual servers on the servers  102 . The NW-SW  104  is coupled to a WAN or the like to communicate to/from client computers outside a virtual computer system. 
     The management server  101  is coupled via the FC-SW  108  to the storage subsystem  105 . The management server  101  manages logical units (LUs) in the storage subsystem  105 . In the example illustrated in  FIG. 1 , the management server  101  manages N LUs, namely, an LU1 to an LUn. 
     On the management server  101 , a control part  110  for managing resources included in the computer systems such as the servers  102  is executed. The control part  110  refers to and updates a management information group  111 . The management information group  111  is updated by the control part  110  in given cycles. 
     The servers  102  included in the management subject system provide virtual servers as described later. The servers  102  are coupled via a PCIex-SW  107  and I/O devices to the NW-SWs  103  and  104 . 
     To the PCIex-SW  107 , the I/O devices compliant with the PCI Express standard are coupled. The I/O devices include I/O adapters such as network interface cards (NICs), host bus adapters (HBAs), and converged network adapters (CNAs). 
     In general, the PCIex-SW  107  is an I/O switch for extending a bus of the PCI Express out from a mother board (or server blade) to couple more PCI-Express devices. It should be noted that a system configuration in which the servers  102  are directly coupled to the NW-SWs  103  and  104  without the intermediation of the PCIex-SW  107  may be employed. 
     The management server  101  is coupled to a management interface  117  of the PCIex-SW  107  to manage coupling relationships between the plurality of servers  102  and the I/O devices. The server  102  makes an access via the I/O devices (in  FIG. 1 , HBAs) coupled to the PCIex-SW  107  to the LU1 to LUn of the storage subsystem  105 . 
     The virtual server management server  151  manages a first virtualization part  401  illustrated in  FIG. 4  and second virtual servers  404  illustrated in  FIG. 4 , which are executed on each of the servers  102 . Specifically, a virtual server management part  161  issues instructions to the first virtualization part  401 . 
     For example, the virtual server management part  161  issues an instruction to execute power supply control for the second virtual servers  404  and an instruction to execute migration of the second virtual servers  404  and the first virtualization part  401 . The management server  101  may include the virtualization server management part  161 . 
     In this embodiment, the servers  102 , the I/O devices, the NW-SW  104 , the storage subsystem  105 , the FC-SW  108 , and others are used to build a plurality of computer systems having given functions. 
       FIG. 2  is a block diagram illustrating the configuration of the management server  101  according to the first embodiment of this invention. 
     The management server  101  includes a processor  201 , a memory  202 , a disk interface  203 , and a network interface  204 . 
     The processor  201  executes programs stored in the memory  202 . The memory  202  stores a program executed by the processor  201  and information necessary to execute the program. What programs and information are stored in the memory  202  is described later. 
     The disk interface  203  is an interface for accessing the storage subsystem  105 . The network interface  204  is an interface for holding communication to and from other apparatus over an IP network. 
     Though not shown in  FIG. 2 , the management server  101  may include a basement management controller (BMC) for controlling power supply and controlling the interfaces, and a PCI-Express interface for coupling to the PCIex-SW  107 . 
     The memory  202  stores a program that implements the control part  110  and the management information group  111 . The control part  110  is constructed of a plurality of program modules and provides functions for performing various types of control. Specifically, the control part  110  includes an event detecting part  210 , a reliability calculating part  211 , a reliability determining part  212 , a configuration determining part  213 , a configuration changing part  214 , an evaluation value changing part  215 , and a display part  216 . 
     The event detecting part  210  detects various events. For instance, the event detecting part  210  detects, as events, migration, power management, a failure in one of the servers  102 , and a request to change settings. The event detecting part  210  calls up one of functional parts described later that is relevant to the detected event. 
     The reliability calculating part  211  calculates a value that indicates the reliability of a computer system. The value indicating the reliability of a computer system is hereinafter also referred to as evaluation value. The reliability determining part  212  determines whether or not a computer system fulfills a given requirement based on an evaluation value calculated by the reliability calculating part  211 . Details of the processing that is executed by the reliability determining part  212  are described later with reference to  FIG. 12 . 
     The configuration determining part  213  determines whether or not a computer system that fulfills a given requirement can be built. Details of the processing that is executed by the configuration determining part  213  are described later with reference to  FIG. 13 . The configuration changing part  214  changes the current computer system configuration in order to build a computer system determined as buildable by the configuration determining part  213 . Details of the processing that is executed by the configuration changing part  214  are described later with reference to  FIG. 14 . 
     The evaluation value changing part  215  changes an evaluation value. Details of the processing that is executed by the evaluation value changing part  215  are described later with reference to  FIG. 15 . The display part  216  displays the results of various types of processing. 
     The processor  201  loads the functional parts, which are the event detecting part  210 , the reliability calculating part  211 , the reliability determining part  212 , the configuration determining part  213 , the configuration changing part  214 , the evaluation value changing part  215 , and the display part  216 , onto the memory  202  as programs, and executes the loaded programs. 
     The processor  201  operates as programmed by the programs of the functional parts, thereby operating as functional parts for implementing given functions. For instance, the processor functions as the reliability calculating part  211  by operating as programmed by the program that implements the reliability calculating part  211 . The same applies to the rest of the programs. The processor  201  also operates as functional parts that respectively implement a plurality of processing procedures executed by the respective programs. 
     The management information group  111  stores various types of information for managing the computer systems. Specifically, the management information group  111  includes system management information  220 , system configuration information  221 , connection relationship evaluation information  222 , configuration requirement information  223 , and service management information  224 . 
     Stored as the system management information  220 , for every computer system included in the management subject system, is information for managing the system configuration of the computer system. Details of the system management information  220  are described later with reference to  FIG. 6 . 
     Stored as the system configuration information  221  is information for managing the detailed configurations of the respective computer systems. Details of the system configuration information  221  are described later with reference to  FIGS. 7A and 7B . 
     Stored as the connection relationship evaluation information  222  is information about a reference for determining the reliability of a computer system and the reliability in a connection relationship between components of a computer system. Details of the connection relationship evaluation information  222  are described later with reference to  FIG. 8 . 
     Stored as the configuration requirement information  223  is information about a computer system configuration requested by a user. Details of the configuration requirement information  223  are described later with reference to  FIG. 9 . Stored as the service management information  224  is information about services provided with the use of the respective computer systems. Details of the service management information  224  are described later with reference to  FIG. 10 . 
     Information to be stored in the management information group  111  may be collected automatically by using a standard interface or an information collection program, or may be input from a console (not shown) of the management server  101  by a system administrator or the like. 
