Abstract:
A storage system is provided which is capable of realizing a remote copy function for speeding up lines virtually by satisfying such demand to distribute copy data into a plurality of lines. In a storage system for connecting a local storage device and a remote storage device via a plurality of lines, the local storage device includes a remote copy program for distributing data of a plurality of logical volumes accessed from a host computer into a plurality of paths on the basis of status of the plurality of paths interposing the plurality of lines, to perform a remote copy from the local storage device to the remote storage device. Accordingly, the local storage device distributes data of the logical volumes into the plurality of lines to copy the data to the remote storage device, resulting in speeding up the lines virtually.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application relates to and claims priority from Japanese Patent Application No. 2008-267051, filed on Oct. 16, 2008, the entire disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a technique of creating a backup of data, and more in particular, to an efficient technique applied to a storage system for performing a remote copy by interposing a plurality of lines. 
         [0004]    2. Description of the Background Art 
         [0005]    As an IT (Information Technology) is introduced into conducting business in an enterprise, important business data are stored in storage devices. In preparation of a large scale of damages such as an earthquake and so on, the enterprise considers a countermeasure such as reserving backups of the business data in a remote place. 
         [0006]    However, an amount invested in the IT is limited in small and medium enterprise and thus a remote backup is required to be realized at a low cost. Such request may become satisfactory by using low-cost lines, for example, for a line for connecting a plurality of bases. 
         [0007]    However, since, for example, an ADSL which is a low-cost line and is generally used has a low data rate in an upload speed which is important upon transmitting data, when copy data amount increases, a manager is required to lease a higher data rate line. The higher data rate line is expensive, and thus a remote copy function capable of using a plurality of cheap and low-speed lines is demanded. 
         [0008]    Therefore, in order to satisfy such demand, data are required to be distributed into a plurality of lines such that a plurality of low-speed lines are bonded for virtual speed-up. For example, Japanese Unexamined Patent Application Publication No. 2004-145855 discloses a method that the remote copy function distributes loads into a plurality of ports. 
       SUMMARY OF THE INVENTION 
       [0009]    However, although the prior art disclosed in Patent Document 1 teaches a remote copy function distributes loads into a plurality of ports, it does not teach a plurality of liens to bond bases and a method of distributing loads into a plurality of lines. 
         [0010]    The present invention is directed to provide a storage system capable of realizing a remote copy function for speeding up lines virtually by satisfying such demand to distribute copy data into a plurality of lines. 
         [0011]    The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings. 
         [0012]    Representative invention disclosed in this document is summarized as follows. 
         [0013]    In other words, in a storage system for connecting a first storage device (a local storage device) and a second storage device (remote storage device) via a plurality of lines, the first storage device includes a remote copy program for distributing data of a plurality of logical volumes accessed from a host computer into a plurality of paths on the basis of status of the plurality of paths interposing the plurality of lines, to perform a remote copy from the first storage device to the second storage device. Thereby, the first storage device distributes data of the logical volumes into the plurality of lines to copy the data to the second storage device, resulting in speeding up the lines virtually. 
         [0014]    Representative effect obtained from the representative intention is described in brief as follows. 
         [0015]    In other words, an effect is obtained that a remote copy function is realized, the remote copy function performing a copy by distributing data into a plurality of cheap and low-speed lines, and thereby it is possible to speed up the lines virtually, resulting in coping with increase of a copy data amount and low cost of lines. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a diagram to illustrate an entire configuration of a storage system according to an embodiment of the present invention; 
           [0017]      FIG. 2  is a diagram to illustrate a configuration of a local storage device according to the embodiment of the present invention; 
           [0018]      FIG. 3  is a diagram to illustrate a configuration of a remote storage device according to the embodiment of the present invention; 
           [0019]      FIG. 4  is a diagram to illustrate a configuration of a management terminal according to the embodiment of the present invention; 
           [0020]      FIG. 5  is a diagram to illustrate a configuration of an IP address table of the local storage device according to the embodiment of the present invention; 
           [0021]      FIG. 6  is a diagram to illustrate a configuration of an IP address table of the remote storage device according to the embodiment of the present invention; 
           [0022]      FIG. 7  is a diagram to illustrate a configuration of an IP address table of virtual ports of the local storage device according to the embodiment of the present invention; 
           [0023]      FIG. 8  is a diagram to illustrate a configuration of an IP address table of virtual ports of the remote storage device according to the embodiment of the present invention; 
           [0024]      FIG. 9  is a diagram to illustrate a configuration of a path management table according to the embodiment of the present invention; 
           [0025]      FIG. 10  is a diagram to illustrate a screen for creating paths according to the embodiment of the present invention; 
           [0026]      FIG. 11  is a diagram to illustrate a screen for displaying path status according to the embodiment of the present invention; 
           [0027]      FIG. 12  is a flowchart to illustrate an order of creation a path by a path creating program according to the embodiment of the present invention; 
           [0028]      FIG. 13  is a flowchart to illustrate an order of checking a path by a path checking program according to the embodiment of the present invention; and 
           [0029]      FIG. 14  is a flowchart to illustrate an order of distributing copy data by a remote copy program according to the embodiment of the present invention. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0030]    Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numerals are given to like elements in the drawings. The present invention is not limited to embodiments of the present invention; rather all the applicable examples to coincide with the scope of the present invention correspond to the present invention. Furthermore, as long as not limited particularly, each element may be singular or plural. 
