Abstract:
An example is a method of controlling a storage system for providing a virtual storage apparatus that includes virtual storage resources associated with real storage resources of real storage apparatus. It includes receiving a virtual storage resource control command of a predetermined type specifying a first virtual storage resource in the virtual storage apparatus and a second virtual storage resource associated with the first virtual storage resource; referring to management information for managing association relations between the virtual storage resources and the real storage resources, to identify a first real storage resource associated with the first virtual storage resource and a first real storage apparatus including the first real storage resource; and selecting a second real storage resource associated with the second virtual storage resource from real storage resources within the first real storage apparatus, or creating the second real storage resource within the first real storage apparatus.

Description:
TECHNICAL FIELD 
       [0001]    This invention relates to a storage system, a storage system control method, and a storage system management method. 
       BACKGROUND ART 
       [0002]    The increased data capacity handled by computer systems has brought about an increase in the number of users who own a plurality of real storage apparatuses, and a reduction in storage running cost is wished for. Patent Literature 1 discloses a method with which a plurality of real storage apparatuses can be managed as a virtual storage apparatus. This method virtualizes numbers assigned to resources of real storage apparatuses such as volumes, pairs, and groups so that an administrator sees those numbers as resources of a virtual storage apparatus. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         [PTL 1] US 2008/0034005 A1 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    Patent Literature 1, however, does not disclose a method that enables the administrator of the virtual storage apparatus to run the virtual storage apparatus without being conscious of physical boundaries of the plurality of real storage apparatuses. 
       Solution to Problem 
       [0005]    An aspect of this invention is a storage system for providing a virtual storage apparatus that includes a plurality of virtual storage resources associated with a plurality of real storage resources of a plurality of real storage apparatuses. The plurality of real storage apparatuses include a first real storage apparatus and a second real storage apparatus. The first real storage apparatus receives a virtual storage resource control command of a predetermined type which specifies a first virtual storage resource in the virtual storage apparatus and a second virtual storage resource associated with the first virtual storage resource. The first real storage apparatus refers to management information for managing association relations between the plurality of virtual storage resources and the plurality of real storage resources, to identify a first real storage resource which is associated with the first virtual storage resource and one of the plurality of real storage apparatuses that includes the first real storage resource. When the one of the plurality of real storage apparatus that includes the first real storage resource is the first real storage apparatus, the first real storage apparatus performs one of selecting a second real storage resource which is associated with the second virtual storage resource from real storage resources that belong to the first real storage apparatus, and creating the second real storage resource. When the one of the plurality of real storage apparatus that includes the first real storage resource is the second real storage apparatus, the second real storage apparatus performs one of selecting the second real storage resource from real storage resources that belong to the second real storage apparatus, and creating the second real storage resource following an instruction from the first real storage apparatus. 
       Advantageous Effects of Invention 
       [0006]    According to this invention, a plurality of real storage apparatus can be run without the need for being conscious of physical boundaries, and the storage running cost is accordingly reduced. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0007]      FIG. 1A  is a block diagram illustrating the overall configuration of a computer system according to a first embodiment of this invention. 
           [0008]      FIG. 1B  is a block diagram illustrating the configuration of a virtual storage management computer and a management computer according to the first embodiment of this invention. 
           [0009]      FIG. 2  is a diagram illustrating an association relation between the real configuration and virtual configuration of storage apparatuses in the first embodiment. 
           [0010]      FIG. 3  is a diagram illustrating conceptually a data configuration in a memory of each storage apparatus in the first embodiment. 
           [0011]      FIG. 4  is a diagram illustrating conceptually the data configuration of a VOL management table of each storage apparatus in the first embodiment. 
           [0012]      FIG. 5  is a diagram illustrating conceptually the data configuration of a POOL configuration management table of each storage apparatus in the first embodiment. 
           [0013]      FIG. 6  is a diagram illustrating conceptually the data configuration of a page allocation management table of each storage apparatus in the first embodiment. 
           [0014]      FIG. 7  is a diagram illustrating conceptually the data configuration of a virtual VOL management table of each storage apparatus in the first embodiment. 
           [0015]      FIG. 8  is a diagram illustrating conceptually the data configuration of a virtual POOL management table of each storage apparatus in the first embodiment. 
           [0016]      FIG. 9  is a flow chart illustrating steps of POOL-VOL adding processing of the storage apparatus in the first embodiment. 
           [0017]      FIG. 10  is a flow chart illustrating steps of DP-VOL creating processing of the storage apparatus in the first embodiment. 
           [0018]      FIG. 11  is a flow chart illustrating steps of POOL-VOL adding processing that is initiated and conducted by a management computer in the first embodiment. 
           [0019]      FIG. 12  is a flow chart illustrating steps of DP-VOL creating processing that is initiated and conducted by the management computer in the first embodiment. 
           [0020]      FIG. 13  is a diagram illustrating an association relation between the real configuration and virtual configuration of storage apparatus in a second embodiment of this invention. 
           [0021]      FIG. 14  is a diagram illustrating conceptually a data configuration in a memory of each storage apparatus in the second embodiment. 
           [0022]      FIG. 15  is a diagram illustrating conceptually the data configuration of a local copy pair configuration management table of each storage apparatus in the second embodiment. 
           [0023]      FIG. 16  is a diagram illustrating conceptually the data configuration of a virtual local copy pair management table of each storage apparatus in the second embodiment. 
           [0024]      FIG. 17  is a flow chart illustrating steps of local copy pair creating processing of the storage apparatus in the second embodiment. 
           [0025]      FIG. 18  is a flow chart illustrating steps of local copy pair creating processing that is initiated and conducted by a management computer in the second embodiment. 
           [0026]      FIG. 19  is a diagram illustrating the real configuration of storage apparatuses in a third embodiment of this invention. 
           [0027]      FIG. 20  is a diagram illustrating the virtual configuration of the storage apparatuses in the third embodiment. 
           [0028]      FIG. 21  is a diagram illustrating conceptually a data configuration in a memory of each storage apparatus in the third embodiment. 
           [0029]      FIG. 22  is a diagram illustrating conceptually the data configuration of a journal group configuration management table of each storage apparatus in the third embodiment. 
           [0030]      FIG. 23  is a diagram illustrating conceptually the data configuration of a remote copy pair configuration management table of each storage apparatus in the third embodiment. 
           [0031]      FIG. 24  is a diagram illustrating conceptually the data configuration of a virtual journal group management table of each storage apparatus in the third embodiment. 
           [0032]      FIG. 25  is a diagram illustrating conceptually the data configuration of a virtual remote copy pair management table of each storage apparatus in the third embodiment. 
           [0033]      FIG. 26  is a flow chart illustrating steps of JVOL adding processing of the storage apparatus in the third embodiment. 
           [0034]      FIG. 27  is a flow chart illustrating steps of remote copy pair creating processing of the storage apparatus in the third embodiment. 
           [0035]      FIG. 28  is a flow chart illustrating steps of JVOL adding processing that is initiated and conducted by a management computer in the third embodiment. 
           [0036]      FIG. 29  is a flow chart illustrating steps of remote copy pair creating processing that is initiated and conducted by a management computer in the third embodiment 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0037]    Embodiments of this invention are described below with reference to the accompanying drawings. It should be noted that the embodiments of this invention are merely an example for carrying out this invention and are not to limit the technical scope of this invention. 
         [0038]    The embodiments of this invention described below relates to control of a virtual storage apparatus that is obtained by virtualizing a plurality of real storage apparatuses as one logical storage resource. 
         [0039]    The embodiments of this invention disclose methods of running and managing real storage resources that are dispersed among a plurality of real storage apparatuses by using virtualized resource numbers (a provisioning method with the locations of storage drives hidden, a copy-system function running method with the locations of real volumes hidden, and the like). Storage resources are, for example, various volumes, pools, and journal groups as described later. 
         [0040]    A virtual storage apparatus receives a management operation (such as provisioning or storage function running) made on a virtualized storage resource, and real storage apparatus determine resource association (mapping) between the virtual storage apparatus and the real storage apparatus that is suited to the management operation. The real storage apparatus determine mapping so that, if possible, I/O or storage function processing is contained within a single real storage apparatus. This prevents processing performance in the virtual storage apparatus from dropping. 
         [0041]    A plurality of real storage apparatuses can thus be run without the need for being conscious of physical boundaries, and the storage running cost is accordingly reduced. In the following description, each component is a real component unless it is stated that the component is virtual. 
       First Embodiment 
       [0042]    (1-1) Computer System Configuration in First Embodiment 
         [0043]      FIG. 1A  is a block diagram illustrating the overall configuration of a computer system in a first embodiment of this invention. The computer system which is denoted by  1  includes host computers  2  (only one host computer  2  is illustrated in  FIG. 1 ), a virtual storage management computer  3 , management computer  8 , at least one storage apparatus  4 , a storage area network (SAN)  5 , and a local area network (LAN)  6 . 
         [0044]    The host computer  2  is coupled to each storage apparatus  4  via the SAN  5 , and the management computer  3  is coupled to each storage apparatus  4  via the LAN  6 . 
         [0045]    The host computer  2  includes a CPU  10 , a memory  11 , a storage device  12 , an interface control unit  13  and a plurality of ports  14 . The CPU  10  is a processor that handles overall operation control of the host computer  2 , reads various programs stored in the memory device  12  onto the memory  11  to execute the programs, and issues an input/output request (access request) which contains a read request or a write request. The memory  11  is used to store various programs read out of the storage device  12  by the CPU  10 , and is also used as a work memory of the CPU  10 . 
         [0046]    The storage device  12  is, for example, a hard disk drive (HDD) or a solid state drive (SSD), and is used to hold various programs and control data. The interface control unit  13  is an adaptor to connect the host computer with the LAN  6 . The ports  14  are each an adaptor for coupling the host computer  2  to the SAN  5 . 
         [0047]      FIG. 1B  is a block diagram illustrating the configuration of the virtual storage management computer  3  and the management computer  8 . The virtual storage management computer  3  is a computer for managing the virtual storage apparatus provided by the storage apparatuses  4 , and includes a CPU  20 , a memory  21 , a storage device  22 , an interface control unit  23 , an input device  24 , and a display device  25 . The CPU  20  is a processor that handles the overall operation control of the virtual storage management computer  3 , and reads various programs stored in the storage device  22  onto the memory  21  from the storage device  22  to execute the programs. The memory  21  is used to store various programs read out of the storage device  22  by the CPU  20 , and is also used as a work memory of the CPU  20 . 
         [0048]    The storage device  22  is, for example, an HDD or an SSD, and is used to hold various programs and control data. The interface control unit  23  is an adaptor for coupling the management computer  3  to the LAN  6 . The input device  24  is constituted of, for example, a keyboard and a mouse. The display device  25  is constituted of, for example, a liquid crystal display. 
         [0049]    The management computer  8  is a computer for managing the storage apparatuses  4 , and the hardware configuration is the same as the virtual storage management computer  3 . Namely, the management computer  8  includes a CPU  80 , a memory  81 , a storage device  82 , an interface control unit  83 , an input device  84 , and a display device  85 . The real resources of the storage apparatuses  4  are managed by the management computer  8 . A management system of this configuration example which is constituted of the virtual storage management computer  3  and the management computer  8  may be made up of a plurality of computers. One of the plurality of computers may be for display use, and processing equivalent to that of the virtual storage management computer  3  or the management computer  8  may be implemented by the plurality of computers in order to enhance the speed and reliability of management processing. 
