Patent Publication Number: US-10762021-B2

Title: Information processing system, and control method of information processing system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Stage entry of PCT Application No: PCT/JP2016/070366 filed Jul. 11, 2016, the contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to an information processing system, and a control method of the information processing system. 
     BACKGROUND ART 
     Conventionally, due to the development of a virtualization technology, plural virtual servers have been built on one physical host computer, a configuration in which the images of the virtual servers and usage data are stored in a storage device has been widely spread, and further data of one or more virtual servers has been concentrated on one logical volume of the storage device. However, in this data concentration configuration, when the local copy function and remote copy function of the storage device are used, a copy unit is composed of plural virtual servers, so that virtual servers that are not target virtual servers and included in the copy unit become wasteful costs. 
     To cope with the above problem, Patent Literature 1 proposes Conglomerate LUN Structure, in which plural logical volumes of a storage device are held together into plural logical groups (LUN Conglomerate), a logical path is set in a representative logical volume (ALU: Administrative Logical Unit, PE (Protocol End Point) in Patent Literature 1) of each logical group; an I/O (Input/Output) command issued from a host computer includes an identifier of a logical volume (SLU: Subsidiary Logical Unit, vvol (virtual volume) in Patent Literature 1) other than the ALU to which the logical path belongs in each logical group; and the storage device delivers the relevant I/O processing to the SLU specified by the reception command. With the use of the above structure, one or more SLUs are assigned to one virtual server on the host computer, so that it becomes possible to assign an appropriate number of logical volumes of the storage device to each virtual server. 
     In addition, Patent Literature 2 discloses a technology in which a control device that controls the logical resources of a storage system includes: a virtual resource preparation unit that prepares virtual resources that are virtual logical resources; a real resource assignment unit that assigns real resources, which are substantial logical resources, to the above-described prepared virtual resources; and a data duplication control unit that duplicates data in a logical volume as duplicate data in a logical volume in a different storage system. Furthermore, in this technology, the identification of the virtual resource of the duplication source logical volume and that of the duplication destination logical volume are set the same, so that a higher-level host computer recognizes the two logical volumes as one logical volume. Therefore, Patent Literature 2 also discloses in this technology that the control device that controls the logical resources of a storage system makes an I/O command transmitted from the host computer to a logical volume in the storage system transferred to a logical volume in another storage systems. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: U.S. Pat. No. 8,775,774 
     Patent Literature 2: WO 2015/162634 
     SUMMARY OF INVENTION 
     Technical Problem 
     In order to enhance the availabilities of logical volumes assigned to a virtual server, a storage cluster configuration in which the logical volumes assigned to the virtual server are reduplicated in different storage devices can be built according to Patent Literature 2. According to Patent Literature 2, if one storage device is in the state of copying formation or in a suspended state, an I/O transfer is executed to another storage device that is in a normal state in the storage cluster configuration. However, because this I/O transfer is executed via a network between the two storage devices, this I/O transfer needs a larger delay time than a normal I/O transfer. 
     According to Patent Literature 1, in the case where a virtual server uses plural logical volumes, because a logical path control unit included in the host computer uses the logical path to the relevant ALU, if there mixedly exist plural SLUs that have various response delays, this causes the processing delay or stoppage of the virtual server or the processing delays or stoppages of an OS and applications on the virtual server. 
     Therefore, the object of the present invention is to provide an information system in which the delay or stoppage of processing performed by a computer, which uses logical volumes, can be suppressed. 
     Solution to Problem 
     An information processing system is connected to one or plural hosts and a second information processing system, and includes a processor. The second information processing system manages a second ALU connected to the one or plural hosts via a second logical path, and plural second SLUs that receive I/O requests from the one or plural hosts via the second logical path. 
     The processor manages a first ALU connected to the one or plural hosts via a first logical path and plural first SLUs that receive I/O requests from the one or plurality of hosts via the first logical path, and builds up a first group including the plural first SLUs. 
     At least one first SLU of the plural of first SLUs and at least one second SLU of the plural second SLUs compose an HA pair, and the HA pair is provided to the one or plural hosts as one volume. 
     The processor evaluates the state of the first logical path on the basis of the pair state of the first SLU that composes the HA pair included in the first group so that priorities with which the one or plural hosts issue I/Os to the first logical path can be determined. 
     Advantageous Effects of Invention 
     According to the above-mentioned technology, I/Os can consistently be issued to logical paths without the occurrences of I/O delays and retries in virtual servers, an OS, or the applications on a host computer, so that the delays or stoppages of pieces of processing performed on the computer using the logical volumes of storage devices can be suppressed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram showing an example of a configuration of a storage system. 
         FIG. 2  is a diagram showing an example of a configuration of a storage device. 
         FIG. 3  is a diagram showing an example of a configuration of a host computer. 
         FIG. 4  is a diagram showing an example of a configuration of a control unit and software included in the host computer. 
         FIG. 5  is a diagram showing an example of a configuration of a management computer. 
         FIG. 6  is a diagram showing an example of a configuration of a virtual server management table included in the host computer. 
         FIG. 7  is a diagram showing an example of a configuration of a logical path management table included in the host computer. 
         FIG. 8  is a diagram showing an example of a configuration of a bound management table included in the host computer. 
         FIG. 9  is a diagram showing examples of configurations of LUN management tables included in the storage device. 
         FIG. 10  is a diagram showing an example of a configuration of a logical volume management table included in the storage device. 
         FIG. 11  is a diagram showing an example of a configuration of a logical volume management table included in the storage device. 
         FIG. 12  is a diagram showing examples of configurations of consistency group management tables included in the storage device. 
         FIG. 13  is a diagram showing examples of configurations of bound management tables included in the storage device. 
         FIG. 14  is a diagram showing an example of virtual server creation processing. 
         FIG. 15  is a diagram showing an example of a flowchart of logical resource creation processing that is included in the storage device and needed at the time of the virtual server creation. 
         FIG. 16  is a diagram showing an example of storage resource operation processing in the configuration of a storage cluster. 
         FIG. 17  is a diagram showing an example of a flowchart of logical path evaluation processing included in the storage device. 
         FIG. 18  is a diagram showing an example of a flowchart of binding processing included in the storage device. 
         FIG. 19  is a diagram showing an example of a flowchart of unbinding processing included in the storage device. 
         FIG. 20  is a diagram showing an example of a configuration of a storage system. 
         FIG. 21  is a diagram showing examples of configurations of consistency group management tables included in a storage device. 
         FIG. 22  is a diagram showing an example of a flowchart of logical resource creation processing included in the storage device. 
         FIG. 23  is a diagram showing an example of a configuration of a storage system. 
         FIG. 24  is a diagram showing examples of configurations of virtual port management tables included in a host computer. 
         FIG. 25  is a diagram showing examples of configurations of host group management tables included in a storage device. 
         FIG. 26  is a diagram showing an example of a flowchart of LUN creation in a storage device management program. 
         FIG. 27  is a diagram showing an example of a flowchart of logical bath evaluation processing included in the storage device. 
         FIG. 28  is a diagram showing an example of a flowchart of logical bath evaluation processing included in the host computer. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments will be explained with reference to the accompanying drawings. 
     In the following descriptions, although various pieces of information about respective embodiments will be explained in the forms of “tables”, it is not always necessary for those pieces of information to be expressed in the forms of tables, and it is also conceivable that those pieces of information are represented in data structures other than in the forms of tables. Furthermore, although there are some cases where “programs” are used as subjects in descriptions, these programs are executed by a processor so that predefined pieces of processing are performed using memories and communication ports, therefore it is conceivable that the processor is a subject in the descriptions instead of the programs. 
     In addition, the pieces of processing performed through the processor&#39;s executing the programs are substantially equal to pieces of processing performed by dedicated hardware, there for part of the pieces of processing or all the pieces of processing can be realized by the dedicated hardware. Therefore, although there are several things each of which is represented by “***unit” in this specification, part of this “***unit” or the entirety of this “***unit” can be realized through a processor&#39;s executing a program, or part of this “***unit” or the entirety of this “***unit” can be realized by dedicated hardware. 
     Furthermore, the programs can be installed from a program delivery server or from a storage medium that is computer-readable. 
     In addition, in the following descriptions, things that are lacking the last alphabets represent generic terms of the things. 