     The management server  110  may store information in which the system management information  220  and the system configuration information  221  are integrated. The control part  110  may hold the pieces of information included in the management information group  111 . 
     The server type of the management server  101  may be any one of a physical server, a blade server, a virtualized server, and a logically or physically divided server, and effects of this invention can be provided by using any one of the servers. 
     Information such as programs for implementing each of the functions of the control part  110  and management information can be stored in memory devices such as the storage subsystem  105 , a non-volatile semiconductor memory, a hard disk drive, and a solid state drive (SSD), or in a computer-readable non-transitory data storage medium such as an IC card, an SD card, and a DVD. 
       FIG. 3  is a block diagram illustrating the configuration of the server  102  according to the first embodiment of this invention. 
     The server  102  includes a processor  301 , a memory  302 , a network interface  303 , a disk interface  304 , a BMC  305 , and a PCI-Express interface  306 . 
     The processor  301  executes programs stored in the memory  302 . The memory  302  stores a program executed by the processor  301  and information necessary to execute the program. What programs and information are stored in the memory  302  is described later. 
     The network interface  303  is an interface for holding communication to and from other apparatus over an IP network. The disk interface  304  is an interface for accessing the storage subsystem  105 . 
     The BMC  305  controls power supply and controls the interfaces. The PCI-Express interface  306  is an interface for coupling to the PCIex-SW  107 . 
     The memory  302  stores programs that implement an OS  311 , an application  321 , and a monitoring part  322 . The processor  301  executes the OS  311  in the memory  302 , thereby managing devices in the server  102 . The application  321  which provides a service and the monitoring part  322  operate under the OS  311 . 
     The memory  302  may store a program that implements a virtualization part for managing virtual servers as described later. 
     While the example of  FIG. 3  illustrates one network interface  303 , one disk interface  304 , and one PCI-Express interface  306 , the server  102  may have a plurality of network interfaces, a plurality of disk interfaces, and a plurality of PCI-Express interfaces. For instance, the server  102  may have a network interface that couples to the NW-SW  103  and a network interface that couples to the NW-SW  104 . 
       FIG. 4  is a block diagram illustrating a configuration example of virtual servers that run on each server  102  according to the first embodiment of this invention. The physical configuration of each server  102  is the same as the one illustrated in  FIG. 3 , and is therefore omitted here. 
     The server  102  of  FIG. 4  is used to construct a multi-stage virtual computer which has the first virtualization part  401  which allocates physical computer resources to a plurality of first virtual servers  402  (or logical partitions), and a second virtualization part  403  which allocates computer resources of one of the plurality of first virtualization servers  402  to a plurality of the second virtual servers  404 . 
     In the memory  302 , the first virtualization part  401  for virtualizing computer resources of the server  102  is deployed as a virtualization part of a lower layer to provide computer resources (the first virtual servers  402 ) to a plurality of second virtualization parts  403 , which are virtualization parts of an upper layer. The second virtualization parts  403  generate a plurality of second virtual servers  404  and store the second virtual servers  404  in the memory  302 . The first virtualization part  401  has, as a control interface, a virtualization part management interface  441 . Though not shown in  FIG. 4 , the second virtualization parts  403  also have virtualization part management interfaces as control interfaces. 
     The first virtualization part  401  virtualizes the computer resources of the server  102  (or the blade server) to construct the plurality of first virtual servers  402 . As the first virtualization part  401 , for example, a hypervisor, a virtual machine monitor (VMM), or the like can be employed. The second virtualization parts  403  further virtualize the computer resources (first virtual servers  402 ) provided by the first virtualization part  401  to generate the plurality of second virtual servers  404 . As the second virtualization part  403 , for example, a hypervisor, a VMM, or the like can be employed. 
     The second virtual servers  404  are constructed by virtual devices (or logical devices) provided by the second virtualization parts  403 . The virtual devices of this embodiment include a virtual processor  411 , a virtual memory  412 , a virtual network interface  413 , a virtual disk interface  414 , a virtual BMC  415 , and a virtual PCIex interface  416 . 
     The above-mentioned logical devices are the computer resources (first virtual servers  402 ) allocated by the first virtualization part  401  to the plurality of the second virtualization parts  403  and further allocated by the second virtualization parts  403  to each of the second virtual servers  404 . 
     An OS  421  is stored in the virtual memory  412 , and the OS  421  manages the virtual devices in the second virtual server  404 . Moreover, an application  431  is executed on the OS  421 . Moreover, a management program  432  running on the OS  421  provides functions such as failure detection, power supply control by the OS, and inventory management. 
     The first virtualization part  401  manages association between the physical computer resources of the server  102  and the computer resources allocated to the second virtualization parts  403 . This embodiment discusses an example in which the first virtualization part  401  allocates the first virtual servers  402  to the second virtualization parts  403 , but the first virtualization part  401  may directly allocate the computer resources of the physical server  102  to the second virtualization parts  403 . In this case, the first virtual servers  402  can be omitted. 
     The first virtualization part  401  can dynamically change the computer resources of the server  102  allocated to the plurality of second virtualization parts  403 , and can cancel the allocation of the computer resources. The first virtualization part  401  holds the amounts of the computer resources allocated to the second virtualization parts  403 , configuration information, and operation history. 
     The second virtualization parts  403  further virtualize computer resources of the first virtual servers  402  to allocate the virtualized resources to the plurality of virtual servers (second virtual servers)  404 . The second virtualization parts  403  manage association between the second virtual servers  404  and computer resources of the first virtual servers  402  that are allocated to the respective second virtual servers  404 . The second virtualization parts  403  can dynamically change computer resources of the first virtual servers  402  to be allocated to the plurality of second virtual servers  404 , and can cancel the allocation of the computer resources. The second virtualization parts  403  hold the amounts of computer resources allocated to the second virtual servers  404 , configuration information, and operation history. 
     In this embodiment, the first virtualization part  401  for providing the first virtual servers  402  acquired by virtualizing the hardware of the server  102  is assumed as a first layer, the second virtualization parts  403  for providing the second virtual servers  404  acquired by further virtualizing the computer resources of the first virtual servers  402  are assumed as a second layer, and the OSs  421  are assumed as a third layer. Then, the third layer side is assumed as the upper layer, and the first layer side is assumed as the lower layer. However, in the case where the structure is not multi-layered, the first virtualization part  401  is the first layer and the OS  421  runs on its upper layer. 
       FIGS. 5A and 5B  are explanatory diagrams outlining the first embodiment of this invention. 
       FIG. 5A  is a diagram illustrating reliability about the redundancy configurations of computer systems.  FIG. 5A  illustrates the configurations of computer systems  1  to  4 . The computer system  1  and the computer system  2  are computer systems having a redundancy configuration such as VMware FT (VMware is a trademark). In this embodiment, the redundancy configurations of computer systems are managed by assigning each redundancy configuration a reliability rank (priority level). 