         [0031]      FIG. 1  is a diagram to illustrate an entire configuration of a storage system of an embodiment of the present invention. The storage system according to the embodiment of the present invention includes, for example, one or more local storage device  101  (one example in  FIG. 1 ), one or more remote storage device  102  (one example in  FIG. 1 ), a management terminal  103  (one example in  FIG. 1 ), one or more host computer  104  (one example in  FIG. 1 ), a plurality of switches  105  and  106  (one example in the local site and one example in the remote site in  FIG. 1 ) and a plurality of router  107  and  108  (N examples of L 1  to LN in the local site and N example of R 1  to RN in the remote site in  FIG. 1 ). 
         [0032]    The local storage device  101  disposed in the local site and the remote storage device  102  disposed in the remote site are connected to each other, for example, via the switch  105  in the local site, the N routers  107  therein, the N lines  111 , the N routers  108  in the remote site and the N switches  106  therein. The local storage device  101  and the management terminal  103  are connected to each other, for example, via a network  113  for management in the local site. The remote storage device  102  and the management terminal  103  are connected to each other, for example, via a network  114  for management in the remote site and a network connection line  112 . The local storage device  101  and the host computer  104  are connected to each other, for example, via the switch  105  in the local site. 
         [0033]    The local storage device  101  is connected to the switch  105  in the local site via a communication line  121  and then is connected to the network  113  for management via a communication line  123 . The remote storage device  102  is connected to the switch  106  in the remote site via a communication line  122 , and then is connected to the network  114  for management via the communication line  124 . The management terminal  103  is connected to the network  113  for management in the local site via a communication line  129 . The host computer  104  is connected to the switch  105  in the local site via the communication line  130 . 
         [0034]    The switch  105  in the local site is connected to the host computer  104  via a communication line  130  and then is connected to the N routers  107  in the local site via communication lines  125 . The switch  106  in the remote switch is connected to the N routers  108  in the remote site via communication lines  126 . The N routers  107  in the local site and the N routers  108  in the remote site are connected to each other via the N lines  111 . The N lines  111  employ a low-speed line which is cheap. 
         [0035]    The network  113  for management of the local site is connected to the network connection line  112  for management via a communication line  127 . The network  114  for management of the remote site is connected to the network connection line  112  for management via a communication line  128 . 
         [0036]    The above-described communication lines  121 ,  122 ,  123 ,  124 ,  127 ,  128 ,  129  and  130  are configured of a wire such as metal cable or an optical fiber cable or the like. However, the connection between the host computer  104  and the local storage device  101  and the connection between the local storage device  101  and the management terminal  103  may be performed by wireless. In this case, the communication lines  121 ,  130 ,  123  and  129  are omitted. 
         [0037]      FIG. 2  is a diagram to illustrate a configuration of the local storage device  101  according to the embodiment of the present invention. The local storage device  101  is a memory device system having one or more memory devices, which is largely classified into a control device  201  and disk devices  211 . In the embodiment of the present invention, one or more logical volumes which are accessed from the host computer  104  are set in the disk devices  211 . Although a hard disk device is used as the disk device  211  as an example, other memory devices such as a flash memory device and the like may be used. The disk devices  211  are connected to the control device  201  via a communication line  210  such as a fiber channel cable or the like. In addition, an RAID (Redundant Array of Independent Disks) configuration can be obtained from a plurality of disk devices  211 . 
         [0038]    A configuration of the control device  201  will now be described. The control device  201  controls writing and reading data into and from the disk devices  211  depending on a command received from the host computer  104 . Access from the host computer  104  is performed for data of one or more logical volumes set in the disk devices  211 . 
         [0039]    The control unit  201  is configured to include, for example, a non-volatile memory  220 , a CPU (Central Processing Unit)  203 , a main memory  204 , a cache memory  205 , a physical port  206 , a management port  208  and a disk interface (the interface is indicated by an abbreviation of I/F in the figure)  209 . Such memories  220 ,  204  and  205 , the CPU  203 , the physical port  206 , the management port  208 , and the disk I/F  209  are mutually connected via a communication line  202  such as a bus and the like. 
         [0040]    In addition, the embodiment of the present invention premises that a plurality of IP addresses can be set in the physical port  206  of the local storage device  101 . As above, virtual ports in which a plurality of IP addresses are set are commonly referred to as virtual ports  207 . For example, when a manager set IP-A, IP-B, IP-C, . . . in the physical port  206 , each thereof becomes virtual ports  207 - 1 ,  2 ,  3 , . . . In this case, an IP address of the physical port  206  and IP addresses of the virtual ports  207  may be identical or different. 