     First Embodiment 
     In this embodiment, disclosed is a storage system in which logical volumes in a storage device, which are dealt with by one or plural virtual servers (hereinafter, referred to as VM (Virtual Machines)) on a host computer, are held together into one logical group in the logical volume (hereinafter, also referred to SLUs) assignment configuration, which is proposed by Conglomerate LUN Structure disclosed in Patent Literature 1) and in the storage cluster disclosed in Patent Literature 2, logical paths to ALUs are evaluated for respective logical groups, and a logical path to which an I/O is issued is selected on the basis of the evaluation result. 
     In order to enhance the availabilities of logical volumes assigned to a virtual server, a storage cluster configuration in which the logical volumes assigned to the virtual server are reduplicated in different storage devices can be built according to Patent Literature 2. Furthermore, according to Patent Literature 1, one or plural logical volumes can be assigned per virtual server. According to Patent Literature 2, if one storage device to be assigned to a storage server is in the state of copying formation or in a suspended state, an I/O transfer is executed to another storage device that is in a normal state in the storage cluster configuration. However, because this I/O transfer is executed via a network between the two storage devices, this I/O transfer needs a larger delay time than a normal I/O transfer, therefore, in the case where a virtual server uses plural logical volumes, because logical volumes that use I/O transfers and logical volumes that do not use I/O transfers mixedly exist, which leads to the processing delay or stoppage of the virtual server or the processing delays or stoppages of the OS and applications on the virtual server. 
     In addition, because a logical path control unit included in a host computer targets logical paths to ALUs, when plural virtual servers have an ALU in common, if an I/O issuance to a logical volume of a virtual server is delayed due to its I/O transfer, or the retry of the I/O issuance is needed, the logical path to the ALU is projected to be abnormal. Therefore, the logical path control unit of the host computer regards the logical path to the ALU as abnormal, and degrades or suppresses the priority of the I/O issuance, so that, even if the logical volumes of other severs that have the ALU in common are in a normal state, I/Os to the logical volumes cannot be issued, which leads to the stoppage of the other virtual servers. 
     According to this embodiment, I/Os can consistently be issued to logical paths without the occurrences of I/O delays and retries in virtual servers, an OS, or applications on a host computer, so that the delays or stoppages of pieces of processing performed on the computer using the logical volumes of storage devices are suppressed. 
       FIG. 1  is a diagram showing an example of a configuration of the storage system according to the first embodiment. A host computer  1000  includes HBAs (Host Bus Adapters)  1200  that are connection I/Fs between the hypervisor  1110 , which expands a virtual machine, and SANs  5000 , and an alternate path software  1120  that deals with Raw Devices (not shown) obtained from the HBAs  1200 . Data dealt with by a VM expanded by the hypervisor  1110  is stored in logical volumes  2500  to which SLU attributes of storage devices  2000  are given (hereinafter, referred to as SLUs); Conglomerate LUN Structure is applied to access to an SLU  2400 , and an HBA  1200  recognizes an ALU via the SAN  5000  and creates a RAW Device (not shown); the alternate path software performs logical path control per RAW DEVICE; and the hypervisor includes a data input/output unit conforming to Conglomerate LUN Structure; recognizes the SLU assigned to the RAW DEVICE, that is to say, to the ALU (hereinafter, this assignment will be referred to as binding), and assigns the SLU to the virtual machine as a virtual disk. This binding processing of the SLU is performed for VM image writing at the time of VM creation, and every time the power-on of a VM is executed. The release of the assignment of the SLU to the ALU (hereinafter, referred to as unbinding) is executed at the time of the completion of VM creation, or every time the power-off of a VM is executed. 
     A storage device  2000  includes: a logic division unit that classifies logical volumes into plural logical partitions (hereinafter, referred to CTGs: Consistency Groups  2500 ); an I/O control unit (data input/output control unit) that is conforming to Conglomerate LUN Structure and transfers an I/O corresponding to a logical volume to another storage device; and a data duplication control unit that duplicates data, which is stored in a logical volume, in a logical volume in another storage device  2000  via a SAN (Storage Area Network)  5000 . A logical volume is provided to the host computer  1000  from a logical port  2110  via SAN  5000   a  or SAN  5000   b.    
     By transferring an I/O regarding a logical volume to a storage device  2000  that is connected via SAN  5000   c  or duplicating the I/O in the storage device  2000 , data stored in the logical volume is reduplicated both in storage device  2000   a  and in storage device  2000   b . Furthermore, a kind of storage cluster system disclosed in Patent Literature 1 is formed in such a way that, by giving the same virtual resource identifiers to logical volumes that compose a pair, plural logical paths on SAN  5000   a  and SAN  5000   b  to the logical volumes that compose a pair are recognized by the host computer  1000  as if these logical paths were an alternate path to one logical volume. 
     As mentioned above, this characteristic that data is reduplicated in plural logical volumes, and plural logical paths to the logical volumes that compose a pair are recognized by the host computer  1000  as if these logical paths were an alternate path to one logical volume is referred to as HA (High Availability). The storage device  2000  can receive an I/O issued to any of volumes composing a pair having an HA characteristic (referred to as an HA pair) by the host computer  1000 . In addition, even if one logical volumes composing a pair, that is to say, one of logical volumes having an HA characteristic becomes inaccessible due to some kind of failure, I/Os issued from the host computer  1000  can be continuously accepted by another volume. 
     Here, as a function of the logic division unit, even if data is duplicated among plural logical volumes belonging to the same CTG  2500 , the consistency among the data can be assured. In other words, even if pairing operation is executed between logical volumes  2400   a  belonging to CTG 1   2500   a  and logical volumes  2400   b  belonging to CTG 2   2500   b , the consistency of data among logic volumes in the same CTG  2500  is retained. 
     The storage devices  2000   a  and  2000   b  provide various configuration management tables included in the storage devices  2000  and management APIs (Application Program Interfaces) provided by configuration control units to a management computer  3000  that is connected to the storage devices  2000   a  and  2000   b  via a management network  6000  typified by a LAN (Local Area Network). The management computer  3000  provides the various management tables of the storage devices  2000  included in the management computer  3000  and the management APIs provided by the configuration control units to the host computer  1000  and a management computer  4000  that are connected to the management computer  3000  via the management network  6000 . 
     Furthermore, a storage manager (not shown) accesses storage management software  3110  via an input/output unit included in the management computer  3000 , and executes the creation, deletion, and configuration change of storage resources such as ALUs, and a virtual machine manager accesses virtual machine management software  4110  via an input/output unit included in the management computer  4000 , and executes the creation, deletion, and configuration change of virtual machines. The virtual machine management software  4110  transmits a virtual machine management operation instruction to the host computer  1000  connected to the management network  6000  in accordance with an instruction issued by the virtual machine manager, and transmits instructions regarding the creation, deletion, and configuration change of a logical volume to the storage management software  3110  included in the management computer  3000 . 
     In addition, the storage devices  2000   a  and  2000   b  include logical path evaluation units that evaluate the appropriateness of I/O processing per LUN, and define the state in which I/O processing can be performed as “STANDBY”, the state in which I/O processing can be optimally performed as “ACTIVE/OPTIMIZED”, and the state in which I/O processing can be performed but there is a possibility of the retry of the I/O processing being requested as “ACTIVE/NON-OPTIMIZED”. The storage devices  2000   a  and  2000   b  respond to logical path evaluation value notification requests that are issued from the alternate path software  1120  on the host computer  1000  via the SANs  5000 , and the alternate path software  1120 , which have received the responses, issue I/Os preferentially to logical paths evaluated as “ACTIVE/OPTIMIZED” on the basis of the response values. 
     Hereinafter, the logical path control that evaluates logical paths on the basis of the states of pairs of bound SLUs or the states of pieces of I/O processing in the logical path evaluation units included in the storage devices  2000   a  and  2000   b  will be explained. First, the configuration of each of the storage devices  2000   a  and  2000   b  will be explained. 
     Here, the storage device  2000  is an example of an information processing system such as a storage system, and therefore the present invention is not limited to configurations shown by the accompanying drawings. A storage system according to the present invention can be a storage system based on software installed on a server. Alternatively, the storage system according to the present invention can be a storage system realized by software installed on a virtual machine running on a cloud. 
