Abstract:
According to this invention, a data arrangement method, the computer connected to a storage system which provides a plurality of logical storage devices comprising a plurality of physical storage devices arranges data in a logical storage volume constructed by integrating the plurality of logical storage devices. The method includes: a step wherein the computer receives an instruction to build the logical storage volume using the plurality of logical storage devices or to rebuild the constructed logical storage volume; a step wherein the computer obtains information about the plurality of physical storage devices constituting each of the plurality of logical storage devices included in the received instruction; and a step wherein the arrangement position of data into the logical storage volume is determined on the basis of the obtained information about the plurality of physical storage devices.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a data arrangement method and a data management system, and more particularly, to a technology of arranging data on a storage system by a computer. 
     It is indispensable for corporate activities to utilize a large amount of business data. Therefore, systems for accumulating the large amount of business data in databases (hereinafter, referred to as DBs), and multidimensionally analyzing the accumulated data are widely used. 
     In the data analysis processing, a database management system (hereinafter, referred to as DBMS) receives a query, and issues a request to read a large amount of data to a storage system storing the DB. 
     If a plurality of storage devices are provided from the storage system to a computer executing the DBMS, a unified storage volume technology for providing a plurality of unified storage devices is known as one of conventional technologies for efficiently processing a large number of data read requests. 
     The unified storage volume technology causes an application program (hereinafter, referred to as AP) such as a DBMS or an operating system (hereinafter, referred to as OS) to unify storage devices provided by the storage system. The unified storage volume technology then evenly stripes and arranges a DB on the unified storage devices in a distributed manner, to thereby enable even use of the plurality of storage devices (A J Lewis, LVM HOWTO, Nov. 27, 2006, pages 31-65). 
     SUMMARY OF THE INVENTION 
     In the above-mentioned conventional storage system, instead of directly providing physical storage devices for the computer, a function of virtually providing a logical storage device, which is a combination of physical storage devices, is generally employed. 
     The redundant array of independent disks (RAID) function for combining a plurality of physical storage devices within a system, thereby realizing redundancy and an increased speed, is widely employed as a specific virtualization function for the storage system. 
     While the storage virtualization function by means of the RAID function is generally used, cases where a plurality of logical storage devices different in configuration of combining physical storage devices are provided for a computer can frequently occur in a real operation. 
     On this occasion, the unified storage volume technology evenly distributes and arranges data on the plurality of logical storage devices recognized by the APs and the OS. Therefore, according to this conventional technology, if a plurality of logical storage devices different in the combinational configuration of physical storage devices are provided, there has been a problem that performances of all the physical storage devices cannot be evenly used for a request to access an entire range of the stored data, and the request to read the large amount of data cannot be efficiently processed. 
     For example, if a logical storage device A is constituted of four physical storage devices, a logical storage device B is constituted of three physical storage devices, the logical storage device A and the logical storage device B are unified into a logical storage volume X, and the logical storage volume X is provided for a computer by means of the conventional unified storage volume technology in a storage system, the conventional technology evenly distributes the quantity of data read/written by the computer to the logical storage device A and the logical storage device B. If performances of the physical storage devices constituting the logical storage volume X are even, and the logical storage device A and the logical storage device B are constituted by means of the RAID function (RAID  5  in which parities are arranged in a distributed manner, for example), the read/write performance of the logical storage device A exceeds that of the logical storage device B. According to the conventional technology, the same amounts of data are read/written on the logical storage device A and the logical storage device B in the logical storage volume X of the conventional technology. As a result, there has been a problem in that the logical storage device A cannot sufficiently exert the read/write performance due to the obstruction by the read/write performance of the logical storage device B. 
     This invention has been made in view of the above-mentioned problem, and therefore has an object to provide a data arrangement method capable of, for providing a computer with a plurality of logical storage devices different in combination of physical storage devices, even use of the physical storage devices constituting the logical storage devices by using the virtualization function of the storage system. 
     According to this invention, a data arrangement method, the computer connected to a storage system which provides a plurality of logical storage devices comprising a plurality of physical storage devices arranges data in a logical storage volume constructed by integrating the plurality of logical storage devices. The method includes: a step wherein the computer receives an instruction to construct the logical storage volume using the plurality of logical storage devices or to reconstruct the constructed logical storage volume; a step wherein the computer obtains information about the plurality of physical storage devices constituting each of the plurality of logical storage devices included in the received instruction; and a step wherein the arrangement position of data into the logical storage volume is determined on the basis of the obtained information about the plurality of physical storage devices. 
     Therefore, according to the embodiment of this invention, even if the storage system provides a computer with a plurality of logical storage devices different in configuration of combining physical storage devices, arrangement positions of data on the logical storage devices can be determined in accordance with configuration information on the physical storage devices, and the arrangement positions enable even use of the physical storage devices. As a result, efficiency of processing of reading a large amount of data can be increased by utilizing input/output processing performances of all the physical storage devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a block diagrams illustrating a hardware configuration and a logical configuration of an information processing system according to the embodiment of this invention. 
         FIG. 1B  is a block diagrams illustrating a hardware configuration and a logical configuration of an information processing system according to the embodiment of this invention. 
         FIG. 2  is a block diagram illustrating a relationship between logical storage devices provided by the storage system according to the embodiment of this invention. 
         FIG. 3  is a flowchart illustrating a processing sequence of building a logical storage volume by the data management module of the host computer according to the embodiment of this invention. 
         FIG. 4  is an explanatory diagram illustrating an example of the physical storage device information according to the embodiment of this invention. 
         FIG. 5  is an explanatory diagram illustrating an example of the data arrangement management information according to the embodiment of this invention. 
         FIG. 6  is a screen image illustrating an example of the GUI output to the console by the DBMS management module according to the embodiment of this invention. 
         FIG. 7  is a flowchart illustrating a processing sequence of rebuilding, by the data management module of the host computer, a logical storage volume already built according to the embodiment of this invention. 
         FIG. 8  is an explanatory diagram illustrating another example of the data arrangement management information according to the embodiment of this invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A description is now given of an embodiment of this invention referring to the accompanying drawings. 
     &lt;Configuration of Information Processing System&gt; 
       FIGS. 1A and 1B  are block diagrams illustrating a hardware configuration and a logical configuration of an information processing system according to the embodiment of this invention. A description is first given of the hardware configuration. 
     The information processing system illustrated in  FIGS. 1A and 1B  includes a host computer  1 , a storage system  2 , a storage management terminal  3 , a storage area network (hereinafter, referred to as SAN)  4 , a network (management network)  5 , and a database management terminal  6 . 
     The host computer  1  is a computer such as a personal computer, a workstation, or a mainframe. On the host computer  1 , an operating system (hereinafter, referred to as OS)  100  suited to the type of the computer, a database management system (hereinafter, referred to as DBMS)  200  for accumulating and managing business data, and application programs (hereinafter, referred to as APs)  300  for issuing queries to the DBMS  200  operate. The OS  100 , the DBMS  200 , and the APs  300  are described later. 
     The host computer  1  includes a processor  12 , a memory  11 , a local storage device  13 , a host bus adapter  15 , and a network adapter  14 . 
