Abstract:
A method for controlling hierarchical storage including: a first step for storing first information relating to the association between the specific processes and the storage regions of the storage tiers; a second step for obtaining second information relating to the access operations of the specific processes as a function of time; a third step for obtaining third information relating to the amount of access to the storage regions as a function of time; and a fourth step for identifying the time of occurrence of a change in the amount of access, from the second information and the third information on the basis of the first information, and determining, according to the identified time of occurrence of the change in the amount of access, a transfer initiation time at which data in the storage regions is to be transferred between storage tiers.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a computer system and a method for controlling its hierarchical storage. 
       BACKGROUND ART 
       [0002]    Generally, the amount of use of services fluctuates with such factors as timing. As a result, a storage system has to keep ready for its storage region having a performance level that can meet the demand in a situation in which the amount of use most increases in a large enough capacity for storing the increasing information. However, as investments in information system do not increase rapidly, inability to make available a required storage region is posing a problem. 
         [0003]    In this connection, according to Patent Literature 1, where a storage system is provided with a storage region having a plurality of different characteristics (including input/output performance and bit cost), written-in data is split into fragments of a fixed size known as pages, and the pages are arranged in a storage region manifesting designated characteristics. And there is disclosed a technique by which the storage system, after data is arranged in the storage region manifesting the designated characteristics, rearranges in the storage region having an appropriate input/output performance according to the frequency of accessing the pertinent pages by a host computer. 
         [0004]    For the convenience of description, hereinafter the storage region manifesting a plurality of different characteristics and provided in the storage system will be referred to as a storage tier, and each of the storage regions constituting the storage tier, as a tier. Further, processing to arrange pages in the storage tier and processing to rearrange pages will be referred to as hierarchical control. 
         [0005]    According to Patent Literature 1, in generally expensive storage regions (to be referred to as superior tiers) with high input/output performance, it is possible to arrange only such data as requiring that performance, but when the use of the service abruptly increases, the data to be accessed by the service may not be arranged in any superior hierarchical storage. As a result, possibility for the information system to complete the service within the expected length of time poses a problem. 
         [0006]    In view of this circumstance, Patent Literature 2 discloses a technique by which, where a response performance required to be satisfied by data used in an application program (hereinafter, an application program may be referred to simply as an application) (to be referred to as a response performance requirement) is assigned, the pertinent file is arranged in a memory device having an appropriate input/output performance for satisfying the response performance requirement is disclosed. According to Patent Literature 2, a delay or a stop in the processing of the application can be prevented by permanently arranging the data to be used by the application in a storage region satisfying the response performance requirement. 
       CITATION LIST 
     Patent Literature 
     Patent Literature 1: U.S. Patent Application Publication 2009/0300285 
     Patent Literature 2: U.S. Patent Application Publication 2012/0185426 
     SUMMARY OF INVENTION 
     Technical Problem 
       [0007]    According to Patent Literature 2, data to be used by an application remains permanently arranged in a superior tier satisfying the response performance requirement irrespective of the state of use of the application. For instance, data to be accessed only at the time of activating an application remains arranged in the superior tier even when the application is not activated or after the activation of the application is completed. As a result, since data for which response performance is not always required depending on the state of use of the application is arranged in a superior tier, the superior tier is wastefully consumed. 
         [0008]    Then, an object of the present invention is to restrain arrangement of less accessed data in a superior tier at each point of time by arranging appropriate data in a storage tier at an appropriate timing for the operation on the application, and at the same time to enhance the performance of response to the application. 
       Solution to Problem 
       [0009]    In a typical method for controlling hierarchical storage according to the present invention is executed by a control unit of a computer system having a plurality of storage tiers differing in accessing performance, an application program executed by a processing unit of the computer system has specific process to access a storage area within the storage tiers, and comprises a first step of storing first information on matching between the specific process and the storage region; a second step of acquiring second information on access actions of the specific process over time; a third step of acquiring third information on the amount of access to the storage region over time; and a fourth step of identifying the time of variation of the amount of access from the second information and the third information on the basis of the first information and so determining a migration start time as to migrate data in the storage region among the storage tiers according to the time of variation of the amount of access. 
       Advantageous Effects of Invention 
       [0010]    According to the invention, it is possible to arrange appropriate data in a storage tier at an appropriate timing for the operation on the application, restrain arrangement of less accessed data in a superior tier at each point of time, and at the same time to enhance the performance of response to the application. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  is a diagram showing an outline of hierarchical control. 
           [0012]      FIG. 2  is a diagram showing an example of configuration of a computer system. 
           [0013]      FIG. 3  is a diagram showing an example of configuration of a management computer. 
           [0014]      FIG. 4  is a diagram showing an example of configuration of a storage system. 
           [0015]      FIG. 5  is a diagram showing an example of configuration of a host computer. 
           [0016]      FIG. 6  is a diagram showing an example of configuration of a subprogram page relationship table. 
           [0017]      FIG. 7  is a diagram showing an example of configuration of an event analysis table. 
           [0018]      FIG. 8  is a diagram showing an example of configuration of I/O analysis data. 
           [0019]      FIG. 9  is a diagram showing an example of configuration of a job management table. 
           [0020]      FIG. 10  is a diagram showing an example of configuration of a page hierarchical control task management table. 
           [0021]      FIG. 11  is a diagram showing an example of configuration of IOPS transition data. 
           [0022]      FIG. 12  is a diagram showing an example of configuration of log file data. 
           [0023]      FIG. 13  is a diagram showing an example of configuration of a log file management table. 
           [0024]      FIG. 14  is a diagram showing an example of configuration of a hierarchical storage performance management table. 
           [0025]      FIG. 15  is a diagram showing an example of configuration of a log file. 
           [0026]      FIG. 16  is a diagram showing an example of configuration of a page hierarchical control management table. 
           [0027]      FIG. 17  is a diagram showing an example of configuration of a hierarchical storage capacity management table. 
           [0028]      FIG. 18  is a diagram showing an example of flow chart of an I/O analysis program. 
           [0029]      FIG. 19  is a diagram showing an example of flow chart of a hierarchical control plan formulation program. 
           [0030]      FIG. 20  is a diagram showing an example of flow chart of processing to migrate a page to a superior tier. 
           [0031]      FIG. 21  is a diagram showing an example of flow chart of processing to migrate a page to an inferior tier. 
           [0032]      FIG. 22  is a diagram showing an example of flow chart of a job end time I/O analysis correction program. 
           [0033]      FIG. 23  is a diagram showing an example of configuration of a management computer in a Second Embodiment. 
           [0034]      FIG. 24  is a diagram showing an example of subprogram page relevance discovering program flow chart of the Second Embodiment. 
           [0035]      FIG. 25  is a diagram showing an example of configuration of a management computer in a Third Embodiment. 
           [0036]      FIG. 26  is a diagram showing an example of configuration of a relative hierarchical storage management table in the Third Embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0037]    A preferable embodiment will be described below with reference to drawings. Incidentally, while various information may be expressed in an “xxx table” pattern in the following description, such information may as well be expressed in some other data structure than tables. To indicate non-dependence on a data structure, an “xxx table” may instead be referred to as “xxx information”. 
         [0038]    Further in the following description, whereas processing may sometimes be described in a sentence whose subject is a “program”, since a prescribed processing is accomplished while appropriately using a storage resource (e.g. a memory) and/or a communication interface device (e.g. a communication port), the grammatical subject of processing may as well be a processor. A processing described by using a program as the subject of processing may be a processing accomplished by a processor or a management system having the processor (e.g. a computer or server for management use). Further, the controller may be the processor itself or include a hardware circuit accomplishing part or the whole of the processing to be accomplished by the controller. The program may be installed in each controller from the program source. The program source may be, for instance, a program distribution server or a storage medium. 
         [0039]    To add, a management computer has an I/O device. Conceivable examples of I/O device include a display, a keyboard and a pointer device, but it may as well be some other device. Alternatively, as a substitute for the I/O device, a serial interface or an Ethernet interface (Ethernet is a registered trade mark) may be used as an I/O device, and connecting a display-use computer having a display, a keyboard or a pointer device to the interface to substitute for inputting and displaying by an input device by having it transmit display-use information to the display-use computer and receive input-use information from the display-use computer to enable the display-use computer to perform displaying or accept inputs. 