       FIG. 2  shows the configuration of the storage device  2000 . The storage device  2000  includes: at least one FEPK (Front End Package)  2100  that is a host I/F unit; at least one MPPK (Microprocessor Package)  2200  that is a control unit; at least one CMPK (Cache Memory Package)  2300  that is a common memory unit; at least one BEPK (Backend Package)  2400  that is a disk I/F unit; an internal network  2500 ; at least one HDD (Hard Disk Drive)  2700 ; and a management server  2600 . Here, instead of the at least one HDD  2700 , at least one another storage device such as at least one SSD (Solid State Drive) can be used. 
     The internal network  2500  connects the at least one FEPK  2100 , the at least one MPPK  2200 , the at least one CMPK  2300 , the at least one BEPK  2400 , and the management server  2600  to one another. Respective MPs  2210  in the at least one MPPK  2200  are configured to be able to communicate with the at least one FEPK  2100 , the at least one CMPK  2300 , and the at least one BEPK  2400  using the internal network  2500 . 
     The at least one FEPK  2100  includes plural logical ports  2110  each of which can be a host I/F. A logical port  2110  is connected to an external network  5000  such as the SAN  5000 , and performs protocol control when an I/O request issued by the host computer  1000  and read/write target data are transmitted or received between the logical port  2110  and the host computer  1000 . The at least one BEPK  2400  includes plural disk I/Fs  2410 . A disk I/F  2410  is connected to the at least one HDD  2700  via, for example, a cable, and at the same time the disk I/F  2410  is connected to the internal network  2500 , so that the disk I/F  2410  plays a role of a mediator for the transmission/reception processing of read/write target data between the internal network  2500  and the at least one HDD  2700 . 
     The at least one CMPK  2300  includes a cache memory  2310  for data and a memory  2320  for control information. The cache memory  2310  and the memory  2320  for control can be volatile memories, for example, DRAMs (Dynamic Random Access Memories). The cache memory  2310  temporarily stores (caches) data to be written in the at least one HDD  2700 , or temporarily stores (caches) data read from the at least one HDD  2700 . The memory  2320  for control information stores information necessary for control, for example, configuration information for ALUs  2120 , SLUs  2400 , CTGs  2500 , and the like that are logical volumes. 
     The at least one MPPK  2200  includes plural MPs (Micro Processors)  2210 , an LM (Local Memory)  2220  and a bus  2230  that connects the plural MPs  2210  and the LM  2220 . An MP  2210  is a processor used for a computer or the like, and plays a role of a logic division unit, an I/O control unit, a configuration control unit, or the like when the MP  2210  operates in accordance with programs stored in the LM  2220 . The LM  2220  stores part of control information for I/O control that is stored in the memory  2320  for control. The management server  2600  is a computer including management applications. The management server transmits an operation request from the management computer  3000  to a control program that has been loaded from the memory  2320  for control to the LM  2220  and executed by MP  2210 . The management server  2600  can also include various programs included in the management computer  3000 . 
     The memory  2320  for control stores information that logic division units and I/O control units deal with. The storage device management program  3110  in the management computer  3000  can obtain information stored in the memory  2320  for control via the management server  2500 . 
     A logic division unit distributes logical volumes (also referred to as LDEVs: Logical Devices) that are provided by the at least one BEPK  2400  and that are used as logical storage areas among the CTGs  2500 , and gives an identifier, which is uniquely identified in each CTG  2500 , to the configuration information of a logical volume  2210  registered in each CTG  2500 , and stores the configuration information in the memory  2320  for control as a CTG management table T 6000 . 
       FIG. 3  shows the configuration of the host computer  1000 . The host computer  1000  is a computer including: a processor  1400 ; a memory  1200 ; HBAs (Host Bus Adapters)  1300 ; an output unit  1600 ; an input unit  1700 ; a management port  1100  that is a network I/F; and the like, and the host computer is, for example, a personal computer, a workstation, a mainframe, or the like. 
     The processor  1400  integratedly controls the entirety of the host computer  1000 , and executes a virtual machine management program  1210 , a storage management program  1220 , a hypervisor  1230 , and the program of alternate path software that are stored in the memory  1200 . For example, the processor  1100  issues a read access request or write access request to the storage device  2000  as an access request by executing the hypervisor  1230 . The memory  1200 , the virtual machine management program  1210 , the storage management program  1220 , and the hypervisor  1230 . The memory  1200  is not only used for storing such programs and the like, but also used as a working memory for the processor  1400 . 
     Furthermore, the storage management program  1220  can transmit operation requests toward the logical volumes  2210  such as SLU assignment or the release of SLU assignment issued from a job application  1210  or an OS to the storage device management program  3110  included in the management computer  3000  via the management network  6000 . In addition, the storage management program  1220  can transmit the operation request of a logical volume to a configuration control unit included in the storage device  2000  via the SAN  5000 . 
     An HBA  1300  performs protocol control at the time of communicating with the storage device  2000 . Because the HBA  1300  performs the protocol control, the transmission and reception of data and commands between the host computer  1000  and the storage device  2000  are performed in accordance with, for example, the fiber channel protocol. 
     The input unit  1700  includes, for example, a keyboard, a switch, pointing device, a microphone, and the like, and the like. The output unit  1600  includes a monitor display, a speaker, and the like. 
       FIG. 4  shows the logical block diagram of the host computer  1000 . The hypervisor  1230  includes: a virtual machine control unit  1231  that expands the virtual machine; a disk control unit  1232  that forms virtual disks from SLUs obtained from RAW DEVICEs; and an alternate path control unit  1233  that controls logical paths through which the logical volumes of the storage device  2000  are accessed. Here, instead of the alternate path control unit  1233 , the logical buses can be controlled by the alternate path software  1120  other than the hypervisor as shown in  FIG. 1 . Hereinafter, “the alternate path control unit  1233 ” can be replaced with “the alternate path software  1120 , and vice versa. 
     The RAW DEVICES  1310  correspond to the ALUs  2120  in the storage devices  2000 , and they are devices that can be replaced with accesses to the ALUs  2120  in the host computer  1000 . The alternate path control unit  1233  controls logical paths extended to the RAW DEVICEs  1310 . The disk control unit  1232  forms one virtual disk corresponding to one SLU  2400  of a storage device  2000  that is accessible via a RAW DEVICE  1310 . Accesses to SLUs  2400  in the host computer  1000  are concentrated on the RAW DEVICEs  1310 . In other words, an access to an SLU  2400  is executed after the alternate path control unit  1233  specifies the target SLU  2400  via a RAW DEVICE associated with the target SLU  2400 . The RAW DEVICEs  1310  are used as devices that reduce overhead by executing I/O processing without temporarily copying data in a page cache (not shown) when a Hyper Visor unit  1400  is accessed. 
     The volume identifier of the target SLU that an HBA  1300  obtains has to be globally unique, and the volume identifier is formed as a combination of the serial number (product number) of the relevant storage device  2000  and the local volume identifier of the target SLU in the storage device  2000 . In this embodiment, the storage device  2000  has a function of sending back the identifier of the relevant ALU in response to the response of the volume identifier. 
       FIG. 5  shows the configuration of the management computer. In the management computer  3000 , a processor  3600  integratedly controls the entirety of the management computer  3000 , and transmits various configuration management operation requests regarding the storage devices  2000  and the host computer  1000  to the storage devices  2000  and the host computer  1000  via a network I/F  3400  and the management network  6000  by executing the storage device management program  3110  and a computer management program (not shown) that are loaded in a memory  3100 . 
     Furthermore, the memory  3100  also stores control information that is used by the storage device management program  3110  and the host computer management. The storage manager inputs an operation request into an input unit  3700  using a keyboard or a mouse, and can obtain an execution result via an output unit  3600  such as a display or a speaker. A storage medium  3300  such as an HDD or an SSD stores the execution logs of the storage device management program  3110 , the host computer management program  3120 , and various control programs. 
     The configuration of the management computer  4000  is similar to that of the management computer  3000  shown in  FIG. 5 , a virtual machine management program  4110  is loaded in a memory  4100 , and the management computer  4000  transmits the configuration management operation requests regarding a virtual machine  1900  and the storage devices  2000  to the storage devices  2000  and the host computer  1000  via the management network  6000 . 