     The processor  12  executes programs such as the OS  100 , the DBMS  200 , and the APs  300 . The memory  11  temporarily stores programs executed by the processor  12  and data used by the programs. The local storage device  13  functions as a storage medium for storing data used by programs such as the APs  300  and the DBMS  200 , and data used by the programs. The host bus adapter  15  is an interface coupling the SAN  4  and the host computer  1  to each other. The host bus adapter  14  is an interface coupling the network  5  and the host computer  1  to each other. 
     It should be noted that the host computer  1  may include a plurality of components such as the processor  12  for securing redundancy. Moreover, the host computer  1  includes an input device and a display device, which are not illustrated. 
     The storage system  2  is a system including a single storage device such as a disk device or a plurality of storage devices such as a disk array. Moreover, the storage system  2  stores data and programs used by the host computer  1 . Then, the storage system  2  receives an input/output (hereinafter, referred to as I/O) processing request from the host computer  1 , carries out processing corresponding to the I/O processing request, and transmits a processing result to the host computer  1 . 
     The storage system  2  includes a control device  20 , a coupling interface  21 , and physical storage devices  22   a  to  22   e . The physical storage devices  22   a  to  22   e  are generally referred to as physical storage devices  22  in the following description. 
     Moreover, the physical storage device  22  stores the data and the programs used by the host computer  1 . The physical storage device  22  is a non-volatile storage device, and is constituted of a hard disk drive including a magnetic disk and a magnetic head, for example. The coupling interface  21  is constituted of a local bus, for example, and couples the physical storage devices  22  and the control device  20  to each other. 
     The control device  20  carries out processing of the I/O processing request from the host computer  1 , and control of the physical storage devices  22 . The control device  20  includes a processor  26 , a memory  27 , a physical storage device adapter  23 , a network adapter  24 , and a network adapter  25 . 
     The processor  26  executes a predetermined control program. The memory  27  stores programs executed by the processor  26 , information required for executing the programs, and setting information and configuration information on the storage system  2 . The memory  27  further temporality stores data input to the storage system  2  from the host computer  1 , data to be transferred from the storage system  2  to the host computer  1 , or data input/output within the storage system  2 . The memory  27  may be constituted of a non-volatile memory and a cache memory, may store the programs and the configuration information in the non-volatile memory, and may store the input/output data in the cache memory. 
     The physical storage device adapter  23  couples to the physical storage devices  22  via the coupling interface  21 . The network adapter  25  couples the storage system  2  and the SAN  4  to each other. The network adapter  24  couples the storage system  2  and the network  5  to each other. 
     It should be noted that the storage system  2  may include a plurality of control devices  20 . Moreover, in order to secure redundancy, the storage system  2  may have a redundant configuration in which each of the components within the system such as the memory  27 , the physical storage device adapter  23 , and the coupling interface  21  is duplexed. 
     The storage management terminal  3  is a computer for managing the components within the storage system  2 . An administrator of the storage system  2  inputs setting information to the storage management terminal  3  when the administrator manages the components of the storage system  2 . The storage management terminal  3  transmits contents input by the administrator to the storage system  2  via the network  5 . 
     The storage management terminal  3  includes a processor  30 , a memory  31 , and a network adapter  32  as the host computer  1  does. The storage management terminal  3  may include a local storage device, which is not illustrated. Moreover, the storage management terminal  3  includes a console  33  including an input device and an output device. 
     The database management terminal  6  is a computer for managing the DBMS  200  executed on the host computer  1 . An administrator of the DBMS  200  inputs setting information to the database management terminal  6  when the administrator manages the DBMS  200  of the host compute  1 . The database management terminal  6  transmits contents input by the administrator to the host computer  1  via the network  5 . 
     The database management terminal  6  includes a processor  60 , a memory  61 , and a network adapter  62  as the host computer  1  does. The database management terminal  6  may include a local storage device, which is not illustrated. Moreover, the database management terminal  6  includes a console  63  including an input device and an output device. 
     The SAN  4  couples the host computer  1  and the storage system  2  to each other, and is used to transmit the I/O processing request from the host computer  1  to the storage system  2 . An optical fiber or a copper wire is used for the SAN  4 . Moreover, a communication protocol such as the Fibre Channel, the small computer system interface (SCSI), or the transmission control protocol/internet protocol (TCP/IP) is used on the SAN  4 . 
     The network  5  functions as a management network for the information processing system, and couples the host computer  1 , the storage system  2 , the storage management terminal  3 , and the database management terminal  6  to one another. The network  5  is used to communicate the configuration information on the storage system  2  and the management information on the DBMS  200  of the host computer  1  among the storage system  2 , the host computer  1 , the storage management terminal  3 , and the database management terminal  6 . A cable and a communication protocol used for the network  5  may be the same as those used for the SAN  4  or may be different from those used for the SAN  4 . 
     &lt;Logical Configuration of Storage System  2  of Information Processing System&gt; 
     A description is now given of a logical configuration of the information processing system in  FIGS. 1A and 1B . The control device  20  of the storage system  2  stores programs constituting a device management module  28  and a command processing module  29  in the memory  27  in order to control processing by the storage system  2  as illustrated in  FIG. 1A . The control device  20  controls processing described later by executing these programs by the processor  26 . 
     A program constituting the device management module  28  is executed by the control device  20  for managing physical storage devices  22  and logical storage devices  280   a  and  280   b  provided for the host computer  1 . It should be noted that, hereinafter, the logical storage devices  280   a  and  280   b  are generally referred to as logical storage devices  280 . 
     The control device  20  executes the device management module  28  to thereby combine the plurality of physical storage devices  22  (illustrated by dotted lines on the memory  27  in  FIG. 2 ) into redundant array of independent disks (RAID) groups. By configuring the RAID groups, the storage system  2  can reduce an I/O processing time by means of the striping technology, thereby distributing and storing data to and in the plurality of physical storage devices  22 , and can increase reliability of the data by means of the parity recording technology, which generates a parity of pieces of data located at the same position on at least two physical storage devices, and stores the parity on another physical storage device. The configuration of the RAID group may be the mirroring configuration which simultaneously copies a content of one physical storage device  22  to another physical storage device  22 . 
     The control device  20  executes the device management module  28 , thereby providing the host computer  1  with one logical storage device  280  from a storage space generated by the plurality of physical storage devices  22  constituting one RAID group. 
       FIG. 2  is a block diagram illustrating a relationship between logical storage devices provided by the storage system  2  for the host computer  1  and physical storage devices. In the example illustrated in  FIG. 2 , a logical storage device “a” ( 280   a ) from a RAID group constituted of the physical storage devices  22   a ,  22   b , and  22   c , and a logical storage device “b” ( 280   b ) from a RAID group constituted of the physical storage devices  22   d  and  22   e  are provided for the host computer  1 . 
     The control device  20  executes the device management module  28 , thereby managing physical storage device information  281 , which is information on the physical storage devices  22  of the logical storage devices  280 . The physical storage device information  281  is described later in detail referring to  FIG. 4 . 