         [0050]    Each storage apparatus  4  includes a plurality of storage devices  30  and a control unit  31 , which controls input/output of data to/from the storage devices  30 . Each storage device  30  is constituted of, for example, an HDD or an SSD. Two or more storage devices out of the plurality of storage devices  30  constitute one RAID group (RAID stands for Redundant Array of Inexpensive Disks), and at least one logical unit is set in a storage area provided by at least one RAID group. Data from the host computer  2  is stored in the logical unit in units of a block of a given size. 
         [0051]    The control unit  31  includes a CPU  40 , a memory  41 , a non-volatile memory  42 , a cache memory  43 , a plurality of host-side ports  44 , a plurality of storage device-side ports  45 , and an interface control unit  46 . The control unit  31  may include at least one external storage-side port  47  as well. 
         [0052]    The CPU  40  is a processor that handles the overall operation control of the storage apparatus  4 , and reads various programs stored in the non-volatile memory  42  onto the memory  41  to execute the programs. The memory  41  is used to store various programs read out of the non-volatile memory  42  by the CPU  40 , and is also used as a work memory of the CPU  40 . The non-volatile memory  42  is used to store and hold various programs and control data. 
         [0053]    The cache memory  43  is mainly used to store, on a temporary basis, data exchanged between the host computer  2  and the plurality of storage devices  30 . The host-side ports  44  are adaptors for coupling the storage apparatus  4  to the SAN  5 . The storage device-side ports  45  are adaptors for connecting the control unit  31  to the storage devices  30 . The interface control unit  46  is an adaptor for coupling the storage apparatus  4  to the LAN  6 . The external storage-side port  47  is an adaptor for connecting the control unit  31  to an external storage apparatus  7 . 
         [0054]      FIG. 2  illustrates an association relation between the real configuration of a plurality of storage apparatuses  4  and a virtual configuration provided to the virtual storage management computer  3  by the plurality of storage apparatuses  4 . While the real configuration includes a plurality of storage apparatuses  4 , the virtual configuration provides one virtual storage apparatus  4 V to the virtual storage management computer  3 . 
         [0055]    In the real configuration, a plurality of logical units (volumes) are set in each storage apparatus  4 . There are three types of logical unit, a volume (VOL)  100 , a dynamic pool volume (DP-VOL)  101 , and a pool volume (POOL-VOL)  102 . Each VOL  100  is allocated statically to a storage area provided by a RAID group. 
         [0056]    Each DP-VOL  101  is allocated dynamically via one POOL-VOL  102  to a storage area provided by a RAID group. Each POOL-VOL  102  is allocated statically to a storage area provided by a RAID group and serves as the allocation source of at least one DP-VOL  101 . The VOLs  100  and the DP-VOLs  101  are provided as input/output target logical units to the host computer  2 , whereas the POOL-VOLs  102  are not provided as input/output target logical units to the host computer  2 . A storage area provided by a RAID group may be provided directly to a POOL without intervention of a POOL-VOL. 
         [0057]    Each storage apparatus  4  manages a DP-POOL  110  which is constituted of at least one POOL-VOL  102 . One storage apparatus  4  may manage a plurality of DP-POOLS  110 . Each DP-VOL  101 , which is not allocated a storage area at the time of creation, is dynamically allocated a storage area from the POOL-VOL  102  included in the DP-POOL  110  when a write request is received from the host computer  2 . 
         [0058]    In the virtual configuration, at least one virtual VOL  100 V, at least one virtual DP-VOL  101 V, at least one virtual POOL-VOL  102 V, and at least one virtual DP-POOL  110 V are set in the virtual storage apparatus  4 V. 
         [0059]    Each virtual VOL  100 V is associated with one of the VOLs  100  on a one-to-one basis. Similarly, each virtual DP-VOL  101 V is associated with one of the DP-VOLs  101  on a one-to-one basis, and each virtual POOL-VOL  102 V is associated with one of the POOL-VOLs  102  on a one-to-one basis. 
         [0060]    Each virtual DP-POOL  110 V is associated with at least one DP-POOL  110 . A plurality of DP-POOLs  110  set in different storage apparatus  4  may be associated with one virtual DP-POOL  110 V. Each virtual DP-POOL  110 V has as a component the virtual POOL-VOL  102 V associated with the POOL-VOL  102  that constitutes any DP-POOL  110  associated with the virtual DP-POOL  110 V. This enables the virtual storage management computer  3  to manage a plurality of DP-POOLs  110  as one virtual DP-POOL. 
         [0061]      FIG. 3  illustrates main configuration information stored in the memory  41  of each storage apparatus  4 . As illustrated in  FIG. 3 , the memory  41  stores a storage apparatus #290, a VOL management table  200 , a POOL configuration management table  210 , a page allocation management table  220 , a virtual VOL management table  230 , and a virtual POOL management table  240 . 
         [0062]    The storage apparatus #290 is a number used to uniquely identify each storage apparatus  4  that constitutes the virtual storage apparatus  4 V. The VOL management table  200 , the POOL configuration management table  210 , and the page allocation management table  220  are local tables for storing information unique to each storage apparatus. 
         [0063]    The virtual VOL management table  230  and the virtual POOL management table  240  are tables common to all virtual storage apparatus  4 V that provide real storage resources to the virtual storage apparatus  4 V. When the virtual VOL management table  230  or the virtual POOL management table  240  is updated in one of the storage apparatus, the rest of the storage apparatuses  4  are notified of the update and update the table themselves. 
         [0064]    The count of tables storing necessary information and the configurations of the respective tables depend on design. The information does not depend on what data structure is employed and information used by the system can be expressed in any data structure. Other than being stored in tables as described below, the information may be stored in a data structure selected appropriately from among, for example, the list format, the database format, and the queue format. Terms used in describing the specifics of each piece of the information, such as “identification information”, “identifier”, “name”, “ID”, and “number”, can be substituted by one another. 
         [0065]      FIG. 4  illustrates a configuration example of the VOL management table  200 . The CPU  40  of each storage apparatus  4  uses the VOL management table  200  to manage information about every real logical unit (VOL  100 , DP-VOL  101 , and POOL-VOL  102 ) within the casing of its own storage apparatus  4 . Registered in the VOL management table  200  for each logical unit are, for example, a real VOL #201, a type  202 , a RAID group #203, a start LBA  204 , an end LBA  205 , a real POOL #206, and a capacity  207 . 
         [0066]    The real VOL #201 is a number used to identify each logical unit uniquely throughout the storage apparatuses  4 . 
         [0067]    The type  202  is information indicating the type of a logical unit that is identified by the real VOL #201, and has a value “normal” or “DP”. When the type  202  is “normal”, a logical unit identified by the real VOL #201 is allocated statically to a storage area provided by a RAID group (one of the VOLs  110  or one of the POOL-VOLs  102 ). When the type  202  is “DP”, on the other hand, a logical unit identified by the real VOL #201 is allocated dynamically to a storage area provided by a RAID group (one of the DP-VOLs  101 ). 
         [0068]    The RAID group #203 is information utilized when the type  202  is “normal”, and is used to identify, uniquely throughout the storage apparatuses  4 , a RAID group that stores data of the logical unit (one of the VOLs  110  or one of the POOL-VOLs  102 ) identified by the real VOL #201. The RAID group #203 is undefined when the type  202  is “DP”. 
         [0069]    The start LBA  204  is information utilized when the type  202  is “normal”, and indicates the start logical block address (LBA) of a storage area that is used by a logical unit (one of the VOLs  110  or one of the POOL-VOLs  102 ) identified by the real VOL #201 to store data in a RAID group identified by the RAID group #203. The start LBA  204  is undefined when the type  202  is “DP”. 
         [0070]    The end LBA  205  is information utilized when the type  202  is “normal”, and indicates the end LBA of a storage area that is used by a logical unit (one of the VOLs  110  or one of the POOL-VOLs  102 ) identified by the real VOL #201 to store data in a RAID group identified by the RAID group #203. The end LBA  205  is undefined when the type  202  is “DP”. 
         [0071]    The real POOL #206 is information utilized when the type  202  is “DP”, and is used to identify, uniquely throughout the storage apparatuses  4 , the DP-POOL  110  that stores data of a logical unit (one of the DP-VOLs  101 ) identified by the real VOL #201. The real POOL #206 is undefined when the type  202  is “normal”. 
         [0072]    The capacity  207  is information indicating the capacity of a logical unit that is identified by the real VOL #201. 
         [0073]      FIG. 5  illustrates a configuration example of the POOL configuration management table  210 . The CPU  40  of each storage apparatus  4  uses the POOL configuration management table  210  to manage information about every DP-POOL  110  within the casing of its own storage apparatus  4 . Registered in the POOL configuration management table  210  for each DP-POOL  110  are, for example, a real POOL #211 and at least one real POOL-VOL #212. 
         [0074]    The real POOL #211 is a number used to identify each DP-POOL  110  uniquely throughout the storage apparatuses  4 . 
         [0075]    The real POOL-VOL #212 is a number used to identify, uniquely throughout the storage apparatuses  4 , each POOL-VOL  102  that constitutes the DP-POOL  110  identified by the real POOL #211. A real POOL-VOL # is a real VOL # assigned to a real POOL-VOL. At least one real POOL-VOL #212 is associated with one real POOL #211. 
         [0076]      FIG. 6  illustrates the data configuration of the page allocation management table  220 . The CPU  40  of each storage apparatus  4  uses the page allocation management table  220  to manage, for every DP-VOL  101  within the casing of its own storage apparatus  4 , page allocation to the DP-VOL  101  from the POOL-VOLs  102 . 
         [0077]    A page is a continuous storage area having a size of, for example, 1 MB or 1 GB. Registered in the page allocation management table  220  for each DP-VOL  101  are, for example, a real DP-VOL #221, at least one intra-DP-VOL page #222, at least one real POOL-VOL #223, and at least one intra-POOL-VOL page #224. 
         [0078]    The real DP-VOL #221 is a number used to identify each DP-VOL  101  uniquely throughout the storage apparatuses  4 . A real DP-VOL # is a real VOL # assigned to a real DP-VOL, and the real DP-VOL #221 corresponds to the real VOL #201 of the VOL management table  200 . 
         [0079]    The intra-DP-VOL page #222 is a number used to uniquely identify a page within each DP-VOL  101 . 
         [0080]    The real POOL-VOL #223 is a number used to identify, uniquely throughout the storage apparatuses  4 , the POOL-VOL  110  that holds a storage area allocated to a page that is identified by the intra-DP-VOL page #222. The real POOL-VOL #223 corresponds to the real VOL #201 of the VOL management table  200 . 
         [0081]    The intra-POOL-VOL page #224 is a number used to uniquely identify a page within the POOL-VOL  110  that is allocated to a page identified by the intra-DP-VOL page #222. 
         [0082]      FIG. 7  illustrates the data configuration of the virtual VOL management table  230 . The CPU  40  of each storage apparatus  4  uses the virtual VOL management table  230  to manage, for every virtual VOL  100 V, virtual DP-VOL  101 V, and virtual POOL-VOL  102 V within the virtual storage apparatus  4 V, information about the association of the virtual VOL  100 V, the virtual DP-VOL  101 V, or the virtual POOL-VOL  102 V with one of the VOLs  100 . Registered in the virtual VOL management table  230  are, for example, a virtual VOL #231, a real storage apparatus #232, and a real VOL #233. 
         [0083]    The virtual VOL #231 is a number used to identify each virtual VOL  100 V, each virtual DP-VOL  101 V, or each virtual POOL-VOL  102 V uniquely throughout the virtual storage apparatus  4 V. 