       FIG. 6  is a diagram showing an example of a configuration of a VM management table T 1000  included in the host computer  1000 . The VM management table T 1000  is referred to when the host computer  1000  executes the hypervisor  1230  and the virtual machine management program  1210 , and can be accessed from various programs included in the management computers  3000  and  4000  via the management network  6000  using an API provided by the host computer  1000 . 
     The VM management table T 1000  includes: the column VM ID T 1010  that registers the identifier of the VM  1900  identifiable in the storage system; the column VOL ID T 1020  that registers the identifiers of SLUs  2400  assigned to the VM  1900 ; the column VOL SIZE T 2030  that registers the capacities of the relevant SLUs  2400 ; the column PROFILE T 1040  that registers a profile regarding the VM  1900 ; and the column STATUS T 1050  that registers the status of the VM  1900 . 
     Here, a profile regarding a VM means the characteristic information of the VM that is specified by a VM administrator when the VM is created. The characteristic information of the VM can be defined on the virtual machine management software included in the management computer  4000 , and the VM administrator can select one or more pieces of characteristic information from the predefined characteristic information when the VM is created. In this embodiment, HA (High Availability) showing being highly available is specified as an example of the characteristic of the VM. If HA is specified, the SLUs  2400  assigned to the VM  1900  become pair of logical volumes having a HA characteristic. 
       FIG. 7  is a diagram showing an example of a configuration of a logical path management table T 2000  included in the host computer  1000 . The logical path management table T 2000  is referred to when processing is performed by the alternate path software  1120  on the host computer  1000 , the alternate path control unit  1231  included in the hypervisor  1230 , or the storage management program  1220 . The logical path management table T 2000  can be accessed from various programs included in the management computers  3000  and  4000  via the management network  6000  using the API provided by the host computer  1000 . 
     The logical path management table T 2000  includes: the column ALU ID T 2010  that registers the identifier of an ALU  2120  that composes a RAW DEVICE  1310  obtained from an HBA  1300 ; the column INITIATOR WWN T 2020  that registers the WWNs (World Wide Names) of HBAs  1300  that recognize the ALU  2120 ; the column TARGET WWN T 2030  that registers the WWNs of logical ports  2110  in the relevant storage device  2000  where the ALU  2120  can be obtained from the relevant HBA  1300 ; the column LUN T 2040  that registers LUNs (Logical Unit Numbers) that are the TARGET WWNs and belong to the ALU  2120  registered in the column T 2010  are registered; and the column STATUS T 2050  in which the statuses of the LUNs are registered. After the alternate path software  1120  or the alternate path control unit  1231  and the storage management program  1220  issue an LUN scanning request (REPORT LUN) to each HBA  1300 , and each HBA  1300  transmits the list of LUNs that each 
     HBA recognizes in response to the request, the logical path management table T 2000  is updated on the basis of the response values. In addition, after the alternate path software  1120  or the alternate path control unit  1231  requests each HBA  1300  to obtain the status of each LUN registered in the column T 2040 , STATUS T 2050  registers the response value in the relevant column. For example, a value in the column STATUS T 4040  of the after-mentioned LUN management table T 4000  that registers the status of a LUN is obtained by the alternate path control unit  1231 , and the obtained value is stored in the column STATUS T 2050  for registering the status of the LUN. 
       FIG. 8  is a diagram showing an example of a configuration of a bound management table T 3000  included in the host computer  1000 . The bound management table T 3000  manages the associations between an ALU and SLUs bound to the ALU. The bound management table T 3000  is referred to when processing is performed by the disk control unit  1231  included in the hypervisor  1230 , the storage management program  1220 , or the virtual machine management program  1210 , and can be accessed from various programs included in the management computers  3000  and  4000  via the management network  6000  using the API provided by the host computer  1000 . 
     The bound management table T 3000  includes the column ALU ID T 3010  that registers the identifier of an ALU  2120  registered in the logical path management table T 2000  and the column BOUND VOL ID T 3020  that registers the identifiers of SLUs  2400  bound to the ALU  2120 . 
       FIG. 9  is a diagram showing examples of configurations of LUN management tables T 4000  included in the storage device  2000 . A LUN management table T 4000  manages LUNs provided by the storage device  2000 . The storage device  2000  refers the LUN management table T 4000  when the storage device  2000  performs logic path processing or logic path evaluation processing, and the management computer  3000  connected to the management network  6000  can also refer to the LUN management table T 4000  using a management API provided by a storage management server  2500  on the storage device  2000 . 
     The LUN management table T 4000  includes: the column PORT ID T 4010  that registers the identifier of a logical port  2110 ; the column PORT WWN T 4020  that registers the WWN of the relevant logical port  2110 ; the column LUN T 4030  that registers the identifier of a LUN; the column STATUS T 4040  that registers the status of the LUN; and the column LDEV ID T 4050  that registers the identity of a logical volume that composes the LUN. Here, a LUN is assigned to a logical volume associated with a logical port  2110  as the identifier of the logical volume. The after-mentioned LDEV ID identifies a logical volume uniquely in the storage device  2000 , while a LUN identifies a logical volume uniquely among logical volumes associated with a logical port  2110 . 
     Each of  FIG. 10  and  FIG. 11  is a diagram showing an example of a configuration of a logical volume management table T 5000  included in the storage device  2000 .  FIG. 10  shows a logical volume management table T 5000   a  included in the storage device  2000   a , and  FIG. 11  shows a logical volume management table T 5000   b  included in the storage device  2000   b . The logical volume management table T 5000  manages logical volumes provided by the storage device  2000 . The storage device  2000  refers the logical volume management table T 5000  when the storage device  2000  performs logical volume configuration control or data duplication control, and the management computer  3000  connected to the management network  6000  can also refer to the logical volume management table T 5000  using a management API provided by the storage management server  2500  on the storage device  2000 . 
     The logical volume management table T 5000  includes: the column LDEV ID T 5010  that registers the identifiable identifiers of logical volumes in the storage device; the column ATTRIBUTES T 5020  that registers attribute information regarding the relevant logical volumes; the column CAPACITY T 5030  that registers the capacities of the relevant logical volumes; the column PAIR LDEV ID T 5040  that registers the identifiers of logical volumes that belong to another storage device and whose data are obtained by duplicating data of some of the relevant logical volumes; and the column PAIR STATUS T 5050  that registers the statuses of the relevant duplicated pairs. 
       FIG. 12  is a diagram showing examples of configurations of CTG management tables included in the storage device  2000 . A CTG management table T 6000  is referred to when the configuration of a logical volume is controlled, the duplication processing of data is performed, and the evaluation processing of a logical path is performed in the storage device  2000 , and the CTG management table T 6000  can be referred to through the management computer  3000  connected to the management network  6000  using a management API provided by the storage management server  2500  on the storage device  2000 . 
     The CTG management table T 6000  includes the column CTG ID T 6010  that registers CGT identifiers, the column LDEV ID T 6020  that registers the identifiers of logical volumes that are components of the CTG, the column PAIR CTG T 6030  that registers the identifier of a CTG, to which the duplication destination the logical volumes in the CTG belong, the column STATUS T 6040  that registers the integrated evaluation values of the data duplication statuses of the logical volumes in the CTG, and the column VM ID T 6050  that registers the identifier of a VM  1900  that uses the logical volumes in the CGT. The integrated evaluation value registered in the column  6040  shows pair statuses as the CTG that are obtained by integratedly evaluating the pair statuses of the logical volumes in the CTG. In the first embodiment, SLUs belonging to the same CTG are bound to one ALU, that is to say, the SLUs in the CTG have one logical path in common. Therefore, the pair statuses of logical volumes in the CTG can be integrally evaluated instead of each SLU being evaluated, with the result that an optimal logical path control can be performed, and the number of I/O transfers among the storage devices  2000  can be reduced. 
       FIG. 13  is a diagram showing examples of configurations of bound management tables T 7000  included in the storage device  2000 . A bound management table T 7000  is referred to when the binding processing is performed in the storage device  2000 , and the bound management table T 7000  can be referred to through the management computer  3000  connected to the management network  6000  using a management API provided by the storage management server  2500  on the storage device  2000 . 
