Patent Publication Number: US-2015081964-A1

Title: Management apparatus and management method of computing system

Description:
TECHNICAL FIELD 
     The present invention relates to a management apparatus and a management method of a computing system. 
     BACKGROUND ART 
     A storage system including a so-called thin provisioning function is known. In the thin provisioning function, a memory area of a volume is regarded as a memory unit aggregation that is called a page. When writing of data is performed on a page, a physical memory area is assigned to the page. Thus, in a virtual logical volume using the thin provisioning function, a logical capacity in excess of a physical storage capacity is allowed to be defined. In addition, the concentration of an input/output (I/O) load for the virtual logical volume is allowed to be suppressed by distributedly allocating a page to two or more storage tiers. 
     As an application technology of the thin provisioning function, a page relocation technology is known in which a page is allocated so as to be distributed to two or more storage tiers (tiers), and data of the page is migrated between the different storage tiers as appropriate (Patent Literature 1). In Patent Literature 1, an input/output (I/O) amount of each of the pages is measured at a specific interval, and the data of the page is migrated to a different tier based on the I/O amount. 
     In addition, a function is known in which data in a virtual logical volume is stored in a mere specific tier and is not migrated to another tier (Patent Literature 2). The technology that achieves the function is called an object-based tier management technology. 
     Here, an object belongs to a specific computer program and indicates a function unit or memory unit including a data area. For example, in a database management system (hereinafter referred to as DBMS), a table or an index is an object. In Patent Literature 2, the arrangement of the object is checked, and a page that is a storage destination of the object is identified. The identified page is migrated to a specific tier, so that the data of the object is allocated to the mere specific tier. 
     In addition, a technology is known in which relocation of a page is optimized by focusing on a relocation time of data (Patent Literature 3). 
     CITATION LIST 
     Patent Literature 
     
         
         [Patent Literature 1] International Publication No. WO 2011/077489 
         [Patent Literature 2] Japanese Patent Laid-Open No. 2011-170833 
         [Patent Literature 3] International Publication No. WO 2011/096017 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     When an object-based tier management function is achieved using the technology in Patent Literature 1, embodiments described below may be conceived. That is, an administrator specifies a data storage destination tier for each object with respect to the management program beforehand. The management program specifies an allocation destination tier of each page to a storage system based on the relation of the object and the page, and the specified contents from the administrator. The storage system relocates the page in consideration of the contents of an instruction in the execution cycle of a specific page relocation process. In such case, a large number of relocation target pages may be generated depending on contents of an instruction from the administrator. As a result, it takes a long time to process the page relocation. Thus, it is probable that the progress of page relocation in an object to be processed more immediately is stacked up. 
     The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a management apparatus and a management method of a computing system, in which a physical memory area used by an object is allowed to be provided between two or more storage tiers based on a priority level determined for each of the objects. 
     Solution to Problem 
     In order to solve the above-described problems, a management apparatus according to the present invention is a management apparatus for managing a computing system including at least one host computer and at least one storage apparatus, and the storage apparatus including at least one virtual logical volume that is supplied to a specific computer program operating in the host computer and at least one pool that includes two or more storage tiers that include different performances and executing a relocation process in which a virtual memory area comprised in the virtual logical volume is associated with a physical memory area of any of the two or more storage tiers in response to a write request from the host computer, and the physical memory area associated with the virtual memory area is allocated to a specific storage tier of the two or more storage tiers based on specific specification information for instructing a relocation destination. The management apparatus includes a memory that is configured to store a management program for performing tier management for the two or more storage tiers, and a microprocessor that is configured to execute the management program stored in the memory, the specific specification information being stored in the memory and holding information for identifying a specific storage tier in which data of two or more objects related to the specific computer program is to be stored, and the microprocessor causes the management program to execute: as a first tier management mode, a priority level determination step of determining each priority level of each of the two or more objects based on priority level management information for determining a priority level related to relocation for each of the two or more objects included in the specific computer program; a relocation information generation step of extracting a physical memory area that is a relocation target for each of the two or more objects based on the specific specification information and storage state information indicating a current storage destination of the physical memory area corresponding to the virtual memory area; a selection step of selecting a specific physical memory area from the extracted physical memory areas that are relocation targets based on the priority level determined for each of the two or more objects; and an instruction step of instructing the storage apparatus to allocate data stored in the selected specific physical memory area to the physical memory area in the specific storage tier indicated in the specification information. 
     In the selection step, the specific physical memory area is allowed to be selected based on a priority level in a range of an upper limit value determined from a relocation performance included in the storage apparatus. 
     The priority level management information is allowed to be created beforehand based on the attribute of an object. 
     The further features of the present invention will become apparent from the description of the present specification and the accompanying drawings. In addition, the aspect of the present invention is realized by being accomplished from elements, combination of various elements, the following detailed description, etc. 
     It should be understood that the description of the present specification is only exemplary, and should not, in any sense, be intended to limit the claims or application example of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates an arrangement of an object-based tier management system. 
         FIG. 2  illustrates a relation of an object of a DBMS and a page relocation process. 
         FIG. 3  illustrates a main flow of information in an object storage destination specification. 
         FIG. 4  illustrates information of the object storage destination specification. 
         FIG. 5  illustrates information of a DBMS priority level evaluation policy. 
         FIG. 6  illustrates information of object priority level evaluation. 
         FIG. 7  illustrates information of an object storage state. 
         FIG. 8  illustrates information of object relocation. 
         FIG. 9  illustrates information of pool management. 
         FIG. 10  illustrates information of a page storage state. 
         FIG. 11  illustrates information of page storage destination specification. 
         FIG. 12  illustrates information of an object arrangement. 
         FIG. 13  illustrates information of object performance. 
         FIG. 14  illustrates a flowchart of a process in the object storage destination specification. 
         FIG. 15  illustrates a flowchart of a process in the page storage destination specification when back pages are not priority. 
         FIG. 16  illustrates a flowchart of the first half of a process in the page storage destination specification when back pages are priority. 
         FIG. 17  illustrates a flowchart of the latter half of a process in the page storage destination specification when back pages are priority. 
         FIG. 18  illustrates a flowchart of a process in the page relocation. 
         FIG. 19  illustrates a display screen of a list of the DBMS. 
         FIG. 20  illustrates an edit screen of the object storage destination. 
         FIG. 21  illustrates a check screen of configuration contents of the object storage destination. 
         FIG. 22  illustrates a display screen of a list of the DBMS after object storage destination edit. 
         FIG. 23  illustrates a detailed display screen of a page relocation execution status. 
         FIG. 24  illustrates a configuration of an object-based tier management system according to a second embodiment. 
         FIG. 25  illustrates a relation of a guest OS and a page relocation process. 
         FIG. 26  illustrates contents of a virtual disk. 
         FIG. 27  illustrates information of virtual disk storage destination specification. 
         FIG. 28  illustrates information of a guest OS priority level. 
         FIG. 29  illustrates information of a virtual disk storage state. 
         FIG. 30  illustrates information of virtual disk relocation. 
         FIG. 31  illustrates information of a guest OS arrangement. 
         FIG. 32  illustrates information of a virtual disk performance. 
         FIG. 33  illustrates a flowchart of a process in the virtual disk storage destination specification. 
         FIG. 34  illustrates a display screen of a list of hypervisor; 
         FIG. 35  illustrates an edit screen of a virtual disk storage destination. 
         FIG. 36  illustrates a check screen of the configuration contents of a virtual disk storage destination. 
         FIG. 37  illustrates scaling of the object; 
         FIG. 38  illustrates a relation of expansion of the object and page relocation. 
         FIG. 39  illustrates information of DBMS priority level evaluation policy according to a third embodiment. 
         FIG. 40  illustrates information of DBMS priority level evaluation policy according to a fourth embodiment. 
         FIG. 41  illustrates a flowchart of a calculation process of an assignment time for each DBMS. 
         FIG. 42  illustrates a flowchart subsequent to  FIG. 41 . 
         FIG. 43  illustrates estimated contents of a method using a weight value for correcting a page relocation amount for each DBMS. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present invention are described below with reference to the accompanying drawings. In the accompanying drawings, functionally the same element may be indicated by the same number. It is noted that the accompanying drawings illustrate specific embodiments and examples according to the principle of the present invention. The embodiments and examples are intended for the understanding of the present invention and should not be used to interpret the present invention to a limited extent. 
     In the embodiments, the descriptions are made in sufficient detail to enable those skilled in the art to practice the invention, and alternatively, it is also possible to apply to another implementation or embodiment. It should be understood that the change of arrangement or structure, and replacement of various elements are possible without departing from the scope and spirit of the technical concept of the present invention. Therefore, the following description should not be interpreted to a limited extent. 
     In addition, as described later, the embodiments of the present invention may be implemented in software that operates on a general-purpose computer, implemented in dedicated hardware, or implemented in the combination of the software and the hardware. 
     It is noted that, as described below, each piece of information of the present invention is explained by a “table” format, the information is not necessarily expressed by a data structure by the table, and alternatively, the information may be expressed by a data structure such as a list, a database (DB), and a queue. Therefore, “table,” “list,” “DB,” “queue,” etc. may be merely referred to as “information” in order to indicate that the expression is independent of the data structure. 
     In addition, when the contents of each pieces of information are explained, “identification information,” “identifier,” “title,” “name,” and “ID” may be used, it is possible that these are substituted each other. 
     In the embodiments of the present invention, each of the processes is explained below using “program” as a subject (subject of the action), and a processor may be used as a subject because the program executes a process defined so as to be executed by the processor using a memory and a communication port (communication control apparatus). In addition, the process discussed using “program” as a subject may be a process performed by a computer or an information processing apparatus such as a management server. A part of the program or the whole program may be realized by dedicated hardware, and may be modularized. Various programs may be installed to each computer by a program distribution server and a storage media. 
     According to the embodiments, in an object-based tier management system, a page relocation process for an object may be executed more properly. As a result, the occurrence of an event in which tier optimization of an object to be immediately processed is stacked up may be suppressed. 
     First Embodiment 
     Embodiments according to the present invention are described below in accordance with the drawings. In the drawings, for convenience, the names of some elements are simplified and described. 
       FIG. 1  illustrates a general arrangement of a computing system according to a first embodiment. The computing system includes, for example, at least one management terminal  10 , at least one management computer  20 , at least one storage  30 , at least one host computer  40 , a management network  51 , and a storage network  52 . The host computer may be abbreviated as “host.” 
     The management terminal  10 , the management computer  20 , each of the storages  30 , and the host computer  40  are bidirectionally communicatively connected to each other through the management network  51 . In addition, the management computer  20 , each of the storages  30 , and the host computer  40  are bidirectionally communicatively connected to each other through the storage network  52 . 
     The management network  51  and the storage network  52  are communication lines and communication paths for transmitting and receiving data between information processing apparatuses. It is noted that, in  FIG. 1 , the management network  51  and the storage network  52  are indicated as different communication lines, and the networks  51  and  52  may be configured to be used as a shared communication line. 
     The management terminal  10  is an information processing apparatus and includes, for example, a memory  11 , a microprocessor (central process unit (CPU) in the drawings)  12 , a display apparatus  13 , a keyboard  14 , a mouse  15 , and a host interface (hereinafter, interface is referred to as I/F)  16 . 
     The memory  11  stores data and a computer program. The microprocessor (hereinafter, referred to as processor)  12  executes the computer program by reading the computer program from the memory  11 . The display apparatus  13  displays data, etc. The keyboard  14  accepts an input of a character from a user. The mouse  15  is used for indicating a specific point on a screen displayed by the display apparatus. The host I/F  16  transmits and receives data to and from the management computer  20  through the management network  51 . For example, an indication apparatus by voice and an indication apparatus by a brain wave may be used as a user interface in addition to the display apparatus, the keyboard, and the mouse. 
     In the memory  11 , a console program  111  is stored. The microprocessor  12  executes the console program  111 , so that a function is realized such as a function that exchanges data with the management computer  20  through the host I/F  16  and the management network  51 , a function that displays information on the display apparatus  13 , and a function that accepts an input from the user through the keyboard  14  and the mouse  15 . 
     The management terminal  10  is used as a front terminal for operating and managing the storage  30  by the user (storage administrator) involved in the operation and management of storage. The management terminal  10  may be configured to be used as a personal computer (PC), a personal digital assistant, a mobile phone, a terminal for operation, etc. Alternatively, a man-machine interface function included in the management terminal  10  may be configured to be provided in the management computer  20 . 
     The management computer  20  is an information processing apparatus that manages a computing system, and includes, for example, a memory  21 , a processor  22 , a SAN I/F  23 , and a host I/F  24 . 
     The memory  21  stores data, a computer program, and management information. The processor  22  executes the computer program by reading the computer program from the memory  21 . The processor  22  executes the computer program, so that each function described later is realized. 
     The SAN I/F  23  is a circuit for issuing an operation instruction or an information query to each of the storages  30  through the storage network  52 . The host I/F  24  is a circuit for performing data communication with other information processing apparatuses  10 ,  30 , and  40  through the management network  51 . 
     An object tier management program  2111  is a computer program for managing the storage  30  in cooperation with a DBMS data collection program  4411  on the host  40  and is stored in the memory  21 . 
     Object storage destination specification information  2112  is definition information for indicating a tier in which an object in a DBMS  4412  is to be stored. For example, an index and a table are examples of an object. DBMS priority level evaluation policy information (evaluation policy in the drawings)  2113  is definition information for indicating an evaluation method of a priority level for each of the DBMSs  4412 . 
     Object priority level evaluation information (priority level evaluation in the drawings)  2114  is information for indicating the priority level of page relocation of an object in the DBMS  4412 . That is, the object priority level evaluation information  2114  manages the priority level of a relocation process in a page storing data of an object. In the first embodiment as described later, a page related to an object having a high priority level, is relocated on a priority basis. 
     Object storage state information  2115  is information for indicating a tier in which an object in the DBMS  4412  is actually stored. That is, the object storage state information  2115  manages a tier in which a page storing data of an object actually exists. 
     Object relocation information  2116  is information related to a page relocation target of an object in the DBMS  4412 . 