         [0041]    As the non-volatile memory  220 , there are a rewritable non-volatile memory such as a flash memory and the like. In such non-volatile memory  220 , for example, a path creation program  221 , a path check program  222 , a remote copy program  223 , an IP address table of local storage device  224 , an IP address table of virtual port of local storage device  225 , an IP address table of virtual port of remote storage device  226  and a path management table  227  can be memorized. 
         [0042]    Each of the programs  221 ,  222  and  223  is transmitted to the main memory  204  from the non-volatile memory  220  and then is run by the CPU  203 . 
         [0043]    The path creation program  221  is a program for the CPU  203  creating one or more paths between the local storage device  101  and the remote storage device  102 . 
         [0044]    The path check program  222  is a program for the CPU  203  checking one or more path status periodically (for example, at an interval of 60 seconds). 
         [0045]    The remote copy program  223  is a program for the CPU  203  distributing data into one or more paths to perform a remote copy from the local storage device  101  to the remote storage device  102 . 
         [0046]    The IP address table of local storage device  224  records IP addresses and default gateways of the physical port  206  and the virtual ports  207  of the local storage device  101 . Detailed description thereof will be made later with reference to  FIG. 5 . 
         [0047]    The IP address table of virtual port of local storage device  225  records IP addresses of the virtual ports  207  of the local storage device  101 . Detailed description thereof will be made later with reference to  FIG. 7 . 
         [0048]    The IP address table of virtual port of remote storage device  226  records IP addresses of virtual ports  307  of the remote storage device  102 . Detailed description thereof will be made later with reference of  FIG. 8 . 
         [0049]    The path management table  227  records a path number, an IP address of virtual port of local storage device, an IP address of virtual port of remote storage device and a path status, between the local storage device  101  and the remote storage device  102 . Detailed description thereof will be made later with reference to  FIG. 9 . 
         [0050]    Each of the programs  221 ,  222  and  223  memorized in the non-volatile memory  220  are transmitted to the main memory  204 , if necessary. The CPU  203  executes the respective programs  221 ,  222  and  223  and thereby a path creation processing, a path check processing and a copy data distribution processing are performed, respectively. 
         [0051]    The cache memory  205  records data received from the host computer  104  and data read out from the disk devices  211 . 
         [0052]    The physical port  206  is connected to the host computer  104  via the communication line  121  or the switch  105 . 
         [0053]    The virtual ports  207  represent virtual ports created in a case where a plurality of IP addresses can be set in the physical port  206 . An IP address of the physical port  206  may be the same as any one of the virtual ports or different therefrom. 
         [0054]    The management port  208  is connected to the management terminal  103  via the communication line  123  or the network  113  for management. 
         [0055]    The disk I/F  209  transmits and receives data between the respective disk devices  211 . The disk I/F  209  is connected to the respective disk devices  211  via the communication line  210 . 
         [0056]    A fundamental operation of the local storage device  101  will be described in brief. The operation of the local storage device  101  is initialized by a write command or a read command, which is received from the host computer  104 , for data of one or more logical volumes set in the disk devices  211 . 
         [0057]    When receiving a write command from the host computer  104 , the control device  201  stores a write data received from the host computer  104  into the cache memory  205 . The control device  201  writes the write data stored in the cache memory  205  into the disk device  211  via the disk I/F  209 . 
         [0058]    In addition, the control device  201  may report the completion of processing for the write command to the host computer  104  at the time of storing the write data into the cache memory  205 , or it may report the completion of processing for the write command to the host computer  104  at the time of writing the write data into the disk device  211 . 
         [0059]    When receiving a read command from the host computer  104 , the control device  201  checks whether or not data requested by the host computer  104  is stored in the cache memory  205 . If the data requested by the host computer  104  is stored in the cache memory  205 , the control device  201  reads out the data from the cache memory  205  to be transmitted to the host computer  104  via the physical port  206 . 
         [0060]    If the data requested by the host computer  104  is not stored in the cache memory  205 , the control device  201  reads out the data from the disk devices  211  via the disk I/F  209  to be transmitted to the cache memory  205 . The control device  201  transmits the data stored in the cache memory  205  to the host computer  104  via the physical port  206 . 
         [0061]      FIG. 3  is a diagram to illustrate a configuration of the remote storage device  102  according to the embodiment of the present invention. The remote storage device  102  is a memory device system having one or more memory devices like the local storage device  101  and can be largely classified into a control device  301  and a disk device  311 . 
         [0062]    The configuration of the control device  301  will now be described. The control device  301  controls writing and reading data into and from the disk devices  311  depending on a command received from the host computer  104 . The control device  301 , like the local storage device  101 , is configured to include, for example, a non-volatile memory  320 , a CPU (Central Processing Unit)  303 , a main memory  304 , a cache memory  305 , a physical port  306 , a management port  308  and a disk I/F  309 . Such memories  320 ,  304  and  305 , the CPU  303 , the physical port  306 , the management port  308 , and the disk I/F  309  are mutually connected via a communication line  302  such as a bus and the like. 