     The bound management table T 7000  includes the column ALU ID T 7010  that registers an identifier of an ALU  2120  included in the storage device  2000  that is identifiable in the storage device, and the column BITMAP T 7020  that registers a bitmap showing a list of bound SLUs. 
     The configuration of a bitmap of the column T 7020  will be explained below. Each bit of the bitmap corresponds to the identifier of an SLU  2400 . The length of the bitmap is equal to the number of logical volumes included the storage device  2000 . For example, in the case where the identifier of a logical volume is represented by hexadecimal form “0x0000”, the first bit represents the relevant volume, and if the logical volume “0x0000” is bound to the ALU  2120  registered in the column T 7010 , the relevant bit is “1”, and if it is not bound, the relevant bit is “0”. A bound management table T 7   000   a  shows that the logical volume 01:01 is bound to ALU 00:00. 
     Hereinafter, VM creation processing according to this embodiment will be explained with reference to  FIG. 14 . First, the VM administrator transmits VM creation instruction to the virtual machine management software  4110  via a GUI (graphical user interface) provided by the input/output unit included in the management computer  4000  (at step S 1000 ). The VM creation instruction is given characteristic information required of a VM to be created, and it will be assumed that “HA” that shows high availability is specified in this embodiment. In addition, the number and capacity of SLUs are specified in this VM creation instruction. 
     Next, the virtual machine management software  4110  transmits the VM creation instruction to the virtual machine management program  1210  included in the host computer  1000  via the management network  6000  (at step S 1010 ). The virtual machine management program  1210  transmits the creation instruction of logical volumes of which the VM is composed, that is to say, the creation instruction of SLUs  2400  to the storage management program  1220  which is also included in the host computer  1000  (at step S 1020 ). 
     The storage management program  1220  transmits the creation instruction of the SLUs  2400 , which indicates that the storage device  2000  under the control of the storage management software  3110  included in the management computer  3000  should create the SLUs  2400 , to the storage management software  3110  (at step S 1030 ). The storage management software  3110  instructs the storage device  2000  to create the SLUs  2400  (at step S 1035 ), and after the completion of the creation of the SLUs  2400 , the storage management software  3110  transmits the identifiers of the created SLUs  2400  to the storage management program  1220 . The storage management program  1220  transmits the received identifiers of the SLUs  2400  to the virtual machine management program  1210 . 
     Next, the virtual machine management program  1210  registers the ID of the new VM in the column T 1010  of the VM management table T 1000 , the received identifiers of the SLUs  2400  and the capacities of the SLUs  2400  in the column T 1020  and the column T 1030  relevant to the new VM respectively, and further registers a profile specified in the VM creation request in the column T 1040 . The virtual machine management program  1210  transmits the binding instruction for the SLUs registered in the column T 1020  to the storage management program  1220  (at step S 1040 ), and the storage management program  1220  instructs the storage management software  3110  to execute the specified binding instruction for the SLUs (at step S 1050 ). After the completion of the binding processing executed in the storage device  3000 , the virtual machine management program  1210  executes VM image write processing for the bound SLUs  2400  to the virtual machine control unit  1231  and the disk control unit  1232  of the hypervisor  1230  (at step S 1060 ). After the completion of the VM image write processing, the virtual machine management program  1210  issues the unbinding instruction of the relevant SLUs  2400  (at step S 1070 ). On receiving the unbinding instruction from the virtual machine management program  1210 , the storage management program  1220  transmits the unbinding instruction to the storage management software  3110  (at step S 1080 ). After the unbinding processing is completed, the storage management software  2110  transmits a VM creation completion response including the identifier of the created VM to the virtual machine management software  4110 , which is the sender of the VM creation instruction, via the storage management program  1220  and the virtual machine management program.  1210 , and the virtual machine management software  4110  informs the VM administrator of the completion of the virtual machine creation processing. 
     Here, the SLU  2400  creation processing at step S 1035  will be explained with reference to  FIG. 15 . 
       FIG. 15  is equivalent to the storage resource creation processing (at step S 1035 ) in the VM creation shown in  FIG. 14 , in which the storage management software  3110  receives an SLU  2400  creation instruction from the storage management program  1220 , and the following processing starts. First, the storage management software  3110  extracts the identifier (ID) and profile specified for a VM to be created and the number and capacity of logical volumes to be created for the VM to be created from the logical volume creation instruction (at step F 1000 ). The storage management software  3110  checks whether “HA” is specified in the profile of the VM to be created or not (at step F 1010 ). If “HA” is not specified (No at step F 1010 ), the storage management software  3110  creates SLUs  2400 , the number and capacity of which are the same as the specified number and capacity, in the primary side storage device  2000   a  of the storage cluster (at step F 1060 ), and finishes this processing. 
     If “HA” is specified (Yes at step F 1010 ), the storage management software  3110  instructs the storage devices  2000   a  and  2000   b , which compose the storage cluster, to create CTGs  2500  corresponding to the VM to be created (at step F 1020 ), and after the completion of the CTGs  2500 , the storage management software  3110  instructs each of the storage devices  2000   a  and  2000   b  to create SLUs  2400  the number and capacity of which are the same as the specified number and capacity (step F 1030 ). The storage management software  3110  instructs the storage devices  2000   a  and  2000   b  to register the created SLUs  2400  in the CTGs created or extracted at step F 1020  (at step F 1040 ), specifies the CTGs  2500  created at step F 1020 , instructs the storage devices  2000   a  and  2000   b  to form HA pairs (at step F 1050 ), and finishes this processing. 
     In this processing, on receiving the instruction of creating the CTGs  2500  corresponding to the created VM at step F 1020 , each of the configuration control units of the storage devices  2000   a  and  2000   b  refers to the CTG management table T 6000 , and scans the column T 6050  to check whether there is the specified VM ID of or not. If the specified VM ID is registered in the CTG management table T 6000 , the configuration control unit sends back the CTG ID of a CTG in which the specified VM ID is registered. If the specified VM ID is not registered in the CTG management tables T 6000 , the configuration control unit registers a new CTG, registers the specified VM ID in the column T 6050  of the new CTG, and sends back the ID of the new CTG. 
     Furthermore, on receiving the instruction to create the SLUs  2400  the number and capacity of which are the same as the specified number and capacity at step F 1030 , the configuration control unit creates LDEVs which are given an SLU-attribute indicating the specified number and specified capacity of SLUs, registers the new LDEVs in the logical volume management table T 5000 , and transmits the notification of completion including the LDEV IDs of the new LDEVs At step F 1040 , on receiving the instruction to register the SLUs  2400  in the CTG, the configuration control unit refers to the CTG management table T 6000  in order to register the specified LDEVs in the specified CTG, and registers the IDs of the specified LDEVs in the column T 6020  of the specified CTG. 
     On receiving the HA pair formation instruction at step F 1050 , the data duplication control unit registers the identifier of a data duplication destination CTG in the column  6030  of the CTG management table  6000 , and creates pairs of LDEVs in the CTG. In the initial data duplication in the pair formation, because the data storage statuses among the logical volumes are mismatched with one another, in the case where only the primary side LDEVs are data-writable, the statuses of the primary side LDEVs are set to “COPY (LOCAL)” statuses which mean that the primary side LDEVs are being copied and I/O processing can be performed on the primary side LDEVs, and the secondary side LDEVs are set to “COPY (BLOCK)” statuses which mean that the secondary side LDEVs are being copied and I/O processing can be performed on the secondary side LDEVs. Furthermore, in the case where the data storage statuses of both primary side and secondary side LDEVs become matched, the LDEV statuses of both primary side and secondary side LDEVs become “PAIR (MIRROR)”, which means that I/O processing can be performed on both primary side and secondary side LDEVs. In the case where I/O processing cannot be performed on the secondary side LDEVs due to some disaster or another, the primary side LDEVs are in the status that each of pairs is not in synchronization with each other, so that the statuses of the primary side LDEVs become “PSUS (LOCAL)” statuses which mean that I/O processing can be performed only on the primary side LDEVs, and the secondary side LDEVs are in the status that each of pairs is not in synchronization with each other, so that the statuses of the secondary side LDEVs become “PSUS (BLOCK)” statuses which mean that I/O processing cannot be performed on the secondary side LDEVs. In the case where I/O processing cannot be performed on the primary side LDEVs due to some disaster or another, the primary side LDEVs are in the status that each of pairs is not in synchronization with each other, so that the statuses of the primary side LDEVs become “SSWS (BLOCK)” statuses which mean that I/O processing cannot be performed on the primary side LDEVs, and the secondary side LDEVs are in the status that each of pairs is not in synchronization with each other, so that the statuses of the secondary side LDEVs become “SSWS (LOCAL)” statuses which mean that I/O processing can be performed only on the secondary side LDEVs. The statuses of these LDEV duplicate pairs are registered in the column T 5050  of the logical volume management table T 5000 . 