     The object tier management program  2111 , the object storage destination specification information  2112 , the DBMS priority level evaluation policy information  2113 , the object priority level evaluation information  2114 , the object storage state information  2115 , and the object relocation information  2116  are stored in the memory  21 . Each of the pieces of the information  2111 ,  2112 ,  2113 ,  2114 ,  2115 , and  2116  are described in detail later. 
     It is noted that, in  FIG. 1 , a case is indicated in which the management computer  20  and the host computer  40  are provided separately, and alternatively, the host computer  40  may function as a management computer. For example, at least one of the two or more host computers  40  may be configured to be provided with a computer program  211  and various pieces of management information  2111  to  2116  included in the management computer  20 . 
     The storage  30  that serves as a “storage apparatus” is an apparatus for storing information. In  FIG. 1 , one storage  30  is indicated, and alternatively, the computing system may include two or more storages  30 . Each of the storages  30  includes, for example, a storage controller  31  and a disk unit  32 . 
     A storage controller  31  includes a host I/F  311 , a SAN I/F  312 , a microprocessor  313 , a memory  314 , and a disk controller  315 . The host I/F  311  is a circuit for being connected to the management network  51 . The SAN I/F  312  is a circuit for being connected to the storage network  52 . 
     In the memory  314 , for example, an I/O processing program (I/O processing in the drawings)  3141 , a page-based tier management program (page tier management in the drawings)  3142 , pool management information  3143 , page storage state information  3144 , and page storage destination specification information  3145  are stored. 
     The microprocessor  313  executes the computer programs  3141  and  3142 , and the management information  3143  by reading the programs and information. The disk controller  315  controls reading and writing of data from and to the disk drive  321 . 
     The disk unit  32  includes two or more disk drives  321 . Physical memory areas included in disk drives  321 , respectively, are grouped, and two or more logical memory areas may be configured to the grouped physical memory area. The logical memory area is referred to as a logical volume  322 . 
     For example, various apparatuses such as a hardware disk drive, a semiconductor memory drive, an optical disk drive, an optical magnetic disk drive on which reading and writing of data may be performed are available as a disk drive. 
     In a case of the hardware disk drive, for example, a Fibre Channel (FC) disk, a Small Computer System Interface (SCSI) disk, Serial AT Attachment (SATA) disk, AT Attachment (ATA) disk, Serial Attached SCSI (SAS) disk, etc. may be used. 
     In addition, for example, various storage apparatuses such as a flash memory, a Ferroelectric Random Access Memory (FeRAM), a Magnetoresistive Random Access Memory (MRAM), a Phase-change memory (Ovonic Unified Memory), and RRAM (registered trademark) may be used as a disk drive. 
     The I/O processing program  3141  defines the logical volume  322  in response to a request from the management computer  20 . In addition, the I/O processing program  3141  performs reading and writing of data on the logical volume  322  and a virtual volume  351  (described later in  FIG. 3 ) in response to the request from the host computer  40 . 
     The page-based tier management program  3142  controls the so-called thin provisioning function. That is, the page-based tier management program  3142  makes available configuration management of a pool, operation management of a pool, configuration management of a virtual volume, operation management of a virtual volume, a function such as data reading and writing, and a page-based tier management function. The page-based tier management function (function that manages a tier in a page unit) includes functions such as operation status management of a page, relocation of a page. The page-based tier management program  3142  performs various operations, and configuration and reference of information in response to an instruction from the object tier management program  2111 . 
     The pool management information  3143 , the page storage state information  3144 , and the page storage destination specification information  3145  are described in detail later. 
     The host computer  40  is an information processing apparatus using the storage  30  and includes, for example, a SAN I/F  41 , a host I/F  42 , a processor  43 , and a memory  40 . 
     The SAN I/F  41  is a circuit for data communication with each of the storages  30  through a storage network  52 . The host I/F  42  is a circuit for data communication with the management computer  20  through the management network  51 . 
     In a memory  44 , for example, a DBMS data collection program (DBMS information in the drawings)  4411 , the DBMS  4412 , an Operating System (OS)  4413 , the object arrangement information  4414 , and object performance information  4415  are stored. The processor  43  executes each of the computer programs  4411 ,  4412 , and  4413  by reading the programs. 
     The DBMS data collection program  4411  is a program that collects information related to the DBMS  4412  and transmits the information to the management computer  20 . The DBMS data collection program  4411  provides the object arrangement information  4414  and the object performance information  4415  for the object tier management program  2111  based on an instruction from the object tier management program  2111 . The object arrangement information  4414  is information for indicating the arrangement of an object in the DBMS  4412 . The object performance information  4415  is information for indicating the performance of an object in the DBMS  4412 . 
     The DBMS  4412  as an example of a “specific computer program” is a database management system and is a program for making available a function such as registration, update, and query of various data. 
     The OS  4413  is basic software that is an execution infrastructure for the DBMS data collection program  4411  and the DBMS  4412 . 
     The object arrangement information  4414  and object performance information  4415  are described later. 
       FIG. 2  schematically illustrates a relation of a storage method of data and page relocation  3522  in an object  44121  in the DBMS  4412 . 
     In the DBMS  4412 , two or more objects  44121  exist. The object  44121  is, for example, a memory unit of data such as a table or an index. The object  44121  is stored in a logical block  45111  in a logical volume  451 . 
     The logical volume  451  is provided by the storage  30 . The logical volume  451  is a memory unit that is recognized by the host  40 . The logical block  45111  is a unit of a memory area comprised in the logical volume  451 . The DBMS  4412  reads and writes data in a unit of the logical block  45111 . Generally, the logical block  45111  is identified by an identification number called a Logical Block Address (LBA). 
     In  FIG. 2 , for example, a number such as “86016” and “86017” is displayed in the logical block  45111 . The number indicates the LBA of the logical block  45111 . 
     In  FIG. 2 , the two or more logical blocks  45111  are enclosed by one broken line  4511 . The range 4511 indicated by the broken line indicates a range of a page that is a memory unit in a case in which the thin provisioning technology is used. A page  4511  in the logical volume  451  is associated with a page  3511  in a virtual volume  351  in the storage  30 . 
     For example, the page  4511  in the logical volume  451  may be called a logical page, a page in the virtual volume  351  may be called a virtual page  3511 , a page  35211  in a tier  3521  described later may be called a physical page. 
     The virtual volume  351  is a memory unit that is on the storage  30  side and is associated with the logical volume  451  on the host  40  side. The virtual volume  351  comprises the one or more pages  3511 . 
     The page  3511  is a memory unit used in the thin provisioning function. The page  3511  is associated with the page  35211  in the tier  3521  including a physical storage medium in a pool  352 . 
     It is noted that, in  FIG. 2 , a numeric character given in the virtual page  3511  is an identification number for uniquely identifying the virtual page  3511  in the virtual volume  351 , that is, a page address. 
     In the first embodiment, an LBA  45111  (addresses of the logical block  45111 ) in the logical volume  451  and a page address of the virtual page  3511  may be converted simply mutual. 
     For example, a case is described in which the size of the logical block  45111  is 512 bytes, and the size of the virtual page  3511  is 42 megabytes. A page address corresponding to an LBA having a value “86016” is “1” obtained by multiplying the value of the LBA by 512 and dividing the value by 44040192 that is a value having 42 megabytes (=86016×512/44040192). An LBA and a page address of the virtual page  3511  may be associated with each other by a specific method, the first embodiment is not limited to the above-described example. 
     The pool  352  is a memory area including two or more tiers  3521  ( 1 ),  3521  ( 2 ), and  3521  ( 3 ). The pool  352  is associated with the virtual volume  351 . When the tiers are not particularly distinguished, the tiers are called the tier  3521 . 
     Each of the tier  3521  ( 1 ), tier  3521  ( 2 ), and tier  3521  ( 3 ) is a memory area that comprises one or more types of physical storage medium. For example, the upper tier  3521  ( 1 ) comprises a memory area included in a disk drive  321  having a relatively high performance. The middle tier  3521  ( 2 ) comprises a memory area included in the disk drive  321  having a moderate performance. The lower tier  3521  ( 3 ) comprises a memory area included in the disk drive  321  having a relatively low performance. The performance includes, for example, a speed of reading and writing of data, etc. 
     The page  35211  ( 1 ) in the tier  3521  ( 1 ) is a memory area in the tier  3521  ( 1 ). A numeric character given in the page  35211  ( 1 ) is an identification number that uniquely identifies the page  35211  ( 1 ) in the tier  3521  ( 1 ). That is, the identification number is a page address in the tier  3521  ( 1 ). In addition, another page (physical page)  35211  is similar to the page  35211  ( 1 ). A number given in the page is an identification number (page address) in the tier  3521 . 
     Data of the page  35211  ( 2 ) in the tier  3521  ( 2 ) may be transferred to another tier  3521  ( 1 ) by the function of the page-based tier management program  3142 . The data transfer process is called the page relocation  3522 . The page relocation  3522  simply copies data and changes the association of the virtual page  3511  and the physical page  35211 . That is, the page relocation  3522  performs process for changing the association destination of the virtual page  3511  from a physical page  35211  ( 2 ) that is a source, to the physical page  35211  ( 1 ) that is a destination. 
     Before an object tier management system is described in detail, the outline of a distinctive process executed in the first embodiment is described. A reference numeral of an object is omitted as appropriate. 
       FIG. 3  illustrates a flow of a main process in a case in which a storage destination of an object is identified. An administrator, etc. of the DBMS  4412  specifies a storage destination of each of the objects in the DBMS  4412  for the object storage destination specification information  2112  using the management terminal  10  ( 711  in  FIG. 3 ). 
     In a process for specifying a storage destination of an object in the object tier management program  2111 , the contents of the object storage destination specification information  2112  is referred to ( 712  in  FIG. 3 ). In addition, in an object storage destination specification process, a storage destination of a page used by an object is specified for the page storage destination specification information  3145  in the order of an object having higher priority level ( 713  ( 1 ) in  FIG. 3 ). In the first specification, in the object storage destination specification process, the storage destination of the page used by the object is specified in a range in which the process is allowed to be performed by one time portion of a page relocation process that is periodically performed ( 713  ( 1 )). 
     The range in which the process is allowed to be performed by one time portion of the page relocation process is, for example, a range of the number of upper limit pages in which relocation is allowed to be performed by one time portion of the page relocation process. In the range of the number of upper limit pages in which the relocation is allowed to be performed, the storage destination of the page used by the object is specified. As described later, when the number of pages of relocation target (the number of pages used by an object) exceeds the number of upper limit pages in which the relocation is allowed to be performed, a relocation process of a page of the exceeding portion is performed next time. 
     The page-based tier management program  3142  periodically executes page relocation. The page-based tier management program  3142  refers to the contents of the page storage destination specification information  3145  just before the start of execution of the page relocation ( 714  ( 1 ) in  FIG. 3 ), and executes the page relocation based on the contents ( 715  ( 1 ) in  FIG. 3 ). 
     In the object storage destination specification process of the object tier management program  2111 , a storage destination of a page used by an object having a low priority level is specified after the start of first page relocation  715  ( 1 ) ( 713  ( 2 )). That is, in the object storage destination specification process, the storage destination of the page used by the object having a low priority level that is not specified in the object storage destination specification  713  ( 1 ) is specified ( 713  ( 2 )). 
     In the page relocation process of the page-based tier management program  3142 , the contents of the page storage destination specification information  3145  is referred to just before the start of the execution of next page relocation ( 714  ( 2 )), the page relocation is executed ( 715  ( 2 )). 
     As described below, the object tier management program  2111  adjusts the storage destination specification of the page used by an object to fit the page relocation executed by the page-based tier management program  3142 . As a result, in the first embodiment, a page used by an object having a high priority level is allowed to be relocated to a specified tier more immediately than a page used by an object having a low priority level. The object storage destination specification process is described in detail later. 
     In the first embodiment, a priority level of page relocation is configured beforehand for each object, and a page included in an object is relocated depending on the priority level. When the priority level of an object is high, each of the pages included in the object is relocated on a priority basis. That is, the method of the first embodiment is different from a method in which relocation is performed for each of the pages based on usage frequency (the number of I/Os) of each of the pages. In the first embodiment, when usage frequency of a page included in an object having a high priority level, the page becomes a target of priority relocation. Even a page included in an object having a high priority level may not become a target of the first page relocation process because the number of upper limit pages in which the process is allowed to be performed by one time required for the page relocation process is limited. 
       FIG. 4  is an arrangement example of the object storage destination specification information  2112  used by the object tier management program  2111 . The object storage destination specification information  2112  is an example of “specific specification information.” 
     The object storage destination specification information  2112  is used for specifying the tier  3521  to be a storage destination for each of the objects  44121  included in the DBMS  4412 . For example, a storage destination of an object is input using the management terminal  10  by the administrator of the DBMS  4412 . Alternatively, a storage destination of an object may be specified automatically or manually by another method. 
     The object storage destination specification information  2112  includes a DBMS identification name  21121 , an object identification name  21122 , and a specified tier  21123 , as the attribute, and holds information in the object  44121  unit in the DBMS  4412 . 
     The DBMS identification name  21121  holds an identification name for uniquely identifying the DBMS  4412 . The object identification name  21122  holds an identification name for uniquely identifying the object  44121  in the DBMS  4412 . In the first embodiment, a table and an index are examples of an object. The specified tier  21123  holds an identification name for uniquely identifying the tier  3521  in which data of an object is to be stored. When a storage destination is an object that is not specified, an identification code indicating that there is no specified tier is configured in the specified tier  21123 . 
     In the object storage destination specification information  2112 , information related to the whole object  44121  in the DBMS  4412  is not necessarily registered. For an unregistered object  44121 , information indicating that there is no specified tier may be configured, and a tier as an initial value may be prepared beforehand to configure the initial value. 
       FIG. 5  is an arrangement example of the DBMS priority level evaluation policy information  2113  used by the object tier management program  2111 . The DBMS priority level evaluation policy information  2113  is an example of “priority level management information.” The DBMS priority level evaluation policy information  2113  defines a policy for determining the priority level of an object. The DBMS priority level evaluation policy information  2113  is used when a priority level of page relocation is determined. For example, when the contents of the DBMS priority level evaluation policy information  2113  is input using the management terminal  10  by the administrator using the DBMS  4412 , the contents may be input by another method. 