     The control device  20  executes the device management module  28 , thereby handling requests from the host computer  1  and the storage management terminal  3 . For example, the device management module  28  defines and sets the logical storage devices  280 , and transmits the physical storage device information  281  in response to a request from the storage management terminal  3 . 
     The control device  20  executes the program of the device management module  28  in order to carry out the I/O processing. The device management module  28  calculates, based on the physical storage device information  281 , an address of a physical storage device  22  corresponding to a logical storage device  280  specified by an I/O processing request. The control device  20  makes an access to the physical storage device  22  based on the calculation result. 
     Moreover, when the control device  20  receives an I/O processing request from the host computer  1  via the network adapter  24 , the control device  20  executes the program of the command processing module  29 . 
     If the I/O processing request received from the host computer  1  is a write processing request for data, the command processing module  29  carries out processing of writing data transferred from the host computer  1  into a predetermined area of the memory  27  or the physical storage device  22 , and the like. 
     If the command processing module  29  receives a read processing request for data from the host computer  1 , the command processing module  29  carries out processing of reading data corresponding to the read processing request from a predetermined area of the memory  27  or the physical storage device  22 , and transferring the read data to the host computer  1 , and the like. 
     If the control device  20  receives a processing request other than those of reading or writing data from the host computer  1 , the control device  20  operates the command processing module  29  to carry out the requested processing. For example, this request includes an Inquiry command (command of instructing the device search) of the SCSI from the host computer  1  or the storage management terminal  3 . 
     The storage system  2  can dynamically change the configuration of the RAID group containing the logical storage device  280  provided for the host computer  1 . As an example of the dynamic configuration change of the RAID group, a RAID group constituted of two physical storage devices is reconstituted with three physical storage devices by adding one physical storage device. The dynamic configuration change of the RAID group is not recognized by the host compute  1 , and is processed in the background. 
     When the configuration of the RAID group is dynamically changed, the control device  20  executes the programs of the command processing module  29  and the device management module  28 , thereby carrying out migration processing for data caused by the change. 
     The control device  20  executes the command processing module  29 , thereby reading data in the physical storage device  22  of a migration source into the memory  27 , and writes the read data to a physical storage device  22  of a migration destination. Moreover, the control device  20  executes the device management module  28 , thereby applying the change in the physical storage device information  281  caused by the configuration change of the RAID group. It should be noted that the control device  20  can receive an I/O processing request intended for all data including a subject of migration even during the migration of data caused by a dynamic configuration change of the RAID group. 
     &lt;Software Configurations of Host Computer  1 , Storage Management Terminal  3 , and Database Management Terminal  6  of Information Processing System&gt; 
     As illustrated in  FIG. 1A , the host computer  1  includes, in the memory  11  and the local storage device  13 , various programs including the OS  100 , the DBMS  200  for accumulating the business data and managing the accumulated business data, and APs  300  for issuing queries to the DBMS  200 , and information required for executing the programs. It should be noted that the AP  300  may be executed on another computer coupled to the network  5  other than the host computer  1  on which the DBMS  200  is running. In this case, the DBMS  200  receives a query from the AP  300  via the network  5 . 
     The OS  100  carries out control of the entire computer such as management of the memory  11  and the local storage device  13 . Moreover, the OS  100  of the host computer  1  recognizes the presence of the two logical storage devices  280   a  and  280   b  provided by the storage system  2  as logical storage devices  280   a ′ and  280   b ′ as illustrated in  FIG. 2 . The logical storage devices  280   a ′ and  280   b ′ are generally referred to as logical storage devices  280 ′. The logical storage devices  280 ′ recognized by the DBMS  200  or the OS  100  of the host computer  1  are the same as the logical storage devices  280  provided by the storage system  2  according to this embodiment. 
     The DBMS  200  stores and manages a database (hereinafter, referred to as DB) of the business data in the storage system  2 . The DB is stored in the physical storage devices  22  via the logical storage devices  280   a ′ and  280   b ′ recognized by the host computer  1 , and constituted of a plurality of tables and indices. 
     The DBMS  200  is constituted of a data management module  210 , a physical storage device information acquisition module  220 , and a query processing module  230  as illustrated in  FIG. 1A . 
     The data management module  210  unifies the logical storage devices  280   a ′ and  280   b ′ recognized by the OS  100  into a logical storage volume  2800 , and manages the logical storage volume  2800 . The DBMS  200  stores the DB in the logical storage volume  2800 . The data management module  210  builds data arrangement management information  2100 , thereby managing the logical storage volume  2800 . The data arrangement management information  2100  contains a ratio of data distributed to and arranged on (stored in) the plurality of logical storage devices  280   a ′ and  280   b ′ constituting the logical storage volume  2800 . The data arrangement management information  2100  is described later in detail referring to  FIG. 5 . 
     The physical storage device information acquisition module  220  receives an instruction from the data management module  210 , thereby acquiring the physical storage device information  281 , which is the information on the physical storage devices  22  of the storage system  2  constituting the logical storage devices  280   a ′ and  280   b ′, from the storage system  2  or physical storage device information  311  described later from the storage management terminal  3 , and retains the physical storage device information  281  or the physical storage device information  311  as the physical storage device information  221 . Moreover, the physical storage device information acquisition module  220  provides a dedicated interface, thereby acquiring information from the database management terminal  6  and the like. 
     The query processing module  230  receives a query from the AP  300 , carries out a plurality of pieces of database processing in response to the received query, and returns an execution result to the AP  300 . When it becomes necessary to read data from the DB, the query processing module  230  issues a data read request to the storage system  2  via the OS  100  during the execution of the database processing. 
     The DBMS  200  can build a database buffer (hereinafter, referred to as DB buffer) for temporarily storing data by using a part of the memory  11  and the local storage device  13 . Moreover, the data management module  210  containing the data arrangement management information  2100  and the physical storage device information acquisition module  220  may operate not within the DBMS  200  but within the OS  100 . 
       FIG. 4  is an explanatory diagram illustrating an example of the physical storage device information  281  of the storage system  2 . It should be noted that the physical storage device information  311  of the storage management terminal  3  is the same as the physical storage device information  281  of the storage system  2 , and the physical storage device information  221  of the DBMS  200  is the same as a table formed by removing a logical storage device number  402  described later from the physical storage device information  281  of the storage system  2 , and hence duplicate description thereof is omitted. 
     Columns of the physical storage device information  281  are respectively a host logical storage device number  401  for storing the number of a logical storage device provided for the host computer  1  by the storage system  2 , the logical storage device number  402  for storing the number of the logical storage device as an identifier internally managed by the storage system  2 , a logical storage device capacity  403  for storing a storage capacity of the logical storage device corresponding to the logical storage device number, a RAID group number  404  for storing a RAID group identifier of the logical storage device, a RAID level  405  for storing the RAID level (type) of the logical storage device, a physical storage device number  406  for storing identifiers of a plurality of physical storage devices  22  constituting the RAID group, and a physical storage device type  407  for storing types of the respective physical storage devices  22 . 