     The value obtained by integratedly evaluating the pair statuses of all the LDEVs in the relevant CTG is registered in the column T 6040 , and if there is only one pair whose status is not “PAIR” status, the CTG status becomes the status of the pair. 
     To put it concretely, even if there is only one SLU  2440  whose status is “COPY (BLOCK)”, “PSUS (BLOCK)”, or SSWS (BLOCK)” (hereinafter, these statuses are referred to as “BLOCK” statuses) in one CTG, “BLOCK” is registered in the column T 6040 . Even if there is no SLU  2400  whose status is “COPY (BLOCK)”, “PSUS (BLOCK)”, or SSWS (BLOCK)“, but there is only one SLU  2400  status is “COPY (LOCAL)”, “PSUS (LOCAL)”, or SSWS (LOCAL)” (hereinafter, these statuses are referred to as “LOCAL” statuses) in one CTG, “LOCAL” is registered in the column T 6040 . In the case where the statuses of all the SLUs  2400  in one CTG are “PAIR (MIRROR)”, “PAIR” is registered in the column T 6040 . 
       FIG. 16  is a diagram showing an example of a sequence of LDEV configuration operation instruction that the storage management software  3110  transmits to the storage devices  2000   a  and  2000   b . In the case of the configuration of an operation target LDEV is HA configuration, the storage management software  3110  transmits the same LDEV configuration operation instruction to the two storage devices  2000  having HV configuration LDEVs, and if both storage devices  2000  finish this configuration operation normally, the storage management software  3110  responses with the normal completion of the configuration operation to the requestor. If one of the two storage devices finishes this configuration operation abnormally, the storage management software  3110  gets back a storage device  2000  that finishes the configuration operation normally in the status before the storage device  2000  is operated, and notifies the requestor of the abnormal completion of the configuration operation. If both storage devices finish this configuration operation abnormally, the storage management software  3110  notifies the requestor of the abnormal completion of the configuration operation. 
       FIG. 17  is a diagram showing an example of a configuration of a flowchart of binding processing in the configuration control unit included in the storage device  2000 . The binding processing is started on receiving a binding instruction from the storage management software  3110  that receives the constituent VOL binding instruction at step S 1050 . 
     In the binding processing, the configuration control unit extracts a binding target SLU  2400  from the binding instruction (at step F 2000 ), and checks whether the specified SLU  2400  is an HA configuration volume or not with reference to the logical volume management table T 5000  (at step F 2010 ). If the specified SLU  2400  is not an HA configuration volume (NO at step F 2010 ), the configuration control unit selects an ALU  2120  that is not given HA attribute from the logical volume management table T 5000  (at step F 2060 ), changes the value of a bit relevant to the specified SLU  2400  in a bitmap in the column T 7020  corresponding to the ALU  2120  into “1” with reference to the bound management table T 7000  (at step F 2070 ), and then finishes this processing. 
     If the specified SLU  2400  is an HA configuration volume (YES at step F 2010 ), the configuration control unit extracts a CTG  2500  to which the specified SLU  2400  belongs with reference to the CTG management table T 6000  (at step F 2020 ), and a list of LDEVs of the CTG  2500  extracted with reference to the CTG management table T 6000  is extracted, and further the configuration control unit selects an ALU relevant to any of the extracted LDEV that is bounded with the column T 7020  of the bound management table T 7000  (at step F 2030 ). If there is no relevant ALU at step F 2030 , the configuration control unit extracts one LDEV that is not given 
     HA attribute with reference to the logical volume management table T 5000 , and sets the LDEV as a selected ALU  2120 . Next, the configuration control unit performs binding processing by changing the value of a bit relevant to the specified SLU  2400  corresponding to the ALU  2120  selected at step F 2030  into “1” in the column T 7020  (at step F 2040 ), performs logical path evaluation processing (at step F 2050 ), and then finishes this processing. This processing is characterized in that SLUs  2400  belonging to the CTG  2500  are bound to the same ALU  2120 . 
       FIG. 18  is a diagram showing an example of a configuration of a flowchart of unbinding processing in which the configuration control unit of the storage device  2000  releases the binding of SLUs  2400 . In the unbinding processing, the configuration control unit extracts an ALU  2120  to which a specified SLU  2400  is bound to reference to the bound management table T 7000  (at step F 3010 ), and changes the value of a bit of a bitmap in the column  17020  relevant to the specified SLU  2400  corresponding to the ALU  2120  in the bound management table T 7000  into “0” (at step F 3020 ). This unbinding processing is characterized in that, if the specified SLU  2400  is HA configuration volume (Yes at step F 3030 ), the logical path control unit performs logical path evaluation processing regarding the ALU  2120  extracted at step F 3010 . 
     Hereinafter, logical path evaluation processing according to this embodiment will be explained. 
       FIG. 19  is a diagram showing an example of a configuration of a flowchart of the logical path evaluation processing performed by the logical path control unit of the storage device  2000 . The logical path evaluation processing is performed after a binding processing control unit binds an SLU  2400  to an ALU  2120  (at step F 2050 ) or when the status of a CTG  2500  is changed in the data duplication control unit (at step F 3040 ). 
     In the logical path evaluation processing, the configuration control unit calculates SLUs  2400  bound to an ALU  2120  specified by a specification source control unit with reference to the bound management table T 7000 , and extracts CTGs  2500  to which the SLUs  2400  belong from the CTG management table T 6000  (at step F 4000 ). The configuration control unit sets “ACTIVE/OPTIMIZED” as the initial value of a logical path evaluation value X (at step F 4010 ), and performs loop processing at step F 4020  on the CTGs  2500  extracted at step F 4000 . The configuration control unit performs the loop processing on every CTG  2500 . First, the configuration control unit refers to the column T 6040  of the CTG management table T 6000 , and if the status of the relevant CTG  2500  is BLOCK status (Yes at step F 4030 ), that is to say, the status in which the relevant CTG  2500  cannot receive an I/O, the configuration control unit checks whether the storage device  2000  includes an inter-storage device I/O transfer function or not, and whether an I/O transfer is available or not (at step F 4040 ). If the I/O transfer is not available (No at step F 4040 ), the configuration control unit sets the value of the logical path evaluation value X to “STANDBY” (at step F 4050 ), and if the I/O transfer is available (Yes at step F 4040 ), the configuration control unit sets the value of X to “ACTIVE/NON-OPTIMIZED” (at step F 4060 ). After the loop processing at step F 4020  is completed, the configuration control unit registers the value of X in the column T 4040  of a row corresponding to the column T 4050  in which the LDEV ID of the specified ALU  2120  is registered with reference to the LUN management table T 4000  (at step F 4080 ), and then finishes this processing. 
     The inter-storage device I/O transfer function will be explained below. If the pair status of an LDEV is “BLOCK” status, it is impossible to perform I/O processing on the LDEV. However, in the case where the storage device  2000  includes the inter-storage device I/O transfer function, an I/O is transferred between the storage devices in order to perform the relevant I/O processing on a volume that makes a pair in cooperation with the LDEV. For example, the storage device  2000   b  including a secondary side LDEV transfers an I/O to the storage device  2000   a , so that the I/O is transferred to a primary side LDEV (“COPY (LOCAL)”) that makes a pair in cooperation with the secondary side LDEV, and the I/O can be performed by the primary side LDEV. In a similar way, a storage device  2000  including the inter-storage device I/O transfer function transfers an I/O to be performed on a logical volume whose status is “PSUS (BLOCK)” or “SSWS (BLOCK)” to another storage device  2000 , and can perform the I/O processing using another logical volume that makes a pair in cooperation with the former logical volume. 