     The DBMS priority level evaluation policy information  2113  includes a DBMS identification name  21131 , index priority  21132 , the large number of I/Os priority  21133 , back page priority  21134 , and back page rate  21135 , as the attribute. The DBMS priority level evaluation policy information  2113  holds information in the DBMS  4412  unit. 
     The DBMS identification name  21131  holds an identification name for uniquely identifying the DBMS  4412 . The index priority  21132  holds information for identifying whether or not that the type of the object  44121  is an index is used as a criterion of priority level evaluation. When “Yes” is configured in the index priority  21132 , the priority level of an object of type “index” is higher than that of an object of type “table.” When “No” is configured in the index priority  21132 , there is no difference of priority levels by the types of objects. In such case, the priority levels of the indexes are equal and the priority levels of objects are equal. 
     The large number of I/O priority  21133  holds information for identifying whether or not the number of I/Os of an object is used as criterion of the priority level evaluation. When “Yes” is configured to the large number of I/O priority  21133 , an object including the large number of I/Os has a higher priority level than that of an object including the small number of I/Os. When “No” is configured to the large number of I/O priority  21133 , the priority level of an object does not change depending on the number of I/Os. The priority level of the object including the large number of I/Os is equal to the priority level of the object including the small number of I/Os. 
     The back page priority  21134  holds information for identifying whether or not high priority is given to back pages of pages used by an object in the priority level evaluation. When an object includes two or more pages, a page address (for example, a page number) is used for giving a higher priority level to back pages than that of another page. When “Yes” is configured in the back page priority  21134 , a priority level of a specific back page of two or more pages included in an object is configured to be higher than that of another page. When “No” is configured in the back page priority  21134 , there is no difference between priority levels of pages included in an object. 
     In the back page rate  21135 , a valid value in a case in which the value of the back page priority  21134  is “Yes” is configured. The back page rate  21135  indicates what percentage of pages from the end of data of an object is regarded as the “back pages.” 
     For example, a case is described in which one object includes data of 10 pages portion in total ranging from a first page to a 10th page, “Yes” is configured in the back page priority  21134 , and “10%” is configured in the back page rate  21135 . In this case, data of 10% portion from the end of the data of the object corresponds to the 10th page that is a last page. Thus, the priority level of the 10th page that corresponds to the last 10% of the data of 10 pages in total in an identical object is higher than that of the first page to the ninth page. 
       FIG. 6  is an arrangement example of the object priority level evaluation information  2114  used by the object tier management program  2111 . Information for evaluating the priority level of an object is managed. 
     The object priority level evaluation information  2114  includes a DBMS identification name  21141 , an object identification name  21142 , an object type  21143 , and the number of I/Os  21144 , as the attribute, and holds information in an object unit in the DBMS  4412 . 
     The DBMS identification name  21141  holds an identification name for uniquely identifying the DBMS  4412 . The object identification name  21142  holds an identification name for uniquely identifying an object in the DBMS  4412 . The object type  21143  holds the type of an object. The number of I/Os  21144  holds the number of I/Os of an object. The number of I/Os  21144  stores, for example, the average number of I/Os per unit time. 
       FIG. 7  is an arrangement example of the object storage state information  2115  used by the object tier management program  2111 . The object storage state information  2115  manages a tier storing a page of an object and an amount of the page. 
     The object storage state information  2115  includes a DBMS identification name  21151 , an object identification name  21152 , and the number of used pages  21153 , as the attribute, and holds information in an object unit in the DBMS  4412 . 
     The DBMS identification name  21151  holds an identification name for uniquely identifying the DBMS  4412 . The object identification name  21152  holds an identification name for uniquely identifying an object in the DBMS  4412 . The number of used pages  21153  is the number of storages obtained by counting the page  3511  corresponding to the logical block  45111  used by an object for each of the tiers  3521 . For example, for data of “Index-B” that is an object of “DBMS-A,” 50 pages are stored in “Tier-1,” 100 pages are stored in “Tier-2,” and 150 pages are stored in “Tier-3.” 
       FIG. 8  is an arrangement example of the object relocation information  2116  used by the object tier management program  2111 . The object relocation information  2116  is information for managing relocation of each page included in an object. 
     The object relocation information  2116  includes a DBMS identification name  21161 , an object identification name  21162 , the number of relocation target pages  21163 , and a page relocation required time  21164 , as the attribute, and holds information in an object unit in the DBMS  4412 . 
     The DBMS identification name  21161  holds an identification name for uniquely identifying the DBMS  4412 . The object identification name  21162  holds an identification name for uniquely identifying an object in the DBMS  4412 . The number of relocation target pages  21163  holds the number of pages that is a target of the relocation process, of two or more pages included in an object for each combination pattern of a source tier and a destination tier. The page relocation required time  21164  holds a time required for the relocation of a page that is a relocation target. 
     For example, when a page is comprised in an object “Index-B” of “DBMS-A” is focused on, it is scheduled that 100 pages are transferred from “Tier-2” to “Tier-1,” 150 pages are transferred from “Tier-3” to “Tier-1.” All pages of “Index-B” may be stored in “Tier-1” that is an upper tier when the page relocation is completed as the object relocation information  2116  illustrated in  FIG. 8 , in comparison to the contents of the object storage state information  2115  in  FIG. 7 . 
       FIG. 9  is an arrangement example of the pool management information  3143  used by the page-based tier management program  3142 . The pool management information  3143  is information for managing the pool  352  with respect to the page relocation. 
     The pool management information  3143  includes a pool identification name  31431 , a page size  31432 , a virtual volume  31433 , the page relocation timing  31434 , and a relocation time per page  31435 , as the attribute, and holds information in the pool  352  unit in the storage  30 . 
     The pool identification name  31431  holds an identification name for uniquely identifying the pool  352  in the storage  30 . The page size  31432  holds a data size per page. A value unique to the storage  30  may be applied to the page size  31432 , and the page size  31432  may be determined when the pool  352  is created. In the first embodiment, a value of the page size  31432  may be used when an address of the logical block  45111  is converted into a page address of the page  3511 . 
     The virtual volume  31433  holds an identification name for uniquely identifying the virtual volume  351  using the pool  352 . Two or more virtual volumes  351  may be provided to the one pool  352 . 
     The page relocation timing  31434  holds information indicating a cycle  314341  and a start time  314342  on which the page relocation is performed for the pool  352  identified by the pool identification name  31431 . In the first embodiment, it is assumed that the page relocation is periodically performed by the page-based tier management program  3142 . The execution cycle  314341  may be customized for each pool, and is configured, for example, by the administrator of the storage  30 . 
     The relocation time per page  31435  holds a time required for a relocation process per page. The pool management information  3143  according to the first embodiment may hold a different value for each combination pattern of a source tier and destination tier in the relocation time per page  31435  because a data read write speed is different for each of the tiers  3521 . A total time required for the relocation process may be further precisely estimated by managing the relocation time per page for each of the combination patterns of the source tier and destination tier. 
     The relocation time per page  31435  may be an actually measured value, a value determined based on a past actual value of, and a value estimated from the performance of the disk drive  321 . When a value of a page relocation time per page  31435  is calculated based on not an actually measured value but the performance of the disk drive  321 , it is desirable to consider the impact, etc. on a normal I/O from the host  40 . The storage  30  is desired to migrate a page between the tiers while processing a regular I/O request from the host  40 . Thus, it is desirable to calculate the relocation time  31435  based on a resource amount available for the page relocation process other than a resource amount required for the regular I/O process. The resource amount required for the regular I/O process depends on the specification of the storage  30 . It is noted that the resource amount is a microprocessor usage rate, a cache memory usage rate, etc. 
       FIG. 10  is an arrangement example of the page storage state information  3144  used by the page-based tier management program  3142 . The page storage state information  3144  is information for managing a storage destination tier of the physical page  35211  corresponding to the virtual page  3511  in the virtual volume  351 . The page storage state information  3144  is updated in the new assignment of a page, in the page relocation, and in the page release. 
     The page storage state information  3144  includes a volume identification name  31441 , a page address  31442 , and a storage destination tier  31443 , as the attribute, and holds information in the page  3511  unit in the virtual volume  351  in the storage  30 . 
     The volume identification name  31441  holds an identification name for uniquely identifying the virtual volume  351  in the storage  30 . The page address  31442  holds an identification name for uniquely identifying the virtual page  3511  in the virtual volume  351 . The storage destination tier  31443  holds an identification name for uniquely identifying a storage destination tier  3521  of a physical page  35211  storing data of the virtual page  3511  in the virtual volume  351 . In the virtual page  3511  in which a physical page is not allocated, an identification name indicating “unassigned” is stored in the storage destination tier  31443 . In the following description, the physical page  35211  storing data of the virtual page  3511  may be referred to as a physical page corresponding to a virtual page. 
       FIG. 11  is an arrangement example of the page storage destination specification information  3145  used by the page-based tier management program  3142 . The page storage destination specification information  3145  manages the tier  3521  to which the physical page  35211  storing the data of a virtual page of the virtual volume  351  is to be provided. The page storage destination specification information  3145  includes a volume identification name  31451 , a page address  31452 , a specified tier  31453 , as the attribute, and holds information in the page  3511  unit in the virtual volume  351  in the storage  30 . 
     The volume identification name  31451  holds an identification name for uniquely identifying the virtual volume  351  in the storage  30 . The page address  31452  holds an identification name for uniquely identifying the virtual page  3511  in the virtual volume  351 . The specified tier  31453  holds an identification name for uniquely identifying the tier  3521  in which the physical page  35211  corresponding to a virtual page  351  is to be stored. When a storage destination is not specified, an identification name indicating “unspecified” is stored in the specified tier  31453 . 
       FIG. 12  is an arrangement example of the object arrangement information  4414  used by the DBMS data collection program  4411 . The object arrangement information  4414  manages the arrangement of an object. The object arrangement information  4414  is created, for example, by obtaining desired information from the DBMS  4412  in response to a request from the object tier management program  2111 . 
     The object arrangement information  4414  includes an object identification name  44141 , an object type  44142 , a storage identification name  44143 , a logical volume identification name  44144 , and a logical block address  44145 , as the attribute, and holds information in an object unit in the DBMS  4412 . 
     The object identification name  44141  holds an identification name for uniquely identifying an object. The object type  44142  holds a value indicating the type of an object. The storage identification name  44143  holds an identification name for uniquely identifying the storage  30  providing the logical volume  451  storing the data of an object. The logical volume identification name  44144  holds an identification name for uniquely identifying the logical volume  451  storing the data of an object. The logical block address  44145  holds the specific number of identification codes for uniquely identifying the logical block  45111  on the logical volume  451  storing the data of an object. 
       FIG. 13  is an arrangement example of the object performance information  4415  used by the DBMS data collection program  4411 . The object performance information  4415  is created by, for example, obtaining desired information from the DBMS  4412  in response to a request from the object tier management program  2111 . 
     The object performance information  4415  includes an object identification name  44151  and the number of I/Os  44152 , as the attribute, and holds information in an object unit in the DBMS  4412 . The object identification name  44151  holds an identification name for uniquely identifying an object. The number of I/Os  44152  holds a value indicating the number of I/Os of an object. 
       FIG. 14  is a flowchart indicating a process for identifying the storage destination of an object. A part of the process or the whole process is an example of a “priority level determination step.” In the object-based tier management system, information for indicating a tier to which an object is to be allocated is configured by a specific method. 
     An allocation destination tier (storage destination tier) on which configuration for an object is performed is configured to all pages used by the object.  FIG. 14  illustrates a series of the processes. The all processes in  FIG. 14  are executed by the object tier management program  2111 . 
     The object tier management program  2111  may refer to the object arrangement information  4414  and the object performance information  4415  through the DBMS data collection program  4411 , as appropriate. In addition, the object tier management program  2111  may refer to the pool management information  3143 , the page storage state information  3144 , and the page storage destination specification information  3145  through the page-based tier management program  3142 , as appropriate. 
     An operation in  FIG. 14  is described. The object tier management program  2111  may be referred to as a management program  2111  below. 
     The management program  2111  prepares the object storage destination specification information  2112  (S 8101 ). As described above, the tier  3521  that is to be an allocation destination of an object in the DBMS  4412  is configured to the object storage destination specification information  2112  by the specific method. For example, a storage destination of an object is allowed to be registered to the object storage destination specification information  2112  by accessing the object tier management program  2111  through the management terminal  10  by the administrator of the DBMS  4412 . 
     After that, the management program  2111  prepares the object priority level evaluation information  2114  (S 8102 ). As described below, the object priority level evaluation information  2114  may be created, for example, based on the object arrangement information  4414  and the object performance information  4415 . 
     That is, the object identification name  44141  of the object arrangement information  4414  and the contents of the object type  44142  are stored to the object identification name  21142  and the object type  21143  of the object priority level evaluation information  2114 , respectively. After that, the number of I/Os  44152  of the object performance information  4415  is stored to the number of I/Os  21144  of the object priority level evaluation information  2114 . In the DBMS identification name  21141  of the object priority level evaluation information  2114 , the identification name may be stored in the DBMS  4412 . 
     When the number of I/Os for each of the pages  3511  is measured in the storage  30 , the number of I/Os for each object may be calculated using the number of I/Os for each of the pages  3511 . That is, the logical block  45111  used by an object is allowed to be identified by referring to the object arrangement information  4414 , and in addition, the page  3511  used by the logical block  45111  is allowed to be identified by the method described in  FIG. 2 . The number of I/Os of an object is allowed to be obtained by acquiring the number of I/Os of each of the pages  3511  used by the object from the storage  30  and counting the number. When the method is used, the object performance information  4415  may be omitted. 
     The management program  2111  determines whether or not the priority level of page relocation is changed based on the size of the number of I/Os (S 8103 ). It is desirable that the relocation is performed as promptly as possible because a page including the large number of I/Os has a large influence on I/O performance. As described in  FIG. 5 , in the first embodiment, the way is provided in which high priority is given to the relocation of a page including the large number of I/Os. 