         [0084]    The real storage apparatus #232 is a number used to uniquely identify the storage apparatus  4  where the VOL  100 , the DP-VOL  101 , or the POOL-VOL  102  that is associated with the virtual VOL  100 V, the virtual DP-VOL  101 V, or the virtual POOL-VOL  102 V that is identified by the virtual VOL #231 is located. 
         [0085]    The real VOL #233 is a number used to identify, uniquely throughout the storage apparatuses  4  identified by the real storage apparatus #232, the VOL  100 , the DP-VOL  101 , or the POOL-VOL  102  that is associated with the virtual VOL  100 V, the virtual DP-VOL  101 V, or the virtual POOL-VOL  102 V that is identified by the virtual VOL #231. The real VOL #233 corresponds to the real VOL #201 of the VOL management table  200 . 
         [0086]      FIG. 8  illustrates a configuration example of the virtual POOL management table  240 . The CPU  40  of each storage apparatus  4  uses the virtual POOL management table  240  to manage, for every virtual DP-POOL  110 V within the virtual storage apparatus  4 V, information about the association of the virtual DP-POOL  110 V with one of the DP-POOLs  110 . Registered in the virtual POOL management table  240  are, for example, a virtual POOL #241, a real storage apparatus #242, and a real POOL #243. 
         [0087]    The virtual POOL #241 is a number used to identify each virtual DP-POOL  110 V uniquely throughout the virtual storage apparatus  4 V. The real storage apparatus #242 is a number used to uniquely identify the storage apparatus  4  where the DP-POOL  110 V that is associated with the virtual DP-POOL  110 V identified by the virtual POOL #241 is located. 
         [0088]    The real POOL #243 is a number used to identify, uniquely throughout the storage apparatuses  4  identified by the real storage apparatus #242, the DP-POOL  110  that is associated with the virtual DP-POOL  110 V identified by the virtual POOL #241. The real POOL #243 corresponds to the real POOL #211 of the POOL configuration management table  210 . 
         [0089]    (1-2) Capacity Pool Constructing Processing in this Embodiment 
         [0090]    Capacity pool constructing processing executed in the computer system  1  is described below. In the following description, letters “SP” prefixed to a reference numeral mean “step”.  FIG. 9  is a flow chart illustrating processing that is executed by one of the storage apparatus  4  that receives a virtual POOL-VOL addition instruction from the virtual storage management computer  3  (hereinafter referred to as virtual POOL-VOL adding processing A). The virtual storage management computer  3  recognizes the provided virtual storage apparatus  4 V as described above. The POOL-VOL addition instruction from the virtual storage management computer  3  here is an instruction to add a virtual POOL-VOL to the virtual storage apparatus  4 V. 
         [0091]    The virtual POOL-VOL adding processing A is implemented by the CPU  40  of the storage apparatus  4  by executing a program. The storage apparatus  4  receives a virtual POOL-VOL addition instruction from the virtual storage management computer  3  (SP 300 ), and first extracts a virtual POOL # and a virtual VOL # from the virtual POOL-VOL addition instruction (SP 301 ). 
         [0092]    The storage apparatus  4  next determines whether or not the VOL  100  that is associated with the virtual VOL # extracted in Step SP 301  is present in its own casing (SP 302 ). Specifically, the storage apparatus  4  refers to the virtual VOL management table  230  to identify an entry in which the same value as the virtual VOL # extracted in Step SP 301  is set to the virtual VOL #231, and determines whether or not the real storage apparatus #232 of the identified entry matches the storage apparatus #290. 
         [0093]    When the result of this determination is positive (SP 302 : YES), the storage apparatus  4  proceeds to Step SP 303  to select one DP-POOL  110  that is associated with the virtual POOL # extracted in Step SP 301  and that is present in its own casing. Specifically, the storage apparatus  4  refers to the virtual POOL management table  240  to identify an entry in which the same value as the virtual POOL # extracted in Step SP 301  is set to the virtual POOL #241, and selects one sub-entry in the identified entry where the same value as the storage apparatus #290 is set to the real storage apparatus #242. 
         [0094]    The storage apparatus  4  next adds the VOL  100  that is associated with the virtual VOL # extracted in Step SP 301  to the DP-POOL  110  that is associated with the real POOL #243 of the sub-entry selected in Step SP 303  (SP 304 ). 
         [0095]    Specifically, the storage apparatus  4  refers to the virtual VOL management table  230  to identify an entry in which the same value as the virtual VOL # extracted in Step SP 301  is set to the virtual VOL #231, and extracts the real VOL #233 from the identified entry. The storage apparatus  4  then updates the POOL configuration management table  210  by adding the extracted VOL #233 to an entry in which the same value as the real POOL #243 of the sub-entry selected in Step SP 303  is set to the real POOL #211. 
         [0096]    Lastly, the storage apparatus  4  transmits a virtual POOL-VOL addition completion notification to the virtual storage management computer  3  (SP 305 ), and ends the virtual POOL-VOL adding processing A. 
         [0097]    In the case where the result of the determination of Step SP 302  is negative (SP 302 : NO), on the other hand, the storage apparatus  4  proceeds to Step SP 306  to transfer the virtual POOL-VOL addition instruction to the storage apparatus  4  where the VOL  100  that is associated with the virtual VOL # extracted in Step SP 301  is located. Specifically, the storage apparatus  4  transmits the virtual POOL-VOL addition instruction to the storage apparatus  4  that is associated with the real storage apparatus #232 of the entry identified in Step SP 302 . 
         [0098]    The storage apparatus  4  to which the virtual POOL-VOL addition instruction has been transferred executes Steps SP 300  to SP 305 . In Step SP 300 , however, the storage apparatus  4  to which the virtual POOL-VOL addition instruction has been transferred receives a virtual POOL-VOL addition instruction from the storage apparatus  4  that has transferred the virtual POOL-VOL addition instruction, instead of from the virtual storage management computer  3 . In addition, the storage apparatus  4  to which the virtual POOL-VOL addition instruction has been transferred always obtains a positive result in the determination of Step SP 302 . 
         [0099]    Further, in Step SP 305 , the storage apparatus  4  to which the virtual POOL-VOL addition instruction has been transferred transmits a virtual POOL-VOL addition completion notification to the storage apparatus  4  that has transferred the virtual POOL-VOL addition instruction, instead of to the virtual storage management computer  3 . 
         [0100]    The storage apparatus  4  that has transferred the virtual POOL-VOL addition instruction receives the virtual POOL-VOL addition completion notification from the storage apparatus  4  to which the virtual POOL-VOL addition instruction has been transferred (SP 307 ), and proceeds to Step SP 305 . 
         [0101]    The flow described above makes it possible to construct within the same storage apparatus  4  a real POOL that is associated with a virtual POOL to which a virtual POOL-VOL is to be added and a real POOL-VOL that is associated with the virtual POOL-VOL to be added, thereby avoiding additional processing that is caused by communication between one storage apparatus  4  and another. 
         [0102]    (1-3) Volume Provisioning Processing in this Embodiment 
         [0103]    Volume provisioning processing executed in the computer system  1  is described below. In the following description, letters “SP” prefixed to a reference numeral mean “processing step”. 
         [0104]      FIG. 10  is a flow chart illustrating processing that is executed by one of the storage apparatus  4  that receives a virtual DP-VOL creation instruction from the virtual storage management computer  3  (hereinafter referred to as virtual DP-VOL creating processing A). The virtual DP-VOL creating processing A is implemented by the CPU  40  of the storage apparatus  4  by executing a program. 
         [0105]    The storage apparatus  4  receives the virtual DP-VOL creation instruction from the virtual storage management computer  3  (SP 400 ), and first extracts a virtual POOL #, a virtual VOL #, and a capacity from the virtual DP-VOL creation instruction (SP 401 ). 
         [0106]    The storage apparatus  4  next selects one DP-POOL  110  that is associated with the virtual POOL # extracted in Step SP 401  (SP 402 ). Specifically, the storage apparatus  4  refers to the virtual POOL management table  240  to identify an entry in which, the same value as the virtual POOL # extracted in Step SP 401  is set to the virtual POOL #241, and selects one sub-entry in the identified entry. 
         [0107]    The storage apparatus  4  next determines whether or not the DP-POOL  110  selected in Step SP 402  is present in its own casing (SP 403 ). Specifically, the storage apparatus  4  determines whether or not the real storage apparatus #242 of the sub-entry selected in Step SP 402  matches the storage apparatus #290. 
         [0108]    When the result of this determination is positive (SP 403 : YES), the storage apparatus  4  proceeds to Step SP 404  to create a new DP-VOL  101  in the DP-POOL  110  selected in Step SP 402 . 
         [0109]    Specifically, the storage apparatus  4  adds one entry to the VOL management table  200 . In the added entry, a number that is not used in any other entry is set to the real VOL #201, “DP” is set to the type  202 , the real POOL #243 of the sub-entry selected in step SP 402  is set to the real POOL #206, and the capacity extracted in Step SP 401  is set to the capacity  207 . The RAID group #203, the start LBA  204 , and the end LBA  205  are left undefined. 
         [0110]    The storage apparatus  4  next associates the DP-VOL  101  created in Step SP 404  with the virtual VOL # extracted in Step SP 401  (SP 405 ). Specifically, the storage apparatus  4  adds one entry to the virtual VOL management table  230 . In the added entry, the virtual VOL # extracted in Step SP 401  is set to the virtual VOL #231, the storage apparatus #290 is set to the real storage apparatus #232, and the number set to the real VOL #201 in Step SP 404  is set to the real VOL #233. 
         [0111]    The storage apparatus  4  also transmits to all other storage apparatus  4  an instruction to update their respective virtual VOL management tables  230 . Receiving the instruction, each storage apparatus  4  adds one entry to the virtual VOL management table  230  in the same way as the storage apparatus  4  that has transmitted the instruction. 
         [0112]    Lastly, the storage apparatus  4  transmits a virtual DP-VOL creation completion notification to the virtual storage management computer  3  (SP 406 ), and ends the virtual DP-VOL creating processing A. 
         [0113]    In the case where the result of the determination of Step SP 403  is negative (SP 403 : NO), on the other hand, the storage apparatus  4  proceeds to Step SP 407  to transfer the virtual DP-VOL creation instruction to the storage apparatus  4  where the DP-POOL  110  selected in Step SP 402  is located. 
         [0114]    Specifically, the storage apparatus  4  transfers the virtual DP-VOL creation instruction to the storage apparatus  4  that is associated with the real storage apparatus #242 of the sub-entry selected in Step SP 402 . When transferring the instruction, the storage apparatus  4  includes in the virtual DP-VOL creation instruction the virtual POOL #, virtual VOL #, and capacity specified by the virtual storage management computer  3 , and a real POOL # of the sub-entry selected in Step SP 402  as well. The transferred virtual DP-VOL creation instruction may not include the virtual POOL #. 
         [0115]    The storage apparatus  4  to which the virtual DP-VOL creation instruction has been transferred executes Step SP 400  and Steps SP 404  to SP 406 . In Step SP 400 , however, the storage apparatus  4  to which the virtual DP-VOL creation instruction has been transferred receives a virtual DP-VOL creation instruction from the storage apparatus  4  that has transferred the virtual DP-VOL creation instruction, instead of from the virtual storage management computer  3 . 