     As explained above, in the case where STSATUS of a CTG in the column T 6040  of the CTG management table T 6000  is “PAIR (MIRROR)” or “LOCAL”, I/O processing can be performed in the storage device  2000  itself. Therefore it is not necessary to execute an I/O transfer between the storage devices  2000  and the delay of the I/O does not occur, so that the status of the relevant logical path becomes “ACTIVE/OPTIMIZED”. In the case where STATUS of the CTG is “BLOCK” status and the inter-storage device I/O transfer is available, I/O processing can be performed although the response delay due to the I/O transfer occurs, therefore the status of the relevant logical path becomes “ACTIVE/NON-OPTIMIZED”. In the case where STATUS of the CTG is “BLOCK” status and the inter-storage device I/O transfer is not available, I/O processing cannot be performed, therefore the status of the relevant logical path becomes “STANDBY”. 
     When the logical path evaluation processing according to this embodiment is performed, the evaluation value of the logical path of an ALU  2120  in the case where an I/O transfer between the storage devices  2000  or retry does not occur can be kept “ACTIVE/OPTIMIZED” in accordance with binding processing or data duplication processing. 
     Second Embodiment 
     In the first embodiment, because plural CTGs  2500  have an ALU  2120  in common, if there is only one CTG  2500  the status of which is other than “PAIR (MIRROR)” of the plural CTGs  2500  having the ALU  2120  in common, the evaluation of the logical path of the ALU  2120  becomes other than “ACTIVE/OPTIMIZED”, with the result that a situation where no logical path the status of which is “ACTIVE/OPTIMIZED” status exists occurs. 
     In this embodiment, logical path control in which one or more logical paths the statuses of which are “ACTIVE/OPTIMIZED” are secured per CTG  2500 , that is to say, per VM  1900 , or per job will be explained. Due to this configuration, the status of a logical path can be prevented from being adversely affected by various kinds of jobs. 
       FIG. 20  is a diagram showing an example of a configuration of a storage system according to this embodiment. Each storage system according to this embodiment is different from the storage system according to the first embodiment in that the host computer  1000  includes a logical partition control unit that classifies VMs into AGs (Availability Groups)  7000  per VM or per job, and other components of this embodiment are the same as those of the first embodiment. It is conceivable that VMs having the same characteristic information are made to belong to the same AG. In other words, the same value is stored in the column PROFILE T 1040  of the VM management table T 1000  regarding each of VMs belonging to the same AG. 
     Hereinafter, a means for classifying VMs  1900  into AGs  7000  that are logical partitions; a storage system including: a means for building up CTGs  2500  per AG  7000 ; a means for assigning ALUs  2120  per CTG  2500  will be explained. 
     First, in order to classify VMs  1900  into AGs  7000 , the VM administrator assigns an identifier for identifying an AG  7000  to the profile given to each VM. The identifier can be an arbitrary character string defined by the VM administrator or an identifier defined in advance in the virtual machine management software  4110  by the VM administrator. The assigned identifier for the AG  7000  is included the configuration operation instruction used at steps S 1000  to S 1035  in the VM creation sequence shown in  FIG. 14 . To put it concretely, the assigned identifier for the AG  7000  is registered in the column T 1040  of the VM management table T 1000  in the VM creation processing by the host computer  1000 , and the storage device  2000  registers the assigned identifier for the AG  7000  in the column T 8050  of a CTG management table T 8000  shown in  FIG. 21  when a CTG  25000  is created. 
     Hereinafter, logical volume creation processing for creating logical volumes composing a VM performed in the storage device  2000  will be explained with reference to  FIG. 22 . In the second embodiment, processing shown in  FIG. 22  is performed instead of the storage resource creation processing in the VM creation shown in  FIG. 15 . 
       FIG. 22  is a diagram showing an example of a configuration of a flowchart of logical volume creation processing performed by the storage management software  3110  in a VM creation processing sequence. On receiving a logical volume creation instruction including the identifier for an AG  7000 , the storage management software  3110  starts this processing, and checks whether HA is specified in a profile obtained from the creation instruction (at step F 4010 ). If HA is not specified (No at step F 4010 ), the storage management software  3110  creates the specified number of SLUs  2400  having specified capacities in a primary side storage device  2000   a  of a storage cluster (at step F 4060 ), and finishes this processing. If HA is specified (Yes at step F 4010 ), the storage management software  3110  creates the specified number of SLUs  24000  having specified capacities in the primary side storage device  2000   a  of the storage cluster (at step F 1060 ), and finishes this processing. The storage management software  3110  instructs the storage devices  2000   a  and  2   000   b  that compose the storage cluster to create CTGs  2500  corresponding to the specified AG  7000  (at step F 4020 ). After the creation of the CTG  2500  is finished, the storage management software  3110  instructs the storage devices  2000   a  and  2000   b  to create ALUs  2120  belonging to the CTGs  2500  created at step F 4020  (at step F 4030 ). Next, the storage management software  3110  instructs the storage devices  2000   a  and  2000   b  to create the specified number of SLUs  2400  having the specified capacities belonging to the CTGs  2500  created at step F 4020  (at step F 4040 ), instructs the storage devices  2000   a  and  2000   b  to form HA pairs of the created SLUs  2400  (at step F 4050 ), and finishes this processing. 
     The storage device  2000 , which receives the instruction of the creation of a CTG  2500  at step F 4020 ; extracts the identifier of the AG  7000  in accordance with the creation instruction, refers to the CTG management table T 8000 ; extracts a CTG  2500  corresponding to the specified AG  7000 ; and, if there is a relevant CTG  2500 , the storage device  2000  sends back the relevant CTG  2500 , and if there is no relevant CTG  2500 , the storage device  2000  creates a new CTG  2500 , and registers the identifier of the specified AG  7000  in the column T 8050  of the created CTG  2500 . 
     As described above, a CTG  2500  can be built up per AG  7000 , and further one ALU  2120  can be set for the CTG  2500 , with the result that, by applying the logical path evaluation processing shown in  FIG. 19 , it becomes possible to perform logical path evaluation on the ALU  2120  per AG  7000 . 
     Third Embodiment 
     In the second embodiment, because an ALU  2120  is consumed per AG  7000 , the depletion of ALUs  2120  occurs. In this embodiment, using a virtual port function included in the host computer  1000 , one or more Initiator Ports are assigned to one AG  7000 , and a VM  1900  uses any of Initiator Ports assigned to an AG  7000  to which the VM  1900  belongs. Hereinafter, a storage system in which the storage device  2000  performs the logical path evaluation of an ALU  2120  per Initiator Port will be explained. 
       FIG. 23  is an example of a configuration of a storage system according to this embodiment. The hypervisor  1230  of the host computer  1000  includes a virtual port control unit, and performs virtual port allocation in which a virtual port  1210  is assigned per AG  7000 . 
     In addition, a logical port  2110  of the storage device  2000  holds together Initiator Ports that enables a login (generally referred to as a fabric login) as an HG (Host Group)  2130  that is a logical partition per logical port  2110 . An I/O from a logical path that passes through an HG  2130  includes an access restriction control unit that receives only from the WWN of a registered Initiator Port. 
       FIG. 24  is a diagram showing examples of configurations of virtual port management tables T 9000  included in the host computer  1000 . A virtual port management table T 9000  is referred to when the virtual port control unit (not shown) of the hypervisor  1230  performs virtual port allocation processing and when the disk control unit  1232  and the alternate path control unit  1233  performs I/O processing, and can be accessed from various programs included in the management computers  3000  and  4000  via the management network  6000  using an API provided by the host computer  1000 . 
     The virtual port management table T 9000  includes: the column PORT WWN T 9010  that registers the WWN of an HBA  1200 ; the column PORT WWN T 9020  that registers the WWN of a virtual port  1210  created from the HBA  1200 ; the column VM ID T 9030  that registers the identifier of the VM  1900  to which the virtual port  1210  is assigned; and the column AG ID T 9040  that registers the identifier of an AG  7000  to which the VM  1900  belongs. 
     The assignment of a virtual port  1210  is executed by a VM administrator using the user interface of a virtual machine management program  1210  provided from an input unit  1700  and an output unit  1600 , and the virtual machine management program  1210  registers information based on the relevant instruction in the virtual port  1210 . 