         [0040]    Hereinafter, a set of more than one computer that manages a computer system and manages and controls a storage system may be referred to as a management system. When a management computer displays display-use information the management computer is a management system. A combination of a management computer and a display-use computer also is a management system. Also, for the purpose of increasing the speed and reliability of management processing, a plurality of computers may realize processing equivalent to the management computer, and in this case the plurality of computers (including a display-use computer when the display-use computer is to accomplish displaying) is the management system. 
         [0041]    Whereas a word “time” is used in the following description, the time may indicate items of information such as year, month and day and, obviously, may also indicate hour, minute and second (including a below-decimal point second). 
       First Embodiment 
     (1-1) Outline of this Embodiment 
       [0042]    In a preferable embodiment, the execution pattern of a plurality of specific processes occurring in connection with operation on an application from log information on the application (hereinafter referred to as a subprogram or subprograms for the purpose of description; detailed description of the subprogram will be given afterwards), and a page accessed to a page by each subprogram and changes in the number of accesses over time are identified. Further, on the basis of the changes in the number of accesses by the subprogram over time, hierarchical control of pages is planned. In this way, appropriate data for operation on the application is arranged in storage tiers at appropriate timing. 
         [0043]      FIG. 1  is a diagram showing an outline of this embodiment. Besides log information on the application, an execution pattern of processing over time can also be extracted from an OS activating log. Here, for instance VM corresponds to the application, and processing A and the like correspond to the subprogram of an application VM 1 . That the processing A accesses page  1  (p 1 ) can be determined from a table of relationships between processes and pages, and measuring and analyzing accesses to pages (IOPS) relative to time can reveal variations over time that, while the number of accesses (I/O number) to page  1  is large at the time of activation, the number of accesses to page  3  by processing B rapidly increases five minutes after activation. For this reason, when a job scheduler has set VM 1  to be activated at 8:00, migrating page  3  to the superior tier is started at 7:51 not to be later than 8:05, five minutes after the activation. 
         [0044]    In  FIG. 1 , bold solid line arrows represent flows of information on I/O analysis, intended for preparation of a plan for hierarchical control of pages to be used in the next round of activation. Bold dotted line arrows represent flows of information for preparation of a plan for hierarchical control of pages to be used in the next round of activation and execution of the plan. 
       (1-2) Hardware Configuration of Computer System 
       [0045]      FIG. 2  shows an example of hardware configuration of a computer system  10 . The computer system  10  is configured of a management computer  100 , a storage system  200  and a host computer  300 . In the computer system  10 , the management computer  100  and the host computer  300  may be the same computer, provided as one computer each or a plurality of computers. Further in the computer system  10 , the storage system  200  may be one unit or a plurality of units. Also in the computer system  10 , the host computer  300  and the storage system  200  may be the same computer, provided as one computer each or a plurality of computers. 
         [0046]    The storage system  200  and the host computer  300  are connected to each other via a communication network (e.g. SAN (Storage Area Network))  500 . Further, the management computer  100  is connected to the host computer  300  and the storage system  200  via a communication network (e.g. LAN (Local Area Network))  550 . To add, the communication networks  500  and  550  may be separate networks as shown in  FIG. 2  or the same network. 
         [0047]      FIG. 3  shows an example of configuration of the management computer  100 . The management computer  100  is a computer having a memory  110 , a disk  120 , an I/F for management use  130 , a data communication I/F  140  and a CPU  150 . The memory  110 , the disk  120 , the I/F for management use  130 , the data communication I/F  140  and the CPU  150  are connected to each other by an internal network  160 . 
         [0048]    The memory  110  stores information required by the CPU  150 . More specifically, the memory  110  stores a subprogram page relationship table  1101 , an event analysis table  1102 , I/O analysis data  1103 , a job management table  1104 , a page hierarchical control task management table  1105 , a page hierarchical control management table  1106  and a hierarchical storage capacity management table  1107 . 
         [0049]    The disk  120  stores programs to be executed by the CPU  150  and permanent information required by the CPU  150 . More specifically, IOPS transition data  1201 , the log file data  1202 , a log file management table  1203 , a hierarchical storage performance management table  1204 , a log file collection program  1251 , a storage I/O amount totalization program  1252 , a page allocation state monitoring program  1253 , an I/O analysis program  1254 , a hierarchical control plan formulation program  1255 , a hierarchical control program  1256  and a job end time I/O analysis correction program  1257 . 
         [0050]    The subprogram page relationship table  1101  stores subprograms to be executed in connection with operation of application programs executed by the CPU of the host computer  300  and information related to pages accessed by the subprograms. The event analysis table  1102  stores analytical information on subprograms executed in connection with execution of various operations on application programs stored in the memory of the host computer  300 . The I/O analysis data  1103  stores the result of analysis regarding the storage system  200  when application programs have been executed by the host computer  300 . The job management table  1104  stores jobs regarding various operations on application programs to be stored in the memory of the host computer  300 . The page hierarchical control task management table  1105  stores task information on management operations on the storage system  200  regarding hierarchical control of pages. The page hierarchical control management table  1106  stores variations of information over time regarding tiers in which pages are arranged and the amount of access to the pages. The hierarchical storage capacity management table  1107  stores variations of tier capacities over time. Details on various tables to be stored in the memory  110  will be described afterwards. 
         [0051]    A log file collection program  1251  is a program for collecting log files stored in the disk of the host computer  300 . A storage I/O amount totalization program  1252  is a program for acquiring information representing the amount of access from the storage system  200  to pages (e.g. 10 PS). A page allocation state monitoring program  1253  is a program for monitoring the state hierarchical control over pages. 
         [0052]    The I/O analysis program  1254  is a program for analyzing variations over time of the amount of access to the storage system  200  generated by subprograms. The hierarchical control plan formulation program  1255  is a program for formulating an execution plan for hierarchical control of pages. The hierarchical control program  1256  is a program for implementing hierarchical control of pages in accordance with the execution plan for hierarchical control of pages. The hierarchical control plan formulation program  1255  is a program for correcting I/O analysis results on the basis of the result of execution after job execution. 
         [0053]    The IOPS transition data  1201  stores information indicating time variations of IOPS relative to pages. The log file data  1202  stores information on log files stored in the disk of the host computer  300 . The log file management table  1203  stores information for managing the log file data  1202  that holds information on logs collected from the host computer  300 . The hierarchical storage performance management table  1204  stores performance information on tiers. Details on various tables stored in the disk  120  will be described afterwards. 
         [0054]    The I/F for management use  130  is an interface for connecting the storage system  200  and the host computer  300  via the communication network  500 . The data communication I/F  140  is an interface for connecting the storage system  200  and the host computer  300  via the communication network  550 . The CPU  150  performs various processes by execution programs stored in the disk  120 . To add, though the I/F for management use  130  and the data communication I/F  140  are not the same in  FIG. 3 , the I/F for management use  130  and the data communication I/F  140  may as well be the same. 
         [0055]      FIG. 4  shows an example of configuration of the storage system  200 . The storage system  200  is equipped with a memory  210 , a controller  220 , a management IF  230 , a data communication I/F  240  and a storage medium  250 . The memory  210 , the controller  220 , the management IF  230 , the data communication I/F  240  and the storage medium  250  are connected to each other via an internal network  260 . To add, though the management IF  230  and the data communication I/F  240  are not the same in  FIG. 4 , the management IF  230  and the data communication I/F  240  may as well be the same. 
         [0056]    The memory  210  stores programs to be executed by the controller  220  and information required by the controller  220 . More specifically, the memory  210  stores an I/O amount monitoring program  2151  and a page allocation control program  2152 . The I/O amount monitoring program  2151  is a program for monitoring the amount of access of the hierarchical storage to pages. The page allocation control program  2152  is a program for allocating pages to the real address space of the storage medium  250  constituting the storage region. 