         [0063]    Hereinafter, only parts different from the local storage device  101  will be described. 
         [0064]    In the non-volatile memory  320 , for example, a path creation program  321 , a path check program  322 , a remote copy program  323 , an IP address table of remote storage device  324 , an IP address table of virtual port of remote storage device  325 , an IP address table of virtual port of remote storage device  326  and a path management table  327  can be memorized. 
         [0065]    The programs  321 ,  322  and  323  and the tables  325 ,  326  and  327  have the same structures as the local storage device  101  and thus the description thereof will be omitted. 
         [0066]    The IP address table of remote storage device  324  records IP addresses and default gateways of the physical port  306  and the virtual ports  307  of the remote storage device  102 . Detailed description thereof will be made later with reference to  FIG. 6 . 
         [0067]    When a remote copy is performed from the local storage device  101  to the remote storage device  102 , the path creation program  321 , the path check program  322 , the remote copy program  323 , the IP address table of remote storage device  324 , and the path management table  327  are memorized into the remote storage device  102  to cope with the remote copy. Reversely, when a remote copy is performed from the remote storage device  102  to the local storage device  101 , the IP address table of virtual port of local storage device  325  and the IP address table of virtual port of remote storage device  326  are necessary in the remote storage device  102 , and thus the configuration including such tables in this embodiment is shown in the figure. 
         [0068]    A fundamental operation of the remote storage device  102  will be described in brief. 
         [0069]    When receiving a write command from the local storage device  101 , the control device  301  stores the write command received from the local storage device  101  into the cache memory  305 . The control device  301  writes a write data stored in the cache memory  305  into the disk device  311  via the disk I/F  309 . In addition, the control device  301  may report the completion of processing for the write command to the local storage device  101  at the time of storing the write data into the cache memory  305 , or it may report the completion of processing for the write command to the local storage device  101  at the time of writing the write data into the disk device  311 . 
         [0070]    When receiving a read command from the local storage device  101 , the control device  301  checks whether or not data requested by the local storage device  101  is stored in the cache memory  305 . If the data requested by the local storage device  101  is stored in the cache memory  305 , the control device  301  reads out the data from the cache memory  305  to be transmitted to the local storage device  101  via the physical port  306 . 
         [0071]    If the data requested by the local storage device  101  is not stored in the cache memory  305 , the control device  301  reads out the data from the disk devices  311  via the disk I/F  309  to be transmitted to the cache memory  305 . The control device  301  transmits the data stored in the cache memory  305  to the local storage-device  101  via the physical port  306 . 
         [0072]      FIG. 4  is a diagram to illustrate a configuration of the management terminal  103  according to the embodiment of the present invention. The management terminal  103  is configured to include, for example, a main memory  401 , a bus  402 , a disk device  403 , a CPU  404 , a pointing device  405 , an input device  406 , an output device  407  and a management I/F  408 . The main memory  401 , the disk device  403 , the CPU  203   404  and the management I/F  408  are mutually connected via the bus  402 . 
         [0073]    A UI control program  410  and a storage communication program  411  stored in the disk device  403  are transmitted to the main memory  401 , if necessary. The CPU  404  executes the respective programs  410  and  411  read in the main memory  401  to perform a UI control processing and a storage communication processing. 
         [0074]    The disk device  403  can record, for example, the UI control program  410  and the storage communication program  411 . 
         [0075]    The UI control program  410  is a program for the CPU  404  displaying a screen such as a path creation screen  1001  (described later in  FIG. 10 ), a path status display screen  1101  (described later in  FIG. 11 ) and the like on the output device  407 . The UI control program  410  enables the CPU  404  to transmit information-inputted by a manager via the pointing device  405  or the input device  406 , to the storage communication program  411 . 
         [0076]    The storage communication program  411  is a program for the CPU  404  communicating with the local storage device  101  via the network  113  for management. 
         [0077]    The configuration of the host computer  104  is the same as that of a conventional host computer. 
         [0078]      FIG. 5  is a diagram to illustrate a configuration of the IP address table of local storage device  224  according to the embodiment of the present invention. The IP address table of local storage device  224  manages, for example, “port type” column  501 , “IP address” column  502  and “default gateway” column  503  in the manner of associating with one another. 
         [0079]    Kinds of ports (in detail, whether the physical port or the virtual port) of IP addresses set in the local storage device  101  are stored in the “port type” column  501 . IP addresses set in the physical port  206  and the virtual ports  207  of the local storage device  101  are stored in the “IP address” column  502 . Default gateways set in the physical port  206  and the virtual ports  207  of the local storage device  101  are stored in the “default gateway” column  503 . For instance, the second row  504  in  FIG. 5  represents that an IP address of the virtual port  207  of the local storage device  101  is “IP-A” and the default gateway is “GW-L 1 .” 