     Step S 8103  is described in detail. The management program  2111  refers to a value of the large number of I/O priority  21133  in a line related to a DBMS that is a processing target of the DBMS priority level evaluation policy information  2113 . The flow proceeds to step S 8104  when the value is “Yes,” and the flow proceeds to step S 8105  when the value is “No.” The DBMS priority level evaluation policy information  2113  is prepared using a specific means. For example, the value is allowed to be registered to the DBMS priority level evaluation policy information  2113  by accessing the object tier management program  2111  through the management terminal  10  by the administrator of the DBMS  4412 . 
     When the large number of I/O priority is selected (S 8103 : YES), the management program  2111  sorts the lines of the object priority level evaluation information  2114  using the value of the number of I/Os  21144  as a key, in descending order (S 8104 ). As a result, the object  44121  included in the DBMS  4412  to be processed is sorted in descending order of the number of I/Os. 
     The management program  2111  determines whether or not high priority is given to an object having an object type “index” (S 8105 ). Generally, an index is often referred to. Thus, an index that is an arrangement element of a DBMS has a large influence on I/O performance because the index includes the large number of I/Os. As described in  FIG. 5 , in the first embodiment, the priority level of the index is configured to be allowed to be higher than the priority level of a table because it is desirable that the index is relocated as promptly as possible. 
     The management program  2111  refers to a value of the high index priority  21132  in a line related to a DBMS that is a processing target, of the DBMS priority level evaluation policy information  2113 . The flow proceeds to step S 8106  when the value is “Yes,” and the flow proceeds to step S 8107  when the value is “No.” 
     Step S 8106  is a process in a case in which high priority is given to an object having an object type “index.” The management program  2111  sorts the lines of the object priority level evaluation information  2114  so that a line including the value of an index is allocated in the top side using the value of the object type  21143  as a key. 
     Step S 8107  is a process for determining whether or not high priority is given to back pages. For example, a case is considered in which data is registered to the table of a DBMS in a write-once manner. In this case, new data is stored about the rear part of the data. Thus, access to a page in the rear part of the object is relatively large. It is desirable that the relocation is performed as promptly as possible because the page having large access has a large influence on the I/O performance. 
     In the first embodiment, a way is provided in which high priority is given to the relocation for back pages. Specifically, the management program  2111  determines the priority by referring to a value of the back page priority  2113  in a line related to a DBMS that is a processing target, of the DBMS priority level evaluation policy information  2113  (step S 8107 ). The flow proceeds to step S 8109  when the value of the back page priority  21134  is “Yes,” and the flow proceeds to step S 8108  when the value is “No.” 
     When high priority is given to back pages (S 8107 : Yes), the management program  2111  executes a page storage destination specification process in which high priority is given to the back pages (S 8109 ). When high priority is not given to the back pages (S 8107 : No), the management program  2111  executes the page storage destination specification process in which high priority is not given to back pages (S 8108 ). 
     When a process in step S 8108  or step S 8109  is completed, an object storage destination specification process ends. 
       FIG. 15  is a flowchart illustrating the detailed process (S 8108  in  FIG. 14 ) for identifying a page storage destination without giving high priority to back pages. The process is also executed by the object tier management program  2111 . 
     Step S 8110  is a process for creating the object storage state information  2115 . The object storage state information  2115  may be created, for example, based on the object arrangement information  4414  and the page storage state information  3144 . 
     The LBA of a logical block  4511  used by an object is allowed to be identified by referring to the logical block address  44145  of object arrangement information  4414 . The page address of the page  3511  corresponding to the logical block  4511  is allowed to be calculated by the method described in  FIG. 2 . Which tier  3521  stores the data of a specific page address, is allowed to be identified by referring to the storage destination tier  31443  of the page storage state information  3144 . Thus, the storage destination tier of a page used by an object is allowed to be identified, and in addition, the number of pages used by an object is allowed to be counted for each of the tiers. 
     Step S 8111  is a process for creating the object relocation information  2116  that is an example of a “relocation information generation step.” The object relocation information  2116  is allowed to be created, for example, based on the object storage destination specification information  2112  and the object storage state information  2115 . 
     As illustrated in  FIG. 8 , the number of relocation target pages  21163  of the object relocation information  2116  holds the number of relocation target pages for each combination pattern of a source tier and a destination tier. The number of relocation target pages  21163  is allowed to be calculated based on the specified tier  21123  of the object storage destination specification information  2112  and the number of used pages  21153  of the object storage state information  2115 . 
     For example, when the line in which a value of the object identification name  21122  of the object storage destination specification information  2112  is “Table-A” is focused on, a value of the specified tier  21123  is “Tier-1.” Therefore, it is indicated that the object “Table-A” is allocated to the tier “Tier-1.” 
     On the other hand, when the line in which a value of the object identification name  21152  of the object storage state information  2115  is “Table-A” is focused on, the number of pages used in “Tier-1” that is the upper tier is “10,” the number of pages used in “Tier-2” that is the middle tier is “100,” and the number of pages used in “Tier-3” that is the lower tier is “200.” 
     It is specified that the page of the object “Table-A” is allocated to the upper tier “Tier-1” by the object storage destination specification information  2112 . Thus, it is found that a page belonging to the middle tier “Tier-2” is to be relocated to the upper tier “Tier-1” by 100 pages, and a page belonging to the lower tier “Tier-3”is to be relocated to the upper tier “Tier-1” by 200 pages. 
     Thus, as described below, the management program  2111  configures a value to the number of relocation target pages  21163  for “Table-A” in the object relocation information  2116  illustrated in  FIG. 8 . That is, the management program  2111  stores “100” in an area “T2 to T1” and “200” in an area “T3 to T1,” respectively. 
     In the page relocation required time  21164  of the object relocation information  2116 , a time required for the page relocation related to the object is held. The required time may be calculated, for example, based on “the number of relocation target pages  21163 ” of the object relocation information  2116  and “relocation time per page  31435 ” of the pool management information  3143 . 
     Using an object having the identification name “Table-A” as an example, a method for obtaining a relocation required time is described. In the object relocation information  2116 , when a value of the number of relocation target pages  21163  in the line of “Table-A” is focused on, “T2 to T1” is “100,” and “T3 to T1” is “200.” That is, it is indicated that migration is performed from the middle tier to the upper tier by 100 pages, and migration is performed from the lower tier to the upper tier by 200 pages. 
     Next, in each of “T2 to T1” and “T3 to T1,” a relocation required time per page is allowed to be calculated by the method described below. 
     That is, it is found that a virtual volume “Volume-A” is used for the object “Table-A” by referring to the value of the logical volume identification name  44144  of the object arrangement information  4414 . In addition, it is found that the virtual volume “Volume-A” belongs to a pool “Pool-A” by referring to the value of virtual volume  31433  of the pool management information  3143 . When values of “T2 to T1” and “T3 to T1” of the relocation time per page  31435  in an identical line are referred to, the required times “2 seconds” and “3.5 seconds” are derived. 
     The required times are obtained by multiplying the number of relocation target pages by relocation required time per page. Thus, “T2 to T1” is 200 seconds, and “T3 to T1” is 700 seconds, so that the total is 900 seconds. The value (900 seconds) is the value of the page relocation required time  21164  in the line of “Table-A” of the object relocation information  2116 . 
     It is noted that the order of the lines of the object relocation information  2116  is sorted so as to be the similar to the order of the line of the object priority level evaluation information  2114 . 
     Step S 8112  is a process for selecting a page that is a relocation target by the number of pages in which the relocation is allowed to be performed in the cycle of the page relocation. Step S 8112  is an example of a “selection step.” It is noted that S 8116 , S 8122 , S 8126 , S 8129 , S 8133 , S 8305 , and S 8309  described later are also examples of the “selection step.” The page relocation cycle is a cycle for executing the page relocation process and is obtained from the cycle  314341  of the pool management information  3143 . 
     As illustrated in  FIG. 9 , for example, when the DBMS  4412  that is processing target uses the virtual volume “Volume-A,” the page relocation cycle is “one hour.” In the pool “Pool-A” to which the virtual volume “Volume-A” belongs to, the page relocation process is executed every hour. 
     The management program  2111  selects a page that is a relocation target by the number of pages corresponding to the cycle of the page relocation from the top of the object relocation information  2116 . For example, when the cycle is one hour, relocation target pages are selected until 3600 seconds in total from the top line is counted. 
     As described below, it is noted that the number of pages defined by the cycle of the page relocation process may be called the number of upper limit pages. The number of upper limit pages is dependent on the page relocation performance of the storage  30  because the number of upper limit pages is the number of pages in which the relocation is allowed to be performed for one cycle of the page relocation process. When the cycle is identical and the page relocation performance is high, the number of upper limit pages increases. Thus, it may be expressed that the number of upper limit pages is a value defined by the performance of the relocation process of a page. 
     In the example of  FIG. 8 , all pages included in objects “Index-B,” “Index-A,” and “Table-B,” and some pages of object “Table-A” are selected as a relocation target page. 
     Step S 8113  that is an example of an “instruction step” is a process for configuring the storage destination specification of a selected page to the storage  30 . The management program  2111  configures the storage destination tier of each of the selected pages to the page storage destination specification information  3145  through the page-based tier management program  3142  in step S 8112 , or step S 8116  described later. It is noted that S 8123 , S 8130 , and S 8306  described later are also examples of the “instruction step.” 
     The management program  2111  determines whether or not the selection of the relocation target page for all objects that are processing targets is completed (S 8114 ). When the relocation target page for all objects that are processing targets is selected and the selected contents are configured to the storage  30  (S 8114 : Yes), the process ends. 
     When an object that is not processed remains (S 8114 : No), that is, an unprocessed page remains, the management program  2111  waits for the cycle of next page relocation process (S 8115 ). 
     The management program  2111  waits for a page relocation cycle subsequent to the page relocation cycle of the processing target executed just before in step S 8113 . The page relocation corresponding to the contents configured to the storage  30  in step S 8113  is processed within one cycle by the waiting process. For example, when the relocation cycle is one hour, the management program  2111  waits by one hour. The relocation of the previously selected page is completed during the waiting time. 
     Step S 8116  is a process for selecting a page that is a relocation target and similar to the process of step S 8112 . A difference between step S 8112  and step S 8116  is described. In step S 8112 , a page indicated in the top line of the object relocation information  2116  is selected in order. On the other hand, in step S 8116 , an unprocessed page that is not processed for the storage  30  is selected in order. 
     For example, in the above-described example, in step S 8112 , all pages included in the object “Index-B,” “Index-A,” and “Table-B” and some pages of the object “Table-A” are selected as a relocation target page. Thus, in step S 8116 , the rest pages of the object “Table-A” and all pages of the object “Table-C” are selected as a relocation target page. 
     It is noted that, in the example of  FIG. 15 , in step S 8113 , the case is described in which a relocation target page is configured to the storage  30  for each cycle of the page relocation process. Alternatively, another method may be employed. For example, when the page-based tier management program  3142  includes a function for performing the page relocation in order of configuration of the object tier management program  2111 , all relocation target pages are selected in step S 8112 , and the process may end immediately after executing step S 8113 . 
       FIG. 16  is a flowchart of the detailed process (S 8109  in  FIG. 14 ) for specifying a page storage destination by giving high priority to back pages. The process is also executed by the object tier management program  2111 . 
     In the process for specifying a page storage destination by giving high priority to back pages, processing for front pages (page other than the back pages) of each object is performed after processing for back pages of each of the objects is performed. A difference between the process contents of  FIGS. 15 and 16  is mainly described because the process contents of  FIG. 16  is similar to the process contents of  FIG. 15 . 
     Step S 8120  is a process for creating the object storage state information  2115  similar to step S 8110  in  FIG. 15 . In step S 8110 , the all pages of all objects are processing targets. On the other hand, in step S 8120 , mere back pages of each of the objects are processing targets. 
     Back pages that are a target is allowed to be identified by referring to the value of the back page rate  21135  of the DBMS priority level evaluation policy information  2113 . For example, in the example of  FIG. 5 , the value of the back page rate  21135  of the line in which the value of the DBMS identification name  21131  is “DBMS-B” is configured to “10%.” Thus, the page of 10% from the end of each of the objects of “DBMS-B” is regarded as back pages. The other pages other than the back pages are called, for convenience, front pages. As described above, the ranges of back pages and front pages are relatively defined by a specified specific value (back page rate). 
     Step S 8121  is substantially the same as step S 8111  in  FIG. 15 . 
     Step S 8122  is substantially the same as step S 8112  in  FIG. 15 . In step S 8112 , a page in which the storage  30  is specified as a storage destination is selected from all relocation target pages of each object. On the other hand, in step S 8122 , a page in which the storage  30  is specified as a storage destination is selected from back pages of relocation target pages of each object. 
     Step S 8123  is substantially the same as step S 8113  in  FIG. 15 . 
     Step S 8124  is substantially the same termination determination operation as step S 8114  in  FIG. 15 . In step S 8114 , it is determined whether or not a selection process for all relocation target pages of each object is completed. On the other hand, in step S 8124 , it is determined whether or not a process for all back pages of relocation target pages of each of the objects is completed. In addition, in step S 8124 , the flow proceeds to step S 8127  described later in  FIG. 17  when the selection process for the all back pages is completed, as compared with step S 8114 . 
     Step S 8125  is substantially the same as step S 8115  in  FIG. 15 . 
     Step S 8126  is substantially the same as step S 8116  in  FIG. 15 . In step S 8116 , pages of the rest objects are selected from all allocation target pages. On the other hand, in step S 8126 , pages of the rest objects are selected from back pages of each of the objects. 
     Description is made with reference to  FIG. 17 . Step S 8127  is substantially similar to step S 8112  in  FIG. 15 . In step S 8112 , a page in which the relocation is specified to the storage  30  is selected from all relocation target pages of each of the objects. On the other hand, in step S 8127 , a page in which storage  30  is specified is selected from front pages of each object. The front pages are pages other than the back pages. That is, when pages storing the no data from the end of the data of an object are back pages, front pages are pages storing the (100−n)% data that are rest portions. 
     Step S 8128  is substantially the same as step S 8113  in  FIG. 15 . 
     Step S 8129  is substantially the same as step S 8112  in  FIG. 15 . In step S 8112 , a page in which the storage  30  is specified as a storage destination is selected from all relocation target pages of each of the objects. On the other hand, in step S 8129 , a page in which storage  30  is specified as a storage destination is selected from front pages of relocation target pages of each of the objects. 