         [0057]    The controller  220  controls the actions of the storage system  200  by executing programs to be stored in the memory  210 . The management IF  230  is an interface for connecting the management computer  100  and the host computer  300  via the communication network  550 . The data communication I/F  240  is an interface for connecting the management computer  100  and the host computer  300  via the communication network  500 . 
         [0058]    The storage medium  250  stores data whose writing is requested by the host computer  300 . The storage medium  250  may be media of multiple types differing in such characteristics as input/output performance and bit cost. For instance, it may be a combination of more than one types of medium such as an SSD (Solid State Disk) group  250 A, an SAS (Serial Attached SCSI) magnetic disk group  250 B and an SATA (Serial ATA) magnetic disk group  250 C. 
         [0059]      FIG. 5  shows an example of configuration of the host computer  300 . The host computer  300  is a computer having a memory  310 , a disk  320 , an I/F for management use  330 , a data communication I/F  340  and a CPU  350 . The memory  310 , the disk  320 , the I/F for management use  330 , the data communication I/F  340  and the CPU  350  are connected to each other via an internal network  360 . 
         [0060]    The memory  310  stores programs to be executed by the CPU  350  and information and the like required by the CPU  350 . More specifically, the memory  310  stores one or a plurality of application programs  3101 . The application program  3101  is a program that defines various processes performed by the CPU  350 . 
         [0061]    The application program  3101  includes one or a plurality of subprograms  3102 . The subprogram  3102  is a part or the whole of programs constituting processes of the application program  3101 , and the program of processes generated in connection with operations on the application program  3101 . The operations of the computer neither specially described nor shown include, for instance, inputting from an ordinary OS (Operating System) to the application program  3101 , which may be activation inputting or data inputting by a user to the application program  3101  or interrupt inputting with a timer or the like. 
         [0062]    The subprogram  3102  is not limited to processes directly generated by any operation. The subprogram  3102  may be a program automatically executed from any processing of the application program  3101  resulting from an operation on the application program  3101 . Also, the subprogram  3102  may be a program executed by combination of a plurality of operations on the application program  3101 . The subprogram  3102  may as well be a program executed by combined operations. Also, a program of processing generated with some relationship with operations on the application program  3101  may be the subprogram  3102 . 
         [0063]    For instance, it may be a DB (database) program regarding a mail automatically executed in connection with an operation by the manager to activate a mail server program, which is the application program  3101 , a mail reception program generated in connection with a user&#39;s receiving operation, or a received mail list display program executed after execution of the mail reception program. To add, the subprogram  3102  is not limited to what has been described so far, but a program matching the following description of the subprogram  3102  may as well be the subprogram  3102 . 
         [0064]    The disk  320  stores programs executed by the CPU  350  and permanent information required by the CPU  350 . More specifically, the disk  320  stores a log file  3201  and a log file transmission program  3251 . The log file  3202  is a file that stores, when logs on various operations performed on the application program  3101  stored in the memory  310  and various operations performed on the application program  3101 , logs and the like on the subprogram  3102  automatically executed by the application program  3101 . The log file transmission program  3251  is a program for transmitting the log file  3201  to the management computer  100 . 
         [0065]    The I/F for management use  330  is an interface for connection of the management computer  100  and the storage system  200  via the communication network  500 . The data communication I/F  340  is an interface for connection of the management computer  100  and the storage system  200  via the communication network  550 . The CPU  350  performs various processes by executing programs stored in the disk  120 . To add, though the I/F for management use  330  and the data communication I/F  340  are not the same in  FIG. 5 , the I/F for management use  330  and the data communication I/F  340  may as well be the same. 
       (1-3) Contents of Various Tables 
       [0066]      FIG. 6  is a diagram showing an example of the subprogram page relationship table  1101  stored in the memory  110  of the management computer  100 . The subprogram page relationship table  1101  is a table for managing programs to be executed by the CPU  350  of the host computer  300  and information related to pages to be accessed by the programs. 
         [0067]    In an application name column  110101 , the name of the application program  3101  to be executed by the CPU  350  of the host computer  300  is stored. In an operation type column  110102 , the types of operation that can be performed on the application program  3101  to be executed by the CPU  350  of the host computer  300  are stored. In a server name column  110103 , the name of the host computer  300  is stored. In a subprogram column  110104 , a series of states of the subprogram  3102  recorded in the log file  3201  stored in the disk  320  of the host computer  300  when any operation is performed on the application program  3101  executed by the CPU  350  of the host computer  300  are stored. In a data ID column  110105 , ID information on data used by the subprogram  3102  (e.g. directory paths of files and file names, data set names of data sets and so forth) is stored. In a page No. column  110106 , page No. information on pages storing sets of data matching the data IDs stored in the data ID column  110105  is stored. 
         [0068]    To add, the contents of the subprogram page relationship table  1101  may be inputted in advance from an input device, not shown, or the like of the management computer  100 . 
         [0069]      FIG. 7  is a diagram showing an example of the event analysis table  1102  stored in the memory  110  of the management computer  100 . The event analysis table  1102  is analytical information on the subprogram  3102  executed in connection with the execution of various operations on the application program  3101  stored in the memory  310  of the host computer  300 . 
         [0070]    In an application name column  110201 , the name of the application program  3101  to be executed by the CPU  350  of the host computer  300  is stored. In an operation type column  110202 , the types of operation that can be performed on the application program  3101  to be executed by the CPU  350  of the host computer  300  are stored. In a server name column  110203 , the name of the host computer  300  is stored. In a subprogram column  110204 , a series of states of the subprogram  3102  recorded in the log file  3201  stored in the disk  320  of the host computer  300  when any operation is performed on the application program  3101  executed by the CPU  350  of the host computer  300  are stored. In a subprogram generation timing column  110205 , the elapsed time since the implementation of operations on the application program  3101  executed by the CPU  350  of the host computer  300  until the state variation of the subprogram  3102  stored in the subprogram column  110204  occurs is stored. In an I/O analysis data ID column  110206 , ID information on I/O analysis data indicating variations in the amount of access to the storage system  200  in connection with state variations of the subprogram column  110204  to be stored in the subprogram  3102  is stored. 
         [0071]      FIG. 8  is a diagram showing an example of the I/O analysis data  1103  stored in the memory  110  of the management computer  100 . The I/O analysis data  1103  is information regarding the result of analysis of accesses to the storage system  200  when the subprogram  3102  is executed by the CPU  350  of the host computer  300 . 
         [0072]    In an I/O analysis data ID column  110301 , ID information for identifying the I/O analysis data  1103  is stored. The pertinent ID information is issued for each combination of information to be stored in the application name column  110201 , the operation type column  110202 , the server name column  110203  and the subprogram column  110204  of the event analysis table  1102 . 
         [0073]    In an elapsed time column  110302 , there is stored the elapsed time since the occurrence of state variation of the subprogram  3102  stored in the subprogram generation timing column  110205  of the event analysis table  1102 . The pertinent elapsed time shown in  FIG. 8  (every 60 seconds) is only an example, and the time intervals may be different from this one. In a page No. column  110303 , there is stored No. information on pages where No. information on pages on which data to be used by the subprogram  3102  is stored. In an average IOPS column  110304 , there is stored information indicating the amount of access (IOPS) occurring to pages in whose page No. column  110303  No. information is stored during the elapsed time, which is stored in the elapsed time column  110302 . In a designated tier column  110305 , there is stored No. information on one or a plurality of tiers designated to be stored in the page No. column  110303 . 
         [0074]    To add, tier information designated in the designated tier column  110305  is set by a program stored in the management computer  100 . For instance in this embodiment, the hierarchical control plan formulation program  1255  sets it on the basis of performance information on the storage system. However, this is but one example and, for instance, the user may set it on the basis of input values, or the host computer  300  may set if on the basis of the required performance of the application program  3101 . Also, by making available in the management computer  100  a program for setting the designated tier column  110305 , a program stored in the host computer  300  may be enabled to alter the designated tier through that program. To add, the setting may as well be based on some other indicator than the performance. 