         [0080]    In this embodiment, it is assumed that a manager registers IP addresses of the routers  107  which traverse different lines for the respective virtual ports, as the default gateways of the virtual ports  207 . 
         [0081]      FIG. 6  is a diagram to illustrate a configuration of the IP address table of remote storage device  324  according to the embodiment of the present invention. The IP address table of remote storage device  324  manages “port type” column  601 , “IP address” column  602  and “default gateway” column  603  in the manner of associating with one another. 
         [0082]    Contents stored in the “port type” column  601 , the “IP address” column  602  and the “default gateway” column  603  are the same as those stored in the IP address table of local storage device  224 . 
         [0083]    For example, the second row  604  in  FIG. 6  represents that an IP address of the virtual port  307  of the remote storage device  102  is “IP-a” and the default gateway is “GW-R 1 .” 
         [0084]    In this embodiment, it is assumed that a manager registers IP addresses of the routers  108  which traverse different lines for the respective virtual ports, as the default gateways of the virtual ports  307 . 
         [0085]      FIG. 7  is a diagram to illustrate a configuration of the IP address table of virtual port of local storage device  225  and  325 . The IP address table of virtual port of local storage device  225  and  325  manages the “number” column  701  and the “IP address” column  702  in the manner of associating with each other. 
         [0086]    In the “number” column  701 , when one row is added, a numeral of adding 1 to a previous number is stored. In this embodiment, the first row is assumed to be “1.” 
         [0087]    IP addresses of the virtual ports  207  of the local storage device  101  are stored in the “IP address” column  702 . 
         [0088]    For example, the second row  703  in  FIG. 7  represents that an IP address of the virtual port  207  of the local storage device  101  which is added “secondly” is “IP-B.” 
         [0089]    The CPU  203  of the local storage device  101  creates a path to read out the IP address of the virtual port  207  from the “IP address” column  502  of the IP address table of local storage device  224  for addition to the IP address table of virtual port of local storage device  225  and  325 . 
         [0090]      FIG. 8  is a diagram to illustrate a configuration of the IP address table of virtual port of local storage device  226  and  326 . The IP address table of virtual port of remote storage device  226  and  326  manages the “number” column  801  and the “IP address” column  802  in the manner of associating with each other. 
         [0091]    In the “number” column  801 , when one row is added, a numeral of adding 1 to a previous number is stored. In this embodiment, the first row is assumed to be “1.” 
         [0092]    IP addresses of the virtual ports  307  of the remote storage device  102  are stored in the “IP address” column  802 . 
         [0093]    For example, the third row  803  in  FIG. 8  represents that an IP address of the virtual port  307  of the remote storage device  102  which is added “thirdly” is “IP-c.” 
         [0094]    According to the path creation program  221  by the CPU  203  of the local storage device  101 , the IP address of the virtual port  307  of the remote storage device  102  is added to the IP address table of virtual port of remote storage device  226  and  326 . 
         [0095]      FIG. 9  is a diagram to illustrate a configuration of the path management table  227  and  327  according to the embodiment of the present invention. The path management table  227  and  327  manages, for example, the “path number” column  901 , the “local IP” column  902 , the “remote IP” column  903  and the “path status” column  904  in the manner of associating with one another. 
         [0096]    In the “path number” column  901 , when one row is added, a numeral of adding 1 to a previous number is stored. An IP address of the local storage device  101  sided virtual port  207  of a created path is stored in the “local IP” column  902 . An IP address of the remote storage device  102  sided virtual port  307  of the created path is stored in the “remote IP” column  903 . In the “path status” column  904 , a status of the path such as normal or blockage is stored. 
         [0097]    For example, the second row  905  in  FIG. 9  represents that the local storage device  101  sided IP address of the secondly added path is “IP-B,” the remote storage device  102  sided IP address is “IP-b,” and a status of the path is “normal.” 
         [0098]    In this embodiment, the “local IP” column  902  and the “remote IP” column  903  are added according to the path creation program  221  by the CPU  203  of the local storage device  101  and a status of the path is updated due to a path check processing by the CPU  203  of the local storage device  101 . 
         [0099]    The local storage device  101  and the management terminal  103  may receive an IP address of the physical port  306  of the remote storage device  102  and an iSCSI Target port number from a manager, create paths on the basis of the information, check status of the paths periodically and display the status of the paths. Furthermore, the local storage device  101  performs remote copy by sorting copy data for one or plural path(s) having normal path status by use of the above-described programs and tables. 
         [0100]    Hereinafter, processings of the local storage device  101  creating a path and checking a path status and processings of the local storage device  101  and the management terminal  103  for displaying the path status on the output device  407  will be explained with reference to  FIGS. 10 ,  11 ,  12  and  13 . In addition, a processing of the local storage device  101  sorting copy data into one or more normal paths to perform a remote copy will be described with reference to  FIG. 14 . 