     Even if it is a same redundancy configuration, the reliability of a computer system can be identified for every a method of a redundancy configuration. 
     The system  3  and the system  4  are created by reconstructing a computer system that has a redundancy configuration as the system  1  and the system  2 . Aggregation are set in the NICs of the server  102  that constructs the computer system  3 . 
     The computer system  3  is therefore higher in reliability than the computer system  4 . In this embodiment, computer systems that have the same reliability rank can be compared with each other with the use of their evaluation values, aside from the priority levels. 
     Calculating an evaluation value for each function that a computer system has also makes more detailed comparison possible. 
       FIG. 5B  is a diagram illustrating reliability about functions of computer systems.  FIG. 5B  illustrates the configurations of computer systems  10  to  13 . 
     In the computer system  10  and the computer system  11 , a heartbeat line is connected so that adapters of the servers  102  are connected directly to each other. In the computer system  12 , on the other hand, a heartbeat line is connected via one NW-SW. The computer system  10  and the computer system  11  are accordingly higher than the computer system  12 , in a case of being evaluated in reliability about the heartbeat function. The computer system  13 , where a heartbeat line is connected via two NW-SWs, is lower in reliability than the computer system  12 . 
     In this embodiment, the reliability of one computer system and another computer system which both have the heartbeat function can be evaluated separately in detail and with precision by calculating, as evaluation values, the differences in reliability described above. 
     This embodiment accomplishes flexible management of the management target system by changing the computer system configuration based on information that indicates system reliability, such as the reliability level and the evaluation value. 
     Events detected by the event detecting part  210  include a request for resources that is issued by a user, a failure in a computer system, and scheduled maintenance. 
     In the case where a resource request is detected and there is a shortage of computer systems that have high reliability, the management server  101  determines whether or not computer systems that have a High Availability (HA) configuration can be built through reconstruction, based on the system management information  220 , the system configuration information  221 , and the connection relationship evaluation information  222 . In a case where those computer systems can be built through reconstruction, the management server  101  reconstructs existing computer systems. 
     In the case where there is a shortage of computer systems that have low reliability, on the other hand, the management server  101  uses existing computer systems as they are, or disables the HA configuration, to secure a necessary count of apparatus and a necessary count of devices. Surplus resources are checked in order to change system counts and device counts that are to be secured for the respective reliability levels based on actual performance and availability status. 
     In a case where a failure occurs in a computer system, the management server  101  performs recalculation of evaluation scores and a reconfiguration process as needed in order to secure necessary counts of computer systems and devices that have given reliability. 
     In scheduled maintenance, the management server  101  performs recalculation of evaluation scores and reconfiguration processing as needed in order to secure necessary counts of computer systems and devices that have given reliability. Scheduled maintenance differs from the processing that is executed in the event of a failure in that the execution of processing can be planned in advance. 
     Additionally introducing a new piece of hardware corresponds to metabolic activity (lifecycle management) of computer systems that triggers the reviewing of evaluation scores by the management server  101 . This keeps evaluation score calculation results fresh and prevents evaluation score calculation results from becoming obsolete. 
     In this embodiment, the computer system configuration is changed to suit a service use in question and a resource request made. 
     The counts of systems and devices that have given reliability can be adjusted by changing redundancy configurations. For instance, conditions for building a computer system that has the VMware FT configuration are that “VMware HA and vMotion are feasible” and that “at least two physical NICs are provided other than those for management and a service”. 
     In a case where a resource request related to VMware FT or VMware HA is made, the management server  101  obtains the count of physical NICs from the system management information  220  and the system configuration information  221  to determine whether or not the conditions given above are satisfied. In the case of the VMware FT configuration, the same processing as in the active server is executed in the standby server with a delay of a few seconds at maximum, which means that the distance between the active server and the standby server over the network needs to be close. A computer system having the VMware FT configuration is therefore configured so that the coupling between the active server and the standby server does not include multiple stages of switches. 
     To change a computer system from which the VMware FT configuration can be built into a VMware HA computer system or a cold standby-use computer system, the management server  101  changes the current configuration into a configuration where the distance is long for a standby server (fewer resources and facilities are shared). This means that recovery takes long but has an effect of being capable of overcoming more points of failure than VMware FT. 
     The management server  101  preferentially uses a configuration where a heartbeat line is connected directly for VMware FT, VMware HA, and the hot standby use. 
     In the case where devices that are compatible with a link-down detection (Media Independent Interface) monitoring function and devices that are not compatible with the MII monitoring function are included, the management server  101  meets users&#39; requests by switching between the MII monitoring function and an ARP monitoring function. 
     The management server  101  secures a necessary count of devices that is needed to meet a user&#39;s request by disabling the aggregation settings and thus increasing the count of devices that can be used individually. 
     A computer system having high reliability can be reconstructed into a plurality of low-reliability systems by disabling the redundancy settings of the high-reliability computer system. 
     To build a computer system that has high reliability, on the other hand, the management server  101  deploys cluster software, virtualization parts, and the like and sets necessary settings. 
     In a case of building a high-reliability computer system, the management server  101  checks, for example, whether processors capable of constructing VMware FT can be secured, and whether as many physical NICs as necessary for VMware Fr can be secured. The management server  101  also checks whether a heartbeat line is connected and the distance between the active server and the standby server over the network by checking the count of stages of switches that couple the active server and the standby server. This reduces the chance of packet loss along the heartbeat line and lowers the probability of erroneous detection. 
     In the case of building a computer system that has a cold standby configuration, the management server  101  checks whether a computer system constructed of the server  102  whose hardware configuration and software configuration are equivalent to those of the computer system to be built can be secured as an auxiliary computer system. 
     In the case of building a computer system that has an N+M cold standby configuration, the management server  101  can set the count of standby servers to a value less than the count of active servers. 
     Guaranteeing the reliability of a computer system is accomplished by securing as many standby servers as the count of active servers, or more, and, with the enhanced reliability, a situation where a switched-to standby server goes down soon after failover can be dealt with. 
     The management server  101  can also evaluate reliability with respect to the storage configuration, and controls the storage configuration by displaying a SAN (HBA), iSCSIs (NICs), FCoE (CNAs), a redundant arrays of independent disks (RAID) configuration, tiering, zone settings that are set in the reconstruction of computer systems, and the like. 
     Securing reliability is in a trade-off relationship with cost. Therefore, a reliable computer system that is in great demand by users can be run by adjusting the system count and the device count for each reliability level depending on how much is charged. 