     Step S 8130  is substantially the same as step S 8113  in  FIG. 15 . 
     Step S 8131  is substantially the same termination determination operation as step S 8114  in  FIG. 15 . In step S 8114 , it is determined whether or not a process for all pages of each of the objects is completed. On the other hand, in step S 8131 , it is determined whether or not a process for all front pages of relocation target pages of each of the objects is completed. 
     Step S 8132  is substantially the same as step S 8115  in  FIG. 15 . 
     Step S 8133  is substantially the same as step S 8116  in  FIG. 15 . In step S 8116 , pages of the rest objects are selected from all relocation target page of each of the objects. On the other hand, in step S 8126 , pages of the rest objects are selected from front pages of each of the objects. 
     As described above, the procedures described in  FIGS. 14 to 17  are executed. As a result, a storage destination of each of the pages used by an object is allowed to be configured to the storage  30  in appropriate order according to a priority level based on arrangement and/or state, etc. of an object  4412 . 
     It is noted that, in step S 8112 , S 8116 , S 8122 , S 8126 , S 8129 , and S 8133  of  FIG. 15 , the case is described in which a page in which a storage destination is configured within one relocation cycle based on the time required for page relocation and a relocation cycle is selected. Alternatively, the range of a page in which a storage destination is configured within one relocation cycle may be selected based on the number of relocation target pages of each of the objects and the number of relocation pages of one relocation cycle. 
     For example, a method may be employed in which the number of upper limit pages is determined from an average time required for relocation per page and a time of a relocation cycle, and pages of an object having high priority level are selected in order until reaching the number of upper limit pages. 
       FIG. 18  is a flowchart of the page relocation process executed by the page-based tier management program  3142  in the storage  30 . The page relocation process is executed according to the value defined by the page relocation timing  31434  of the pool management information  3143  for each of the pools  352 . The specific processing contents are described below. The page-based tier management program  3142  may be referred to as the tier management program  3142  below. 
     Step S 8201  is a process for enumerating the virtual volumes  351  belonging to the pool  352  of a processing target. The tier management program  3142  is allowed to extract all of the virtual volumes  351  belonging to the specific pool  352  by referring to the virtual volume  31433  of the pool management information  3143  (S 8201 ). 
     The tier management program  3142  selects the top virtual volume  351  from the virtual volumes  351  enumerated in step S 8201  (S 8202 ). 
     The tier management program  3142  selects the top page  3511  from pages used by the virtual volume  351  selected in step S 8202  (S 8203 ). 
     The tier management program  3142  determines the necessity of relocation of the page  351  selected in step S 8203  (S 8204 ). 
     The tier management program  3142  identifies the storage destination tier  31443  of the selected page  351  by referring to the page storage state information  3144 . After that, the tier management program  3142  identifies a tier  31453  specified as the storage destination of the selected page  351  by referring to the page storage destination specification information  3145 . In addition, the tier management program  3142  compares the current storage destination tier  31443  of the selected page  351  and the tier  31453  specified as the storage destination of the selected page  351  (S 8204 ). 
     When a current storage destination tier and a specified tier are different (S 8204 : No), it is determined that page relocation is desired, and the flow proceeds to step S 8205 . When a current storage destination tier and a specified tier are same (S 8204 : Yes), it is determined that page relocation is not desired, and the flow proceeds to step S 8206 . When “unspecified” is configured to the specified tier  31453  of a page storage destination specification  3145 , it is determined that page relocation is not desired, and the flow proceeds to step S 8206 . 
     The tier management program  3142  migrates the data of the page selected in step S 8203  to the tier  3521  identified in the specified tier  31453  (S 8205 ). Specifically, the data is copied from a source page (physical page corresponding to a virtual page selected in S 8203 ) belonging to a source tier (current storage destination tier) to a destination page (physical page) belonging to a destination tier (specified tier). In addition, the physical page corresponding to the virtual page is changed from the source page to the destination page. 
     The tier management program  3142  determines whether or not a time for one cycle of the page relocation process elapses after the start of the page relocation (S 8206 ). The process ends when the time for one cycle of the page relocation process elapses (S 8206 : Yes), and the flow proceeds to step S 8207  when the time for one cycle of the page relocation process does not elapse (S 8206 : No). 
     The tier management program  3142  determines whether or not the processing for all of the pages  3511  of the virtual volume  351  selected in step S 8202  is completed (S 8207 ). When the last page  3511  of the selected virtual volume  351  is selected and there is no subsequent page  3511  (S 8207 : No), the flow proceeds to step S 8209 . 
     When there is an unprocessed page (S 8207 : Yes), the tier management program  3142  selects the page  3511  (S 8208 ), the flow returns to step S 8204 . 
     The tier management program  3142  determines whether or not the processing for all virtual volumes is completed (S 8209 ). The process ends when the last virtual volume  351  of the virtual volumes  351  enumerated in step S 8201  is being selected and there is no subsequent virtual volume  351  (S 8209 : No), and the flow proceeds to step S 8210  when the last virtual volume  351  of the virtual volumes  351  enumerated in step S 8201  is not being selected or there is a subsequent virtual volume  351 . 
     The tier management program  3142  selects the unprocessed virtual volume  351  of the virtual volumes  351  enumerated in step S 8201  (S 8210 ), the flow returns to step S 8203 . 
     As described above, the page-based tier management program  3142  relocates pages based on the contents of the page storage destination specification information  3145  specified by the object tier management program  2111  by the process illustrated in  FIG. 18 . 
     Next, an example of an operation screen according to the first embodiment is described. A screen described below may be displayed when accessing the object tier management program  2111  using the management terminal  10  by the administrator, etc. of the DBMS  4412 . 
       FIG. 19  is a screen  911  for displaying a list of DBMS. The screen  911  of DBMS list displays a list of the DBMS  4412  that is a management target of an object tier management program  2111 . 
     A DBMS display area  9111  displays an identification name of the DBMS  4412  that is a management target. A status display area  9112  displays the progress of the page relocation process. When “-” is displayed, it is indicated that the page relocation process is not started. 
     An edit button  9114  is a button for editing the specification of a storage destination. The edit button  9114  specifies the storage destination of a page of each object included in the selected DBMS  9113 . When the button  9114  is pressed by the administrator, etc. of the DBMS  4412 , a screen  912  of  FIG. 20  is opened. The screen  912  may be opened as a new screen different from the screen  911 , and the transition of screen is performed from the screen  911  to the screen  912 . Another screen described below is similar to the screens. 
     A detail button  9115  is a button for displaying the detailed information of a status of the page relocation process related to the selected DBMS  9113 . When the button  9115  is pressed by the administrator, etc. of the DBMS  4412 , a screen of  FIG. 21  is opened. 
     A close button  9116  is a button for closing the screen  911  illustrated in  FIG. 19 . 
       FIG. 20  is a screen  912  for editing the storage destination of an object. The screen  912  for editing the storage destination of an object is used for specifying the storage destination tier of an object in the specific DBMS  4412 . 
     An object display area  9120  displays the identification name of an object. A storage destination specification area  9121  is an area for specifying the storage destination of an object. The storage destination specification area  9121  includes a current state display area  9122  and a change option  9123 . 
     The current state display area  9122  displays the contents of storage destination specification configured to the object displayed in the object display area  9120 . When storage destination is not specified, “unspecified” is displayed. 
     The change option  9123  provides a function for specifying the storage destination of an object. The desired storage destination is allowed to be specified using the change option  9123  by the administrator, etc. of the DBMS  4412 . 
     A check button  9125  is a button for fixing the contents selected in the change option  9123 . When the check button  9125  is pressed by the administrator, etc. of the DBMS  4412 , the screen proceeds to a screen in  FIG. 21 . 
     A cancel button  9126  is a button for canceling the contents selected in the change option  9123 . When the cancel button  9126  is pressed by the administrator, etc. of the DBMS  4412 , the screen in  FIG. 20  is closed and the screen returns to the screen of  FIG. 19 . 
       FIG. 21  illustrates the screen  913  for checking the configuration contents of an object storage destination. The contents configured in the screen  912  illustrated in  FIG. 20  are checked through the check screen  913  of the configuration contents by the administrator, etc. of the DBMS  4412 . 
     A required time display area  9130  displays a time required for page relocation. For example, processes corresponding to step S 8110  and step S 8111  in  FIG. 15  are executed, and the total value of the page relocation required time  21164  of the object relocation information  2116  may be displayed in the required time display area  9130 . 
     An object display area  9131  displays the identification name of an object. The storage destination specification area  9132  displays the storage destination specification of an object. The storage destination specification area  9132  includes a current state display area  9133  and a changed state display area  9134 . 
     The current state display area  9133  displays the contents of the storage destination specification configured to the object identified by the object display area  9131 . When storage destination is not specified, “unspecified” is displayed. The changed state display area  9134  displays the contents configured in the change option  9123  of the screen  912  in  FIG. 20 . 
     A relocation priority order display area  9135  displays a priority level related to the page relocation of each object. In the display area  9135 , numbers in order of the priority corresponding to the sequence of the lines of the object priority level evaluation information  2114  may be displayed. 
     A relocation capacity display area  9136  displays the relocation target capacity of each object. In the display area  9136 , the capacity based on the number of relocation target pages  21163  of the object relocation information  2116  may be displayed. 
     An execution button  9137  is a button for instructing the execution of the page relocation. When the execution button  9137  is pressed by the administrator, etc. of the DBMS  4412 , the screen  913  of  FIG. 21  is closed and the screen proceeds to the screen  911  ( 2 ) of  FIG. 22  while the page relocation starts. 
     A cancel button  9138  is a button for canceling the instruction of execution of the page relocation. When the cancel button  9138  is pressed by the administrator, etc. of the DBMS  4412 , the screen  913  of  FIG. 21  is closed and the screen proceeds to the screen  912  of  FIG. 20 . 
     The screen  911  ( 2 ) of  FIG. 22  illustrates the state of the screen  911  for a DBMS list during the execution of the page relocation. In order to distinguish the screen  911  ( 2 ) from the screen  911  of  FIG. 19 , “( 2 )” is given to the screen  911  ( 2 ) in  FIG. 22 . 
     In the status display area  9112  ( 2 ) of the screen  911  ( 2 ), the progress of the page relocation is displayed. In the progress, the percentage of the completed relocation is displayed by a numerical value or a graph. 
       FIG. 23  illustrates a screen  914  for indicating the detailed states of the page relocation. An entire status display area  9141  displays the entire progress of the page relocation related to the selected DBMS  4412 . 
     An object display area  9142  displays the identification name of an object. A storage destination specification display area  9143  displays the contents of the storage destination specification configured to each object. An individual status display area  9144  displays the status of execution of the page relocation for each object. The display contents of the individual status display area  9144  may be created based on a page selected in step S 8112 , step S 8116 , etc. that are processes illustrated in  FIG. 15  and a page already processed. 
     A close button  9145  is a button for closing the screen  914  of  FIG. 23 . When the button  9145  is pressed by the administrator, etc. of the DBMS  4412 , the screen  914  of  FIG. 23  is closed and the screen returns to the screen  911  ( 2 ) of  FIG. 22 . 
     In the first embodiment described above, the management computer  20  determines each priority level of the page relocation in an object unit and instructs the page relocation depending on the priority level to the storage  30 . Thus, in the first embodiment, the relocation is allowed to be performed in order of a page of an object having a high priority level. As a result, for example, an object (for example, an index of a DBMS) having high access frequency is allowed to be migrated to an appropriate tier promptly, thereby improving the response performance. 
     In the first embodiment, a page in which the relocation is instructed to the storage  30  is selected from relocation target pages based on the priority level of an object and the page relocation performance (upper limit value of the number of pages allowed to be processed by one page relocation process) of the storage  30 . Thus, the page relocation is allowed to be completed efficiently and promptly using the relocation performance of the storage  30 . 
     In the first embodiment, the priority level of the page relocation is allowed to be configured depending on the attribute of an object. Thus, for example, in a case of a DBMS, the priority level of an index is allowed to be configured higher than that of a table. As a result, the page relocation is allowed to be performed by giving high priority to an index having high frequency of reference, thereby improving the response performance. 
     In addition, in the first embodiment, the priority level related to the page relocation is allowed to be configured for each object by considering the number of I/Os. Thus, when there are two or more objects having high frequency of reference that is a technological property, a higher priority level may be configured to be given to the larger number of I/Os. As a result, the page of an object having higher usage frequency is allowed to be relocated on a priority basis. 
     In the first embodiment, the priority level related to the page relocation is allowed to be configured for each object by considering the structure of the page of an object. For example, in a case of an object having a type in which the latest data is appended at any time, a back page in which latest data is allocated is allowed to be relocated on a priority basis. As a result, a page of an object having high usage frequency is relocated promptly, thereby improving the response performance. 
     In the first embodiment, two or more policies such as a priority level configuration policy based on the attribute of an object, a priority level configuration policy based on the number of I/Os, and a priority level configuration policy based on the configuration of the page of an object are combined and allowed to be used as appropriate. Thus, a priority level is allowed to be configured properly depending on the nature and the use condition of an object. As a result, the page to be used by an object is allowed to be relocated efficiently and promptly. 
     In the first embodiment, the range of back pages of an object is allowed to be configured as appropriate. Thus, depending on the nature and structure of an object, the range of the back pages dealt with on a priority basis is allowed to be configured by the administrator. As a result, the range of back pages is allowed to be configured depending on the type of applications as appropriate, thereby improving the usability. 
     In the first embodiment, the priority level for each of the objects is allowed to be displayed on the screen  913 . Thus, a page of an object to be relocated first is allowed to be checked easily by the administrator, thereby improving the usability. 
     Second Embodiment 
     A second embodiment is described with reference to  FIGS. 24 to 37 . The second embodiment is an example of the object-based tier management system that targets a virtual machine environment. The second embodiment is described with reference to the drawings in order while focusing on the difference between the first embodiment and the second embodiment because there are many common points between the first embodiment and the second embodiment. In the second embodiment, the guest OS  4423  is an example of a “specific computer program.” In the second embodiment, as illustrated in  FIG. 26 , various pieces of information  44261 ,  44262 ,  44263 , and  44264  included in a virtual disk  4426  are examples of “object.” 