         [0101]      FIG. 10  is a diagram to illustrate a path creation screen  1001  according to the embodiment of the present invention. The path creation screen  1001  may be provided with, for example, input portions  1002  and  1003  and buttons  1004  and  1005 . 
         [0102]    The input portion  1002  enables a manager to input an IP address of the physical port  306  of the remote storage device  102 . The input portion  1003  enables a manager to input an iSCSI Target port number. The button  1004  enables a manager to decide the information inputted to the path creation screen  1001 . The button  1005  enables a manager to cancel the information inputted to the path creation screen  1001 . 
         [0103]    The CPU  404  of the management terminal  103  transmits an IP address of the physical port  306  of the remote storage device  102  and an iSCSI Target port number inputted by the manager to the local storage device  101  according to the storage communication program  411 . The CPU  203  of the local storage device  101  receives the IP address of the physical port  306  of the remote storage device  102  and the iSCSI Target port number. 
         [0104]      FIG. 11  is a diagram to illustrate a path status display screen  1101  according to the embodiment of the present invention. The path status display screen  1101  may be provided with, for example, display units  1102  and buttons  1103 ,  1104  and  1105 . 
         [0105]    The display unit  1102  displays a created path status. The button  1103  enables the path creation screen  1001  to be displayed. The button  1104  enables the path creation program  221  by the CPU  203  of the local storage device  101  to be run when a path is changed (in detail, for example, when a path is added or an IP address of a virtual port is changed). The button  1105  enables a designated path to be deleted. 
         [0106]    The CPU  203  of the local storage device  101  transmits the path management table  227  to the management terminal  103  after the path creation processing and the path check processing are finished. The CPU  404  of the management terminal  103  receives the path management table  227  from the local storage device  101  according to the storage communication program  411  and displays the path management table  227  on the path status display screen  1101  according to the UI control program  410 . 
         [0107]      FIG. 12  is a flowchart to illustrate an order of creating a path by the path creation program  221  according to the embodiment of the present invention, and the creation processing will be described in detail with reference to the flowchart. In the description of each flow, the step is abbreviated to “S.” 
         [0108]    When the button  1004  is operated after necessary information is inputted by use of the path creation screen  1001  displayed on the management terminal  103 , the input information is transmitted to the local storage device  101  to initialize the path creation processing. 
         [0109]    First, the CPU  203  of the local storage device  101  sets “the number of virtual IP addresses of the local storage device (hereinafter, abbreviated to NL)” to “0” as an initial value, “the number of virtual IP addresses of the remote storage device (hereinafter, abbreviated to NR)” to “0” as an initial value, and variables “i” and “j” to “1,” respectively, as initial values (S 1201 ). 
         [0110]    The CPU  203  of the local storage device  101  reads out an IP address which belongs to a row where the “port type” ( 501 ) of the IP address table of local storage device  224  is the “virtual port” and then stores it into the IP address table of virtual port of local storage device  225  (S 1202 ). 
         [0111]    The CPU  203  of the local storage device  101  substitutes the number of virtual IP addresses of the local storage device  101  for the value of “NL” (S 1203 ). 
         [0112]    The CPU  203  of the local storage device  101  reads out an IP address of the physical port  306  of the remote storage device  102  and an iSCSI Target port number which have been inputted into the input portions  1002  and  1003  of path creation screen  1001  (S 1204 ). 
         [0113]    The CPU  203  of the local storage device  101  transmits “iSCSI Send Targets” to the read IP address target. In this embodiment, as parameters of such “iSCSI Send Targets,”“Target Address” is taken as “an IP address (e.g., IP-R) of the physical port  306  of the remote storage device  102 ” and “Send Targets” is taken as “ALL” (S 1205 ). 
         [0114]    Subsequently, the CPU  203  of the local storage device  101  determines whether or not a response from the remote storage device  102  is present in a watchdog timer (S 1206 ). 
         [0115]    If there is no response from the remote storage device  102  in the watchdog timer (a result at the step S 1206  is “No”), the CPU  203  of the local storage device  101  reports disablement of creation of a path to the management terminal  103  (S 1209 ) to finish the path creation processing. 
         [0116]    On the other hand, if there is a response from the remote storage device  102  in the watchdog timer (a result at the step S 1206  is “Yes”), the CPU  203  of the local storage device  101  performs the processing of the step S 1207 . 
         [0117]    In the processing of the step S 1207 , the CPU  203  of the local storage device  101  acquires all of the IP addresses of the virtual ports  307  of the remote storage device  102  from the response message from the remote storage device  102  and stores the IP addresses into the IP address table of virtual port of remote storage device  226 . 
         [0118]    Then, the CPU  203  of the local storage device  101  substitutes the number of virtual IP addresses of the remote storage device for a value of “NR” (S 1208 ). 
         [0119]    The CPU  203  of the local storage device  101  determines whether or not a value of “i” is less than a value of “NL” (S 1210 ). 