       FIG. 6  is an explanatory diagram showing an example of the system management information  220  according to the first embodiment of this invention. 
     The system management information  220  stores information for managing the configurations of computer systems in the management subject system that have already been built. Specifically, the system management information  220  includes a system ID  601 , an HW configuration  602 , a software configuration  603 , and a priority level  604 . 
     The system ID  601  is an identifier for identifying a computer system. 
     Stored as the HW configuration is information about the hardware configuration of the computer system, specifically, the apparatus configuration. For instance, the counts and identification information of the servers  102 , the NW-SWs  104 , and the storage subsystems  105  that are used in the computer system are stored. 
     A software configuration introduced in the computer system is stored as the software configuration  603 . 
     A value indicating the reliability of the computer system is stored as the priority level  604 . The reliability of a computer system is an indicator that indicates the system&#39;s importance level and the degree of influence of the system. In this embodiment, the reliability of a computer system is classified into a rank based on the priority level  604 . A computer system that has a smaller value as the priority level  604  is higher in reliability in this embodiment. 
       FIGS. 7A and 7B  are explanatory diagrams showing an example of the system configuration information  221  according to the first embodiment of this invention. 
     The system configuration information  221  stores information for managing the configurations of apparatus constructing computer systems. Specifically, the system configuration information  221  includes an identifier  701 , a universal unique identifier (UUID)  702 , an apparatus  703 , a device  704 , properties  505 , a coupled device  706 , and a reliability type  707 . 
     Stored as the identifier  701  is an identifier for identifying an entry in the system configuration information  221 . Entry identifiers are automatically assigned in ascending order in this embodiment. 
     The identifier  701  can be omitted by specifying one of the other columns, or a combination of a plurality of columns, in the system configuration information  221 . 
     Stored as the UUID  702  is a UUID, which is an identifier in a format defined so as to avoid duplication. Each server  102  holds a UUID so that server identifiers are guaranteed an absolute uniqueness. The UUID is therefore very effective in server management that covers a wide range. 
     Using the UUID is desirable but not indispensable because there is no problem in employing as the identifier  701  identifiers that are used by the system administrator to identify the servers  102 , as long as identifier duplication is avoided among the servers  102  that are management subjects. For example, the MAC address or the World Wide Name (WWN) can be used for the identifier  701 . 
     Stored as the apparatus  703  is information that indicates the type of an apparatus constructing a computer system. For example, a name that indicates an IT equipment type such as “server”, “storage”, or “network” is stored as the apparatus  703 . A facility name such as “power supply apparatus” or “rack” may also be stored. 
     Stored as the device  704  is information that indicates the type of a device included in the apparatus. For example, in the case where “server” is stored as the apparatus  703 , the type of a device that is included in the server, such as the processor  301  and the memory  302 , is stored as the device  704 . In an entry for an apparatus that corresponds to a computer system itself, such as the servers  102 , the device  704  remains blank. 
     Stored as the properties  705  is information about a subject apparatus or a subject device. Examples of information that can be stored as the properties  705  include types such as “HBA”, “NIC”, and “CNA”, a WWN that is the identifier of the HBA, an MAC address that is the identifier of the NIC, performance information, architecture information, generation information, a model number, a support function, a vendor type, firmware information, driver information, I/F information, switch information, RAID information, a virtualization type, and virtualization association information. 
     Stored as the coupled device  706  is information about an apparatus or a device to which the subject apparatus or the subject device is coupled. Coupling between an apparatus and a device, coupling between one apparatus and another apparatus, or coupling between devices can thus be determined. For instance, the control part  110  can determine whether or not building a system that uses a directly connected heartbeat line is possible based on the coupled device  706 . 
     Stored as the reliability type  707  is the type of reliability, in other words, information about a function that is implemented by the apparatus or the device. Examples of information that can be stored as the reliability type  707  are given below. 
     In the case where an apparatus itself is the subject, information that indicates disaster recovery (DR) •fault tolerant (FT) or HA •cluster is stored. “HA •cluster” here means a computer system that has a cluster configuration for hot standby, cold standby, or the like. In the case of cold standby, information for identifying whether the cold standby configuration is a 1:1 configuration or an N+M configuration may be added. 
     In a case where the subject is a memory, information that indicates the presence or absence of an error check and correct (ECC) function is stored as the reliability type  707 . In a case where the subject is an NIC and an HBA, information that indicates the presence or absence of aggregation such as teaming and bonding, and the presence or absence of multiplexing is stored as the reliability type  707 . In a case where the subject is a storage apparatus, information that indicates the presence or absence of a RAID configuration in SSDs or HDDs, and information that indicates a RAID level are stored as the reliability type  707 . 
     The pieces of information stored in the respective columns are given as an example, and are not to limit this invention. 
       FIG. 8  is an explanatory diagram showing an example of the connection relationship evaluation information  222  according to the first embodiment of this invention. 
     The connection relationship evaluation information  222  stores an evaluation value for each apparatus/device performance or configuration. Specifically, the connection relationship evaluation information  222  includes an identifier  801 , an apparatus/device  802 , properties  803 , and an evaluation value  804 . 
     Stored as the identifier  801  is an identifier for identifying an entry in the connection relationship evaluation information  222 . 
     The type of an evaluation subject apparatus or an evaluation subject device is stored as the apparatus/device  802 . For example, a name that indicates an IT equipment type such as “server”, “storage”, or “network” is stored as the apparatus type. A facility type such as “power supply apparatus” and “rack” may also be stored as the apparatus/device  802 . A name that indicates a device type such as “processor”, “memory”, “NIC”, “HBA”, “HDD (SAS or SATA)”, or “SSD” is stored as the device type. 
     The control part  110  can use the apparatus/device  802  to search for a device that is coupled via multiple stages of switches. 
     Stored as the properties  803  is information that serves as an indicator of the reliability of an apparatus or a device that corresponds to the apparatus/device  802  in terms of performance, coupling relationship, function, and the like. 
     The evaluation value of the apparatus or device corresponding to the apparatus/device  802  is stored as the evaluation value  804 . A predetermined value is stored as the evaluation value  804  in this embodiment. The evaluation value  804 , however, can be changed as described later. 
     In the example of  FIG. 8 , an entry where the identifier  801  is “4” shows that, the subject is an NIC and in a case where aggregation is set in the NIC, the subject has an evaluation value “1.5”. An entry where the identifier  801  is “5” shows that, the subject is an NIC and in a case where the NIC is connected directly to another NIC, the subject has an evaluation value “2.0”. An entry where the identifier  801  is “6” shows that, the subject is an NIC and in a case where the NIC is coupled to an IP switch, the subject has an evaluation value “0.8”. An entry where the identifier  801  is “1” shows that, the subject is a processor and in a case where the processors  301  of at least two servers  102  have the same performance, the subject has an evaluation value “1.0”. 