         [0075]      FIG. 9  is a diagram showing an example of the job management table  1104  stored in the memory  110  of the management computer  100 . The job management table  1104  is information for managing jobs regarding various operations on the application program  3101  stored in the memory  310  of the host computer  300 . 
         [0076]    In a job ID column  110401 , ID information for identifying jobs is stored. In an execution time column  110402 , the times of executing jobs is stored. In an application name column  110403 , the name of the application program  3101  to be executed by the CPU  350  of the host computer  300  is stored. In an operation type column  110404 , the types of operation that can be performed on the application program  3101  to be executed by the CPU  350  of the host computer  300  is stored. In a server name column  110405 , the name of the host computer  300  is stored. 
         [0077]      FIG. 10  is a diagram showing an example of the page hierarchical control task management table  1105  stored in the memory  110  of the management computer  100 . The page hierarchical control task management table  1105  shows information on management operation tasks on the storage system  200  regarding hierarchical control of pages. 
         [0078]    In a hierarchical control task ID column  110501 , ID information for identifying tasks is stored. In an the execution time column  110502 , future times at which tasks are scheduled for execution or past times at which tasks were executed are stored. In a scheduled completion time column  110503 , future times at which tasks are scheduled for completion at the respective execution times of tasks are stored. In a completion time column  110504 , if a task is not completed, “-” is stored to indicate that the task is not completed or, if a task is completed, the time at which the task was completed is stored. To add, “-” indicating incompletion of the task is but one example, but some other form of indication may be used as well. In a page ID column  110505 , the Nos. of pages under hierarchical control are stored. In a destination tier column  110506 , the destination tier Nos. of the pages are stored. In a job ID column  110507 , ID information on the jobs using the Nos. of pages under hierarchical control is stored. 
         [0079]      FIG. 11  is a diagram showing an example of the IOPS transition data  1201  stored in the disk  120  of the management computer  100 . The IOPS transition data  1201  is information showing variations over time of the amount of access (IOPS) to pages. 
         [0080]    In an IOPS transition data ID column  120101 , there are stored IDs that are identifiers differing from one storage system  200  to another. In a time column  120102 , time information on the measured amount of access to pages by the storage system  200  is stored. In a page No. column  120103 , the Nos. of pages the amount of access to which has been measured by the storage system  200  is stored. In an IOPS column  120104 , information indicating the amount of access to pages of Nos. stored in the page column  120103  having occurred during the time stored in the time column  120102  (e.g. IOPS) is stored. 
         [0081]      FIG. 12  is a diagram showing an example of log file data  1202  stored in the disk  120  of the management computer  100 . The log file data  1202  is information on the log file  3201  collected from the host computer  300 . 
         [0082]    In a log file ID column  120201 , ID information for identifying the log file  3201  collected from the host computer  300  is stored. In a time column  120202 , information on the execution times of various subprograms  3102  in connection with operations on the application program  3101  is stored, and in a subprogram column  120203 , the state of the subprogram  3102  is stored. The time column  120202  and the subprogram column  120203  respectively match a time column  320103  and a subprogram column  320104  of the log file  3201  (details will be described afterwards with reference to  FIG. 15 ) collected from the host computer. 
         [0083]      FIG. 13  is a diagram showing an example of log file management table  1203  stored in the disk  120  of the management computer  100 . The log file management table  1203  is information related to the IOPS transition data  1201  and the log file data  1202 . 
         [0084]    In an application name column  120301 , the name of the application program  3101  to be executed by the CPU  350  of the host computer  300  is stored. In an operation type column  120302 , the type of operation executed buy the CPU  350  of the host computer  300  on the application program  3101  is stored. In a server name column  120303 , the name of the host computer  300  is stored. In an execution time column  120304 , the time at which an operation to be stored into the operation type column  120302  was executed on the application program  3101  to be stored into the application name column  120301  is stored. In a log file ID  120305 , an ID to identify the log file data  1202  is stored. The sets of information stored in the application name column and the operation type column  120302  respectively match the sets of information ( 320103  and  320104 ) matching the log file data  1202  indicated by log files ID stored in the log file  3201  and the log file ID columns  120305  on the same line. 
         [0085]      FIG. 14  is a diagram showing an example of the hierarchical storage performance management table  1204  stored in the disk  120  of the management computer  100 . The hierarchical storage performance management table  1204  is performance information on each tier. 
         [0086]    In a tier ID column  120401 , tier information is stored. For instance in  FIG. 14 , the smaller this tier No., the higher the performance levels (e.g. throughput and IOPS) of the storage region. In a Read throughput column  120402 , the read performance (e.g. MB/s) of the pertinent tier is stored and, in a Write throughput column  120403 , the write performance (e.g. MB/s) of the pertinent tier. In an upper limit IOPS column  120404 , the upper limit of the IOPS can the pertinent tier can respond to is stored. To add, though it was stated that the smaller the tier No. in  FIG. 14 , the higher the performance levels, but this is not the only applicable content. For instance, the name of the medium constituting the tier, instead of the tier No., can as well be used as the content of the tier ID column  120401 . 
         [0087]      FIG. 15  is a diagram showing an example of the log file  3201  stored in the disk  320  of the host computer  300 . The log file  3201  is a file for log information on the application program  3101 . 
         [0088]    In an application name column  320101 , the name of the application program  3101  to be executed by the CPU  350  of the host computer  300  is stored. In an operation type column  320102 , the type of the application program  3101  that the CPU  350  of the host computer  300  can operate on is stored. In a time column  320103 , the execution time information of the subprogram  3102  in connection with operation on the application program  3101  is stored. 
         [0089]    In a subprogram column  320104 , the state of the subprogram  3102  is stored. The subprogram  3102  here is, for instance, one or another of the subprograms described below. First type subprogram: A subprogram automatically executed by the application program  3101  in connection with execution of an operation on the application program  3101 . Second type subprogram: A subprogram executed by the following operation executed on the application program  3101  after execution of the operation on the application program  3101 . Third type subprogram: A subprogram executed by utilization of the application program  3101  after execution of the operation on the application program  3101 . 
         [0090]    To add, the subprogram is an example of the subprogram  3102  executed in connection with execution of an operation on the application program  3101 , but it may as well be a subprogram executed at some other momentum, as a result of some causal relationship or by executing means. 
         [0091]      FIG. 16  is a diagram showing an example of the page hierarchical control management table  1106  stored in the memory  110  of the management computer  100 . The page hierarchical control management table  1106  information on variations of information indicating the amounts of accesses to the tier in which a page is arranged and to the page. 
         [0092]    In a time column  110601 , time sections marked at fixed intervals are stored; more specifically, pairs each of a start time and an end time are stored. In a page No. column  110602 , Nos. for identifying pages are stored. In a tier ID column  110603 , at the corresponding time in the time column  110601 , the No. of the tier in which the page is to be arranged is stored. In an IOPS column  110604 , information (e.g. IOPS) indicating the number of accesses to the page is stored. In a designated tier column  110605 , the No. of the tier in which the page is designated to be arranged at the time of the time column  110601  is stored. 
         [0093]      FIG. 17  is a diagram showing an example of the hierarchical storage capacity management table  1107  stored in the memory  110  of the management computer  100 . 
         [0094]    In a time column  110701 , time sections divided at fixed intervals are stored; more specifically, pairs each of a start time and an end time are stored. In a tier ID column  110702 , tier Nos. are stored. In an overall capacity (GB) column  11070 , the capacity available for use by the tier are stored; more specifically, it is the sum of the capacity of the storage region to which page are already allocated and the unoccupied capacity (GB) to be described afterwards. An unoccupied (GB) column  110704  shows the tier capacity to which pages can be allocated. A fixed capacity (GB) column  110705  shows the total capacity of pages arranged in a fixed manner in the tier of the tier ID column  110702  in the time sections of the time column  110701 . 