         [0120]    If the value of “i” is more than the value of “NL” (a result at the step S 1210  is “No”), the CPU  203  of the local storage device  101  finishes the path creation processing. 
         [0121]    In contrast, if the value of “i” is less than the value of “NL” (a result at the step S 1210  is “Yes”), the CPU  203  of the local storage device  101  performs the processing of the step S 1211 . 
         [0122]    In the processing of the step S 1211 , the CPU  203  of the local storage device  101  determines whether or not a value of “j” is less than a value of “NR.” 
         [0123]    Subsequently, the CPU  203  of the local storage device  101  performs the processing of the step S 1213 , if the value of “j” is more than the value of “NR” (a result at the step S 1211  is “No”). 
         [0124]    In contrast, the CPU  203  of the local storage device  101  performs the processing of the step S 1212 , if the value of “j” is less than the value of “NR” (a result at the step S 1211  is “Yes”) 
         [0125]    In the processing of the step S 1212 , the CPU  203  of the local storage device  101  takes an IP address of a row in which the “number” ( 701 ) of the IP address table of virtual port of local storage device  225  is “i” as an IP address of a source and takes an IP address of a row in which the “number” ( 801 ) of the IP address table of virtual port of remote storage device  226  is “j” as an IP address of a target, and then transmits “iSCSI Login” request. 
         [0126]    The CPU  203  of the local storage device  101  determines whether or not a response from the remote storage device  102  is present in the watchdog timer (S 1213 ). 
         [0127]    If there is no response from the remote storage device  102  in the watchdog timer (a result at the step S 1213  is “No”), the CPU  203  of the local storage device  101  performs the processing of the step S 1215 . 
         [0128]    In the processing of the step S 1215 , the CPU  203  of the local storage device  101  adds 1 to the value of “j” to perform the processing of the step S 1211 . 
         [0129]    In contrast, if there is a response from the remote storage device  102  in the watchdog timer (a result at the step S 1213  is “Yes”), the CPU  203  of the local storage device  101  performs the processing of the step S 1214 . 
         [0130]    In the processing of the step S 1214 , the CPU  203  of the local storage device  101  adds 1 to the value of “i” to perform the processing of the step S 1210  again. 
         [0131]    According to such path creation processing, if a manager has only to input an IP address of the physical port  306  of the remote storage device  102 , the local storage device  101  can create a plurality of paths in the IP address target of the virtual ports  307  of the remote storage device  102 . 
         [0132]      FIG. 13  is a flowchart to illustrate an order of checking a path by the path check program  222  according to the embodiment of the present invention. This processing is performed periodically (for example, at an interval of 60 seconds). 
         [0133]    The CPU  203  of the local storage device  101  first sets an initial value of the variable “k” to “1” (S 1301 ). 
         [0134]    The CPU  203  of the local storage device  101  determines whether the value of “k” is less than a value of “NL” (S 1302 ) 
         [0135]    If the value of “k” is more than the value of “NL” (a result at S 1302  is “No”), the CPU  203  of the local storage device  101  performs the processing of the step S 1308 . 
         [0136]    In the processing of the step S 1308 , the CPU  203  of the local storage device  101  displays the path management table  227  on the path status display screen  1101  and then finishes the path check processing. 
         [0137]    In contrast, if the value of “k” is less than the value of “NL” (a result at the step S 1302  is “Yes”), the CPU  203  of the local storage device  101  performs the processing of the step S 1303 . 
         [0138]    In the processing of the step S 1303 , the “local IP” ( 902 ) of a row in which the “path number” ( 901 ) of the pass management table  227  is “k” as a source IP address and takes the “remote IP” ( 903 ) thereof as a target IP address, and then transmits “Nop-in.” 
         [0139]    Subsequently, the CPU  203  of the local storage device  101  determines whether or not a response from the remote storage device  102  is present in the watchdog timer (S 1304 ). In addition, a check time of the watchdog timer is less than an interval of the path check processing being performed. 
         [0140]    If there is no response from the remote storage device  102  in the watchdog timer (a result at the step S 1304  is “No”), the processing of the step S 1307  is performed. 
         [0141]    In the processing of the step S 1307 , the “path status” ( 904 ) of a row in which the “path number” ( 901 ) of the path management table  227  is “k” is overwritten with “blockage” to perform the processing of the step S 1306 . 
         [0142]    If there is a response from the remote storage device  102  in the watchdog timer (a result at the step S 1304  is “Yes”), the CPU  203  of the local storage device  101  overwrites the “path status” ( 904 ) of a row in which the “path number” ( 901 ) of the path management table  227  is “k” with “normal” (S 1305 ). 
         [0143]    Subsequently, the CPU  203  of the local storage device  101  adds 1 to the value of “k” to perform the processing of the step S 1302  again. 
         [0144]    Such path check processing can check path status periodically and thereby can notify a manager of the path status. 