         [0116]    Before executing Step SP 404 , the storage apparatus  4  to which the virtual DP-VOL creation instruction has been transferred extracts a virtual VOL #, a capacity, and a real POOL # from the transferred virtual DP-VOL creation instruction. In Step SP 404 , the storage apparatus  4  to which the virtual DP-VOL creation instruction has been transferred sets the real POOL # included in the transferred virtual DP-VOL creation instruction to the real POOL #206. 
         [0117]    Step SP 405  is as described above. In Step SP 406 , the storage apparatus  4  to which the virtual DP-VOL creation instruction has been transferred transmits a virtual DP-VOL creation completion notification to the storage apparatus  4  that has transferred the virtual DP-VOL creation instruction, instead of to the virtual storage management computer  3 . 
         [0118]    The storage apparatus  4  that has transferred the virtual DP-VOL creation instruction receives the virtual DP-VOL creation completion notification from the storage apparatus  4  to which the virtual DP-VOL creation instruction has been transferred (SP 408 ), and proceeds to Step SP 406 . 
         [0119]    The flow described above makes it possible to construct within the same storage apparatus  4  a real POOL that is associated with a virtual POOL from which a virtual DP-VOL is to be created and a real DP-VOL that is associated with the virtual DP-VOL to be created, thereby avoiding additional processing that is caused by communication between one storage apparatus  4  and another. 
         [0120]    (1-4) the Configuration and Processing for the Case where the Management Computer Takes Initiative 
         [0121]    The capacity pool constructing processing and the volume provisioning processing in which the relevant storage apparatus  4  takes a central role in the description given above may be initiated and conducted by the management computer  8 . 
         [0122]    In the case where the management computer  8  initiates and conducts the processing, the management computer  8  holds the virtual VOL management table  230  and the virtual POOL management table  240  in the memory  81 , and keeps the tables consistent with the virtual VOL management table  230  and the virtual POOL management table  240  that each storage apparatus  4  holds in the memory  41 . 
         [0123]      FIG. 11  is a flow chart illustrating processing that is executed by the management computer  8  when a virtual POOL-VOL addition instruction is received from a virtual storage administrator (hereinafter referred to as virtual POOL-VOL addition processing B). The virtual storage administrator, for example, sends the instruction using the virtual management computer  3 . The virtual POOL-VOL addition processing B is implemented by the CPU  80  of the management computer  8  by executing a program. This may lessen the load on the storage apparatus  4 . 
         [0124]    The management computer  8  receives a virtual POOL-VOL addition instruction from the virtual storage administrator (SP 310 ), and first extracts a virtual POOL # and a virtual VOL # from the virtual POOL-VOL addition instruction (SP 311 ). 
         [0125]    The management computer  8  next selects one DP-POOL  110  that is associated with the virtual POOL # extracted in Step SP 311  and that is present in the same casing (the same storage apparatus  4 ) as the VOL  100  that is associated with the virtual VOL # extracted in Step SP 311  (SP 312 ). 
         [0126]    Specifically, the management computer  8  refers to the virtual POOL management table  240  of the memory  81  to identify an entry in which the same value as the virtual POOL # extracted in Step SP 311  is set to the virtual POOL #241. 
         [0127]    The management computer  8  also refers to the virtual VOL management table  230  of the memory  81  to identify an entry in which the same value as the virtual VOL # extracted in Step SP 311  is set to the virtual VOL #231, and extracts the real storage apparatus #232 from the identified entry. The management computer  8  then selects one sub-entry in the identified entry of the virtual POOL management table  240  where the same value as the extracted real storage apparatus #232 is set to the real storage apparatus #242. 
         [0128]    The management computer  8  next transmits a real POOL-VOL addition instruction to the storage apparatus  4  where the DP-POOL  110  selected in Step SP 312  is located (SP 313 ). Specifically, the management computer  8  transmits a real POOL-VOL addition instruction to the storage apparatus  4  that is associated with the real storage apparatus #242 of the sub-entry selected in Step SP 312 . When transmitting the instruction, the management computer  8  includes in the real POOL-VOL addition instruction the real POOL #243 of the sub-entry selected in Step SP 312  and the real VOL #233 of the entry of the virtual VOL management table  230  that has been identified in Step SP 312 . 
         [0129]    The storage apparatus  4  that has received the real POOL-VOL addition instruction adds the specified VOL  100  to the specified DP-POOL  110  following the real POOL-VOL addition instruction, and transmits a real POOL-VOL addition completion notification to the management computer  8 . 
         [0130]    The management computer  8  receives the real POOL-VOL addition completion notification from the storage apparatus  4  (SP 314 ), transmits a virtual POOL-VOL addition completion notification to the virtual storage administrator (SP 315 ), and ends the virtual POOL-VOL adding processing B. 
         [0131]      FIG. 12  is a flow chart illustrating processing that is executed by the management computer  8  when a virtual DP-VOL creation instruction is received from a virtual storage administrator (hereinafter referred to as virtual DP-VOL creation processing B). The virtual DP-VOL creation processing B is implemented by the CPU  80  of the management computer  8  by executing a program. This may lessen the load on the storage apparatus  4 . 
         [0132]    The management computer  8  receives a virtual DP-VOL creation instruction from the virtual storage administrator (SP 410 ), and first extracts a virtual POOL # and a virtual VOL # and capacity from the virtual DP-VOL creation instruction (SP 411 ). 
         [0133]    The management computer  8  next selects one DP-POOL  110  that is associated with the virtual POOL # extracted in Step SP 411  (SP 412 ). Specifically, the management computer  8  refers to the virtual POOL management table  240  of the memory  81  to identify an entry in which the same value as the virtual POOL # extracted in Step SP 411  is set to the virtual POOL #241, and selects one sub-entry in the identified entry. 
         [0134]    The management computer  8  next transmits a real DP-VOL creation instruction to the storage apparatus  4  where the DP-POOL  110  selected in Step SP 412  is located (SP 413 ). Specifically, the management computer  8  transmits the real POOL-VOL creation instruction to the storage apparatus  4  that is associated with the real storage apparatus #242 of the sub-entry selected in Step SP 412 . When transmitting the instruction, the management computer  8  includes in the real DP-VOL creation instruction the real POOL #243 of the sub-entry selected in Step SP 412  and the capacity extracted in Step SP 411 . 
         [0135]    The storage apparatus  4  that has received the real DP-VOL creation instruction creates a new DP-VOL  101  in the specified DP-POOL  110  following the real DP-VOL creation instruction, and transmits a real DP-VOL creation completion notification to the management computer  8 . When transmitting the notification, the storage apparatus  4  includes the real VOL # of the newly created DP-VOL  101  in the real DP-VOL creation completion notification. 
         [0136]    The management computer  8  receives the real DP-VOL creation completion notification from the storage apparatus  4  (SP 414 ), and extracts the real VOL # from the real DP-VOL creation completion notification (SP 415 ). 
         [0137]    The management computer  8  next associates the DP-VOL  101  created by the storage apparatus  4  with the virtual VOL # extracted in Step SP 411  (SP 416 ). Specifically, the management computer  8  adds one entry to the virtual VOL management table  230  of the memory  81 . In the added entry, the virtual VOL # extracted in Step SP 411  is set to the virtual VOL #231, the real storage apparatus #242 of the sub-entry selected in Step SP 412  is set to the real storage apparatus #232, and the real VOL # extracted in Step SP 415  is set to the real VOL #233. 
         [0138]    The management computer  8  also transmits to all storage apparatus  4  an instruction to update their respective virtual VOL management tables  230 . Receiving the instruction, each storage apparatus  4  adds one entry to the virtual VOL management table  230  in the same way as the management computer  8 . 
         [0139]    Lastly, the management computer  8  transmits a virtual DP-VOL creation completion notification to the virtual storage administrator (SP 417 ), and ends the virtual DP-VOL creating processing B. 
         [0140]    As has been described, according to this embodiment, a plurality of real storage apparatuses which provide a virtual storage apparatus can be run without the need for being conscious of physical boundaries (real boundaries), and the storage running cost is accordingly reduced. When adding a virtual POOL-VOL to a virtual POOL or when creating a virtual DP-VOL from a virtual POOL, a real storage resource associated with the virtual POOL-VOL, or a real storage resource associated with the virtual DP-VOL, can be constructed within a single storage apparatus, and the processing efficiency in the virtual storage apparatus is thus prevented from dropping. 
       Second Embodiment 
       [0141]    A computer system of a second embodiment of this invention is the same as the computer system of the first embodiment, except a part of the configuration and processing. The following description focuses on the difference from the first embodiment. 
         [0142]    (2-1) Computer System Configuration in this Embodiment 
         [0143]      FIG. 13  illustrates an association relation between the real configuration of the storage apparatus  4  and a virtual configuration provided to the virtual storage management computer  3  by the storage apparatus  4 . 
         [0144]    In the real configuration, each storage apparatus  4  manages at least one local copy pair made up of a PVOL  101 P, which is the copy source DP-VOL  101 , and an SVOL  1015 , which is the copy destination DP-VOL  101 . 
         [0145]    When creating the local copy pair  111 , the storage apparatus  4  copies every piece of data in the PVOL  101 P to the SVOL  1015 . The storage apparatus  4  then makes update write to the PVOL  101 P reflected on the SVOL  101 S as well as manages a differential between the PVOL  101 P and the SVOL  101 S, depending on the state of the local copy pair  111 . 
         [0146]    In the virtual configuration, a virtual local copy pair  111 V, a virtual PVOL  101 PV, and a virtual SVOL  101 SV are set in the virtual storage apparatus  4 V. Each virtual local copy pair  111 V is associated with one of the local copy pairs  111  on a one-to-one basis. Each virtual PVOL  101 PV is associated with one of the PVOLs  101 P on a one-to-one basis. Each virtual SVOL  101 SV is associated with one of the SVOLs  101 S on a one-to-one basis. 
         [0147]      FIG. 14  illustrates main configuration information stored in the memory  41  of each storage apparatus  4 . As illustrated in  FIG. 14 , the memory  41  stores a local copy pair configuration management table  250  and a virtual local copy pair management table  260 . The local copy pair configuration management table  250  is a local table for storing information unique to each storage apparatus  4 . The virtual local copy pair management table  260  is common to all storage apparatus  4  that provide real storage resources to the virtual storage apparatus  4 V. The table  260  is updated in the same way as in the first embodiment. 
         [0148]      FIG. 15  illustrates a configuration example of the local copy pair configuration management table  250 . The CPU  40  of each storage apparatus  4  uses the local copy pair configuration management table  250  to manage information about the local copy pairs  111 . Registered in the local copy pair configuration management table  250  for each local copy pair  111  are, for example, a real pair #251, a real PVOL #252, a real SVOL #253, and a pair state  254 . 
         [0149]    The real pair #251 is a number used to identify each local copy pair  111  uniquely throughout the storage apparatuses  4 . The real PVOL #252 is a number used to identify, uniquely throughout the storage apparatuses  4 , the PVOL  101 P of the local copy pair  111  that is identified by the real pair #251. 
         [0150]    The real SVOL #253 is a number used to identify, uniquely throughout the storage apparatuses  4 , the SVOL  1015  of the local copy pair  111  that is identified by the real pair #251. 
         [0151]    The pair state  254  is information indicating the state of the local copy pair  111  that is identified by the real pair #251, and has a value “PAIR” or “PSUS”. When the pair state  254  is “PAIR”, the storage apparatus  4  makes update write to the PVOL  101 P that is identified by the real PVOL #252 reflected on the SVOL  1015  that is identified by the real SVOL #253 as well. 