     The host logical storage device number  401  is an identifier allocated to a logical storage device provided for the host computer  1  by the device management module  28  of the storage system  2 . The DBMS  200  and the OS  100  identify a logical storage device provided by the storage system  2  by the host logical storage device number  401 . The logical storage device number  402  to the logical storage device type  407  are information on the logical storage device  280  and the physical storage devices  22  set by the device management module  28  of the storage system  2 . 
     The logical storage device number  402  is an identifier of the logical storage device set by the storage system  2 . The logical storage device capacity  403  is the capacity of the logical storage device provided for the host computer  1  by the storage system  2 . 
     The RAID group number  404  and the RAID level  405  are information on the RAID configuration of the logical storage device, and are managed by the storage system  2 . The RAID level  405  stores the type of the RAID such as 0, 10, 5, and 6. The physical storage device number  406  stores identifiers of the plurality of physical storage devices  22  which are managed by the storage system  2  and constitute the RAID group. 
     The physical storage device type  407  stores types of the plurality of physical storage devices  22  constituting the RAID group indicated by the RAID group number  404 , and stores types of interface such as FC, SATA, and SAS as the types. 
     In addition to the above-mentioned examples, information manageable by the device management module  28  of the storage system  2  may be included in the physical storage device information  221 , and the seek time and the rotation speed of the physical storage devices  22 , for example, may be stored as performance information. 
     As described above, the host computer  1  using the storage system  2  can recognize the RAID configuration and the physical storage devices  22  of the logical storage devices  280  ( 280 ′) by forwarding the physical storage device information  281  managed by the device management module  28  of the storage system  2  to the physical storage device information  221  of the DBMS  200  of the host computer  1  or to the physical storage device information  311  of the storage management terminal  3 . 
       FIG. 5  is an explanatory diagram illustrating an example of the data arrangement management information  2100  managed by the data management module  210  of the DBMS  200 . 
     Columns of the data arrangement management information  2100  are respectively a logical storage volume name  2101  for storing a name of a logical storage volume managed by the DBMS  200  (or OS  100 ), a logical storage volume number  2102  for storing an identifier of the logical storage volume managed by the DBMS  200  (or OS  100 ), a logical storage volume capacity  2103  for storing a capacity of the logical storage volume, a host logical storage device number  2104  for storing identifiers of logical storage devices constituting the logical storage volume, a data arrangement ratio  2105  for storing a ratio for distributing the data to the logical storage devices by the data management module  210 , and a stripe size  2106  for storing a unit of the data (stripe size) to be distributed to the logical storage devices by the data management module  210 . 
     The logical storage volume  2800  is constituted of a plurality of logical storage devices  280 , and the host logical storage device number  2104  of the data arrangement management information  2100  stores the host logical storage device numbers  401  of the host logical storage devices constituting the logical storage volume  2800  out of the host logical storage devices identified by the host logical storage device numbers  401  illustrated in  FIG. 4 . 
     The data arrangement ratio  2105  is set by the data management module  210 , and stores a ratio of data to be read/written (to be allocated) on the logical storage devices identified by the host logical storage device number  2104 . The host logical storage device number  2104  stores “ 101 ” and “ 102 ” as illustrated, and if the data arrangement ratio  2105  is “3:2”, it means that the data is arranged at the ratio of “3” (3/5) on the logical storage device having the host logical storage device number  2104  of “ 101 ” to “2” (2/5) on the logical storage device having the host logical storage device number  2104  of “ 102 ”. Moreover, the stripe size  2106  is also a value set by the data management module  210 . 
     Referring again to  FIG. 1B , the storage management terminal  3  stores a program of a storage management module  310  and information required for executing the program in the memory  31  and the local storage device (not shown). The storage management terminal  3  may include an OS, which is not illustrated, for controlling the computer. 
     The storage management module  310  manages a configuration of the storage system  2 . Moreover, the storage management module  310  acquires, from the storage system  2 , and stores the physical storage device information  311  on the physical storage devices  22  constituting the logical storage devices  280  in the storage system  2 . The physical storage device information  311  is the same as the physical storage device information  281  existing on the device management module  28  of the storage system  2 . The storage management module  310  updates the physical storage device information  311  periodically or when the physical storage device information  281  is updated, thereby synchronizing this information with that in the storage system  2 . 
     The database management terminal  6  then stores a program for managing a DBMS management module  610  and information required for executing the program in the memory  61  and the local storage device (not shown). The database management terminal  6  may include an OS, which is not illustrated, for controlling the computer. 
     The DBMS management module  610  manages the DBMS  200  of the host computer  1 . The DBMS management module  610  determines a configuration of the logical storage volume  2800  from/to which the DBMS  200  of the host computer  1  reads/writes the business data, and instructs the DBMS  200  of the host computer  1  to provide the configuration, thereby managing the DBMS  200 , for example. 
     In order for that, the DBMS management module  610  outputs a graphical user interface (GUI) to the display device of the console  63  as illustrated in  FIG. 6  as described later, thereby receiving an input from the administrator. The DBMS management module  610  receives from the input device of the console  63  an instruction to build the logical storage volume  2800  using the plurality of the logical storage devices  280   a ′ and  280   b ′, or an instruction to rebuild the logical storage volume  2800  already built. The DBMS management module  610  then transmits the received instruction to build or rebuild the logical storage volume  2800  to the DBMS  200  of the host computer  1 . 
       FIG. 6  is a screen image illustrating an example of the GUI output to the console  63  by the DBMS management module  610  of the database management terminal  6 . The screen in  FIG. 6  is a user interface for building a logical storage volume, and is provided by the DBMS  200  to the database management terminal  6 . It should be noted that the DBMS  200  can provide the host computer  1  and other computers including a display device with the GUI in  FIG. 6 . It should be noted that the DBMS  200  can provide an equivalent interface in a form of the command line. 
     A database (DB) administrator for managing the DBMS  200  of the host computer  1  uses this screen on the database management terminal  6  to control the DBMS  200  to acquire the physical storage device information and to build the logical storage volume. 
     In  FIG. 6 , a window  64  is mainly constituted of fields  641  to  643  for storing specifications of the logical storage volume to be built by the data management module  210 , checkboxes  645  to  647  for selecting destinations from which the physical storage device information is acquired, and a build execution button  648  for instructing to start building (or rebuilding) the logical storage volume  2800 . 
     The field  641  stores a name of the logical storage volume  2800  to be built by the data management module  210 . The field  642  stores the capacity of the logical storage volume  2800 . The filed  643  stores identifiers (numbers) of logical storage devices  280 ′ to be allocated to the logical storage volume  2800 . The identifier of the logical storage device  280 ′ may be selected from the host logical storage device number  401  of the physical storage device information  281  illustrated in  FIG. 4 . 
     If the administrator then selects the checkbox  645  for selecting the destination from which the physical storage device information is acquired, this selection indicates that the information on the physical storage devices is to be acquired from the physical storage device information  281  of the storage system  2 . If the administrator selects the checkbox  646 , this selection indicates that the information on the physical storage devices is to be acquired from the physical storage device information  331  of the storage management terminal  3 . If the administrator selects the checkbox  647 , values input to fields  6471  to  6475  from the console  63  are to be used as information on the physical storage devices as described later. 