       FIG. 9  is an explanatory diagram showing an example of the configuration requirement information  223  according to the first embodiment of this invention. 
     The configuration requirement information  223  stores information about system configuration requirements to be fulfilled in order to secure reliability demanded by a user or the like. Examples of information stored in the configuration requirement information  223  include configuration information necessary to implement a given cluster, information that indicates the presence or absence of a heartbeat line in an HA configuration, information that indicates whether or not the heartbeat line is connected directly to a device, and information that indicates whether or not the heartbeat line can be connected via a switch. Also stored are information that indicates the presence or absence of aggregation (whether or not a necessary count of adapters can be secured by disabling aggregation), and information that indicates whether or not a switch and a device, or one device and another device, are coupled in a criss-crossed manner. 
     Specifically, the configuration requirement information  223  includes an identifier  901 , a configuration name  902 , and requirements  903 . 
     Stored as the identifier  901  is an identifier for identifying an entry in the configuration requirement information  223 . Information that indicates the configuration of a computer system is stored as the configuration name  902 . 
     Concrete configuration requirements of the computer system specified in the configuration name  902  are stored as the requirements  903 . Specifically, the requirements  903  include hardware requirements  921 , software requirements  922 , manager requirements  923 , and a priority level  924 . 
     Configuration requirements related to hardware in the computer system are stored as the hardware requirements  921 . Examples of what is stored as the hardware requirements  921  include information that indicates whether or not a heartbeat line is necessary, information that indicates whether or not the same system and the same device are necessary, information that indicates whether or not shared storage is needed, information about the count of adapters, and information about the method of coupling to another piece of IT equipment. 
     Configuration requirements related to software in the computer system are stored as the software requirements  922 . Examples of what is stored as the software requirements  922  include information that indicates the cluster software type, information that indicates the virtualization part type, information that indicates whether or not a virtual switch is necessary, information that indicates whether or not a dedicated network is necessary, information that indicates the vendor type, and information that indicates whether or not a particular function is supported. This makes it possible to, for example, determine whether or not a cluster configuration can be built based on the information that indicates the vendor type. 
     Configuration requirements related to a manager in the computer system are stored as the manager requirements  923 . Specifically, information that indicates whether or not manager software dedicated to system configuration management is necessary is stored as the manager requirements  923 . 
     The priority level  924  is the same as the priority level  604 . 
       FIG. 10  is an explanatory diagram showing an example of the service management information  224  according to the first embodiment of this invention. 
     The service management information  224  stores information about a service of a computer system that is run, such as the service type and the software type, settings of the computer system, the priority level of the service, and requirements (a user request or a service request) for the reliability of the computer system. 
     Specifically, the service management information  224  includes a service identifier  1001 , a UUID  1002 , a service type  1003 , service settings information  1004 , and a priority order  1005 . 
     An identifier for identifying a service which is provided by using the virtual servers  420  or the like is stored as the service identifier  1001 . The UUID  1002  is the same as the UUID  1002 . 
     Stored as the service type  1003  is information about the service type and software that specifies the service, such as an application and middleware to be used. 
     Settings information necessary for the service is stored as the service settings information  1004 . Examples of what is stored as the service settings information  1004  include a logical IP address that is used in the service, an ID, a password, a disk image, and the port number of a port that is used in the service. The disk image is a disk image of a system disk in which the service before and after setting is deployed to the OS on the active server. Information about a disk image that is stored as the business settings information  1004  may include information of a data disk. 
     Stored as the priority order  905  are the place in priority order of the service and the specifics of the requirements for reliability. For example, the place in priority order among services and requirements for the service in question are stored as the priority order  1005 . A service that is to be executed preferentially can thus be set. 
       FIG. 11  is a flow chart illustrating processing that is executed by the control part  110  according to the first embodiment of this invention. 
     The control part  110  starts the processing in a case where an event is detected (Step S 1101 ). Specifically, the event detecting part  210  detects an event that triggers reconstruction of computer systems. 
     Events that are possibly detected include a user request and an alert for notifying a shortage of computer systems that have a necessary level of reliability. In this invention, any event can be detected as long as the event can be a cause for computer system reconstruction. The event detected in this embodiment is a request made by a user to provide a computer system that fulfills given configuration requirements. 
     The control part  110  refers to the system management information  220 , the system configuration information  221 , the connection relationship evaluation information  222 , and the configuration requirement information  223  (Step S 1102 ). 
     The control part  110  evaluates the reliability of a system that fulfills the configuration requirements demanded (Step S 1103 ). Specifically, the following processing is executed. 
     In a first step, the reliability calculating part  211  refers to the system management information  220  and the system configuration information  221  to grasp the configurations of computer systems included in the management subject system. 
     In a second step, the reliability calculating part  211  selects one of the computer systems, and calculates an evaluation value for each component of the computer system. Components of a computer system here refer to apparatus that construct the computer system and devices that are included in the apparatus. Specifically, the evaluation value is calculated in a manner described below. 
     The reliability calculating part  211  refers to the HW configuration  602  of the system management information  220  to check the apparatus configuration of the selected computer system. The reliability calculating part  211  refers to the apparatus  703  of the system configuration information  221  to obtain, for each apparatus, information (entry) about the configuration of the apparatus. 
     The reliability calculating part  211  further refers to the connection relationship evaluation information  222  based on the properties  705 , the coupled device  706 , and the reliability type  707  in the obtained entry, and calculates an evaluation value for each device and each apparatus. 
     The evaluation value calculated in this step is a value indicating reliability that corresponds to the reliability type  707  of the obtained entry. 
     In a third step, the reliability calculating part  211  calculates an overall evaluation value of the selected computer system. Specifically, the reliability calculating part  211  calculates the sum of the evaluation values of the respective devices and the respective apparatus. 
     In a fourth step, the reliability calculating part  211  refers to the configuration requirement information  223  to calculate the evaluation value of the requested computer system. Specifically, the evaluation value of the requested computer system is calculated as follows. 
     The reliability calculating part  211  refers to the configuration requirement information  223  to obtain an entry for the requested computer system. 
     The reliability calculating part  211  refers to the apparatus/device  802  and the properties  803  in the obtained entry and the connection relationship evaluation information  222  to calculate the evaluation value of the requested computer system. This calculation is performed by the same calculation method that is used in the second step and the third step. 