       (1-4) Details of Actions of Computer System 
     (1-4-1) Details of Actions of I/O Analysis 
       [0095]    First, the actions of I/O analysis by the management computer  100  will be described in detail. The management computer  100 , using the IOPS transition data  1201  and the log file data  1202  stored in the disk  120 , analyzes the execution timing of the subprogram  3102  executed in connection with an operation performed on the application program  3101  executed by the CPU  350  of the host computer  300  on the basis of the I/O analysis program  1254  and I/O to or from the storage system  200  by the subprogram  3102 . 
         [0096]    The IOPS transition data  1201  and the log file data  1202  used by the I/O analysis program  1254  are generated by the storage I/O amount totalization program  1252  and the log file collection program  1251 , respectively. The IOPS transition data  1201  is generated by the execution of the storage I/O amount totalization program  1252  by the CPU  150  of the management computer  100  to execute, for instance, the following processes (a1) and (a2). 
         [0000]    (a1) The storage I/O amount totalization program  1252  periodically acquires the cumulative total number of accesses to a page from the storage system  200 .
 
(a2) The storage I/O amount totalization program  1252 , when it receives from the storage system  200  the cumulative total number of accesses to the page, calculates from the totalized result the difference from the cumulative total received last time, and adds to the IOPS transition data  1201  the number of accesses made to the page during the period between the last reception time and the latest reception time.
 
         [0097]    The storage system  200 , in preparation for execution of (a1) above, executes the I/O amount monitoring program  2151  with the controller  220  and performs, for instance the following processes (b1) and (b2). 
         [0000]    (b1) In accordance with the I/O amount monitoring program  2151 , the controller  220  monitors the number of accesses to a page, and holds the cumulative total number of accesses to the page.
 
(b2) The I/O amount monitoring program  2151  transmits the cumulative total number of accesses to the management computer  100  in response to a request for transmission of the cumulative total number of accesses resulting from execution of (a1) above.
 
         [0098]    The log file data  1202  is generated by execution of the log file collection program  1251  by the CPU  150  of the management computer  100  to execute, for instance, the following processes (c1) through (c3). 
         [0000]    (c1) The log file collection program  1251  periodically collects           the log file  3201  for the host computer  300 .
 
(c2) The log file collection program  1251  generates the log file data  1202  on the basis of the time  320103  and the subprogram information  320104  included in the log file  3201 .
 
(c3) The log file collection program  1251  adds to the log file management table  1203  the ID of the log file data  1202 , generated by (c2) as stated above, together with information of the application name  320101  and the operation type  320102 .
 
         [0099]    To add, periodic execution of the log file collection program  1251  is one example of possible momentums for execution of the log file collection program  1251 , and it may as well be executed upon completion of job execution as a momentum. 
         [0100]    Further the host computer  300 , when it receives from the management computer  100  a request for acquisition of the log file  3201  (e.g. the request for log file collection in (c1) above), transmits the log file  3201  to the management computer  100  in accordance with the log file transmission program  3251 . 
         [0101]    An example of flow chart of the I/O analysis program  1254  is shown in  FIG. 18 . The CPU  150  of the management computer  100  (hereinafter to be described as the management computer  100 ) periodically executes the I/O analysis program  1254  with a combination of the application name  120301  and the operation type  120302  and the server name  120303  shown in  FIG. 13  as the input. Some other momentum of execution may as well be adopted; for instance it may be the timing of collecting the log file  3201  from the host computer  300  in accordance with the log file collection program  1251 . Further, for the purpose of description, the combination of the application name  120301  and the operation type  120302  and the server name  120303  will be referred to as an event. Also, execution of an operation on the application program  3101  by the CPU  350  of the host computer  300  indicated by the event will be referred to as generation of an event. 
         [0102]    The management computer  100 , when the I/O analysis program  1254  is executed, acquires from the log file management table  1203  all the log file IDs  120305  matching the event given as the input. Next, it acquires the log file data  1202  matching the acquired log file IDs  120305  (step S 1005 ). 
         [0103]    Next, the management computer  100  compares the group of log file data  1202  acquired at step S 1005 , and presumes the subprogram  3102  to be executed upon occurrence of an event on the basis of information on the number of sets of the log file data  1202  when the subprogram  3102  of the subprogram column  120203  emerges (step S 1010 ). The usable method of presumption here may be statistical hypothesis testing or the like. More specifically, first, a hypothesis that a specific subprogram  3102  is executed when an event has occurred is set. A suitable significant level (e.g. 1%) is set, and hypothesis testing can be done about the log file data  1202 . The probability of emergence of the subprogram  3102  of the subprogram column  120203  in the log file data  1202  can be calculated from the ratio of log file data in which the subprogram  3102  of the subprogram column  120203  in two or more sets of log file data  1202  emerges to all the sets of log file data. 
         [0104]    The management computer  100  executes processing of each subprogram  3102  from step S 1020  to step S 1050  once or a plurality of times (step S 1015  and step S 1055 ). 
         [0105]    The management computer  100  acquires from the log file data  1202  in which the subprogram  3102  emerges, out of the log file data group  1202  used at step S 1010 , a time  120202  at which the subprogram  3102  was executed. Further, the management computer  100  acquires from the log file management table  1203  the execution time  120304  of the event matching the log file ID  120201  of the log file data  1202  in which the subprogram  3102  emerges, out of the log file data group used at step S 1010 . Next, the management computer  100  calculates on the basis of information of the execution time  120304  of one or more events acquired as stated above and the time  120202  at which the subprogram  3102  was executed matching the execution time  120304 , the elapsed time since the occurrence of the event until the execution of the subprogram  3102 . 
         [0106]    The management computer  100  estimates the elapsed time since the occurrence of a representative event until the execution of the subprogram  3102  on the basis of the group elapsed time since the occurrence of each event calculated from two or more sets of log file data  1202  as described above until the execution of the subprogram  3102 . As the method of estimation, for instance, a feature detection method such as a differential edge detection method. More specifically, the feature detection method may be applied to the group of elapsed times to detect an elapsed time which is a characteristic value (hereinafter, for the purpose of description, a representative elapsed time since the occurrence of a presumed event until the execution of the subprogram  3102  will be referred to as the timing of executing the subprogram  3102 ) (step S 1020 ). 
         [0107]    At step S 1025 , the management computer  100  references the subprogram page relationship table  1101  shown in  FIG. 6  and determines whether or not sets of information ( 110101  through  110103 ) matching the event given as an input to the I/O analysis program  1254  are included in the subprogram page relationship table  1101 . If they are, it determines whether or not information ( 110104 ) of the subprogram  3102  is included in the subprogram page relationship table  1101 . 
         [0108]    If the result of determination at step S 1025  is negative, processing of the pertinent subprogram  3102  is stopped, and processing regarding another subprogram  3102  is started at step  1015 . 
         [0109]    If the result of determination at step S 1025  is affirmative, the management computer  100  acquires from the subprogram page relationship table  1101  an event and a page No. matching the subprogram  3102  from the page No. column  110106  (step S 1030 ). 
         [0110]    The management computer  100  acquires from the log file data group  1202  in which the subprogram  3102  used at step  1020  emerges the time group in which the subprogram  3102  is executed. And it extracts from the IOPS transition data  1201  the IOPS transition at each of the times referred to above. 
         [0111]    The management computer  100  executes, for instance, the following processing steps (d1) through (d3) on the basis of the IOPS transitions acquired by the foregoing processes, and extracts the timing of variation of the number of accesses to the page matching the page No. in the page No. column  110106  identified at step S 1030  (hereinafter, for the purpose of description, the elapsed time since the occurrence of the subprogram  3102  until the variation of the number of accesses to the page will be expressed as the timing of variation of the number of accesses to the page) (step S 1035 ). 
         [0000]    (d1) From the IOPS transition data  1201  shown in  FIG. 11 , the time column  120101  matching the page No. in the page No. column  110106  identified at step  1030  and information of the IOPS column  120104  are acquired.
 
(d2) From the transition of the IOPS value in the IOPS column  120104 , the time at which the IOPS value varies greatly is detected. As the detection method, for instance, a feature detection method such as a differential edge detection method.
 
(d3) From the time detected as stated in (d2) above, the execution timing of the subprogram  3102  and the time in the execution time column  120304  of the event, the elapsed time since the execution of the subprogram  3102  until The IOPS value varies is calculated.