     If the administrator selects any one of the check boxes  645  and  646 , the administrator selects a criterion for determining a data arrangement ratio, which is a ratio of data arranged by means of the striping on the plurality of logical storage devices  280 ′, using any one of checkboxes  6461  to  6464 . 
     If the administrator selects the checkbox  6461 , the selection indicates that the data arrangement ratio is to be determined based on the number of the physical storage devices  22  constituting the logical storage devices  280 ′. If the administrator selects the checkbox  6462 , the selection indicates that the data arrangement ratio is to be determined based on information on the RAID of the logical storage devices  280 ′ (such as the level of the RAID). If the administrator selects the checkbox  6463 , the selection indicates that the data arrangement ratio is to be determined based on performance information on the physical storage devices  22  (information affecting the throughput such as the type of interface) constituting the logical storage devices  280 ′. If the administrator selects the checkbox  6464 , the selection indicates that the data arrangement ratio is to be determined based on capacities of the logical storage devices  280 ′. 
     If the administrator selects the checkbox  647 , the administrator is required to input information on the logical storage devices  280 ′ in the fields  6471  to  6475 . 
     The field  6471  stores the number of the physical storage devices  22  constituting the logical storage devices  280 ′. The field  6472  stores identifiers of RAID groups of the logical storage devices  280 ′. It should be noted that the administrator can refer to the RAID group number  404  of the physical storage device information  281  in  FIG. 4  for inputting the identification numbers of the RAID groups. The field  6473  stores the levels of RAID. The administrator can refer to the values of the RAID level  405  of the physical storage device information  281  illustrated in  FIG. 4  for inputting the RAID level. 
     The field  6474  stores the types of the physical storage devices  22 . The administrator can refer to the values of the physical storage device type  407  of the physical storage device information  281  in  FIG. 4  for inputting the types of the physical storage devices  22 . The field  6475  stores the capacity of the logical storage devices  280 ′. The administrator can refer to the logical storage device capacity  403  of the physical storage device information  281  in  FIG. 4  for inputting the capacity of the logical storage devices  280 ′. 
     After the corresponding information is set to the specifications and the checkboxes  645  to  647  of the logical storage volume  2800 , when the administrator clicks the building execution button  648 , the database management terminal  6  transmits a building instruction of the logical storage volume  2800  to the host computer  1 . The building instruction contains the values of the checkboxes and the fields input on the window  64 . The DBMS  200  of the host computer  1  builds the logical storage volume  2800  based on the building instruction. 
     If the number of the physical storage devices, the RAID group information (identification information and RAID levels), and the performance information (physical storage device types) are specified (acquired or input), this embodiment arranges the data so that the performance of the physical storage devices is maximally utilized. On the other hand, if the capacities of the host storage devices are specified (acquired or input), the data is arranged depending on the capacities of the respective host storage devices. 
     &lt;Processing Overview&gt; 
     The configuration of this embodiment of this invention has been described. A description is now given of the processing of this embodiment of this invention. When the data management module  210  of the host computer  1  receives the instruction to build the logical storage volume  2800  or the instruction to rebuild the logical storage volume  2800  already built from the database management terminal  6 , the data management module  210  outputs an instruction to update the physical storage device information  221  to the physical storage device information acquisition module  220 . The physical storage device information acquisition module  220  issues a transmission instruction of the physical storage device information to the storage management terminal  3  or the storage system  2 . 
     A description is now given of a case in which the instruction to build the logical storage volume  2800  or the instruction to rebuild the logical storage volume  2800  is transmitted from the database management terminal  6  according to this embodiment. However, a computer other than the database management terminal  6  may transmit the instruction to build or the instruction to rebuild the logical storage volume  2800 , or the instruction may be received from a console, which is not shown, of the host computer  1 . Moreover, the physical storage device information acquisition module  220  of the DBMS  200  may acquire the physical storage device information  311  of the storage management terminal  3  or the physical storage device information  281  of the storage system  2  at a predetermined cycle, thereby updating the physical storage device information  221 . 
     The physical storage device acquisition module  220  acquires the physical storage device information  281  (or  311 ) via the storage system  2 , the storage management terminal  3 , or the dedicated interface, thereby updating the physical storage device information  221  in the memory  11 . 
     The data management module  210  determines, as the data arrangement ratio, the ratio of data arranged on the plurality of logical storage devices  280   a ′ and  280   b ′ constituting the logical storage volume  2800  by means of the striping based on the physical storage device information  221  acquired by the physical storage device information acquisition module  220  as described later. The data management module  210  updates the data arrangement management information  2100  regarding the determined data arrangement ratio, and defines the logical storage volume  2800  based on the data arrangement management information  2100 . 
     For example, in the case of  FIG. 2 , the physical storage device information which the host computer  1  can acquire from the storage system  2  is information indicating that the number of the physical storage devices  22  constituting the logical storage device  280   a ′ is three ( 22   a ,  22   b , and  22   c ) and the number of the physical storage devices  22  constituting the logical storage device  280   b ′ is two ( 22   d  and  22   e ). 
     When the data management module  210  evenly arranges data on physical storage devices  22  different from one another, the ratio of data distributed to and arranged on the logical storage devices  280   a ′ and  280   b ′ is determined to 3:2 in proportion to the numbers of the physical storage devices  22 , and the ratio is set to the data arrangement ratio  2105  of the data arrangement management information  2100 . The data arrangement ratio represents a ratio of data quantity for distributing data to the plurality of logical storage devices  280 ′. 
     The data management module  210  then divides data received from the query processing module  230  into a plurality of management units having a predetermined size (such as the stripe size) and distributes the data to the logical storage devices  280   a ′ and  280   b ′ in accordance with the data arrangement ratio. 
     In other words, the data management module  210  divides the data received from the query processing module  230  into the predetermined management units such as management units “ 1 ” to “ 5 ” (“ 1 ” to “n” denote data management units of the logical storage volume  2800 ) and stores “ 1 ”, “ 3 ”, and “ 5 ” in the logical storage device  280   a ′ and stores “ 2 ” and “ 4 ” in the logical storage device  280   b ′ in accordance with the data arrangement ratio of 3:2 indicated by the data arrangement management information  2100 , thereby arranging the data in the distributed manner. 
     For the following data “ 6 ” to “ 10 ”, the data management module  210  also arranges striped data to the plurality of logical storage devices  280  at the same ratio. It should be noted that the management unit treated by the data management module  210  may be the same as or different from a data quantity of a data block read/written from/to the logical storage devices  280 ′. 
     As a result, when the logical storage volume  2800  is built by unifying the plurality of logical storage devices  280  different in combination or configuration of physical storage devices  22 , the DBMS  200  can evenly use the physical storage devices  22  of the storage system  2  in accordance with the physical storage device information  221 , thereby maximally utilizing the input/output processing performance of all the physical storage devices  22 . 
     &lt;Processing in Detail&gt; 
     A detailed description is now given of the processing of this embodiment of this invention.  FIG. 3  is a flowchart illustrating a processing sequence of building a logical storage volume  2800  by the data management module  210  of the host computer  1  according to the embodiment of this invention. This processing is executed when the data management module  210  receives the instruction to build the logical storage volume  2800  from the database management terminal  6 . It should be noted that the rebuilding instruction is described later referring to  FIG. 7 . 