         [0152]    Update copy for making update write reflected may be executed in synchronization with the update write, or may be executed out of synchronization with the update write. When the pair state  254  is “PSUS”, on the other hand, the storage apparatus  4  does not execute update copy and executes processing of managing a differential between the PVOL  101 P that is identified by the real PVOL #252 and the SVOL  101 S that is identified by the real SVOL #253. 
         [0153]      FIG. 16  illustrates a configuration example of the virtual local copy pair management table  260 . The CPU  40  of each storage apparatus  4  uses the virtual local copy pair management table  260  to manage information about the association between one virtual local copy pair  111 V and one local copy pair  111 . Registered in the virtual local copy pair management table  260  are, for example, a virtual pair #261, a real storage apparatus #262, and a real pair #263. 
         [0154]    The virtual pair #261 is a number used to identify each virtual local copy pair  111 V uniquely throughout the virtual storage apparatus  4 V. The real storage apparatus #262 is a number used to uniquely identify the storage apparatus  4  where the local copy pair  111  that is associated with the virtual local copy pair  111 V identified by the virtual pair #261 is located. 
         [0155]    The real pair #263 is a number used to identify, uniquely throughout the storage apparatuses  4  identified by the real storage apparatus #262, the local copy pair  111  that is associated with the virtual local copy pair  111   v  identified by the virtual pair #261. The real pair #263 corresponds to the real pair #251 of the local copy pair configuration management table  250 . 
         [0156]    (2-2) Local Copy Pair Constructing Processing in this Embodiment 
         [0157]    Virtual local copy pair constructing processing executed in the computer system  1  of this embodiment is described below. In the following description, letters “SP” prefixed to a reference numeral mean “processing step”. 
         [0158]      FIG. 17  is a flow chart illustrating processing that is executed by one of the storage apparatus  4  that receives a virtual local copy pair creation instruction from the virtual storage management computer  3  (hereinafter referred to as virtual local copy pair creating processing A). The virtual local copy pair creating processing A is implemented by the CPU  40  of the storage apparatus  4  by executing a program. 
         [0159]    The storage apparatus  4  receives a virtual local copy pair creation instruction from the virtual storage management computer  3  (SP 500 ), and first extracts a virtual pair #, a virtual PVOL #, and a virtual SVOL # from the virtual local copy pair creation instruction (SP 501 ). 
         [0160]    The storage apparatus  4  next determines whether or not the DP-VOL  101  that is associated with the virtual PVOL # extracted in Step SP 501  is present in its own casing (SP 502 ). Specifically, the storage apparatus  4  refers to the virtual VOL management table  230  to identify an entry in which the same value as the virtual PVOL # extracted in Step SP 501  is set to the virtual VOL #231, and determines whether or not the real storage apparatus #232 of the identified entry matches the storage apparatus #290. 
         [0161]    When the result of this determination is positive (SP 502 : YES), the storage apparatus  4  proceeds to Step SP 503  to determine whether or not the DP-VOL  101  that is associated with the virtual SVOL # extracted in Step SP 501  is present in its own casing. Specifically, the storage apparatus  4  refers to the virtual VOL management table  230  to identify an entry in which the virtual VOL #231 matches the virtual SVOL # extracted in Step SP 501 , and determines whether or not the real storage apparatus #232 of the identified entry matches the storage apparatus #290. 
         [0162]    When the result of this determination is positive (SP 503 : YES), the storage apparatus  4  proceeds to Step SP 504  to create one local copy pair  111  between two DP-VOLs  101  associated respectively with the virtual PVOL # and the virtual SVOL # that have been extracted in Step SP 501 . 
         [0163]    Specifically, the storage apparatus  4  adds one entry to the local copy pair configuration management table  250 . In the added entry, a number that is not used in any other entry is set to the real pair #251, the real VOL #233 of the entry identified in Step SP 502  is set to the real PVOL #252, a real VOL # of the entry identified in Step SP 503  is set to the real SVOL #253, and “PAIR” is set to the pair state  254 . 
         [0164]    The storage apparatus  4  next associates the local copy pair  111  created in Step SP 504  with the virtual pair # extracted in Step SP 501  (SP 505 ). Specifically, the storage apparatus  4  adds one entry to the virtual local copy pair management table  260 . In the added entry, the virtual pair # extracted in Step SP 501  is set to the virtual pair #261, the storage apparatus #290 is set to the real storage apparatus #262, and a number set to the real pair #251 in Step SP 504  is set to the real pair #263. 
         [0165]    The storage apparatus  4  also transmits to all other storage apparatus  4  an instruction to update their respective virtual pair local copy management table  260 . Receiving the instruction, each storage apparatus  4  adds one entry to the virtual pair local copy management table  260  in the same way as the storage apparatus  4  that has transmitted the instruction. 
         [0166]    Lastly, the storage apparatus  4  transmits a virtual local copy pair creation completion notification to the virtual storage management computer  3  (SP 506 ), and ends the virtual local copy pair creating processing A. 
         [0167]    In the case where the result of the determination of Step SP 502  is negative (SP 502 : NO), on the other hand, the storage apparatus  4  proceeds to Step SP 511  to transfer the virtual local copy pair creation instruction to the storage apparatus  4  where the DP-VOL  101  that is associated with the virtual PVOL # extracted in Step SP 501  is located. Specifically, the storage apparatus  4  transfers the virtual local copy pair creation instruction to the storage apparatus  4  that is associated with the real storage apparatus #232 of the entry identified in Step SP 502 . 
         [0168]    The storage apparatus  4  to which the virtual local copy pair creation instruction has been transferred executes Steps SP 500  to SP 506 . In Step SP 500 , however, the storage apparatus  4  to which the virtual local copy pair creation instruction has been transferred receives a virtual local copy pair creation instruction from the storage apparatus  4  that has transferred the virtual local copy pair creation instruction, instead of from the virtual storage management computer  3 . In addition, the storage apparatus  4  to which the virtual local copy pair creation instruction has been transferred always obtains a positive result in the determination of Step SP 502 . Further, in Step SP 506 , the storage apparatus  4  to which the virtual local copy pair creation instruction has been transferred transmits a virtual local copy pair creation completion notification to the storage apparatus  4  that has transferred the virtual local copy pair creation instruction, instead of to the virtual storage management computer  3 . 
         [0169]    The storage apparatus  4  that has transferred the virtual local copy pair creation instruction receives the virtual local copy pair creation completion notification from the storage apparatus  4  to which the virtual local copy pair creation instruction has been transferred (SP 512 ), and proceeds to Step SP 506 . 
         [0170]    In the case where the result of the determination of Step SP 503  is negative (SP 503 : NO), the storage apparatus  4  proceeds to Step SP 507  to create a new DP-VOL  101  in one of the DP-POOLs  110  within its own casing. Specifically, the storage apparatus  4  adds one entry to the VOL management table  200 . In the added entry, a number that is not used in any other entry is set to the real VOL #201, and “DP” is set to the type  202 . 
         [0171]    The storage apparatus  4  also selects one entry from the POOL configuration management table  210  to set the real POOL #211 of the selected entry to the real POOL #205. The capacity of the DP-VOL  101  that is associated with the virtual SVOL # extracted in Step SP 501  is set to the capacity  207 . The RAID group #203, the start LBA  204 , and the end LBA  205  are left undefined. 
         [0172]    The storage apparatus  4  next associates the DP-VOL  101  created in Step SP 507  with the virtual SVOL # extracted in Step SP 501  (SP 508 ). Specifically, the storage apparatus  4  adds one entry to the virtual VOL management table  230 . In the added entry, the virtual SVOL # extracted in Step SP 501  is set to the virtual VOL #231, the storage apparatus #290 is set to the real storage apparatus #232, and the number set to the real VOL #201 in Step SP 507  is set to the real VOL #233. 
         [0173]    The storage apparatus  4  next transmits a DP-VOL removal instruction to the storage apparatus  4  where the DP-VOL  101  that is associated with the virtual SVOL # extracted in Step SP 501  is located (SP 509 ). Specifically, the storage apparatus  4  transmits a DP-VOL removal instruction to the storage apparatus  4  that is associated with the real storage apparatus #232 of the entry identified in Step SP 503 . When transmitting the instruction, the storage apparatus  4  includes in the DP-VOL removal instruction a real VOL # of the entry identified in Step SP 503 . The removal of the DP-VOL may be omitted. 
         [0174]    The storage apparatus  4  that has received the DP-VOL removal instruction removes the DP-VOL  101  that is associated with the real VOL # included in the DP-VOL removal instruction. Specifically, the storage apparatus  4  that has received the DP-VOL removal instruction updates the VOL management table  200  by deleting an entry in which the real VOL #201 matches the real VOL # included in the DP-VOL removal instruction. The storage apparatus  4  that has received the DP-VOL removal instruction then transmits a DP-VOL removal completion notification to the storage apparatus  4  that has transmitted the DP-VOL removal instruction. 
         [0175]    The storage apparatus  4  that has transmitted the DP-VOL removal instruction receives the DP-VOL removal completion notification from the storage apparatus  4  that has received the DP-VOL removal instruction (SP 510 ), and proceeds to Step SP 504 . 
         [0176]    (2-3) the Configuration and Processing for the Case where the Management Computer Takes Initiative 
         [0177]    The virtual local copy pair creating processing in which the relevant storage apparatus  4  takes a central role in the description given above may be initiated and conducted by the storage management computer  8 . This may lessen the load on the storage apparatus  4 . 
         [0178]    In the case where the storage management computer  8  initiates and conducts the processing, the storage management computer  8  holds the virtual VOL management table  230  and the virtual local copy pair management table  260  in the memory  81 , and keeps the tables consistent with the virtual VOL management table  230  and the virtual local copy pair management table  260  that each storage apparatus  4  holds in the memory  41 . 
         [0179]      FIG. 18  is a flow chart illustrating processing that is executed by the storage management computer  8  when a virtual local copy pair creation instruction is received from the virtual storage administrator (hereinafter referred to as virtual local copy pair creating processing B). The virtual local copy pair creating processing B is implemented by the CPU  80  of the storage management computer  8  by executing a program. 
         [0180]    The storage management computer  8  receives a virtual local copy pair creation instruction from the virtual storage administrator (SP 520 ), and first extracts a virtual pair #, a virtual PVOL #, and a virtual SVOL # from the virtual local copy pair creation instruction (SP 521 ). 
         [0181]    The storage management computer  8  next determines whether or not the PVOL  101 P that is associated with the virtual PVOL # extracted in Step SP 521  and the SVOL  1015  that is associated with the virtual SVOL # extracted in Step SP 521  are present in the same casing (the same storage apparatus  4 ) (SP 522 ). 
         [0182]    Specifically, the storage management computer  8  refers to the virtual VOL management table  230  of the memory  81  to identify an entry in which the same value as the virtual PVOL # extracted in Step SP 521  is set to the virtual VOL #231, and an entry in which the same value as the virtual SVOL # extracted in Step SP 521  is set to the virtual VOL #231, and determines whether or not the identified entries have a matching value as the real storage apparatus #232. 
         [0183]    When the result of this determination is positive (SP 522 : YES), the storage management computer  8  proceeds to Step SP 523  to transmit a real local copy pair creation instruction to the storage apparatus  4  where the PVOL  101 P that is associated with the virtual PVOL # extracted in Step SP 521  is located. When transmitting the instruction, the storage management computer  8  includes in the real local copy pair creation instruction the real VOL #233 of the entry that is associated with the virtual PVOL # identified in Step SP 521  and the real VOL #233 of the entry that is associated with the virtual SVOL # identified in Step SP 521 . 