 
         [0112]    Next, the management computer  100  detects any outlier regarding the timing of variation of the IOPS value relative to the page calculated at step S 1035 . In the processing at and after step S 1045 , the management computer  100  performs processing with the IOPS transition matching the detected outlier and the log file data  1202  matching it. As the outlier detection method, for instance a statistical outlier detection method may be used (step S 1040 ). 
         [0113]    The management computer  100 , on the basis of IOPS transitions at the execution times of the subprogram  3102  stored in the log file data  1202  to be processed, calculates the average of IOPS values in the elapsed time since the execution of each subprogram  3102  on each page acquired at step S 1030 . Further, the management computer  100  stores the time in an elapsed time column  110302  after the execution of the subprogram  3102  into the I/O analysis data  1103 , the page No acquired at step S 1030  into a page No. column  110303  and the average of IOPS values calculated as described above into an average IOPS column  110304 . To add, the method using the average is but on example, but some other statistical method using a median or the like can be used as well (step S 1045 ). 
         [0114]    The management computer  100  at step S 1050  stores into the event analysis table  1102  shown in  FIG. 7  information on the pertinent event ( 110201  through  110203 ), information of the subprogram  3102  ( 110204 ), the execution timing of the subprogram  3102  calculated at step S 1020  ( 110205 ) and the ID of the I/O analysis data  1103  ( 110206 ) generated at step S 1050 . 
         [0115]    At step S 1055 , the management computer  100  determines, with respect to every subprogram  3102  extracted at step S 1010 , whether or not the processes at step S 1020  through step S 1050  have been executed. If the processes at step S 1020  through step S 1050  have been executed on every subprogram  3102 , the I/O analysis program  1254  is ended. If the processes at step S 1020  through step S 1050  have not been executed on every subprogram  3102 , the flow returns to step S 1015 , and processing is started on other subprograms  3102  extracted at step S 1010 . 
         [0116]    As described so far, execution of the I/O analysis program  1254  by the management computer  100  makes possible analysis of I/O variations to and from pages over time during the execution of the subprogram  3102  in connection with event execution on the basis of the IOPS transition data  1201  acquired from the log file  3201  and the storage system  200  stored in the disk  320  of the host computer  300 . To add, though the foregoing description supposed presumption of the subprogram  3102  executed in connection with an event from probability information on the execution of the subprogram  3102  in the log file data  1202 , the subprogram  3102  may as well be notified to the management computer  100  by the user&#39;s designation or otherwise. In that case, the processes from step S 1005  through step S 1010  would be unnecessary. 
       (1-4-2) Details of Actions of Hierarchical Control Plan Formulation 
       [0117]    Actions of the management computer  100  to formulate a hierarchical control plan will be described in detail. The management computer  100 , using the event analysis table  1102  stored in the disk  120 , generates tasks for performing hierarchical control over the storage system  200  on the basis of the hierarchical control plan formulation program  1255 . 
         [0118]      FIG. 19  shows an example of flow chart of hierarchical control plan formulation program  1255  for the management computer  100 . The management computer  100  starts implementing the hierarchical control plan formulation program  1255  when a new job is added to the job management table  1104  shown in  FIG. 9  (step S 2000 ). First, the management computer  100  acquires the newly added job from the job management table  1104  (step S 2005 ). 
         [0119]    The management computer  100  extracts information of an event (the application name column  110403 , the operation type column  110404  and the server name column  110405 ) from the job, and determines whether or not the event analysis table  1102  shown in  FIG. 7  includes information matching the extracted event (step S 2010 ). If at step S 2010  no information matching the event is found included, processing of the hierarchical control plan formulation program  1255  is ended. 
         [0120]    If, on the other hand, information matching the event is found included at step S 2010 , the management computer  100  acquires from the subprogram column  110204  of the event analysis table  1102  a list of subprograms  3102  generated in connection with event execution. The management computer  100  executes processing of step S 2020  through step S 2070  that follow on each of the acquired subprogram  3102  as loop (A) once or a plurality of times (step S 2015 ). 
         [0121]    At step S 2020 , the management computer  100  identifies the elapsed time since the event generation until execution of the subprogram  3102  and the I/O analysis data matching the event to be processed and the subprogram  3102 , and acquires them from the subprogram generation timing column  110205  and the I/O analysis data ID column  110206  of the event analysis table  1102  (step S 2020 ). 
         [0122]    The management computer  100  acquires elapsed times since the execution of the subprogram  3102  from the elapsed time column  110302  of the I/O analysis data  1103  identified from the ID of the I/O analysis data acquired at step S 2020 . The management computer  100  executes processing of step S 2030  through step  2065  that follow on each of acquired elapsed times as a loop (B) once or a plurality of times (step S 2025 ). 
         [0123]    The management computer  100  acquires from the page No. column  110303  of the I/O analysis data  1103  identified from the ID of the I/O analysis data acquired at step S 2020  the pages referenced by the subprogram  3102  at the pertinent elapsed time. The management computer  100  executes processing of step S 2040  through step  2060  that follow on each of the acquired page as a loop (C) once or a plurality of times (step S 2035 ). 
         [0124]    The management computer  100  at step S 2040  determines whether or not a tier designated for arrangement of the pertinent page is higher in input/output performance than the previous elapsed time step. Since it is defined that, as described with reference to  FIG. 14 , the smaller the tier No., the higher the performance levels (e.g. throughput and IOPS) of the storage region, it references the designated tier column  110305  of the I/O analysis data  1103  and determines whether or not tiers bearing smaller Nos. than the I/O analysis data  1103  along with the variation of the elapsed time step are designated. Further, as a result of referencing the designated tier column  110305  of the I/O analysis data  1103 , it is found that no tier in which to arrange pages was designated at the previous elapsed time step and a tier in which to arrange pages is designated at the present elapsed time step, an affirmative determination is made, or if no tier in which to arrange pages is designated at the present elapsed time step, a negative determination is made. 
         [0125]    To add, at the first time of loop (C) execution, if a tier in which to arrange pages is designated at the present elapsed time step, an affirmative determination is made or, if no tier in which to arrange pages is designated, a negative determination is made. 
         [0126]    If the result of determination at step  2040  is a negative one, the management computer  100  references the I/O analysis data  1103  and compares the IOPS value of the page at the previous elapsed time step and the IOPS value of the page at the present elapsed time step. To add, if it is the first execution of loop (C), in order to decide upon an appropriate tier for the pertinent page in comparison with the IOPS values of other pages, the management computer  100  makes an affirmative determination after designating every tier No. to the designated tier column  110305  of the object I/O analysis data  1103  (step S 2045 ). 
         [0127]    If the result at step S 2040  is affirmative or is negative and the result at step S 2045  is affirmative, the management computer  100  at step S 2050  executes processing to migrate a page to be referred to afterwards to a superior tier. Or if the result at step S 2040  is step S 2040  is negative and the result at step S 2045  is also negative, the management computer  100  at step S 2060  executes processing to migrate a page to be referred to afterwards to an inferior tier. 
         [0128]    At step S 2065 , the management computer  100  determines whether or not processing has been performed on every object page of loop (C). If processing has been performed, the management computer  100  executes step S 2070  or, if not, the management computer  100  returns processing to step S 2035 . At step S 2070 , the management computer  100  determines whether or not processing has been performed on every object page of loop (B). If processing has been performed, the management computer  100  executes step S 2075  or, if not, the management computer  100  returns processing to step S 2025 . At step S 2075 , the management computer  100  determines whether or not processing has been performed on every object page of loop (A). If processing has been performed, the management computer  100  ends the hierarchical control plan formulation program  1255  or, if not, the management computer  100  returns processing to step S 2015 . 
         [0129]    Processing for migrating a page to a superior tier (step S 2050  in  FIG. 19 ) will be described in detail with reference to  FIG. 20 . 