     First, the data management module  210  receives the instruction to build the logical storage volume  2800  from the database management terminal  6  in Step S 1 . This building instruction contains the information received on the GUI in  FIG. 6 . It should be noted that the instruction to build or the instruction to rebuild the logical storage volume  2800  may be received from a console (not shown) of the host computer  1 . 
     The data management module  210  instructs the physical storage device information acquisition module  220  to update the physical storage device information  221  in Step S 2 . The physical storage device information acquisition module  220  acquires, based on the instruction, the physical storage device information  281  or  311  on physical storage devices  22  which are components of logical storage devices  280 ′ contained in the building instruction from the storage system  2  or the storage management terminal  3 , thereby updating the physical storage device information  221  on the memory  11 . 
     In Step S 3 , if a plurality of logical storage devices  280 ′ are contained in the building instruction, the data management module  210  determines whether or not the physical configurations of the physical storage devices  22  constituting each of the logical storage devices  280 ′ are the same. 
     This determination is based on the determination criterion for the physical configuration received by the database management terminal  6  on the GUI in  FIG. 6 . The determination criterion for the physical configuration is any one of the checkboxes  6461  to  6464  in  FIG. 6 . The checkboxes  6461  to  6464  respectively represent the different items in information on the plurality of physical storage devices  22 . 
     In this embodiment, if the checkbox  6461  is selected, the number of the physical storage devices  22  constituting the logical storage devices  280  is used as the determination criterion for the physical configuration. If the checkbox  6462  is selected, the RAID group (or RAID level) constituting the logical storage devices  280  is used as the determination criterion for the physical configuration. 
     If the checkbox  6463  is selected, the performance information of the physical storage devices  22  constituting the logical storage devices  280  is used as the determination criterion for the physical configuration. If the checkbox  6464  is selected, the capacity of the logical storage devices  280  is used as the determination criterion for the physical configuration. The performance information of the physical storage devices  22  may be the types of interface (FC, SCSI, SATA, and SAS) stored in the physical storage device type  407  of  FIG. 4 , but the performance information may instead be the seek time, the rpm, or the capacities of the physical storage devices  22 . 
     The data management module  210  proceeds to Step S 4  if a determination result is that the physical configurations of the plurality of the logical storage devices  280 ′ are not the same. On the other hand, the data management module  210  proceeds to Step S 5  if they are the same. 
     In Step S 4 , the data management module  210  warns the database management terminal  6  that the logical storage volume  2800  to be built is formed by unifying the plurality of logical storage devices  280 ′ different in the physical configuration. The database management terminal  6  displays the warning (notification) from the data management module  210  of the host computer  1  on the console  63 . On this occasion, a DB administrator or the like may transmit an instruction to stop building the logical storage volume  2800  from the console  63  to the host computer  1 , and if the data management module  210  receives the stopping instruction, the data management module  210  can finish the building of the logical storage volume  2800 . 
     In Step S 5 , the data management module  210  determines the data arrangement ratio, which is the ratio of the data arranged on the plurality of the logical storage devices  280 ′ by means of the striping, based on the criterion for the physical configuration contained in the building instruction input on the GUI in  FIG. 6 . The data arrangement ratio is determined depending on the difference in the criterion for the physical configuration as follows. 
     The data arrangement ratio can be determined in accordance with the physical configuration of the physical storage devices  22  constituting the logical storage devices  280 ′ for the following cases (1) to (4), for example. 
     (1) Data Arrangement Ratio Determined in Accordance with the Number of Physical Storage Devices  22   
     The number of the physical storage devices  22  constituting the logical storage device  280  is used as the criterion for the data arrangement ratio. For example, when respective numbers of physical storage devices  22  of logical storage devices A, B, and C are different, and when the number of the physical storage devices  22  of the logical storage device A is 4, the number of the physical storage devices  22  of the logical storage device B is 3, and the number of the physical storage devices  22  of the logical storage device C is 2, the data management module  210  determines the data arrangement ratio as 4:3:2. 
     In other words, if the total number of the physical storage devices  22  constituting the logical storage volume  2800  is n, and the number of the physical storage devices  22  in the logical storage device  280 ′ is x, the distribution ratio to this logical storage device  280 ′ is represented as x/n. 
     (2) Data Arrangement Ratio Determined in Accordance with RAID Levels of Logical Storage Devices 
     The logical storage devices have the RAID configurations. The data management module  210  acquires the number of physical storage devices  22  accessible from the host computer  1  and determines the data arrangement ratio in accordance with this number and the RAID levels. For example, if the logical storage device A is configured by means of the RAID  5  and has three physical storage devices  22 , the logical storage device B is configured by means of the RAID  1  and has two physical storage devices  22 , and the logical storage device C is configured by means of the RAID  0  and has two physical storage devices  22 , in which a physical storage device for mirroring of the RAID  1  is not accessible from the host computer  1 , then the data arrangement ratio is thus determined as 3:1:2 in accordance with the numbers of the physical storage devices  22  excluding the inaccessible physical storage device. 
     In other words, if the total number of the physical storage devices  22  accessible from the host computer  1  in the logical storage devices  280 ′ constituting the logical storage volume  2800  is n and the number of the physical devices  22  accessible from the host computer  1  in a logical storage device  280 ′ is x, the distribution ratio to this logical storage device  280 ′ is represented as x/n. 
     (3) Data Arrangement Ratio Determined in Accordance with Performance Information on Physical Storage Devices 
     If the data arrangement ratio is determined in accordance with the performance information on the physical storage devices  22 , the data management module  210  determines the data arrangement ratio in accordance with the physical storage device type  407 . For example, the data arrangement ratio is determined in accordance with the transfer rate (theoretical value) of the physical storage device type  407  such as 3 for the FC, 2 for the SAS, and 2 for the SATA in the physical storage device type  407 . 
     In other words, the data management module  210  sets a value x for each of the physical storage device types  407  in advance. If the total of the values x of the respective logical storage devices  280 ′ constituting the logical storage volume  2800  is X, the distribution ratio of each of the logical storage devices  280 ′ is represented as x/X. 
     (4) Data Arrangement Ratio Determined in Accordance with Capacities of Logical Storage Devices 
     If the data arrangement ratio is determined in accordance with the capacities of the logical storage devices, the data management module  210  determines the data arrangement ratio in accordance with the capacities of the respective logical storage devices, thereby using the capacities of the respective logical storage devices without waste. For example, if the capacity of the logical storage device A is 2 TB, the capacity of the logical storage device B is 1 TB, and the capacity of the logical storage device C is 500 GB, the data arrangement ratio determined in accordance with a capacity ratio is 4:2:1. 
     In other words, the total of the capacities of the logical storage devices  280 ′ constituting the logical storage volume  2800  is X and the capacity of the each of the logical storage devices  280 ′ is Y, the distribution ratio of each of the logical storage devices  280 ′ is represented as Y/X. 