     In the case where reliability to be evaluated is specified in advance, the reliability calculating part  211  only needs to calculate a relevant evaluation value. The reliability calculating part  211  may store the calculation result in the memory  202 . In this way, when an evaluation value is needed, the control part  110  can read the calculation result out of the memory  202 , thereby reducing the cost of calculation. In this embodiment, the evaluation value of a computer system is stored in the memory  202  in association with the identifier of the computer system. 
     The reliability calculating part  211  may generate display information for displaying to the administrator the processing result of the first step to the fourth step, namely, the calculated evaluation values. 
     The display part  216  in this case can display the computer system reliability of the currently built computer systems at each priority level based on the generated display information as illustrated in  FIG. 16 . The display unit  216  displays the priority level and evaluation value of the requested computer system along with the computer system reliability as illustrated in  FIG. 16 . This enables the administrator to easily determine whether or not the requested computer system can be implemented based on the information displayed on the display part  216 . 
     In this embodiment, the management server  101  determines whether or not a requested computer system can be implemented and changes the configurations of computer systems. 
     The calculation processing of Step S 1103  has now been described. 
     The control part  110  determines whether or not there is a computer system that fulfills configuration requirements demanded based on the system management information  220  and the configuration requirement information  223  (Step  1104 ). Configuration requirements include hardware performance, hardware functions, software performance, and the like. Details of Step S 1104  are described later with reference to  FIG. 12 . 
     In a case where it is determined that there is a computer system that fulfills configuration requirements demanded, the control part  110  displays information about this computer system (Step S 1105 ), and ends the processing. 
     The display part  216  may display information about a computer system as soon as one computer system that fulfills the requirements is found, or may display computer system information in a list format after all computer systems that fulfill the requirements are found. The display part  216  may also display calculated evaluation values along with the computer system information. 
     In a case where it is determined that there is no computer system that fulfills configuration requirements demanded, the control part  110  determines whether or not a computer system that fulfills configuration requirements demanded can be built based on the calculated evaluation values (Step S 1106 ). Details of Step S 1106  are described later with reference to  FIG. 13 . 
     In a case where it is determined that a computer system that fulfills configuration requirements demanded cannot be built, the control part  110  displays a message to the effect that the requested computer system cannot be built (Step S 1107 ), and ends the processing. Specifically, the display part  216  displays a message to the effect that the requested system cannot be built. 
     In a case where it is determined that a computer system that fulfills configuration requirements demanded can be built, the control part  110  reconstructs computer systems (Step S 1108 ), and ends the processing. Specifically, the configuration changing part  214  reconstructs computer systems. Details of Step S 1108  are described later with reference to  FIG. 14 . 
       FIG. 12  is a flow chart illustrating processing that is executed by the reliability determining part  212  according to the first embodiment of this invention. 
     The reliability determining part  212  refers to the system management information  220 , the system configuration information  221 , and the configuration requirement information  223  (Step S 1201 ) to search for a computer system that matches configuration requirements demanded, or a computer system whose specifications exceed configuration requirements demanded (over spec. computer system) (Step S 1202 ). The search can be performed by the following method. 
     The reliability determining part  212  compares the value of the priority level  604  and the value of the priority level  924 , and searches the system management information  220  for an entry where the value of the priority level  604  matches the value of the priority level  924 . The reliability determining part  212  next refers to the system configuration information  221  based on the HW configuration  602  of the found entry to obtain an entry that holds an associated apparatus and device. 
     Based on the information obtained from the system management information  220  and the information obtained from the system configuration information  221 , the reliability determining part  212  determines whether or not the configuration matches, or is an over spec. with respect to, configuration requirements indicated by the requirements  903 . 
     For example, in the case where the system requested by the user is a computer system that has a hot standby function and four servers in which 2-GHz processors each have a core count of 2, the reliability determining part  212  searches for an entry in which “2 GHz” and “core count: 2 ” are written as the properties  605 . An entry that stores “3 GHz” and “core count: 4” as the properties  605  is found as an over spec. computer system in this case. 
     This invention is not limited to the search method described above. 
       FIG. 13  is a flow chart illustrating processing that is executed by the configuration determining part  213  according to the first embodiment of this invention. 
     The configuration determining part  213  determines whether or not a system with high reliability is needed (Step S 1301 ). Specifically, the configuration determining part  213  refers to the configuration requirement information  223  to determine whether or not the priority level  924  of the entry for the requested computer system is equal to or more than a given threshold. Here, the threshold is set in advance. 
     In a case where it is determined that a computer system with high reliability is needed, the configuration determining part  213  searches for computer systems that have low reliability (Step S 1302 ). 
     Specifically, the configuration determining part  213  refers to the system management information  220  to search for a computer system that has a value smaller than a given threshold as the priority level  604 . The threshold can be the same one that is used in Step S 1201 . The configuration determining part  213  preferentially searches for systems that are not being used for services. 
     The configuration determining part  213  selects a processing subject computer system from among computer systems found through the search (Step S 1303 ). 
     Specifically, the configuration determining part  213  selects the computer systems one by one in descending order of the value of the priority level  604 , in other words, in ascending order of computer system reliability. In the case where the priority level  604  has the largest value in a plurality of computer systems, the configuration determining part  213  obtains the evaluation values of the respective computer systems to select the computer systems one by one in ascending order of their evaluation values. 
     The count of computer systems selected at a time is not limited to one, and a plurality of computer systems may be selected depending on configuration requirements demanded. 
     Computer systems having low reliability are searched for because there is a chance that a system that fulfills configuration requirements demanded can be built by reconstructing computer systems with low reliability. 
     A computer system selected by the configuration determining part  213  is hereinafter also referred to as subject computer system. A subject computer system selected in Step S 1303  is referred to as a first subject computer system, and a subject computer system selected in Step S 1312  is referred to as a second subject computer system. 
     The configuration determining part  213  executes simulation to determine whether a computer system that fulfills configuration requirements demanded can be built by changing the configuration of the first subject computer system (Step S 1304 ). 
     For example, the configuration determining part  213  changes the type of the coupled device or apparatus repeatedly until an objective device type or apparatus type is reached. The objective device type or apparatus type can be reached efficiently and quickly by starting the search with devices/apparatus that are low in service priority level, that are not in use, and whose reliability type has a low priority level. 
     The configuration determining part  213  may determine that a computer system that fulfills configuration requirements demanded can be built in a case where there is a computer system that fulfills at least hardware configuration requirements out of configuration requirements demanded. This is because necessary software can be deployed later in the found computer system. 
     Based on the result of the simulation, the configuration determining part  213  determines whether or not a computer system that fulfills configuration requirements demanded can be built (Step S 1305 ). 