       FIG. 24  illustrates general arrangement of a computing system according to the second embodiment. The general arrangement according to the second embodiment is different from the general arrangement according to the first embodiment illustrated in  FIG. 1  in terms of a program and information stored in the memory  21  of the management computer  20 , and a program and information stored in the memory  44  of the host  40 . 
     The contents stored in the memory  21  of the management computer  20  are described. A virtual disk tier management program  2121  is a program for managing a tier for each virtual disk. The virtual disk tier management program  2121  manages the storage  30  in collaboration with a guest OS data collection program  4421  on the host  40 . 
     Virtual disk storage destination specification information  2122  is information for identifying the storage destination of a virtual disk. The virtual disk storage destination specification information  2122  defines the tier to which the virtual disk  4426  used by the guest OS  4423  is to be stored. 
     Guest OS priority level information  2123  is definition information indicating the priority level of each area in a guest OS. Virtual disk relocation information  2125  is information related to a relocation target page of pages included in the virtual disk  4426  used by the guest OS  4423 . 
     The contents of the memory  44  of the host  40  are described. The guest OS data collection program  4421  is a program for collecting information related to the guest OS  4423  and transmitting the information to the management computer  20 . The guest OS data collection program  4421  provides the virtual disk tier management program  2121  with guest OS arrangement information  4424  and virtual disk performance information  4425 . 
     The hypervisor  4422  is a foundation program for performing the execution management and operation management of the guest OS  4423 . The guest OS  4423  is basic software for operating on the hypervisor  4422  and executing an application program, etc. The guest OS arrangement information  4424  is information related to internal arrangement of the guest OS  4423 . The virtual disk performance information  4425  is information related to the performance of the virtual disk  4426  used by the guest OS  4423 . 
       FIG. 25  illustrates a relation between the guest OS  4423  and the page relocation. The hypervisor  4422  is allowed to cause the one or more guest OSs  4423  to operate. The virtual disk  4426  is used as the memory area of the guest OS  4423 . The virtual disk  4426  uses a logical block  45211  on the logical volume  451 . The inside of the logical volume  451  and the storage  30  according to the second embodiment is similar to the arrangement described in  FIG. 2  in the first embodiment, so that the description is omitted. 
       FIG. 26  illustrates the information type stored in the virtual disk  4426 . In the virtual disk  4426 , for example, all of or part of a system program  44261 , system data  44262 , an application program  44263 , and application data  44264  are stored. 
     The system program  44261  includes one or more files holding a program that is the guest OS  4423  itself. The system data  44262  includes one or more files holding data used by the system program  44261 . 
     The application program  44263  includes one or more files holding an application program operating on the guest OS  4423 . The application data  44264  includes one or more files holding data used by the application program  44263 . 
       FIG. 27  illustrates an arrangement example of the virtual disk storage destination specification information  2122  used by the virtual disk tier management program  2121 . The virtual disk storage destination specification information  2122  is used for identifying a tier that is to be a storage destination for each of the virtual disks  4426  used by the guest OS  4423 . The virtual disk storage destination specification information  2122  is allowed to accept an input of the contents of the management terminal  10 , for example, by using the management terminal  10  by the administrator of the host  40 . Alternatively, the contents may be input by another means. 
     The virtual disk storage destination specification information  2122  includes a hypervisor identification name  21221 , a virtual disk identification name  21222 , and a specified tier  21223 , as the attribute, and holds information in the virtual disk  4426  unit used by the guest OS  4423 . 
     The hypervisor identification name  21121  holds an identification name for uniquely identifying the hypervisor  4422 . The virtual disk identification name  21222  holds an identification name for uniquely identifying the virtual disk  4426  used by the guest OS  4423 . The specified tier  21223  holds one of an identification name for uniquely identifying the tier  3521  that is a storage destination and an identification code indicating that there is no specified tier. 
     In the object storage destination specification information  2112 , information for all of the virtual disks  4426  in the hypervisor  4422  may be not necessarily registered. For an unregistered virtual disk  4426 , it may be configured that there is no specified tear, or an initial value of a specified tier may be applied to the unregistered virtual disk  4426  by defining the initial value beforehand. 
       FIG. 28  is an arrangement example of guest OS priority level information  2123  used by the virtual disk tier management program  2121 . The guest OS priority level information  2123  is an example of “priority level management information.” The guest OS priority level information  2123  manages the priority level of information related to the guest OS  4423  for each information type. The guest OS priority level information  2123  is allowed to accept an input of the contents of the management terminal  10 , for example, using the management terminal  10  by the administrator of the host  40 . Alternatively, the contents may be input by another means. 
     The guest OS priority level information  2123  includes a hypervisor identification name  21231 , a guest OS identification name  21232 , and a priority level  21233  for each information type, as the attribute, and holds information in the guest OS  4423  unit. 
     The hypervisor identification name  21121  holds an identification name for uniquely identifying the hypervisor  4422 . The virtual disk identification name  21222  holds an identification name for uniquely identifying the virtual disk  4426  used by the guest OS  4423 . A priority level  21233  for each information type holds an identification code for identifying the priority level for each information type. In the priority level  21233  for each information type, the priority level  212331  of a system program, the priority level  212332  of system data, the priority level  212333  of an application program, and the priority level  212334  of application data are included. 
     In the guest OS priority level information  2123 , information for all of the guest OSs  4423  in the hypervisor  4422  may be not necessarily registered. To the unregistered the guest OS  4423 , an initial value may be applied. 
       FIG. 29  is an arrangement example of virtual disk storage state information  2124  used by a virtual disk tier management program  2121 . The virtual disk storage state information  2124  includes a hypervisor identification name  21241 , a guest OS identification name  21242 , a virtual disk identification name  21243 , an information type  21244 , and the number of used pages  21245 , as the attribute, and holds information for each of the information types allocated in a virtual disk  4426 . 
     The hypervisor identification name  21241  holds an identification name for uniquely identifying the hypervisor  4422 . The guest OS identification name  21242  holds an identification name for uniquely identifying the guest OS  4423 . The virtual disk identification name  21243  holds an identification name for uniquely identifying the virtual disk  4426  used by the guest OS  4423 . The information type  21244  holds information for identifying the information type stored in the virtual disk  4426 . The number of used pages  21145  is obtained by counting, for each of the tiers  3521 , the number of pages  3511  corresponding to the logical block  4511  to be used, for each information type stored in the virtual disk  4426 . 
       FIG. 30  is an arrangement example of the virtual disk relocation information  2125  used by the virtual disk tier management program  2121 . The virtual disk relocation information  2125  includes a hypervisor identification name  21251 , a guest OS identification name  21252 , a virtual disk identification name  21253 , an information type  21254 , the number of relocation target pages  21255 , and a page relocation required time  21256 , as the attribute, and holds information for each of the information types allocated in the virtual disk  4426 . 
     The hypervisor identification name  21251  holds an identification name for uniquely identifying the hypervisor  4422 . The guest OS identification name  21252  holds an identification name for uniquely identifying the guest OS  4423 . The virtual disk identification name  21253  holds an identification name for uniquely identifying the virtual disk  4426  used by the guest OS  4423 . The information type  21254  holds information for identifying the information type stored in the virtual disk  4426 . The number of relocation target pages  21255  holds the number of relocation target pages for each combination pattern of a source tier and a destination tier. The page relocation required time  21256  holds a time required for the page relocation. 
       FIG. 31  is an arrangement example of the guest OS arrangement information  4424  used by a guest OS data collection program  4421 . The guest OS arrangement information  4424  is created, for example, by obtaining desired information from the hypervisor  4422  in response to a request from the virtual disk tier management program  2121 . 
     The guest OS arrangement information  4424  includes a guest OS identification name  44241 , a virtual disk identification name  44242 , an information type  44243 , a storage identification name  44244 , a logical volume identification name  44245 , and a logical block address  44246 , as the attribute, and holds information for each of the information types in the virtual disk  4426 . 
     The guest OS identification name  44241  holds an identification name for uniquely identifying the guest OS  4423 . The virtual disk identification name  44242  holds an identification name for uniquely identifying the virtual disk  4426  used by the guest OS  4423 . The information type  44243  holds information for identifying the information type stored in the virtual disk  4426 . The storage identification name  44244  holds an identification name for uniquely identifying the storage  30  providing the logical volume  451  storing the data of the virtual disk  4426 . The logical volume identification name  44245  holds an identification name for uniquely identifying the logical volume  451  storing the data of the virtual disk  4426 . The logical block address  44246  holds the specific number of identification codes for uniquely identifying a logical block on the logical volume  451  storing the data of the virtual disk  4426 . 
       FIG. 32  is an arrangement example of virtual disk performance information  4425  used by the guest OS data collection program  4421 . The virtual disk performance information  4425  is created, for example, by obtaining desired information from the hypervisor  4422  in response to a request from the virtual disk tier management program  2121 . 
     The virtual disk performance information  4425  includes a guest OS identification name  44251 , a virtual disk identification name  44252 , and the number of I/Os  44253 , as the attribute, and holds information in the virtual disk  4426  unit used by a guest OS  4423 . 
     The guest OS identification name  44251  holds an identification name for uniquely identifying the guest OS  4423 . The virtual disk identification name  44252  holds an identification name for uniquely identifying the virtual disk  4426 . The number of I/Os  44253  holds a value indicating the number of I/Os of the virtual disk  4426 . 
       FIG. 33  is a flowchart of a process for identifying the storage destination of a virtual disk. In the system according the second embodiment, an allocation destination tier (storage destination tier) is configured to the page  3511  used by the virtual disk  4426 . 
       FIG. 33  illustrates a series of processes for instructing the page relocation, the series of processes are executed by the virtual disk tier management program  2121 . The virtual disk tier management program  2121  is allowed to refer to the guest OS arrangement information  4424  and the virtual disk performance information  4425  through the guest OS data collection program  4421  and refer to the pool management information  3143 , the page storage state information  3144 , and the page storage destination specification information  3145  through the page-based tier management program  3142 , as appropriate. 
     The virtual disk tier management program  2121  prepares the virtual disk storage destination specification information  2122  (S 8301 ). The virtual disk tier management program  2121  configures the tier  3521  that is to be an allocation destination of the virtual disk  4426  used by the guest OS  4423 , to the virtual disk storage destination specification information  2122  by a specific method. For example, a method may be provided in which a value is registered to the virtual disk storage destination specification information  2122  by accessing the virtual disk tier management program  2121  through the management terminal  10  by the administrator, etc. of the host  40 . 
     The virtual disk tier management program  2121  creates the virtual disk storage state information  2124  (S 8302 ). The virtual disk storage state information  2124  is allowed to be created based on, for example, the guest OS arrangement information  4424  and the page storage state information  3144 . 
     The LBA of the logical block  4511  used by information of each of the types of the guest OS  4423  is allowed to be identified by referring to the logical block address  44246  of the guest OS arrangement information  4424 . The page address of the page  3511  corresponding to the logical block  4511  is allowed to be calculated by the method described in  FIG. 2 . The tier to which the data of a specific page address is stored is allowed to be identified by referring to the storage destination tier  31443  of the page storage state information  3144 . 
     By the methods, the storage destination tier of the page used by the information of each of the types (hereinafter referred to as information type) related to the guest OS  4423  is allowed to be identified, and the number of pages used by each of the information types of the guest OS  4423  is allowed to be counted for each of the tiers. 
     The virtual disk tier management program  2121  creates the virtual disk relocation information  2125  (S 8303 ). The virtual disk relocation information  2125  is allowed to be created based on, for example, the virtual disk storage destination specification information  2122  and the virtual disk storage state information  2124 . The creation method is similar to the method for creating the object relocation information  2116  (step S 8111  in  FIG. 15 ). 
     The virtual disk tier management program  2121  executes a sorting process for the virtual disk relocation information  2125  (S 8304 ). The virtual disk tier management program  2121  sorts the lines of the virtual disk relocation information  2125  in ascending order of the priority level  21233  for each information type in the guest OS priority level information  2123 . When the priority level  21233  have the same values between different guest OSs  4423 , high priority may be given to the guest OS  4423  having the larger number of I/Os  44252  of the virtual disk performance information  4425 . 
     The virtual disk tier management program  2121  selects a relocation target page in a range in which the relocation is allowed to be performed within one cycle of the page relocation (S 8305 ). The page relocation cycle is obtained by referring to the cycle  314341  of the pool management information  3143 . For example, when the hypervisor  4422  that is a processing target uses “Volume-A,” the cycle is “one hour.” 
     Relocation target pages of which the portion is allowed to be allocated within one cycle of the page relocation are selected from the top of the virtual disk relocation information  2125 . For example, when the page relocation cycle is one hour, relocation target pages are selected until a page relocation required time counted from the top line reaches 3600 seconds. In the example of  FIG. 30 , all pages of the information types from the first line to the third line of the virtual disk relocation information  2125  and a page up to the middle of the information type of the fourth line are the targets. That is, all relocation target pages of system data of a guest OS “Guest-B,” all relocation target pages of application data of a guest OS “Guest-A,” all relocation target pages of system data of the guest OS “Guest-A,” and a part of relocation target pages of the guest OS “Guest-B” are selected. 
     The virtual disk tier management program  2121  configures the storage destination specification of the page selected in step S 8305  to the storage (S 8306 ). The virtual disk tier management program  2121  configures the storage destination tier of each page selected in step S 8305  or step S 8310  to the page storage destination specification information  3145  through the page-based tier management program  3142 . 
     The virtual disk tier management program  2121  determines whether or not there is an unprocessed page (S 8307 ). In previous step S 8306 , when the selection process for pages of one cycle portion of the relocation process is not performed, there is no unprocessed page (S 8307 : No), so that the process ends. In step S 8306 , relocation target pages are selected by the number of pages (the number of upper limit pages) allowed to be processed by the page relocation process for one cycle portion (page relocation process for one time). Thus, in step S 8306 , when relocation target pages are not selected up to the number of upper limit pages, it is indicated that the selection of all relocation target pages is completed. 
     The virtual disk tier management program  2121  waits for subsequent page relocation timing (S 8308 ). By the waiting process, the page relocation corresponding to the contents configured to the storage  30  in step S 8306  is processed within the one cycle. 