       FIG. 25  is a diagram showing examples of configurations of host group management tables U 1000  included in a logical port  2110  of the storage device  2000 . A host group management table U 1000  is referred to when the configuration control unit included in the storage device  2000  performs host group configuration change processing and logical path control processing and when an I/O control unit included in the storage device performs access control processing, and can be accessed from the management computer  3000  that is connected to the management network  6000  using a management API provided by a storage management server  2500  on the storage device  2000 . 
     The host group management table U 1000  includes: the column PORT ID U 1010  that registers the identifier of a logical port  1210 ; the column PORT WWN U 1020  that registers the WWN of the relevant logical port  1210 ; the column HG U 1030  that registers the identifiers of HGs  2130  belonging to the relevant logical port  1210 ; the column INITIATOR WWN U 1040  that registers the WWNs of Initiator Ports registered in the relevant HGs  2130 ; the column AG ID U 1050  that registers the identifiers of AGs  7000  corresponding to the relevant HGs  2130 ; the column LUN T 1060  that registers the identifiers of LUNs belonging to the relevant HGs  2130 ; and the column LDEV ID U 1070  that registers the identifiers of LDEVs that are the substances of the relevant LUNs. 
       FIG. 26  is a diagram showing an example of a configuration of a flowchart of Initiator Port WWN registration processing in which the WWN of an Initiator Port is registered in a HG  2130 . This processing is started when a storage manager requests the configuration control unit of the storage device  2000  to perform this processing via a management user interface provided by storage management software  3110  or by the storage management server  2500 . 
     In the above-mentioned WWN registration processing, the configuration control unit extracts the identifier of an AG  7000  from request information (at step F 5000 ), and obtains the WWN of a virtual port  1210  assigned to the AG  7000  at step F 5000  from a virtual machine management software  4110  of the management computer  4000  that is connected to the configuration control unit via the management network  6000  (at step F 5010 ). The configuration control unit extracts an HG  2130  in which the AG  7000  the identifier of which is extracted at step F 5000  is registered with reference to the host group management table U 1000  (at step F 5020 ), registers the WWN obtained at step F 5010  for the extracted HG  2130  in the relevant column U 1040  of the host group management table U 1000  (at step F 5030 ), and assigns an ALU  2120  to the HG  2310  extracted at step F 5020 . 
     If there is no relevant HG  2130  at step F 5020 , the configuration control unit newly creates an HG  2130  in one logical port  1210  that has already been physically connected to the SAN  5000 , and registers the identifier of the AG  7000  extracted at step F 5000  in the column U 1050  of the newly created HG  2130 . 
     At step F 5020 , in the case where the AG  7000  is extracted at step F 5000 , because “HA” is specified in the profiles of VMs  1900  belonging to the relevant AG  7000 , only ALUs  2120  that are given HA attribute are assigned to the relevant HG  2130 , and further in the case where ALUs  2120  are registered in an HG  2120 , which corresponds to the relevant HG  2120  in this processing, in the counterpart storage device  2000  of the storage cluster, ALUs  2120 , the identifiers of the virtual resources of which are the same as those of the ALUs assigned at step S 020 , are assigned. 
       FIG. 27  is a diagram showing an example of a configuration of a flowchart of logical bath evaluation processing per HG  2130  in the configuration control unit included in the storage device  2000  according to this embodiment. As is the case with the first embodiment or the second embodiment, this processing is performed when an SLU  2400  is bound to an ALU  2120  or unbound from an ALU  2120 , or when the reduplication status of an SLU  2400  is changed. This processing is performed instead of the processing of the first embodiment shown in  FIG. 19 . 
     First, the configuration control unit extracts an HG  2310 , to which an ALU  2120  regarding the occurrence of binding or unbinding belongs, and the identifier of an AG  7000 , to which the HG  2310  belongs, are extracted (at step F 6000 ), and “ACTIVE/OPTIMIZED” is set as the initial value of the evaluation value of the relative logical path (at step F 6010 ). The configuration control unit performs a loop processing shown at step F 6020  on all the CTG  250  belonging to the AG  7000  extracted at step F 6000 . In the loop processing, the configuration control unit checks the status of a selected CTG  2500  (at step F 6030 ), and if the status is “BLOCK”, the configuration control unit checks whether an inter-storage device I/O transfer is available or not (at step F  6040 ). If the inter-storage device I/O transfer is available, the evaluation value X is set to “ACTIVE/OPTIMIZED” (at step F 6060 ), and if not, the evaluation value X is set to “STANDBY” (at step F 6050 ). 
     Next, after the loop processing at step F 6020  is finished, the configuration control unit sets the evaluation values of all LUNs belonging to the HG  2310  extracted at step F 6000  in the column T 4040  of T 4000  to the evaluation value X with reference to the LUN management table T 4000  (at step F 6080 ), and finishes this processing. 
     The above-described processing makes it possible to set the evaluation value of the logical path of an ALU  2310  per HG  2310 , that is to say, per VM that uses an Initiator Port having its WWN in the HG  2310 . 
     Fourth Embodiment 
     This embodiment relates to blockage processing for Conglomerate LUN Structure in the host computer  1000 , and a storage system including logical path control, in which, even in the case where retries are executed regarding the logical path of an ALU  2120 , and the predefined number of the retries occur, the logical path is not immediately blocked, but the statuses of SLUs  2400  bound to the relevant ALU  2120  are checked, and if there is an SLU  2400  that can receive an I/O, the relevant logical path is set to “ACTIVE/NON-OPTIMIZED”, will be explained. 
     The configuration of the host computer  1000  according to this embodiment is the same as that shown in  FIG. 3  or that shown in  FIG. 4 . 
       FIG. 28  is a diagram showing an example of a configuration of a flowchart of logical bath evaluation processing performed in I/O processing, especially in I/O retry processing by the hypervisor  1230 . This processing is performed when the number of retries regarding the logical path to an ALU  2120  exceeds a threshold that is predefined by a VM administrator. 
     In this processing, the configuration control unit or the hypervisor  1230  extracts SLUs  2400  bound to an ALU  2120  assigned to a logical path the number of retries regarding which exceeds the threshold with reference to the logical path management table T 2000  and the bound management table T 3000  (at step F 7000 ), sets the initial value of the evaluation value of the logical path to “STANDBY” (at step F 7010 ), and performs loop processing at step F 7020  on all SLUs  2400  obtained at step F 7000  (at step F 7020 ). In this loop processing, the disk control  1232  issues a disk read I/O to the relevant SLU  2400 , the alternate path control unit  1233  issues an I/O to the ALU  2120  via the relevant logical path (at step F 7030 ), and if a normal response is obtained, the evaluation value is set to “ACTIVE/NON-OPTIMIZED” (at step F 7050 ). When the above loop processing is finished, X is set to the evaluation value of the specified logical path (at step F 7070 ). 
     With the above-described processing, if an ALU  2120  assigned to a logical path the number of retries regarding which exceeds the threshold includes only one SLU  2400  capable of performing I/O processing, it becomes possible that the relevant logical path is not blocked but it is set as a non-recommendable logical path in preparation for the issuance of an I/O to the SLU  2400 . 
     LIST OF REFERENCE SIGNS 
       1000  . . . Host Computer,  2000  . . . Storage Device,  3000  . . . Management Computer,  4000  . . . Management Computer,  5000  . . . Storage Area Network,  6000  . . . Management Network, T 1000  . . . Virtual Server Management Table, T 2000  . . . Logical Path Management Table, T 3000  . . . Bound Management Table, T 4000  . . . LUN Management Table, T 5000  . . . Logical Volume Management Table, T 6000  . . . Consistency Group Management Table, T 7000  . . . Bound Management Table, T 8000  . . . Consistency Group Management Table, T 9000  . . . Virtual Port Management Table, U 1000  . . . Host Group Management Table, S 1000  . . . Virtual Server Creation Processing, S 2000  . . . Logical Resource Operation Processing, F 1000  . . . Logical Resource Creation Processing, F 2000  . . . Binding Processing, F 3000  . . . Unbinding Processing, F 4000  . . . Bound Group Assignment Processing, F 5000  . . . ALU Assignment Processing, F 6000  . . . Logical Path Evaluation Processing, F 7000  . . . Logical Path Evaluation Processing