     In a case where it is determined that the requested computer system cannot be built, the configuration determining part  213  returns to Step S 1303  to execute the same processing. The configuration determining part  213  in this case excludes the first subject computer system that has been selected before the return to Step S 1303  from selection subjects. 
     In a case where it is determined that the requested computer system can be built, the configuration determining part  213  calculates the evaluation score of the new computer system (Step S 1306 ). Specifically, the configuration determining part  213  requests the reliability calculating part  211  to calculate the evaluation value of the new computer system by sending information about the new computer system (the simulation result). The evaluation value is calculated by the same method that is used in Step S 1103  and a description thereof is omitted. 
     The configuration determining part  213  determines the configuration of the new computer system based on the calculated evaluation value (Step S 1307 ), and ends the processing. In the case where there are a plurality of computer system candidates, for example, the following approach can be taken. 
     The configuration determining part  213  selects a system that has the highest evaluation value of the computer system candidates. Alternatively, the display part  216  displays information with “excuse” to the user, who then selects based on the displayed information. “Excuse” is information such as “the system can be built if a heartbeat line is configured via a switch”. The display part  216  may display an evaluation value for each reliability type. The display part  216  may also display information that indicates the influence of the reconstruction of the system. 
     The configuration determining part  213  generates information necessary for the computer system reconstruction and outputs the generated information to the configuration changing part  214 . 
     In a case where it is determined in Step S 1301  that a system with high reliability is not needed, in other words, a computer system with low reliability is needed, the configuration determining part  213  searches for computer systems that have high reliability (Step S 1312 ). 
     Specifically, the configuration determining part  213  refers to the system management information  220  to search for a computer system that has a value equal to or larger than a given threshold as the priority level  604 . The threshold can be the same one that is used in Step S 1301 . The search can be performed by a method that is substantially the same as the one used in Step S 1302 , except that computer systems having a redundancy configuration, namely, computer systems with high reliability, are preferentially searched for. 
     The configuration determining part  213  selects a processing subject computer system from among computer systems found through the search (Step S 1313 ). 
     Specifically, the configuration determining part  213  selects the computer systems one by one in descending order of the value of the priority level  604 , in other words, in ascending order of computer system reliability. In the case where the priority level  604  has the largest value in a plurality of computer systems, the configuration determining part  213  obtains the evaluation values of the respective computer systems to select the computer systems one by one in ascending order of their evaluation values. This is in order to secure computer systems with high reliability as successfully as possible. 
     The count of computer systems selected at a time is not limited to one, and a plurality of computer systems may be selected depending on configuration requirements demanded. 
     Computer systems having high reliability are searched for because there is a chance that a system that fulfills configuration requirements demanded can be built by disabling the redundancy configuration of computer systems with high reliability. 
     The configuration determining part  213  executes simulation to determine whether a computer system that fulfills configuration requirements demanded can be built by changing the configuration of the second subject resource (Step S 1314 ). Specifically, the configuration determining part  213  determines whether or not a computer system that fulfills configuration requirements demanded can be built by disabling the redundancy configuration of the second subject computer system. 
     For example, the configuration determining part  213  compares a computer system created after the redundancy configuration of the second subject computer system is disabled against the system that fulfills configuration requirements demanded, and determines whether or not the computer system matches, or is an over spec. with respect to, the configuration requirements demanded. The configuration determining part  213  may request the reliability determining part  212  to execute this determination processing. 
     Based on the result of the simulation, the configuration determining part  213  determines whether or not a computer system that fulfills configuration requirements demanded can be built (Step S 1315 ). 
     In a case where it is determined that the requested computer system cannot be built, the configuration determining part  213  returns to Step S 1313  to execute the same processing. The configuration determining part  213  in this case excludes the second subject computer system that has been selected before the return to Step S 1313  from selection subjects. 
     In a case where it is determined that the requested computer system can be built, the configuration determining part  213  calculates the evaluation score of the new computer system (Step S 1306 ). 
     The configuration determining part  213  determines the configuration of the new computer system based on the calculated evaluation value (Step S 1307 ), and ends the processing. 
     In Step S 1303  and Step S 1313 , the display part  216  may display computer systems for each priority level so that the user selects a computer system based on the display. The display part  216  in this case may display evaluation values along with the computer systems. 
       FIG. 14  is a flow chart illustrating processing that is executed by the configuration changing part  214  according to the first embodiment of this invention. 
     The configuration changing part  214  builds a new computer system based on the processing result of the configuration determining part  213  (Step S 1401 ). The configuration changing part  214  in this embodiment builds a new computer system by combining a plurality of apparatus and devices, or builds a plurality of computer systems by disabling the redundancy configuration of a computer system. 
     For example, in the case of building a computer system that has a hot standby function, the configuration changing part  214  configures a cluster from a plurality of servers  102  based on the processing result of the configuration determining part  213 , and sets necessary settings in the respective servers  102 . In the case of building a computer system that needs aggregation of NICs, the configuration changing part  214  sets settings necessary for aggregation in a plurality of NICs. 
     The method used here for system building is a known technology, and a detailed description thereof is omitted. 
     The configuration changing part  214  updates the system management information  220 , the system configuration information  221 , and the configuration requirement information  223  (Step S 1402 ), and ends the processing. 
       FIG. 15  is a flow chart illustrating processing that is executed by the evaluation value changing part  215  according to the first embodiment of this invention. The evaluation value changing part  215  executes the processing independently of processing that is executed for system reconstruction. 
     The control part  110  starts the processing in a case where an event is detected (Step S 1501 ). Specifically, the event detecting part  210  detects an event that triggers the changing of evaluation values. 
     Events that are possibly detected include cyclic events, year passage marking events, the occurrence of a failure, regular maintenance, and metabolic activities of IT systems and facilities. In this embodiment, any event can be detected as long as the event can be a cause for the changing of evaluation values. 
     The evaluation value changing part  215  refers to the system management information  220 , the system configuration information  221 , the connection relationship evaluation information  222 , and the configuration requirement information  223  (Step S 1502 ). The evaluation value changing part  215  recalculates evaluation values of apparatus and devices (Step S 1503 ). For example, the evaluation value changing part  215  recalculates evaluation values based on a given algorithm. Different algorithms may be used for different apparatus and different devices. 
     The evaluation value changing part  215  updates the system management information  220 , the system configuration information  221 , the connection relationship evaluation information  222 , and the configuration requirement information  223  (Step S 1504 ), and ends the processing. 
       FIG. 16  is an explanatory diagram illustrating an example of a resource management screen according to the first embodiment of this invention. 
     The display part  216  can display a resource management screen  1600  as illustrated in  FIG. 16 . In  FIG. 16 , information on a computer system-by-computer system is displayed. 