     Step S 8309  is substantially the same as step S 8305 . A difference between steps S 8309  and S 8305  is described. In step S 8305 , pages are selected in order of the information type in the top line of the virtual disk relocation information  2125 . On the other hand, in step S 8309 , pages are selected in order of an unprocessed information type in which the configuration to the storage  30  is not completed. 
     In an example of  FIG. 33 , the case is described in which the configuration to the storage  30  is performed for each one cycle of the page relocation process in step S 8306 . Alternatively, when the page-based tier management program  3142  includes a function for performing the page relocation in order of the configuration of the virtual disk tier management program  2121 , all relocation target pages are selected in step S 8305 , and the process may ends after executing step S 8306 . 
     Next, an example of an operation screen according to the second embodiment is described with reference to the drawings. The screen described below may be displayed, for example, when accessing the virtual disk tier management program  2121  using the management terminal  10  by the administrator, etc. of the host  40 . 
       FIG. 34  illustrates a hypervisor list screen  921 . The hypervisor list screen  921  displays a list of the hypervisor  4422  that is a management target of a virtual disk tier management program  2121 . 
     In a hypervisor display area  9211 , the identification name of the hypervisor  4422  that is a management target is displayed. A status display area  9212  is used for checking a status related to the page relocation process, and when the page relocation process is in progress, the status is displayed on the status display area  9212 . 
     An edit button  9214  is a button for specifying a storage destination for selected hypervisor  9213 . When the edit button  9214  is pressed by the administrator, etc. of the host  40 , a screen of  FIG. 35  is opened. 
     A detail button  9215  is a button for displaying the detailed information of the status of the page relocation process related to the selected hypervisor  4422 . When the detail button  9215  is pressed by the administrator, etc. of the host  40 , the detail screen of a status is opened. The detail screen of a status includes contents similar to the contents of screen  914  illustrated in  FIG. 23 . However, a text displayed in the screen is different from that of the first embodiment. A close button  9216  is a button for closing screen  921  of  FIG. 34 . When the close button  9216  is pressed by the administrator, etc. of the host  40 , the screen  921  of  FIG. 34  is closed. 
       FIG. 35  is an edit screen  922  of a virtual disk storage destination. The edit screen  922  is used for specifying a target storage destination tier of a virtual disk  44121  in the hypervisor  4422 . 
     On a guest OS display area  9220 , the identification name of the guest OS  4423  is displayed. On a virtual disk display area  9221 , the identification name of the virtual disk  4426  is displayed. A storage destination specification area  9222  is used for specifying the storage destination of an object in a virtual disk. The storage destination specification area  9222  includes a current state display area  9223  and a change option  9224 . 
     On the current state display area  9223 , the contents of a storage destination specification configured to the virtual disk  4426  are displayed. When a storage destination is not specified, “unspecified” is displayed. The change option  9225  provides a function for specifying the storage destination of the virtual disk  4426 . A desired storage destination is allowed to be specified using the change option  9225  by the administrator, etc. of the host  40 . 
     A check button  9226  is a button for fixing the contents selected by a change option  9225 . When the check button  9226  is pressed by the administrator, etc. of the host  40 , the screen proceeds to a screen  923  of  FIG. 36 . A cancel button  9227  is a button for cancelling the contents selected in the change option  9225 . When the cancel button  9227  is pressed by the administrator, etc. of the host  40 , the screen  922  of  FIG. 35  is closed and the screen returns to the screen  921  of  FIG. 34 . 
       FIG. 36  illustrates the screen  923  for checking the configuration contents of a virtual disk storage destination and is a screen for checking the contents configured in the screen  922  of  FIG. 35 . 
     On a required time display area  9230 , the time required for page relocation is displayed. For example, processes corresponding to step S 8302  to step S 8305  of  FIG. 33  may be performed, and the total value of the page relocation required time  21256  of the virtual disk relocation information  2125  may be displayed on the required time display area  9230 . 
     On a guest OS display area  9231 , the identification name of the guest OS  4423  is displayed. On a virtual disk display area  9232 , the identification name of the virtual disk  4426  is displayed. 
     A storage destination specification area  9233  is used for displaying the change of the storage destination specification contents of a virtual disk, and includes a current state display area  9234  and a changed state display area  9235 . On the current state display area  9234 , the contents of storage destination specification currently configured as the virtual disk  4426  are displayed. When the storage destination is not specified, “unspecified” is displayed. On the changed state display area  9235 , the contents configured in the changed state display area  9224  of the screen  922  of  FIG. 35  are displayed. 
     An information type  9236  displays information for identifying an information type included in the virtual disk  4426 . A relocation capacity display area  9237  displays the relocation target capacity of each of the information types. The display area  9237  may display a capacity based on the number of relocation target pages  21255  of the virtual disk relocation information  2125 . 
     A relocation priority order display area  9238  displays the priority level of the page relocation of each of the information types. The display area  9238  may display a number corresponding to the described order in the virtual disk relocation information  2125  as the priority level. 
     An execution button  9139  is a button for instructing the execution of page relocation. When the execution button  9139  is pressed by the administrator, etc. of the host  40 , the page relocation starts while the screen  923  of  FIG. 36  is closed and the screen returns to screen  921  of  FIG. 34 . A cancel button  9140  is a button for cancelling the execution of page relocation. When the cancel button  9140  is pressed by the administrator, etc. of the host  40 , the screen  923  of  FIG. 36  is closed and the screen returns to the screen  921  of  FIG. 34 . 
     In the second embodiment, the case is described in which the priority level of the page relocation is determined based on the guest OS priority level information  2123  mainly illustrated in  FIG. 28 . In addition to the method, for example, a priority level may be determined by a method described below. 
     (1) the Operation Status of a Guest OS 
     A guest OS is allowed to operate and stop. The priority level of page relocation may be reduced because access to the virtual disk  4426  does not occur during the stop of a guest OS. In addition, determination of the priority level of page relocation may be performed based on the operation status of a program executed on a guest OS, in addition to checking of the operation status of a guest OS. For example, when a guest OS operates and a program does not operate on the guest OS, the priority level may be reduced. 
     (2) the Running Schedule of a Guest OS 
     It is probable that a guest OS is operated based on a schedule. In this case, page relocation is performed so that the page relocation is completed before the operation of the guest OS. Thus, configuration timing to the storage  30  is adjusted so that the page relocation is completed before the operation of the guest OS. When a guest OS is about to proceed to a termination time period, the configuration to the storage  30  may be put off. It is noted that the priority level of page relocation may be determined based on the running schedule of a program executed on a guest OS instead of the running schedule of a guest OS. 
     (3) the Front Part or Back Part of a Page Group Used by a Guest OS 
     In the first embodiment, the case is described in which high priority is given to back pages of pages included in an object. High priority may be given to the page relocation of front pages or back pages of pages included in information types related to a guest OS using the method. 
     It is noted that the above-described (1) and (2) are allowed to be applied to the DBMS described in the first embodiment. 
     The above-described second embodiment is also allowed to obtain effects similar to the first embodiment. 
     Third Embodiment 
     A third embodiment is described with reference to  FIGS. 37 to 43 . In the third embodiment, a technology is described that complements the object-based tier management system described in the first embodiment. The general system arrangement is similar to the arrangement in  FIG. 1 . A difference between the first embodiment and the third embodiment is mainly described below. 
     In the first embodiment, the process in a case in which the object storage destination specification information  2112  is registered or updated is described with reference to the flowchart of  FIG. 14 . Another timing at which the storage destination of a page is specified to the storage  30  may be time to change the virtual page  3511  assigned to an object. 
     In the DBMS  4412 , when data is added to a table, the data capacity increases. On the contrary, when data is deleted from the table, the data capacity decreases.  FIG. 37  illustrates a state in which the data capacity of an object increases and a state in which the data capacity of an object decreases. 
     On the upper side of  FIG. 37 , two types of the objects  44121  and  44122  are illustrated. Initial states in which data does not increase and decrease are displayed as  44121  ( 1 ) and  44122  ( 1 ), respectively. States in which data increases and decreases are displayed as  44121  ( 2 ) and  44122  ( 2 ), respectively. Any of the objects  44121  and  44122  has a type of a table. 
     In the initial state, “Table-A” object  44121  ( 1 ) includes a data capacity  441211  ( 1 ), and “Table-B” object  44122  ( 1 ) includes a data capacity  441221  ( 1 ). 
     On the lower side of  FIG. 37 , cases in which data capacity increases and decreases are illustrated, respectively. The increased portion  441212  ( 2 ) of a usage area is generated in “Table-A” object  44121  ( 2 ) because data is added to “Table-A” object  44121  ( 2 ). The deleted portion  441222  ( 2 ) of the usage area is generated in “Table-B” the object  44122  ( 2 ) because data is deleted from “Table-B” object  44122  ( 2 ). 
       FIG. 38  illustrates a case in which the data capacity of the object  44121  increases. The increased portion  441212  ( 2 ) of a usage area of the object  44121  ( 2 ) uses a logical block  45121  on the logical volume  451 . The logical block  45121  uses the virtual page  3512  on the virtual volume  351 , and the virtual page  3512  uses a page  35213  of the lower tier  3521 . 
     The page-based tier management program  3142  of the storage  30  does not detect an object by which the virtual page  3512  that is newly used in the virtual volume  351  is used. Thus, the page-based tier management program  3142  configures the value of the specified tier  31453  of the page storage destination specification information  3145  as an initial value, for example, “unspecified” for a newly assigned virtual page. 
     As described above, when the usage area of an object increases, a page to which a value of the specified tier  31453  of the page storage destination specification information  3145  is not configured appropriately, of pages used by the object is generated. In addition, when the usage area of an object decreases, the page is generated. 
     In order to deal with increase or decrease in the usage area of an object in the third embodiment, the contents of the page storage destination specification information  3145  are updated periodically or when it is detected that the usage area of an object increases or decreases. 
     The contents of the process are substantially the same as that of the object storage destination specification process illustrated in  FIG. 14 , and the process of the third embodiment is different from the object storage destination specification process illustrated in  FIG. 14  in terms that step S 8101  is not executed. 
     It is probable that the above-described process in which increase or decrease in the usage area of an object is dealt with and the process described in the first embodiment in which the object storage destination specification information  2112  is registered or updated are executed in the same period. For convenience, the process in which the increase or decrease in the usage area of an object is dealt with may be referred to as a usage area increase or decrease process below. For convenience, the process in which the object storage destination specification information  2112  is registered or updated may be referred to as a storage destination registration process below. 
     In the third embodiment, the storage destination of a page is specified to the storage  30  by considering the load of page relocation generated in each of the usage area increase or decrease process and the storage destination registration process. Therefore, in the third embodiment, the page relocation performance of the storage  30  is assigned to the usage area increase or decrease process and the storage destination registration process at a specific rate. 
     For example, 80% of the page relocation performance of the storage  30  is assigned to the usage area increase or decrease process, and the rest 20% is assigned to the storage destination registration process. For example, as illustrated in page relocation performance assignment rate  21136  of  FIG. 39 , the allocate rate to each of the processes may be defined as one item of the DBMS priority level evaluation policy information  2113 . 
     As described above, the page relocation performance assignment rate  21136  indicates rates at which the page relocation performance is assigned to two or more different processes (usage area increase or decrease process and storage destination registration process). As illustrated in step S 8112  of  FIG. 15 , etc., the value of the page relocation performance assignment rate  21136  is considered when a page is selected so as to be processed within one cycle of relocation process. 
     For example, a case is descried in which the number of upper limit pages allowed to be processed within one cycle of page relocation performance is 3600 pages and the assignment rate to the storage destination registration process (step S 8112 , etc. in  FIG. 15 ) is 20%. In this case, in the storage destination registration process, the relocation target pages having high priority level are selected in order while configuring the number of upper limit pages as 720 pages (=3600×0.2). 
     When there is the excess of page relocation performance assigned to one process, the excess relocation performance may be assigned to the other process. 
     The priority level of page relocation may be changed by distinguishing the increase in the usage area of an object from the decrease in the usage area of an object. The capacity of the upper tier  3521  ( 1 ) having a high speed performance of an I/O process of each of the tiers  3521  of the pool  352  is generally smaller than that of the middle tier  3521  ( 2 ) and the lower tier  3521  ( 3 ). Thus, the free capacity of the upper tier  3521  ( 1 ) becomes lacking. 
     Therefore, when the virtual page  3511  that is no longer in use with the decrease in the usage area of an object uses a page  35212  of the upper tier  3521  ( 1 ), the storage destination specification for the virtual page  3511  that is no longer in use is cleared to return to the upper tier  3521  ( 1 ). As a result, it is desirable that the virtual page  3511  that is no longer in use is assigned to another object. 
     On the other hand, when the upper tier  3521  ( 1 ) is specified as the storage destination of an object, it is estimated that the object is critical in terms of performance. Thus, it is desirable that the page of the object required to be processed with high performance is relocated more immediately. 
     Storage destination specification clear priority  21137  and upper tier-related process priority  21138  included in the DBMS priority level evaluation policy information  2113  ( 2 ) described in  FIG. 39  are definition information prepared based on the above-described background. 
     To the storage destination specification clear priority  21137 , information that indicates whether or not high priority is given to the specification clear of a tier is configured. The high priority is given to the specification clear, when “Yes” is configured to the storage destination specification clear priority  21137 , and the high priority is not given to the specification clear when “No” is configured to the storage destination specification clear priority  21137 . The assignment of the page that is used as a virtual page in the upper tier is cleared when “Yes” is configured to the storage destination specification clear priority  21137 . 
     To the upper tier-related process priority  21138 , information that indicates whether or not high priority is given to the page relocation (storage destination specification) related to the upper tier is configured. The high priority is given to the page relocation when “Yes” is configured to the upper tier-related process priority  21138 , and the high priority is not given to the page relocation when “No” is configured to the upper tier-related process priority  21138 . There are page migration from the middle tier or lower tier to the upper tier and page migration from the upper tier to the middle tier or lower tier, as the process related to the upper tier. 