         [0184]    The storage apparatus  4  that has received the real local copy pair creation instruction creates one local copy pair  111  following the real local copy pair creation instruction, and transmits a real local copy pair creation completion notification to storage management computer  8 . In transmitting the notification, the storage apparatus  4  includes the real pair # of the newly created local copy pair  111  in the real local copy pair creation completion notification. 
         [0185]    The storage management computer  8  receives the real local copy pair creation completion notification from the storage apparatus  4  (SP 524 ), and extracts the real pair # from the real local copy pair creation completion notification (SP 525 ). 
         [0186]    The storage management computer  8  next associates the local copy pair  111  created by the storage apparatus  4  with the virtual pair # extracted in Step SP 521  (SP 526 ). Specifically, the storage management computer  8  adds one entry to the virtual local copy pair management table  260  in the memory  81 . In the added entry, the virtual pair # extracted in Step SP 521  is set to the virtual pair #261, the real storage apparatus #232 of the entry identified in Step SP 522  is set to the real storage apparatus #262, and the real pair # extracted in Step SP 525  is set to the real pair #263. 
         [0187]    The storage management computer  8  also transmits to all storage apparatus  4  an instruction to update their respective virtual local copy pair management tables  260 . Receiving the instruction, each storage apparatus  4  adds one entry to the virtual local copy pair management table  260  in the same way as the storage management computer  8 . 
         [0188]    Lastly, the storage management computer  8  transmits a virtual local copy pair creation completion notification to the virtual storage administrator (SP 526 ), and ends the virtual local copy pair creating processing B. 
         [0189]    In the case where the result of the determination of Step SP 522  is negative (SP 522 : NO), on the other hand, the storage management computer  8  proceeds to Step SP 528  to transmit a real DP-VOL creation instruction to the storage apparatus  4  where the PVOL  101 P that is associated with the virtual PVOL # extracted in Step SP 521  is located. 
         [0190]    The storage apparatus  4  that has received the real DP-VOL creation instruction creates one DP-VOL  101  following the real DP-VOL creation instruction, and transmits a real DP-VOL creation completion notification to the storage management computer  8 . When transmitting the notification, the storage apparatus  4  includes the real VOL # of the newly created DP-VOL in the real DP-VOL creation completion notification. 
         [0191]    The storage management computer  8  receives the real DP-VOL creation completion notification from the storage apparatus  4  (SP 529 ), and extracts the real VOL # from the real DP-VOL creation completion notification (SP 530 ). 
         [0192]    The storage management computer  8  next associates the DP-VOL  101  created by the storage apparatus  4  with the virtual SVOL # extracted in Step SP 521  (SP 531 ). Specifically, the storage management computer  8  adds one entry to the virtual VOL management table  230  of the memory  81 . 
         [0193]    In the added entry, the virtual SVOL # extracted in Step SP 521  is set to the virtual VOL #231, the real storage apparatus #232 of the entry that has been identified in Step SP 522  as an entry where the same value as the virtual PVOL # extracted in Step SP 521  is set to the virtual VOL #231 is set to the real storage apparatus #232, and the real VOL # extracted in Step SP 530  is set to the real VOL #233. 
         [0194]    The storage management computer  8  next transmits a real DP-VOL removal instruction to the storage apparatus  4  where the SVOL  101 S that is associated with the virtual SVOL # extracted in Step SP 521  is located (SP 532 ). When transmitting the instruction, the storage management computer  8  includes in the real DP-VOL removal instruction the real VOL # of the SVOL  101 S that is associated with the virtual SVOL # extracted in Step SP 521 . 
         [0195]    The storage apparatus  4  that has received the real DP-VOL removal instruction removes the specified DP-VOL  101  following the real DP-VOL removal instruction, and transmits a real DP-VOL removal completion notification to the storage management computer  8 . The storage management computer  8  receives the real DP-VOL removal completion notification from the storage apparatus  4  (SP 533 ), and proceeds to Step SP 523 . 
         [0196]    As has been described, according to this embodiment, a plurality of real storage apparatuses which provides a virtual storage apparatus can be run without the need for being conscious of physical boundaries (real boundaries), and the storage running cost is accordingly reduced. When creating a virtual local copy pair, two real VOLs that are respectively associated with a virtual PVOL and a virtual SVOL can be constructed within a single storage apparatus, and the lowering of processing efficiency due to inter-storage communication can thus be prevented. 
         [0197]    The processing described above that accompanies the creation of a virtual local copy pair is applicable to a storage system that does not use pools. 
       Third Embodiment 
       [0198]    A computer system of a third embodiment is the same as the computer system of the first embodiment of this invention, except a part of the configuration and processing. The following description focuses on the difference from the first embodiment. 
         [0199]    (3-1) Computer System Configuration in this Embodiment 
         [0200]      FIG. 19  illustrates the real configuration of a computer system  1  in this embodiment. The computer system  1  in this embodiment includes at least one main storage apparatus  4 M, which is a copy source storage apparatus  4 , and at least one remote storage apparatus  4 R, which is a copy destination storage apparatus  4 . The main storage apparatus  4 M and the remote storage apparatus  4 R are associated with each other on a one-to-one basis. 
         [0201]    Each main storage apparatus  4 M includes at least one M-DVOL  101 MD, at least one M-JVOL  101 MJ, and at least one M-JNLG  112 M. The M-DVOL  101 MD is the copy source DP-VOL  101 , and the M-JVOL  101 MJ is the DP-VOL  101  for temporarily saving a journal of update write to the M-DVOL  101 MD. 
         [0202]    The main storage apparatus  4 M manages at least one M-JVOL  101 MJ as the M-JNLG  112 M, and manages at least one M-DVOL  101 MD in association with one M-JNLG  112 M. 
         [0203]    Each remote storage apparatus  4 R includes at least one R-DVOL  101 RD, at least one R-JVOL  101 RJ, and at least one R-JNLG  112 R. The R-DVOL  101 RD is the copy destination DP-VOL  101 , and the R-JVOL  101 RJ is the DP-VOL  101  for temporarily saving a journal of update copy from the main storage apparatus  4 M. 
         [0204]    The remote storage apparatus  4 R manages at least one R-JVOL  101 RJ as the R-JNLG  112 R, and manages at least one R-DVOL  101 RD in association with one R-JNLG  112 R. 
         [0205]    The main storage apparatus  4 M receives update write to the M-DVOL  101 MD from the host computer  2 . The main storage apparatus  4 M then writes update data in the M-DVOL  101 MD, saves a journal of the update write in the M-JNLG  112 M that is associated with the M-DVOL  101 MD, and transmits a response to the update write to the host computer  2 . The main storage apparatus  4 M copies the journal saved in the M-JNLG  112  to the remote storage apparatus  4 R out of synchronization with the update write. 
         [0206]    Receiving the journal from the main storage apparatus  4 M, the remote storage apparatus  4 R saves the journal in the R-JNLG  112 R. The remote storage apparatus  4 R makes the journal that is saved in the R-JNLG  112 R reflected on the R-DVOL  101 RD out of synchronization with the reception of the journal. 
         [0207]      FIG. 20  illustrates the virtual configuration of the computer system  1  in this embodiment. The computer system  1  in this embodiment includes a virtual main storage apparatus  4 MV, which is a copy source virtual storage apparatus, and a virtual remote storage apparatus  4 RV, which is a copy destination virtual storage apparatus. 
         [0208]    The virtual main storage apparatus  4 MV includes at least one virtual M-DVOL  101  MDV, at least one virtual M-JVOL  101 MJV, and at least one virtual M-JNLG  112 MV. 
         [0209]    Each virtual M-DVO  101 MDV is associated with one of the M-DVOLs  101 MD on a one-to-one basis. Each virtual M-JVOL  101 MJV is associated with one of the M-JVOLs  101 MJ on a one-to-one basis. Each virtual M-JNLG  112 MV is associated with one of the M-JNLGs  112 M on a one-to-one basis. 
         [0210]    The virtual remote storage apparatus  4 RV includes at least one virtual R-DVOL  101 RDV, at least one virtual R-JVOL  101 RJV, and at least one virtual R-JNLG  112 RV. 
         [0211]    Each virtual R-DVOL  101 RDV is associated with one of the R-DVOLs  101 RD on a one-to-one basis. Each virtual R-JVOL  101 RJV is associated with one of the R-JVOLs  101 RJ on a one-to-one basis. Each virtual R-JNLG  112 RV is associated with one of the R-JNLGs  112 R on a one-to-one basis. 
         [0212]      FIG. 21  illustrates main configuration information stored in the memory  41  of each main storage apparatus  4 M and each remote storage apparatus  4 R. As illustrated in  FIG. 21 , the memory  41  stores a journal group configuration management table  800 , a remote copy pair configuration management table  810 , a virtual journal group management table  820 , and a virtual remote copy pair management table  830 . 
         [0213]    The journal group configuration management table  800  and the remote copy pair configuration management table  810  are local tables for storing information unique to each storage apparatus  4 . The virtual journal group management table  820  and the virtual remote copy pair management table  830  are tables common to all storage apparatus  4  that provide real storage resources to the virtual storage apparatus  4 V. The tables are updated in the manner described in the first embodiment. 
         [0214]      FIG. 22  illustrates a configuration example of the journal group configuration management table  800 . The CPU  40  of each main storage apparatus  4 M uses the journal group configuration management table  800  to manage information about each M-JNLG  112 M, and the CPU  40  of each remote storage apparatus  4 R uses the journal group configuration management table  800  to manage information about each R-JNLG  112 R. Registered in the journal group configuration management table  800  for each M-JNLG  112 M or for each R-JNLG  112 R are, for example, a real JNLG #801 and at least one real VOL #802. 
         [0215]    The real JNLG #801 is a number used to identify each M-JNLG  112 M uniquely throughout the main storage apparatus  4 M, or a number used to identify each R-JNLG  112 R uniquely throughout the remote storage apparatus  4 R. 
         [0216]    The real VOL #802 is a number used to identify, uniquely throughout the main storage apparatus  4 M or throughout the remote storage apparatus  4 R, each M-JVOL  112 M that constitutes the M-JNLG  112 M identified by the real JNLG #801, or each R-JVOL  112 R that constitutes the R-JNLG  112 R identified by the real JNLG #801. At least one real VOL #802 is associated with one real JNLG #801. 
         [0217]      FIG. 23  illustrates a configuration example of the remote copy pair configuration management table  810 . The CPU  40  of each main storage apparatus  4 M uses the remote copy pair configuration management table to manage information about a remote copy pair. Registered in the remote copy pair configuration management table  810  for each remote copy pair are, for example, a real pair #811, a real M-DVOL #812, a real M-JNLG #813, a remote storage apparatus #814, an R-DVOL #815, an R-JNLG #816, and a pair state  817 . 
         [0218]    The real pair #811 is a number used to identify each remote copy pair uniquely throughout the main storage apparatus  4 M. The real M-DVOL #812 is a number used to identify, uniquely throughout the main storage apparatus  4 M, the M-DVOL  101 MD of a remote copy pair identified by the real pair #811. 
         [0219]    The real M-JNLG #813 is a number used to identify, uniquely throughout the main storage apparatus  4 M, the M-JNLG  112 M that temporarily saves a journal of update write to the M-DVOL  101 MD of a remote copy pair identified by the real pair #811. 
         [0220]    The remote storage apparatus #814 is a number used to uniquely identify the remote storage apparatus  4 R that is the copy destination of a remote copy pair identified by the real pair #811. 