     The control part  110  refers to the pieces of information included in the management information group  111  to grasp the computer system state for each priority level, and generates display information for displaying what is illustrated in  FIG. 16 . The display part  216  displays the resource management screen  1600  based on the generated display information. 
     The resource management screen  1600  includes an area for displaying current computer systems and an area for displaying a requested computer system. 
     The area for displaying current computer systems displays computer system information, such as the count of computer systems and the utilization state of the computer systems, based on priority levels and evaluation values. 
     In the example of  FIG. 16 , each system has a priority level displayed in the lateral direction and an evaluation value displayed in the longitudinal direction. The reliability of computer systems can thus be displayed hierarchically. One cell corresponds to one system in the example of  FIG. 16 . Hatched portions in  FIG. 16  represent systems that are actually being used by services. 
     The area for displaying a requested computer system displays a priority level and an evaluation value. 
     The administrator of computer systems can determine from which priority level to which priority level resources are to be moved in order to increase/reduce resources by referring to the resource management screen  1600 . 
     While the management server  101  manages a management subject system in the first embodiment, this invention is not limited thereto and the server  102  that is included in a management subject system may have the control part  110  and the management information group  111 . 
     Second Embodiment 
     A second embodiment of this invention describes an example of reconstructing systems by disabling NIC aggregation and thus dividing aggregated NICs into a plurality of separate NICs. Here, a user requests a computer system needing a plurality of NICs that are not given redundancy. 
     In a case where it is determined in Step S 1104  that there is no computer system that fulfills configuration requirements demanded by the user, the control part  110  executes the following processing. 
     The configuration determining part  213  determines in Step S 1301  that a system with high reliability is not needed because a system having a plurality of NICs that are not given redundancy is a system with low reliability. 
     In Step S 1312 , the configuration determining part  213  searches for a computer system in which NIC aggregation is set. 
     The configuration determining part  213  determines in Step S 1314  and Step S 1315  whether or not the requested count of NICs can be secured by disabling the NIC aggregation settings of the found computer system. 
     In other words, the configuration determining part  213  determines whether or not a computer system that has a necessary count of devices can be built by changing a computer system that has used a plurality of NICs as one NIC logically into a computer system that can use a plurality of NICs individually. 
     In the case where a sufficient count of computer systems can be secured, a computer system capable of providing a necessary count of devices may be built through reconstruction by integrating a plurality of redundancy configuration computer systems. 
     In the case of NICs that have a virtual NIC function, the presence or absence of the virtual NIC function is checked as the need arises, and a computer system capable of providing a necessary count of devices may be built through reconstruction by turning on the virtual NIC function. 
     In the case where a user requests a system in which aggregation is set, on the other hand, the control part  110  uses NICs that do not have a redundancy configuration to build through reconstruction a computer system in which aggregation is set. 
     Third Embodiment 
     A third embodiment of this invention describes an example in which a system that has a heartbeat line is to be built through reconstruction and the heartbeat line is connected via a switch, and an example in which the heartbeat line in the system to be built through reconstruction is connected via switches that have a multi-stage configuration. Here, a user requests a system having a heartbeat line that directly connects devices. 
     In a case where it is determined in Step S 1104  that no system has a heartbeat line that directly connects devices, the control part  110  executes the following processing. 
     The configuration determining part  213  determines in Step S 1301  that a system with high reliability is needed because a system having a heartbeat line is a system with high reliability. 
     The configuration determining part  213  determines in Steps S 1302  to S 1305  whether or not a computer system having a heartbeat line that connects via a switch can be built. Here, the configuration determining part  213  determines that this computer system can be built. 
     In Step S 1307 , the configuration determining part  213  presents the evaluation values, configuration information, and the like of computer systems that can be built, receives the user&#39;s selection, and determines a computer system to be built. The display part  216  may present to the user a fact that “a system close to the demanded reliability level can be built with the use of a heartbeat line that connects via a switch” in this step. 
     In the case where the heartbeat line connects via multiple stages of switches, the display part  216  presents the configurations of computer systems to the user. The display part  216  in this case may additionally present messages that latency becomes large and the count of points of failure increases. 
     Because the count of points of failure increases, the reliability calculating part  211  calculates evaluation scores so that the reliability levels of the computer systems drop. 
     The configuration changing part  214  may adjust the computer systems in which the heartbeat line connects via multiple stages of switches so that the heartbeat interval is long, because of the increased latency in those computer systems. The configuration changing part  214  may also adjust the computer systems conversely so that the heartbeat interval is short, in order to detect a failure early. 
     Fourth Embodiment 
     A fourth embodiment of this invention describes a case in which a user requests a computer system that has the VMware FT configuration or the VMware HA configuration. 
     In a case where it is determined in Step S 1104  that no system has the VMware FT configuration or the VMware HA configuration, the control part  110  executes the following processing. 
     The configuration determining part  213  determines in Step S 1301  that a computer system with high reliability is needed because a system having the VMware FT configuration or the VMware HA configuration is a system with high reliability. 
     The configuration determining part  213  determines in Steps S 1302  to S 1305  whether or not a computer system having the VMware FT configuration or the VMware HA configuration can be built by using low-reliability systems. Here, a plurality of computer systems have a priority level equal to or higher than a given level, and as many devices as necessary for the VMware FT configuration or the VMware HA configuration are available. 
     In Step S 1302 , the configuration changing part  214  configures a cluster by integrating a plurality of computer systems, and builds a computer system that fulfills configuration requirements demanded by the user by deploying a hypervisor in each server  102 . 
     Computer systems with low reliability may also be built by disabling the VMware FT configuration or the VMware HA configuration and using the resultant systems as a virtualization environment, or by re-deploying another computer system. 
     Fifth Embodiment 
     A fifth embodiment of this invention assumes a case where a user requests a system for migration to the second virtual servers  404 . 
     The control part  110  builds a computer system that has the VMware FT configuration or the VMware HA configuration in a cross configuration. The hypervisor on the first layer builds the VMware FT configuration or the VMware HA configuration between one hypervisor and another hypervisor on the second layer which run on separate pieces of hardware. 
     The control part  110  utilizes a server in which the first layer is divided physically or logically to localize the influence of a failure, thereby reconstructing computer systems so that the reliability does not drop lower than when virtual servers are utilized. 
     In a case where a necessary count of systems are not available, the control part  110  secures the necessary count of systems by migration to the same piece of hardware, though the reliability level drops in this case. 
     According to one embodiment of this invention, the reliability of each computer system can be evaluated as a numerical value by calculating a value that indicates the reliability of the computer system. Resources can therefore be moved automatically between computer systems of different levels of reliability based on the numerical value.