         [0130]    At step S 3005 , the management computer  100  calculates the object time information from a new job stored in the job management table  1104  shown in  FIG. 9 , which is input information for the hierarchical control plan formulation program  1255 ; the subprogram  3102 , which is the object of processing in a state of executing step S 2050 ; the elapsed time since the subprogram  3102  was executed; and page information. More specifically, the management computer  100  calculates the time from the time of job generation from the execution time column  110402  of the job management table  1104 , the elapsed time since event generation from the subprogram generation timing column  110205  of the event analysis table  1102 , the elapsed time since event generation until execution of the subprogram  3102  and the elapsed time since execution of the subprogram  3102 , which is the object or processing (hereinafter, the time calculated here will be referred to as the I/O occurrence time for the purpose of description). 
         [0131]    Next, the management computer  100  references the hierarchical storage capacity management table  1107  and acquires capacity information (the overall capacity column  110703 , the unoccupied capacity information column  110704  and the fixed capacity column  110705 ) on each tier at the I/O occurrence time. Further, the management computer  100  acquires, in the I/O analysis data  1103  which is the object of processing when executing step S 2050 , the tier No. of the designated tier No. column  110305  matching the elapsed time and the page number, which are the objects of in-column processing of the elapsed time column  110302  and the page No. column  110303 . The management computer  100  determines from the unoccupied capacity information on each tier and information on tier No. whether or not there is any unoccupied capacity in a tier higher in input/output performance than the tier designated at the I/O occurrence time. 
         [0132]    If the determination at step S 3005  is affirmative, the management computer  100  chooses at step S 3010  as the migrating destination tier of the page to be processes a tier higher in input/output performance out of tiers having any unoccupied capacity. On the other hand, if the determination at step S 3005  is negative, the management computer  100  executes step S 3015 . 
         [0133]    At step S 3015 , the management computer  100  references the hierarchical storage capacity management table  1107 , compares the overall capacity  110703  and the fixed capacity  110705  of each tier at the I/O occurrence time, and calculates the capacities of regions in which the pages of tiers are not fixed. The management computer  100  determines, on the basis of information on the capacity of regions where no tier page is fixed calculated as described above, whether or not there is any page that can be altered in tier placement at the I/O occurrence time from the designated tier to another tier higher in input/output performance than the designated tier. 
         [0134]    If the determination at step S 3015  is negative, the management computer  100  further executes step S 3030 . At step S 3030 , the management computer  100  references the page hierarchical control management table  1106 , and identifies in the page No. column  110602  any page No. arranged in a tier having not lower input/output performance than the designated tier. And the management computer  100  compares the IOPS value in the IOPS column  110604  regarding the identified page No. and the IOPS value of the page to be processed, and determines if any page whose IOPS is no higher than the IOPS value of the object of processing is in a tier whose input/output performance is no lower than the designated tier. 
         [0135]    If the determination at step S 3015  is affirmative or if the determination at step S 3030  is affirmative, the management computer  100  at step S 3020  identifies a page that makes a vacancy in a superior tier by migrating from a page already arranged in a tier having an input/output performance no lower than the designated tier, namely by migrating from the page already arranged in a tier to a replaceable page, namely an inferior tier, and sets a hierarchical control task regarding the replaceable page. More specifically, the management computer  100  references the page hierarchical control management table  1106 , and identifies in the page No. column  110602  pages arranged in a tier having an input/output performance not lower than the designated tier. And the management computer  100  selects out of the identified pages one page whose tier No. in the designated tier column  110605  is not equal to its tier No. in the tier ID column  110603 . Next, the management computer  100  generates a page hierarchical control task regarding the chosen page on the basis of migrating the page to a superior tier. 
         [0136]    The management computer  100  chooses the tier in which the replaceable page has been arranged as the destination of migrating the page to be processed (step S 3025 ). 
         [0137]    If the determination at step S 3030  is negative, the management computer  100  determines that the page cannot be migrated to a superior tier, ends processing for migrating the page to an inferior tier and returns to processing shown in  FIG. 19 . 
         [0138]    At step S 3040 , the management computer  100  calculates the time taken to migrate a page from the tier in which the page to be processed is arranged at the I/O occurrence time (hereinafter referred to as the origin tier) to the destination tier. More specifically, it references the page hierarchical control management table  1106  for the tier in which the page to be processed at the I/O occurrence time. Next, the management computer  100  references the hierarchical storage performance management table  1204  and acquires the Read throughput of the origin tier and the Write throughput of the destination tier. On the basis of these pieces of performance information, the time required for page hierarchical control is calculated according to (time required for page hierarchical control)=Min (the Read throughput of the origin tier and the Write throughput of the destination tier)*(page capacity). 
         [0139]    The management computer  100  calculates the execution time of the hierarchical control task by subtracting from the I/O occurrence time the page hierarchical control calculated as described above (step S 3045 ). 
         [0140]    At step S 3050 , the management computer  100  generates the hierarchical control task on the basis of the destination tier and the execution time of the hierarchical control task. More specifically, first the management computer  100  sets the No. of a destination tier for the tier ID column  110603  of the record in the page hierarchical control management table  1106  matching the combination of the I/O occurrence time the page to be processed, sets IOPS information in the page to be processed stored in the I/O analysis data  1103  for the IOPS column  110604 , and sets into the designated tier column  110605  the No. of a designated tier for the page to be processed. 
         [0141]    Next, the management computer  100  updates the capacity information on the record in the hierarchical storage capacity management table  1107  matching the origin tier and the destination tier of the I/O occurrence time. Namely, a field matching the unoccupied capacity of the origin tier is decreased by an equivalent of the page capacity, and a field matching the unoccupied capacity of the destination tier is increased by an equivalent of the page capacity. A field matching the fixed capacity of the origin tier, if the tier ID set for the origin tier at the I/O occurrence time in the page hierarchical control management table  1106  is the same as the designated tier, is decreased by an equivalent of the page capacity. Further, a field matching the fixed capacity of the destination tier, if the tier ID set for the destination page at the I/O occurrence time in the page hierarchical control management table  1106  is the same as the designated tier, is increased by an equivalent of page capacity. Further, the management computer  100  generates a page hierarchical control task on the basis of information on the task execution time, the I/O occurrence time, the page to be processed and the destination tier, and adds it to the page hierarchical control task management table  1105 . 
         [0142]    Processing for migrating a page to an inferior tier (step S 2060  in  FIG. 19 ) will be described in detail.  FIG. 21  shows an example of flow chart of processing to migrate a page to an inferior tier. 
         [0143]    The management computer  100  references the I/O analysis data  1103  and acquires the variations over time of the tier No. designated to the page to be processed. Further, the management computer  100  compares the designated tier before and after the I/O occurrence time (step S 4005 ). 
         [0144]    If, as a result of comparison, a tier higher in input/output performance than before or the designated tier is unchanged at the I/O occurrence time, the processing for migrating the page to inferior tier is ended, and the sequence returns to the processing shown in  FIG. 19 . Or if a tier lower in input/output performance than before or no tier is designated tier at the I/O occurrence time, processes at and after step S 4010  are executed. 
         [0145]    At step S 4010 , the management computer  100  references the page hierarchical control management table  1106  and acquires from the page No. column  110602  pages arranged in the tier designated to the page to be processed at the I/O occurrence time and higher tiers. Further, the management computer determines whether or not there is any page, among the acquired pages, whose tier No. in the tier ID column  110603  indicates a lower input/output performance than the tier No. of the designated tier column  110605 . 
         [0146]    If the determination at step S 4010  is affirmative, the management computer  100  selects as the replaceable page for the page to be processed one of the pages whose tier No. in the tier ID column  110603  is lower in input/output performance than the tier acquired at S 4010  in the designated tier column  110605  (step S 4015 ). 
         [0147]    On the other hand, if the determination at step S 4010  is negative, at step S 4020  the management computer  100  references the page hierarchical control management table  1106  and acquires from the page No. column  110602  page Nos. arranged in the tier designated to the page to be processed at the I/O occurrence time and higher tiers. Further, the management computer determines whether or not there is any page smaller in IOPS value in the IOPS column  110604  than the IOPS value for the page to be processed among the acquired pages. 