         [0221]    The R-DVOL #815 is a number used to identify, uniquely throughout the main storage apparatus  4 M, the R-DVOL  101 RD that is the copy destination of a remote copy pair identified by the real pair #811. 
         [0222]    The R-JNLG #816 is a number used to identify, uniquely throughout the copy destination remote storage apparatus  4 R, the R-JNLG  112 R that is the copy destination of a remote copy pair identified by the real pair #811. 
         [0223]    The pair state  817  is information indicating the state of a remote copy pair identified by the real pair #811, and has a value “PAIR” or “PSUS”. When the pair state  817  is “PAIR”, the main storage apparatus  4 M copies update write performed on the M-DVOL  101 MD that is identified by the real M-DVOL #812 to the remote storage apparatus  4 R that is identified by the remote storage apparatus #814. 
         [0224]    When the pair state  817  is “PSUS”, on the other hand, the main storage apparatus  4 M does not execute copy and manages a differential between the M-DVOL  101 MD identified by the ream M-DVOL #812 and the R-DVOL  101 RD identified by the remote storage apparatus #814 and by the R-DVOL #815. 
         [0225]      FIG. 24  illustrates the data configuration of the virtual journal group management table  820 . The CPU  40  of each main storage apparatus  4 M uses the virtual journal group management table to manage information about the association between one virtual M-JNLG  112 MV and one M-JNLG  112 M. The CPU  40  of each remote storage apparatus  4 R uses the virtual journal group management table to manage information about the association between one virtual R-JNLG  112 RV and one R-JNLG  112 R. 
         [0226]    Registered in the virtual journal group management table  820  for each virtual M-JNLG  112 MV or for each virtual R-JNLG  112 RV are, for example, a virtual JNLG #821, a real storage apparatus #822, and a real JNLG #823. 
         [0227]    The virtual JNLG #821 is a number used to identify each virtual M-JNLG  112 MV or each virtual R-JNLG  112 RV uniquely throughout the virtual main storage apparatus  4 MV or throughout the virtual remote storage apparatus  4 RV. 
         [0228]    The real storage apparatus #822 is a number used to uniquely identify the main storage apparatus  4 M where the M-JNLG  112 M that is associated with the virtual M-JNLG  112 MV identified by the virtual JNLG #821 is located, or the remote storage apparatus  4 R where the R-JNLG  112 R that is associated with the virtual R-JNLG  112 RV identified by the virtual JNLG #821 is located. 
         [0229]    The real JNLG #823 is a number used to identify, uniquely throughout the main storage apparatus  4 M or the remote storage apparatus  4 R that is identified by the real storage apparatus #822, the M-JNLG  112 M that is associated with the virtual M-JNLG  112 MV identified by the virtual JNLG #821 or the R-JNLG  112 R that is associated with the virtual R-JNLG  112 RV identified by the virtual JNLG #821. The real JNLG #823 corresponds to the real JNLG #801 of the journal group configuration management table  800 . 
         [0230]      FIG. 25  illustrates a configuration example of the virtual remote copy pair management table  830 . The CPU  40  of each main storage apparatus  4 M uses the virtual remote copy pair management table  830  to manage information about the association between a virtual remote copy pair and a remote copy pair. Registered in the virtual remote copy pair management table  830  for each virtual remote copy pair are, for example, a virtual pair #831, a real storage apparatus #832, and a real pair #833. 
         [0231]    The virtual pair #831 is a number used to identify each virtual remote copy pair uniquely throughout the virtual main storage apparatus  4 MV. The real storage apparatus #832 is a number used to uniquely identify the main storage apparatus  4 M where a remote copy pair that is associated with a virtual remote copy pair identified by the virtual pair #831 is located. 
         [0232]    The real pair #833 is a number used to identify, uniquely throughout the main storage apparatus  4 M identified by the real storage apparatus #832, a remote copy pair that is associated with a virtual remote copy pair identified by the virtual pair #831. The real pair #833 corresponds to the real pair #811 of the remote copy pair configuration management table  810 . 
         [0233]    (3-2) Journal Group Constructing Processing in this Embodiment 
         [0234]    Journal group constructing processing executed in the computer system  1  is described below. In the following description, letters “SP” prefixed to a reference numeral mean “processing step”. 
         [0235]      FIG. 26  is a flow chart illustrating processing that is executed by one of the main storage apparatus  4 M or one of the remote storage apparatus  4 R that receives a virtual JVOL addition instruction from the virtual storage management computer  3  (hereinafter referred to as virtual JVOL adding processing A). The virtual JVOL adding processing A is implemented by the CPU  40  of the main storage apparatus  4 M or of the remote storage apparatus  4 R by executing a program. 
         [0236]    The main storage apparatus  4 M or the remote storage apparatus  4 R receives a virtual JVOL addition instruction from the virtual storage management computer  3  (SP 600 ), and first extracts a virtual JNLG # and a virtual VOL # from the virtual JVOL addition instruction (SP 601 ). 
         [0237]    The main storage apparatus  4 M or the remote storage apparatus  4 R next determines whether or not the DP-VOL  101  that is associated with the virtual VOL # extracted in Step SP 601  is present in its own casing (SP 602 ). Specifically, the main storage apparatus  4 M or the remote storage apparatus  4 R refers to the virtual VOL management table  230  to identify an entry in which the virtual VOL #231 matches the virtual VOL # extracted in Step SP 601 , and determines whether or not the real storage apparatus #232 of the identified entry matches the storage apparatus #290. 
         [0238]    When the result of this determination is positive (SP 602 : YES), the main storage apparatus  4 M or the remote storage apparatus  4 R proceeds to Step SP 603  to select one M-JNLG  112 M or one R-JNLG  112 R that is associated with the virtual JNLG # extracted in Step SP 601  and that is present in its own casing. 
         [0239]    Specifically, the main storage apparatus  4 M or the remote storage apparatus  4 R refers to the virtual JNLG management table  820  to identify an entry in which the virtual JNLG #821 matches the virtual JNLG # extracted in Step SP 601 , and selects one sub-entry in the identified entry where the real storage apparatus #822 matches the real storage apparatus #290. 
         [0240]    The main storage apparatus  4 M or the remote storage apparatus  4 R next adds the DP-VOL  101  that is associated with the virtual VOL # extracted in Step SP 601  to the M-JNLG  112 M or the R-JNLG  112 R that is associated with the real JNLG #823 of the sub-entry selected in Step SP 603  (SP 604 ). 
         [0241]    Specifically, the main storage apparatus  4 M or the remote storage apparatus  4 R refers to the virtual VOL management table  230  to identify an entry in which the virtual VOL #231 matches the virtual VOL # extracted in Step SP 601 , and extracts the real VOL #233 from the identified entry. 
         [0242]    The main storage apparatus  4 M or the remote storage apparatus  4 R then updates the journal group configuration management table  800  by adding the extracted VOL #233 to an entry in which the real JNLG #801 matches the real JNLG #823 of the sub-entry selected in Step SP 603 . 
         [0243]    Lastly, the main storage apparatus  4 M or the remote storage apparatus  4 R transmits a virtual JVOL addition completion notification to the virtual storage management computer  3  (SP 605 ), and ends the virtual JVOL adding processing A. 
         [0244]    In the case where the result of the determination of Step SP 602  is negative (SP 602 : NO), on the other hand, the main storage apparatus  4 M or the remote storage apparatus  4 R proceeds to Step SP 606  to transfer the virtual JVOL addition instruction to the main storage apparatus  4 M or the remote storage apparatus  4 R where the DP-VOL  101  that is associated with the virtual VOL # extracted in Step SP 601  is located. Specifically, the main storage apparatus  4 M or the remote storage apparatus  4 R transfers the virtual JVOL addition instruction to the main storage apparatus  4 M or the remote storage apparatus  4 R that is associated with the real storage apparatus #232 of the entry identified in Step SP 602 . 
         [0245]    The main storage apparatus  4 M or the remote storage apparatus  4 R to which the virtual JVOL addition instruction has been transferred executes Steps SP 600  to SP 605 . In Step SP 600 , however, the main storage apparatus  4 M or the remote storage apparatus  4 R to which the virtual JVOL addition instruction has been transferred receives a virtual JVOL addition instruction from another storage apparatus  4 , instead of from the virtual storage management computer  3 . 
         [0246]    In addition, the main storage apparatus  4 M or the remote storage apparatus  4 R to which the virtual JVOL addition instruction has been transferred always obtains a positive result in the determination of Step SP 602 . Further, in Step SP 605 , the main storage apparatus  4 M or the remote storage apparatus  4 R to which the virtual JVOL addition instruction has been transferred transmits a virtual JVOL addition completion notification to the main storage apparatus  4 M or the remote storage apparatus  4 R that has transferred the virtual JVOL addition instruction, instead of to the virtual storage management computer  3 . 
         [0247]    The main storage apparatus  4 M or the remote storage apparatus  4 R that has transferred the virtual JVOL addition instruction receives the virtual JVOL addition completion notification from the main storage apparatus  4 M or the remote storage apparatus  4 R to which the virtual JVOL addition instruction has been transferred (SP 607 ), and proceeds to Step SP 605 . 
         [0248]    The flow described above makes it possible to construct within the same storage apparatus  4  a real JNLG that is associated with a virtual JNLG to which a virtual JVOL is to be added and a real JVOL that is associated with the virtual JVOL to be added, thereby avoiding the lowering of processing efficiency that is caused by communication between one storage apparatus  4  and another. 
         [0249]    (3-3) Remote Copy Pair Constructing Processing in this Embodiment 
         [0250]    Remote copy pair constructing processing executed in the computer system  1  is described below. In the following description, letters “SP” prefixed to a reference numeral mean “processing step”. 
         [0251]      FIG. 27  is a flow chart illustrating processing that is executed by one of the main storage apparatus  4 M that receives a virtual remote copy pair creation instruction from the virtual storage management computer  3  (hereinafter referred to as virtual remote copy pair creating processing A). The virtual remote copy pair creating processing A is implemented by the CPU  40  of the main storage apparatus  4 M by executing a program. 
         [0252]    The main storage apparatus  4 M receives a virtual remote copy pair creation instruction from the virtual storage management computer  3  (SP 700 ), and first extracts parameters from the virtual remote copy pair creation instruction (SP 701 ). Specifically, the main storage apparatus  4 M extracts a virtual pair #, a virtual M-DVOL #, a virtual M-JNLG #, a remote storage apparatus #, an R-DVOL #, and an R-JNLG # from the virtual remote copy pair creation instruction. 
         [0253]    The main storage apparatus  4 M next determines whether or not the DP-VOL  101  that is associated with the virtual M-DVOL # extracted in Step SP 701  is present in its own casing (SP 702 ). Specifically, the main storage apparatus  4 M refers to the virtual VOL management table  230  to identify an entry in which the virtual VOL #231 matches the virtual M-DVOL # extracted in Step SP 701 , and determines whether or not the real storage apparatus #232 of the identified entry matches the storage apparatus #290. 
         [0254]    When the result of this determination is positive (SP 702 : YES), the main storage apparatus  4 M proceeds to Step SP 703  to select one M-JLNG  112 M that is associated with the virtual M-JNLG # extracted in Step SP 701 . Specifically, the main storage apparatus  4 M refers to the virtual journal group configuration management table  820  to identify an entry in which the virtual JNLG #821 matches the virtual M-JNLG # extracted in Step SP 701 , and selects one sub-entry in the identified entry where the same value as the storage apparatus #290 is set to the real storage apparatus #822. 