     In other words, processing in Step S 5  is processing of determining in which logical storage device  280 ′ write data to be received from the query processing module  230  is stored in accordance with the data arrangement ratio and processing determining distributed locations of the data. 
     In Step S 6 , the data management module  210  stores the information input in  FIG. 6  and the data arrangement ratio determined in Step S 5  in the data arrangement management information  2100 . 
     Specifically, the data management module  210  sets the name input to the logical storage volume name  641  on the GUI in  FIG. 6  to the logical storage volume name  2101  of the data arrangement management information  2100  in  FIG. 5 , sets the logical storage devices specified in the logical storage device number  643  to the host logical storage device number  2104  of the data arrangement management information  2100 , sets the capacity specified in the logical storage volume capacity  642  to the logical storage volume capacity  2103  of the data arrangement management information  2100 , sets the data arrangement ratio determined in Step S 5  to the data arrangement ratio  2105  of the data arrangement management information  2100 , and sets a value set in advance to the stripe size  2106  of the data arrangement management information  2100 , thereby building the new logical storage volume  2800 . 
     In Step S 7 , the data management module  210  defines the logical storage volume  2800  constituted of the plurality of the logical storage devices  280 ′ based on the updated data arrangement management information  2100 , and provides the query processing module  230  with the logical storage volume  2800 . 
     When the above-mentioned processing has been completed, if a write request or a read request is issued from the query processing module  230  to the logical storage volume  2800 , the data management module  210  writes/reads data to/from the plurality of the logical storage devices  280 ′ constituting the logical storage volume  2800  in accordance with the data arrangement ratio  2105  corresponding to the configuration and combination of the physical storage devices  22 . 
     As described above, the logical storage volume  2800  instructed by the DB administrator from the database management terminal  6  is built for the host computer  1 , and the data arrangement ratio  2105  is determined by the data management module  210  of the DBMS  200  corresponding to the configuration and combination of the physical storage devices  22 . 
     If the query processing module  230  of the DBMS  200  issues a write request to the logical storage volume  2800 , the data management module  210  divides data received from the query processing module  230  into the predetermined management units, and writes the divided pieces of data respectively to the logical storage devices  280   a ′ and  280   b ′ in accordance with the data arrangement ratio  2105 . 
     For example, if the logical storage device  280   a ′ is constituted of the three physical storage devices  22   a ,  22   b , and  22   c , and the logical storage device  280   b ′ is constituted of the two physical storage devices  22   d  and  22   e  as illustrated in  FIG. 2 , and the checkbox  6461  “NUMBER OF PHYSICAL STORAGE DEVICES” is selected on the GUI of  FIG. 6 , the data management module  210  determines the data arrangement ratio of 3:2 in accordance with the numbers of the physical storage devices  22   a - 22   e , and sets the data arrangement ratio to the data arrangement management information  2100 . 
     When the data management module  210  receives the data to be written from the query processing module  230 , the data management module  210  divides the received data in accordance with the predetermined management unit (stripe size according to this embodiment), thus divides the received data into the management units “ 1 ”-“ 5 ” (hereinafter, referred to as stripes) as illustrated in  FIG. 2 , for example. The data management module  210  then allocates the divided pieces of data “ 1 ”-“ 5 ” by means of the round robin in accordance with the data arrangement ratio  2105  to the logical storage device  280   a ′ and the logical storage device  280   b′.    
     As a result, the pieces of data “ 1 ”, “ 3 ”, and “ 5 ” are allocated to the logical storage device  280   a ′ having the three physical storage devices  22 , and the pieces of data “ 2 ” and “ 4 ” are allocated to the logical storage device  280   b ′ having the two physical storage devices  22 , and those pieces of data are written to the respective logical storage devices  280 ′. The pieces of data are written in parallel to the plurality of physical storage devices  22  in each of the logical storage devices  280 ′. It should be noted that the read processing is inverse to the above-mentioned processing, and the logical storage devices  280 ′ carry out reading in units of the stripe size in parallel from the physical storage devices  22 . 
     On the other hand, the conventional technology evenly distributes the data to those two logical storage devices  280   a ′ and  280   b ′ without referring to the physical configurations of the physical storage devices  22  constituting the logical storage devices  280   a ′ and  280   b ′. Therefore, according to the conventional technology, compared with the read/write speeds from/to the logical storage device  280   a ′ constituted of the three physical storage devices  22 , the read/write speeds from/to the logical storage device  280   b ′ constituted of the two physical storage devices  22  are low. Therefore, in terms of the read/write performance of the logical storage volume  2800 , the logical storage device  280   b ′, which is slow in speed, constitutes a bottle neck, and the performance of the physical storage devices  22  of the logical storage device  280   a ′ becomes excessive. 
     On the other hand, according to this invention, the data arrangement ratio  2105  for each of the logical storage devices  280 ′ is determined in accordance with the physical configurations of the physical storage devices  22  constituting the logical storage devices  280 ′, and hence the read/write speeds for each of the logical storage devices  280 ′ can be equalized, thereby maximizing the read/write performance of the logical storage volume  2800 . 
     As described above, if a logical storage volume  2800  constituted of a plurality of logical storage devices  280  different in physical configuration using the virtualization function of the storage system is provided for the computer, the data management module  210  according to this invention can set the data arrangement ratio for the plurality of the logical storage devices  280  for maximally using the performance of the physical storage devices  22 , thereby using the performance of each of the physical storage devices  22  without waste. 
       FIG. 7  is a flowchart illustrating a processing sequence of rebuilding, by the data management module  210  of the host computer  1 , a logical storage volume  2800  already built according to the embodiment of this invention. In Step S 11  of the processing flow, if any one of the following events occurs, the data management module  210  receives the event as an instruction for rebuilding, and starts rebuilding of the logical storage volume  2800  already built. 
     A first event is an instruction received from the database management terminal  6  in order to add a logical storage device  280  to the logical storage volume  2800 . If the DBMS  200  receives the instruction to add the new logical storage device  280  to the existing logical storage volume  2800  from the database management terminal  6 , the data management module  210  executes processing starting from Step S 12 . 
     A second event is an instruction received from the database management terminal  6  in order to remove a logical storage device  280  from the logical storage volume  2800 . If the DBMS  200  receives the instruction to remove the logical storage device  280  from the existing logical storage volume  2800  from the database management terminal  6 , the data management module  210  executes processing starting from Step S 12 . 
     A third event is an instruction received from the database management terminal  6  in order to change the capacity of the logical storage volume  2800 . If the DBMS  200  receives the instruction to change the capacity of the existing logical storage volume  2800  from the database management terminal  6 , the data management module  210  executes processing starting from Step S 12 . 
     A fourth event is a notification received from the storage system  2  or the storage management terminal  3  indicating a change in configuration of a logical storage device  280 . If the DBMS  200  or the DBMS management module  610  receives a notification from the storage system  2  or the storage management terminal  3  indicating a change in configuration of a logical storage device  280 ′ constituting the existing logical storage volume  2800 , the database management module  210  executes processing starting from Step S 12 . 