         [0145]      FIG. 14  is a flowchart to illustrate an order of distributing copy data by the remote copy program  223  according to the embodiment of the present invention. A unit of the copy data distributed into for each path may be a block, a packet, a command or a logical volume in the embodiment of the present invention. 
         [0146]    The CPU  203  of the local storage device  101  sets an initial value of the variable “m” to 1 and sets the number of created paths to the number of a path (hereinafter, abbreviated to NP) (S 1401 ). 
         [0147]    The CPU  203  of the local storage device  101  determines whether or not copy data are present (S 1402 ). 
         [0148]    If the copy data are not present (a result at the step S 1402  is “No”), the CPU  203  of the local storage device  101  performs the processing of the step S 1401  again. 
         [0149]    In contrast, if the copy data are present (a result at the step S 1402  is “Yes”), the CPU  203  of the local storage device  101  performs the processing of the step S 1403 . 
         [0150]    In the processing of the step S 1403 , it is determined whether or not a value of “NP” is other than “0.” 
         [0151]    If the value of “NP” is “0” (a result at the step S 1403  is “No”), the processing of the step S 1408  is performed. 
         [0152]    In the processing of the step S 1408 , the CPU  203  of the local storage device  101  reports to the management terminal  103  that there are no paths and thus copy is impossible, to finish the copy data distribution processing. 
         [0153]    In contrast, if the value of “NP” is other than “0” (a result at the step S 1403  is “Yes”), the CPU  203  of the local storage device  101  performs the processing of the step S 1404 . 
         [0154]    In the processing of the step S 1404 , the CPU  203  of the local storage device  101  determines whether or not a value of “m” is less than the value of “NP.” 
         [0155]    If the value of “m” is more than the value of “NP” (a result at S 1404  is “NO”), the CPU  203  of the local storage device  101  again performs the processing of the step S 1401 . 
         [0156]    In contrast, if the value of “m” is less than the value of “NP” (a result at the step S 1404  is “Yes”), the CPU  203  of the local storage device  101  performs the processing of the step S 1405 . 
         [0157]    In the processing of the step S 1405 , the CPU  203  of the local storage device  101  determines whether or not the “path status” ( 904 ) of a row in which the “path number” ( 901 ) of the path management table  227  is “m” is “normal.” 
         [0158]    If the “path status” ( 904 ) is not “normal” (a result at the step S 1405  is “No”), the CPU  203  of the local storage device  101  performs the processing of the step S 1407 . 
         [0159]    In contrast, if the “path status” ( 904 ) is “normal” (a result at the step S 1405  is “Yes”), the CPU  203  of the local storage device  101  performs the processing of the step S 1406 . 
         [0160]    In the processing of the step S 1406 , the CPU  203  of the local storage device  101  transmits the copy data to a path of which the “path number” ( 901 ) is “m.” 
         [0161]    The CPU  203  of the local storage device  101  adds “1” to the value of “m” (S 1407 ) to perform the processing of the step S 1404  again. 
         [0162]    Such copy data distribution processing can distribute data into a plurality of paths, and further the remote copy keeps going as long as all the paths are not blockaded. 
         [0163]    As described above, according to the storage system of this embodiment, the local storage device  101  includes the path creation program  221 , the path check program  222  and the remote copy program  223  executed by CPU  203  and thereby the following effects can be obtained. 
         [0164]    (1) Under a premise that virtual ports in which a plurality of IP addresses can be set in a single physical port of the local storage device  101  and the remote storage device  102  can be created, the CPU  203  of the local storage device  101  executes the path creation program  221  and thereby can create a plurality of paths interposing a plurality of lines  111  between the local storage device and the remote storage device  102 . In addition, if a manager has only to register an IP address of a physical port of the remote storage device  102 , the CPU  203  of the local storage device  101  can create a plurality of paths between the local storage device  101  and the remote storage device  102 . 
         [0165]    (2) The CPU  203  of the local storage device  101  executes the pass check program  222  and thereby can check a plurality of path status between the local storage device  101  and the remote storage device  102 . In addition, the CPU  203  of the local storage device  101  executes the path check program  222  periodically and thereby checks a plurality of path status to display it on the output device  407  of the management terminal  103  for notifying a manager of the path status. 
         [0166]    (3) The CPU  203  of the local storage device  101  executes the remote copy program  223  and thereby can distribute data of logical volumes accessed from the host computer  104  into a plurality of normal paths, to perform a remote copy from the local storage device  101  to the remote storage device  102 . In addition, the CPU  203  of the local storage device  101  checks the path status and thereby can distribute the data into the normal paths to perform the remote copy in the remote copy program  223  as long as not all of the paths are closed. 
         [0167]    (4) Since the remote copy function that data are distributed into a plurality of lines  111  which are cheap and have a low data rate to perform a copy can be realized, it is possible to speed up the lines virtually, to enable coping with increase of an amount of copy data and low cost of lines to be compatible. 
         [0168]    Various modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this is not limited to the illustrative embodiments set forth herein.