         [0255]    The main storage apparatus  4 M next creates a real remote copy pair (SP 704 ). Specifically, the main storage apparatus  4 M adds one entry to the remote copy pair configuration management table  810 . In the added entry, an unused number is set to the real pair #811, and a real VOL # of the entry identified in Step SP 702  is set to the real M-DVOL #812. 
         [0256]    The real JNLG #823 of the sub-entry selected in Step SP 703  is set to the real M-JNLG #813. The remote storage apparatus #, the R-DVOL #, and the R-JNLG # that have been extracted in Step SP 701  are set to the remote storage apparatus #814, the R-DVOL #815, and the R-JNLG #816, respectively. A value “PAIR” is set to the pair state  817 . 
         [0257]    The main storage apparatus  4 M next associates the real remote copy pair created in Step SP 704  with the virtual pair # extracted in Step SP 701  (SP 705 ). Specifically, the main storage apparatus  4 M adds one entry to the virtual remote copy pair management table  830 . In the added entry, the virtual pair # extracted in Step SP 701  is set to the virtual pair #831, the storage apparatus #290 is set to the real storage apparatus #832, and the number set to the real pair #811 in Step SP 704  is set to the real pair #833. 
         [0258]    Lastly, the main storage apparatus  4 M transmits a virtual remote copy pair creation completion notification to the virtual storage management computer  3  (SP 706 ), and ends the virtual remote copy pair creating processing A. 
         [0259]    In the case where the result of the determination of Step SP 702  is negative (SP 702 : NO), on the other hand, the main storage apparatus  4 M proceeds to Step SP 707  to transfer the virtual remote copy pair creation instruction to the main storage apparatus  4 M where the DP-VOL  101  that is associated with the virtual M-DVOL # extracted in Step SP 701  is located. Specifically, the main storage apparatus  4 M transfers the virtual remote copy pair creation instruction to the main storage apparatus  4 M that is associated with the real storage apparatus #232 of the entry identified in Step SP 702 . 
         [0260]    The main storage apparatus  4 M to which the virtual remote copy pair creation instruction has been transferred executes Steps SP 700  to SP 706 . In Step SP 700 , however, the main storage apparatus  4 M to which the virtual remote copy pair creation instruction has been transferred receives a virtual remote copy pair creation instruction from the main storage apparatus  4 M that has transferred the virtual remote copy pair creation instruction, instead of from the virtual storage management computer  3 . 
         [0261]    In addition, the main storage apparatus  4 M to which the virtual remote copy pair creation instruction has been transferred always obtains a positive result in the determination of Step SP 702 . Further, in Step SP 706 , the main storage apparatus  4 M to which the virtual remote copy pair creation instruction has been transferred transmits a virtual remote copy pair creation completion notification to the main storage apparatus  4 M that has transferred the virtual remote copy pair creation instruction, instead of to the virtual storage management computer  3 . 
         [0262]    The main storage apparatus  4 M that has transferred the virtual remote copy pair creation instruction receives the virtual remote copy pair creation completion notification from the main storage apparatus  4 M to which the virtual remote copy pair creation instruction has been transferred (SP 708 ), and proceeds to Step SP 706 . 
         [0263]    The flow described above makes it possible to construct within the same storage apparatus  4  a real JNLG and a real M-DVOL that are respectively associated with a virtual JNLG and a virtual M-DVOL that are used to create a virtual remote copy pair, thereby avoiding the lowering of processing efficiency that is caused by communication between one storage apparatus  4  and another. 
         [0264]    (3-3) the Configuration and Processing for the Case where the Management Computer Takes Initiative 
         [0265]    The journal group constructing processing and the remote copy pair constructing processing in which the relevant storage apparatus  4  takes a central role in the description given above may be initiated and conducted by the management computer  8 . This lessens the load on the storage apparatus  4 . 
         [0266]    In the case where the management computer  8  initiates and conducts the processing, the management computer  8  holds the virtual VOL management table  230 , the virtual journal group management table  820 , and the virtual remote copy pair management table  830  in the memory  81 , and keeps the tables consistent with the virtual VOL management table  230 , the virtual journal group management table  820 , and the virtual remote copy pair management table  830  that each storage apparatus  4  holds in the memory  41 . 
         [0267]      FIG. 28  is a flow chart illustrating processing that is executed by the management computer  8  when a virtual JVOL addition instruction is received from the virtual storage administrator (hereinafter referred to as virtual JVOL adding processing B). The virtual JVOL adding processing B is implemented by the CPU  80  of the management computer  8  by executing a program. 
         [0268]    The management computer  8  receives a virtual JVOL addition instruction from the virtual storage administrator (SP 610 ), and first extracts a virtual JNLG # and a virtual VOL # from the virtual JVOL addition instruction (SP 611 ). 
         [0269]    The management computer  8  next selects one M-JNLG  112 M or one R-JNLG  112 R that is associated with the virtual JNLG # extracted in Step SP 611  and that is present in the same casing (the same storage apparatus) as the DP-VOL  101  that is associated with the virtual JVOL # extracted in Step SP 611  (SP 612 ). 
         [0270]    Specifically, the management computer  8  refers to the virtual journal group management table  820  of the memory  81  to identify an entry in which the same value as the virtual JNLG # extracted in Step SP 611  is set to the virtual JNLG #821. The management computer  8  also refers to the virtual VOL management table  230  of the memory  81  to identify an entry in which the same value as the virtual VOL # extracted in Step SP 611  is set to the virtual VOL #231, and extracts the real storage apparatus #232 from the identified entry. 
         [0271]    The management computer  8  then selects one sub-entry in the identified entry of the virtual journal group management table  820  where the same value as the extracted real storage apparatus #232 is set to the real storage apparatus #822. 
         [0272]    The management computer  8  next transmits a real JVOL addition instruction to the main storage apparatus  4 M or the remote storage apparatus  4 R where the M-JNLG  112 M or the R-JNLG  112 R that has been selected in Step SP 612  is located (SP 613 ). Specifically, the management computer  8  transmits a real JVOL addition instruction to the main storage apparatus  4 M or the remote storage apparatus  4 R that is associated with the real storage apparatus #822 of the sub-entry selected in Step SP 612 . In transmitting the instruction, the management computer  8  includes in the real JVOL addition instruction the real JNLG #823 of the sub-entry selected in Step SP 612  and the real VOL #233 of the entry of the virtual VOL management table  230  that has been identified in Step SP 612 . 
         [0273]    The main storage apparatus  4 M or the remote storage apparatus  4 R that has received the real JVOL addition instruction adds the specified DP-VOL  101  to the M-JNLG  112 M or to the R-JNLG  112 R following the real JVOL addition instruction, and transmits a real JVOL addition completion notification to the management computer  8 . 
         [0274]    The management computer  8  receives the real JVOL addition completion notification from the main storage apparatus  4 M or from the remote storage apparatus  4 R (SP 614 ), transmits a virtual JVOL addition completion notification to the virtual storage administrator (SP 615 ), and ends the virtual JVOL adding processing B. 
         [0275]    In remote copy pair constructing processing, the management computer  8  transmits a virtual remote copy pair creation instruction that specifies a virtual M-JNLG # to the storage apparatus  4  that has a real M-DVOL associated with a specified virtual M-DVOL #. The storage apparatus  4  that has received the instruction associates the specified real M-DVOL with its own real M-DVOL that is associated with the specified virtual M-JNLG #. 
         [0276]      FIG. 29  is a flow chart illustrating processing that is executed by the management computer  8  when a virtual remote copy pair creation instruction is received from the virtual storage administrator. The processing is implemented by the CPU  80  of the management computer  8  by executing a program. 
         [0277]    The management computer  8  receives a virtual remote copy pair creation instruction from the virtual storage administrator (SP 710 ), and first extracts parameters from the virtual remote copy pair creation instruction (SP 711 ). Specifically, the management computer  8  extracts a virtual pair #, a virtual M-DVOL #, a virtual M-JNLG #, a remote storage apparatus #, an R-DVOL #, and an R-JNLG # from the virtual remote copy pair creation instruction. 
         [0278]    The management computer  8  next selects one M-JNLG  112 M that is associated with the virtual M-JNLG # extracted in Step SP 711  and that is present in the same casing as the M-DVOL  101 MD that is associated with the virtual M-DVOL # extracted in Step SP 711  (SP 712 ). 
         [0279]    Specifically, the management computer  8  refers to the virtual journal group management table  820  of the memory  81  to identify an entry in which the same value as the virtual M-JNLG # extracted in Step SP 711  is set to the virtual JNLG #821. 
         [0280]    The management computer  8  also refers to the virtual VOL management table  230  of the memory  81  to identify an entry in which the same value as the virtual M-DVOL # extracted in Step SP 711  is set to the virtual VOL #231, and extracts the real storage apparatus #232 from the identified entry. The management computer  8  then selects one sub-entry in the identified entry of the virtual journal group management table  820  where the same value as the extracted real storage apparatus #232 is set to the real storage apparatus #242. 
         [0281]    The management computer  8  next transmits the real remote copy pair creation instruction to the main storage apparatus  4 M where the M-JNLG  112 M selected in Step SP 712  is located (SP 713 ). When transmitting the instruction, the management computer  8  includes, in the remote copy pair creation instruction, the real VOL #233 of the entry of the virtual VOL management table  230  that has been identified in Step SP 712 , the real JNLG #823 of the entry of the virtual journal group management table  820  that has been identified in Step SP 712 , and the remote storage apparatus #, the R-DOVL #, and the R-JNLG # extracted in Step SP 711 . 
         [0282]    The main storage apparatus  4 M that has received the real remote copy pair creation instruction creates a real remote copy pair following the remote copy pair creation instruction, and transmits a real remote copy pair creation completion notification to the management computer  8 . 
         [0283]    The management computer  8  receives the remote copy pair creation completion notification from the main storage apparatus  4 M (SP 714 ), transmits a remote copy pair creation completion notification to the virtual storage administrator (SP 715 ), and ends the remote copy pair creating processing B. 
         [0284]    As has been described, according to this embodiment, a plurality of real storage apparatuses which provide a virtual storage apparatus can be run without the need for being conscious of physical boundaries (real boundaries), and the storage running cost is accordingly reduced. When adding a virtual JVOL to a virtual JNLG or when creating a virtual remote copy pair, a real storage resource associated with the virtual JNLG and a real storage resource associated with the virtual JVOL, or a real storage resource associated with the virtual JNLG and a real storage resource associated with the virtual M-DVOL, can be constructed within a single storage apparatus, and the processing efficiency in the virtual storage apparatus is thus prevented from dropping. 
         [0285]    The processing described above that relates to virtual remote copy pairs is applicable to a storage system that does not use pools. 
         [0286]    Embodiments of this invention have now been described. However, this invention is not limited to the embodiments described above, and it would be easy for those skilled in the art to modify, add, or convert elements of the embodiments described above within the scope of this invention. For instance, a system or an apparatus to which this invention is applied can have only a part of the configurations of the plurality of embodiments described above, or can include all components of the plurality of embodiments described above. This invention allows for substituting some elements of the configuration of one embodiment with elements of another embodiment, and allows for adding a part of the configuration of one embodiment to another embodiment. 
         [0287]    The configurations, functions, processing modules, processing units, and the like described above may partially or entirely be implemented by hardware by, for example, designing in the form of an integrated circuit. Information such as programs, tables, and files for implementing the respective functions can be stored in a storage device such as a non-volatile semiconductor memory, a hard disk drive, or a solid state drive, or in a computer-readable, non-transitory data storage medium such as an IC Card, an SD card, or a DVD.