     A fifth event is an event instructing the DBMS  200  to periodically activate the data management module  210  to start the processing starting from Step S 12 . Each time the predetermined period elapses, the DBMS  200  controls the data management module  210  to execute the processing starting from Step S 12  of  FIG. 7 , thereby monitoring a change such as addition or removal of a physical storage device  22  constituting a logical storage device  280  being used by the logical storage volume  2800 . 
     In Step S 12 , the data management module  210  determines whether or not the data management module  210  has been activated as a result of the fifth event. If the data management module  210  determines that the data management module  210  has been activated as a result of the fifth event (elapse of predetermined period), the data management module  210  monitors a change in configuration of the logical storage devices  280 ′ constituting the logical storage volume  2800  in Steps S 15  and S 16 . 
     In Step S 15 , the data management module  210  instructs the physical storage device information acquisition module  220  to acquire the physical storage device information  281  or  311  from the storage system  2  or the storage management terminal  3 . It should be noted that the physical storage device information acquisition module  220  may acquire the physical storage device information from a preset one out of the storage system  2  and the storage management terminal  3 . 
     In Step S 16 , the data management module  210  compares the physical storage device information  221  to the physical storage device information  281  or  331  acquired by the physical storage device information acquisition module  220  from the storage system  2  or the storage management terminal  3 , thereby determining whether or not the both pieces of the physical configuration information on the physical storage devices  22  are the same. If the physical storage device information  281  or  331  and the physical storage device information  221  are the same, the data management module  210  determines that there is no change in the physical storage devices  22  constituting the logical storage devices  280 ′, and finishes the processing. 
     On the other hand, if the acquired physical storage device information and the physical storage device information  221  held by the DBMS  200  are not the same, the physical configuration of the logical storage device  280 ′ has changed, and the data management module  210  proceeds to Step S 17 . 
     If it is then determined in Step S 12  that the event that has occurred is an event other than the fifth event, in Step S 13 , the data management module  210  determines whether the generated event is the first event (addition of a logical storage device  280  to the logical storage volume  2800 ). If the event that has occurred is the first event, the data management module  210  proceeds to Step S 14 , acquires information on physical storage devices  22  constituting the logical storage device  280  to be added, and proceeds to Step S 17 . On the other hand, if the event that has occurred is not the first event (occurrence of second to fourth events), the database management module  210  directly proceeds to Step S 17 . 
     In Step S 17 , the data management module  210  then refers to the physical storage device information  221 , thereby acquiring information on physical storage devices  22  constituting logical storage devices  280 ′ contained in the logical storage volume  2800  already built. 
     On this occasion, if the event that has occurred is the first event, and types of the physical storage devices constituting the logical storage device to be added to the logical storage volume  2800  and the types of the physical storage devices  22  constituting the logical storage devices  280 ′ of the existing the logical storage volume  2800  are different, the data management module  210  may output a warning (notification) that the physical configuration of the logical storage device to be added is different from those of the existing logical storage devices to the database management terminal  6  or another terminal. This can prevent the administrator from combining logical storage devices different in physical configuration by mistake, thereby configuring the logical storage volume  2800 . 
     Further, the data management module  210  may output the warning (notification) that the physical configuration is different from those of the existing logical storage devices to the database management terminal  6 , and may then receive an instruction to stop rebuilding the logical storage volume  2800  from the database management terminal  6 . The data management module  210  stops the processing if the data management module  210  receives the instruction to stop rebuilding the logical storage volume  2800 . 
     In Step S 18 , as in Step S 5  of  FIG. 3 , the database management module  210  calculates the data arrangement ratio based on the physical configuration of the plurality of logical storage devices  280 ′ constituting the logical storage volume  2800 . The criteria for the physical storage device  22  in order to determine the data arrangement ratio are the same as (1)-(4) described in Step S 5 , and the data management module  210  acquires the data arrangement ratio in accordance with any one of these criteria. 
     In Step S 19 , as in Step S 6  of  FIG. 3 , the data management module  210  then stores the information specified by the instruction for rebuilding and the data arrangement ratio determined in Step S 18  in the data arrangement management information  2100 , thereby updating the data arrangement management information  2100 . 
     In Step S 20 , as in Step S 7  of  FIG. 3 , the data management module  210  rebuilds (redefines) the logical storage volume  2800  constituted of the plurality of the logical storage devices  280 ′ based on the updated data arrangement management information  2100 , and provides the query processing module  230  with the logical storage volume  2800 . 
     The data management module  210  then rearranges the data in accordance with the new data arrangement ratio  2105  for the added logical storage device  280 ′ or the removed logical storage device  280 ′. If a physical storage device is added to the logical storage device  280   b  in the example of  FIG. 2 , for example, the data arrangement ratio is updated from 3:2 to 1:1. The data management module  210  controls the data in the logical storage device  280   a ′ and the logical storage device  280   b ′ to migrate to corresponding logical storage devices  280 ′ for attaining the new ratio. 
     When the above-mentioned processing has been completed, if a write request or a read request is issued from the query processing module  230  to the logical storage volume  2800 , the data management module  210  writes/reads data to/from the plurality of the logical storage devices  280 ′ constituting the rebuilt logical storage volume  2800  in accordance with the data arrangement ratio corresponding to the configuration and combination of the physical storage devices  22 . 
     As described above, the data arrangement ratio  2105  is determined by the data management module  210  of the DBMS  200  corresponding to the physical configuration and the combination of the physical storage devices  22  also for rebuilding the logical storage volume  2800 . As a result, the read/write speeds for the respective logical storage devices  280  can be equalized, thereby maximizing the read/write performance of the logical storage volume  2800 . 
     It should be noted that, though the DBMS  200  includes the data management module  210  for determining the data arrangement ratio, and distributing the data to the logical storage devices  280  in the above-mentioned example, the data management module  210  may be provided in the OS  100  of the host computer  1 . 
     Moreover, the logical storage volume  2800  to be provided for the query processing module  230  of the DBMS  200  is constituted using a plurality of logical storage devices  280 ′ recognized by the OS  100  of the host computer  1  in the above-mentioned preferred configuration example. This embodiment is not limited to this configuration, and a logical storage space may be constituted using a plurality of logical storage devices  280  of the storage system  2  recognized by the host computer  1 , a logical storage volume  2800  may be built in the logical storage space, a data arrangement ratio may be determined in accordance with the physical configuration of the logical storage devices  280  as described above, and the data may be distributed, and arranged (stored). 
     Moreover, if the RAID  5  or  6  is applied to the host computer  1  by means of software, the parity may also be distributed and stored based on the data arrangement ratio in addition to the data arranged on the storage system  2 . 
     Moreover, the stripe size  2106  of the data distribution management information  2100  may store a plurality of stripe sizes for respective host logical storage devices as illustrated in  FIG. 8  in the above-mentioned configuration, and the data management module  210  may access the different stripe sizes for the respective storage devices  280 , thereby managing the substantial data arrangement ratio. 
     Though the detailed description has been given of this invention referring to the drawings, this invention is not limited to this specific configuration, and includes various variations and equivalent configurations within the gist of the accompanying claims. 
     As described above, this invention can be applied to a computer system using a storage system provided with a plurality of logical storage devices and a distributed arrangement method for data.