     When “(ALL)” is configured to the value of a DBMS identification name  2113  of  FIG. 39 , the configuration is applied to all of the DBMSs  4412 . When the identification name of the specific DBMS  4412  is configured to an identification name  2113 , the contents illustrated in  FIG. 39  may be applied to the mere DBMS  4412 . 
     The values of the storage destination specification clear priority  21137  and the upper tier-related process priority  21138  are allowed to be obtained by the filtering of a processing target page, similar to the process in the back page priority described in  FIG. 14  of the first embodiment. 
     In the process related to a page relocation performance assignment rate  2135 , a page relocation process depending on the number of I/Os (hereinafter also referred to as conventional page relocation process) may be considered. In the third embodiment, a page relocation process based on the page storage destination specification information  3145  (hereinafter also referred to as page relocation process according to the third embodiment) is described. 
     However, when the page relocation process according to the third embodiment and the conventional page relocation process share the page relocation performance of the storage  30 , it is probable that the page relocation performance included in the storage  30  is used up by the mere page relocation process according to the third embodiment. 
     In order to avoid the occurrence of the problem, for example, the total of each of the rates  211361  and  211362  specified in the page relocation performance assignment rate  2135  may be configured as less than 100%. 
     For example, when 15% of the page relocation performance is assigned to an object storage destination specification responding process  211361  and 65% of the page relocation performance is allocated to an object scaling responding process  211362 , the rest 20% (20% of the page relocation performance included in the storage  30 ) is allowed to be used for the conventional page relocation process. 
     On the contrary, it is probable that the page relocation performance of the storage  30  is almost exhausted by the mere conventional page relocation process. Therefore, for example, a new area (may be referred to as “conventional page relocation process  211353 ” if the area needs a name or numeral) is added to the page relocation performance assignment rate  21136 . In addition, each of the values may be configured so that the total value of the value of the object storage destination specification responding process  211361 , the value of the object scaling responding process  211362 , and the value of the conventional page relocation process is 100%. 
     It is noted that the third embodiment may be applied to both of the first embodiment and the second embodiment. In addition, in the third embodiment, the case is described in which the increased or decreased usage area is processed on a priority basis, and alternatively, a portion that is not changed may be processed on a priority basis. For example, the value of the object storage destination specification responding process  211361  may be 80%, and the value of the object scaling responding process  211362  may be 20%. 
     Fourth Embodiment 
     A fourth embodiment is described with reference to  FIGS. 40 to 43 . In the fourth embodiment, another technology for complementing the object-based tier management system described in first embodiment is described. The entire system arrangement is similar to the configuration of  FIG. 1  described in the first embodiment. Description is performed by focusing on a difference of the fourth embodiment and the first embodiment. 
     In the first embodiment, mainly, the case is described in which the page relocation is performed based on the priority level of each of the object in the storage destination specification process for an object in one DBMS  4412 . In the fourth embodiment, a case is described in which the storage destination specification of an object is performed for each of the two or more DBMSs  4412 , together. 
     For example, it is assumed that the two or more DBMSs  4412  ( 1 ) and  4412  ( 2 ) that are page relocation targets exist on identical or different hosts  40 . If the page relocation performance included in the storage  30  is almost exhausted by the mere storage destination specification process of an object related to the first DBMS  4412  ( 1 ), the progress of the page relocation of the second DBMS  4412  ( 2 ) gets stacked up. Therefore, the amount of the page relocation of each of the DBMSs  4412  ( 1 ) and  4412  ( 2 ) is controlled appropriately. 
     A method for adjusting the page relocation amount between the two or more DBMSs  4412  is described. In a first method, an assignment rate is configured in each of the DBMSs  4412  similar to the relocation performance assignment rate  21136  (See  FIG. 39 ) of the third embodiment. The page relocation process in each of the DBMSs uses the page relocation performance of the storage  30  depending on the assignment rate. 
     In the first method, it is allowed to be avoided that the specific DBMS  4412  almost exhausts the page relocation performance of the storage  30 . However, in the first method, in the DBMS  4412  having a low assignment rate, a time to complete the page relocation process is increased when a large amount of relocation target page occurs. 
     In a second method, the first method is improved. In the second method, a weight value for correcting a page relocation amount is configured for each of the DBMSs  4412 . 
       FIG. 40  is an example of the DBMS priority level evaluation policy information  2113  ( 3 ) when the second method is used. A DBMS-based page relocation priority level  21138  is added to the DBMS priority level evaluation policy information  2113  ( 3 ), as the attribute. The DBMS-based page relocation priority level  21138  defines the priority level of page relocation for each of the DBMSs  4412 . In the example of  FIG. 40 , three values of “High (10),” “Mid (3),” and “Low (1)” are employed. The numbers in parentheses indicate the weight. 
       FIGS. 41 and 42  illustrate flowcharts of processes for calculating an assignment time for each of the DBMSs  4412 . In the process, the page relocation process period allowed to be used for each of the DBMSs  4412  is calculated so that the total value of the time required for the page relocation process of each of the DBMSs  4412  is within one cycle of the page relocation process. The contents of the process are described below based on calculation results illustrated in  FIG. 43 . 
     First, the contents of the process are described below with reference to  FIG. 41 . The object tier management program  2111  creates a list of a DBMS (S 8401 ). The list of a DBMS is allowed to be created by extracting the DBMS identification name  21131  from the DBMS priority level evaluation policy information  2113  ( 3 ) illustrated in  FIG. 40  (See, the DBMS identification name  21412  of  FIG. 43 ). 
     The management program  2111  substitutes the time for one cycle of the page relocation process for a variable (E) (S 8402 ). The time of one cycle of the page relocation process is obtained by referring to the cycle  314341  of the pool management information  3143  illustrated in  FIG. 9 . In the fourth embodiment, description is performed while configuring the time of one cycle of the page relocation process as 3600 seconds (See, a page relocation cycle  21411  of the storage of  FIG. 43 ). 
     The management program  2111  calculates a time (A) required for the page relocation for each of the DBMSs  4412  (S 8403 ). The time required for the page relocation of each object in the DBMS  4412  is allowed to be calculated by the method described in the first embodiment. 
     It is assumed that the time for “DBMS-A” is 800 seconds, the time for “DBMS-B” is 1200 seconds, and the time for “DBMS-C” is 10000 seconds when the page relocation required time (A) is calculated for each of the DBMSs  4412  (See, page relocation required time  21413  of  FIG. 43 ). 
     The management program  2111  calculates a time (B) by multiplying the page relocation required time (A) of each of the DBMSs  4412  by the weight value of the DBMS-based page relocation priority level  21138  illustrated in  FIG. 40  (S 8404 ). 
     As illustrated in  FIG. 40 , the weight value of “DBMS-A” is 3, the weight value of “DBMS-B” is 10, and the weight value of “DBMS-C” is 1. Thus, after the weighting, the time required for “DBMS-A” is 2400 seconds (=800 seconds×3), the time required for “DBMS-B” is 12000 seconds (=1200 seconds×10), and the time required for “DBMS-C” is 10000 seconds (=10000 seconds×1). The results are indicated in a post-weighting required time  21414  of  FIG. 43 . 
     The management program  2111  calculates the total value (C) of the time (B) obtained in step S 8404  (S 8405 ). The total value (C) is 24400 seconds (=2400 seconds+12000 seconds+10000 seconds). 
     The management program  2111  selects the DBMS  4412  having a maximum value after the weighting (S 8406 ). The management program  2111  selects “DBMS-B” because the “DBMS-B” has a maximum value 10 after the weighting. 
     The management program  2111  calculates a page relocation time (D) assigned to the selected DBMS (S 8407 ). Specifically, the required time (B) of the DBMS  4412  selected in step S 8406  obtained after the weighting is divided by the total value (C) of required times of all of the DBMSs obtained after the weighting, and is multiplied by the value of variable (E) ((D)=((B)/(C))×(E)). 
     In the above-described example, 12000 seconds (See, the second line of the required time  21414  obtained after the weighting in  FIG. 43 ) is divided by 24400 seconds that is the calculation result in step S 8405 , and is multiplied by 3600 seconds that is the value of variable (E), so that 1770 seconds that is an assignment time (D) is obtained (See, the second line of the assignment time  21415  obtained after the reallocation in  FIG. 43 ). 
     Description is made with reference to  FIG. 42 . The management program  2111  determines whether or not the required time (A) of the original page relocation related to the selected DBMS  4412  exceeds the assignment time (D) calculated in step S 8407  (S 8408 ). 
     When the original required time (A) does not exceed the assignment time (D) (S 8408 : Yes), the original required time (A) is used as a page relocation time assigned to the selected DBMS  4412  (S 8409 ). In addition, the flow proceeds to step S 8410 , and the management program  2111  subtracts the time (A) applied in step S 8409  from the variable (E) ((E)=(E)−(A)). 
     When the original required time (A) exceeds the assignment time (D) (S 8408 : No), the management program  2111  uses the assignment time (D) calculated in step S 8407  as a page relocation time assigned to the selected DBMS  4412  (S 8411 ). In addition, the flow proceeds to step S 8412 , and the management program  2111  subtracts time (D) applied in step S 8411  from the variable (E) ((E)=(E)−(D)). 
     In the above-described example, the original required time (A) related to the selected “DBMS-B” (the second line of page relocation required time  21413 ) is 1200 seconds, and the assignment time (D) (the second line of the assignment time  21415  obtained after the relocation in  FIG. 43 ) is 1770 seconds. The required time of 1200 seconds is applied (See, the second line of the assignment time  21416  obtained after the DBMS-B correction in  FIG. 43 ) because the required time (A) does not exceed the assignment time (D), and the applied 1200 seconds are subtracted from the value of 3600 seconds of the variable (E). As a result, the value of the variable (E) is 2400 seconds. 
     In step S 8413 , the management program  2111  removes the selected DBMS  4412  from the DBMS list created in step S 8401 . In the above-described example, the selected “DBMS-B” is removed from the DBMS list. 
     The management program  2111  determines whether or not the DBMS  4412  remains in the DBMS list (S 8414 ). When the DBMS  4412  does not remain in the DBMS list (S 8414 : No), the process ends. When the DBMS  4412  remains in the DBMS list (S 8414 : Yes), the flow returns to step S 8403  in  FIG. 3 , and the process continues. 
     In the above-described example, when the processes from step S 8403  to step S 8414  are repeated, the assignment time of “DBMS-A” is 465 seconds, and the assignment time “DBMS-C” is 1953 seconds, eventually (See, post-DBMS-B correction assignment time  21416  in  FIG. 43 ). 
     In the example of  FIG. 40 , in the “DBMS-C”, the value of the DBMS-based page relocation priority level  21138  is Low (1), and the priority level is low. However, an assignment time that is relatively long as compared to another “DBMS-A” and “DBMS-B” is configured because 10000 seconds of the page relocation required time of the “DBMS-C” is long. Thus, in the fourth embodiment, when the priority level of the “DBMS-C” is low and a large amount of relocation target page is generated, the process period for page relocation is allowed to be configured long. 
     Thus, in the fourth embodiment, when the page relocation process is performed in the two or more DBMSs  4412  together, the page relocation performance of the storage  30  is allowed to be assigned depending on the weight value configured to each of the objects beforehand. Therefore, when a weight value is given to a DBMS for which high speed process is required or when a low weight value is given to a less important DBMS, the page relocation performance of the storage  30  is allowed to be effectively used depending on the nature of a DBMS. 
     In addition, in the fourth embodiment, the initial assignment time (D) calculated from the weight value of each of the DBMSs is not used as-is, and the initial required time (A) that is required for the page relocation and calculated in the original calculation is compared with the initial assignment time (D). In the fourth embodiment, when the initial required time (A) is shorter than the initial assignment time (D), the initial required time (A) is selected as a last assignment time. Thus, it is allowed to be suppressed to assign a page relocation time longer than necessary to a DBMS including a relocation target page allowed to be processed by the initial assignment time (A). As a result, the page relocation performance of the storage  30  is shared between the two or more DBMSs appropriately. 
     It is noted that there is a method that is for adjusting the page relocation amount between the two or more DBMSs  4412  and in which any of the first method and the second method is not used. For example, the evaluation method for a priority level described in the first embodiment may be applied to all of the objects of two or more DBMSs. That is, a priority level is configured to each of the objects that is a management target of the management computer  20 , of each of the DBMSs. As a result, when page relocation starts between the two or more DBMSs together, depending on the priority level configured to each of the objects, the page relocation performance included in the storage  30  is allowed to be shared. 
     The present invention is allowed to be expressed as an invention of a computer program as described below. 
     “An expression 1: 
     A computer program causing a computer to function as a management apparatus for managing a computing system including at least one host computer and at least one storage apparatus, the storage apparatus including at least one virtual logical volume that is supplied to a specific computer program operating in the host computer and at least one pool that includes two or more storage tiers that include different performances, and executing a relocation process in which a virtual memory area comprised in the virtual logical volume is associated with a physical memory area of any of the two or more storage tiers in response to a write request from the host computer, and the physical memory area associated with the virtual memory area is allocated to a specific storage tier of the two or more storage tiers based on specific specification information for instructing a relocation destination, 
     the computer including a memory that is configured to store a management program for performing tier management for the two or more storage tiers and a microprocessor that is configured to execute the management program stored in the memory, the specific specification information being stored in the memory and holding information for identifying a specific storage tier in which data of two or more objects related to the specific computer program is to be stored, 
     the computer program causing the computer to execute, as a first tier management mode: 
     a priority level determination step of determining each priority level of each of the two or more objects based on priority level management information for determining a priority level related to relocation for each of the two or more objects included in the specific computer program; 
     a relocation information generation step of extracting a physical memory area that is a relocation target for each of the two or more objects based on the specific specification information and a storage state information indicating a current storage destination of the physical memory area corresponding to the virtual memory area; 
     a selection step of selecting a specific physical memory area from the extracted physical memory areas that are relocation targets based on the priority level determined for each of the two or more objects; and 
     an instruction step of instructing the storage apparatus to allocate data stored in the selected specific physical memory area to the physical memory area in the specific storage tier indicated in the specification information”. 
     REFERENCE SIGNS LIST 
     
         
           10 : management terminal,  20 : management computer,  30 : storage,  40 : host,  351 : virtual volume,  352 : pool, and  3521 : tier