         [0148]    If the result of determination at step S 4020  is affirmative, the management computer.  100  selects as the replaceable page for the page to be processed one of the pages whose IOPS value in the IOPS column  110604  is smaller than the IOPS value for the page to be processed acquired at step S 4020  (step S 4025 ). 
         [0149]    On the other hand, if the determination at step S 4020  is negative, the management computer  100  determines that there is no need to migrate the page to the inferior tier, ends the processing for migrating the page to the inferior tier, and returns to the processing shown in  FIG. 19 . 
         [0150]    At step S 4030 , the management computer  100  updates the page hierarchical control management table  1106  and the hierarchical storage capacity management table  1107 , generates a hierarchical control task to replace the page to be processed with the replaceable page, and adds it to the page hierarchical control task management table  1105 . The processing to update the page hierarchical control management table  1106  and the hierarchical storage capacity management table  1107  and the processing to generate the hierarchical control task are the same as at step S 3050 . 
       (1-4-3) Details of Actions to Correct I/O Analysis Upon End of Job 
       [0151]    Actions of the management computer  100  to correct I/O analysis at the end of a job will be described in detail. The management computer  100 , using the event analysis table  1102  stored in the disk  120 , generates a task for performing hierarchical control over the storage system  200  on the basis of the hierarchical control plan formulation program  1255 . 
         [0152]      FIG. 22  shows an example of flow chart of the hierarchical control plan formulation program  1255  in the management computer  100 . The management computer  100 , upon ending execution of a job stored in the job management table  1104  shown in  FIG. 9 , executes the hierarchical control plan formulation program  1255  (step S 6000 ). The management computer  100 , upon detecting the end of the job, extracts IOPS transitions from the job start time till end time from the IOPS transition data  1201  (step S 6005 ). 
         [0153]    The management computer  100  references the page hierarchical control management table  1106  and acquires hierarchical control information from the job start time till end time (step S 6010 ). Then, the management computer  100  identifies from the event analysis table  1102  a record, which is an event matching the ended job, and acquires the subprogram column  110204  of the identified record, the subprogram generation timing column  110205 , a list of subprograms  3102  included in the I/O analysis data ID column  110206 , and the execution timings and I/O analysis data IDs of those subprograms  3102 . Next, the management computer  100  executes on each of the acquired subprograms  3102  step S 6020  through step S 6060  that follow as the loop (A) once or a plurality of times (step S 6015 ). 
         [0154]    At step S 6020 , the management computer  100  acquires the I/O analysis data  1103  from I/O analysis data IDs matching subprograms  3102  (step S 6020 ). Next, the management computer  100  executes step S 6030  through step S 6055  that follow as the loop (B) once or a plurality of times on each of the elapsed time steps since the execution of the subprogram  3102  included in the I/O analysis data  1103  acquired at step S 6020  (step S 6025 ). Further, the management computer  100  executes on each of the page Nos., which are the objects of processing at the elapsed time step to be processed in the I/O analysis data  1103  acquired at step S 6020 , step S 6035  through step S 6050  that follow as the loop (C) once or a plurality of times (step S 6030 ). 
         [0155]    At step S 6035 , the management computer  100  determines whether or not the performance was insufficient in the tier in which the page to be processed was arranged at the time of job execution. More specifically, the management computer  100  calculates time information from the job execution time, the execution timing of the subprogram  3102  acquired at step S 6015  from the event analysis table  1102  and the elapsed time since the execution of the subprogram  3102  acquired at step S 6025  from the I/O analysis data  1103 . Next, the management computer  100  acquires, at the time calculated as described above, from the IOPS transition data generated at step  6005  the IOPS value generated with respect to the page to be processed. Similarly, the management computer  100  acquires, at the time calculated as described above, from the hierarchical control information acquired at step  6010  the tier in which the page to be processed was arranged. Next, the management computer  100  references the hierarchical storage performance management table  1204  and acquires the IOPS upper limit of the tier in which the page to be processed was arranged. Then, the management computer  100  compares IOPS value generated with respect to the page to be processed and the IOPS upper limit of the tier in which the page to be processed was arranged, and determines whether or not the IOPS generated with respect to the page to be processed at the time of job execution was at its upper limit (step S 6035 ). 
         [0156]    If the result of determination at step S 6035  is affirmative, the management computer  100  determines whether or not the tier in which the page to be processed was arranged is a tier higher in input/output performance than in the tier designated by the I/O analysis data  1103  (step S 6037 ). 
         [0157]    If the result of determination at step S 6037  is affirmative, the management computer  100  alters information on the tier set to the field of the designated tier matching the page designated at step S 6030 , out of the elapsed times in the I/O analysis data  1103  designated at step S 6025 , to a superior tier (step S 6040 ). If the result of determination at step S 6037  is negative, the management computer  100  performs processes at and after step S 6055 . 
         [0158]    If the result of determination at step S 6035  is negative, the management computer  100  determines whether or not the page to be processed was allocated at the time of job execution to a tier having a higher than required performance level. More specifically, the management computer  100  compares the IOPS value generated on the page to be processed at step  6035  and IOPS upper limit information on each tier in the hierarchical storage performance management table  1204 , and determines whether or not the upper limit value of a tier not lower than the actually arranged tier is higher than the IOPS value generated for the page to be processed (step S 6045 ). 
         [0159]    If the result of determination at step S 6045  is affirmative, the management computer  100  determines that the page to be processed was allocated at the time of job execution to a tier having a higher than required performance level, and alters tier information set in the field reference at step S 6045  in the designated tier to an inferior tier. If the result of determination at step S 6045  is negative, the management computer  100  performs the processes at and after step S 6055 . 
         [0160]    At step S 6055 , the management computer  100  determines whether or not processing is executed on every page covered by the loop (C). If processing is executed, the management computer  100  executes step S 6060  or, if not, the management computer  100  returns processing to step S 6030 . At step S 6060 , the management computer  100  determines whether or not processing is executed on every elapsed time step covered by the loop (B). If processing is executed, the management computer  100  executes step S 6070  or, if not, the management computer  100  returns processing to step S 6025 . At step S 6070 , the management computer  100  determines whether or not processing is executed on every subprogram  3102  covered by the loop (A). If processing is executed, the management computer  100  ends the hierarchical control plan formulation program  1255  or, if not, the management computer  100  returns processing to step S 6015 . 
         [0161]    To add, in the foregoing description, determination on correction of the hierarchical control plan was based on performance information (IOPS) regarding the storage system  200  and the IOPS upper limit of tiers, but this is just one example of correcting the hierarchical control plan, and the information to be utilized in correcting the hierarchical control plan is not limited to performance information regarding the hierarchical storage (IOPS) and the IOPS upper limit of tiers. For instance, response performance information on the application program  3101  of the host computer  300  and required performance set in the application program  3101  may be used instead. 
         [0162]    As hitherto described, it is possible to migrate pages with a large amount of access to subprograms  3102  to a superior tier before executing the subprograms  3102 , and response performance to application programs can be thereby improved. It is also possible to migrate pages with a small amount of access to subprograms  3102  to an inferior tier, and occupation of superior tiers by pages with a small amount of access can be thereby prevented. 
       Second Embodiment 
     (2-1) Outline of This Embodiment 
       [0163]    Regarding the computer system of the Second Embodiment, the following description will cover only those parts different from the First Embodiment. For the First Embodiment, it was presupposed that the relevance between subprograms  3102  and pages constituting the application program  3101  could be set in advance in the subprogram page relationship table  1101  stored in the disk  120  of the management computer  100 . However, in the Second Embodiment, the I/O analysis program  1254  can be applied also to an application program  3101  in which this relevance cannot be set in advance. More specifically, the management computer identifies pages relevant to the subprogram  3102  in accordance with a subprogram page relevance discovering program, and updates the subprogram page relationship table  1101 . 
       (2-2) Hardware Configuration of Computer System 
       [0164]    The computer system of the Second Embodiment is configured of a management computer  100 A, a storage system  200  and a host computer  300 , and they are connected to one another via a communication network  500  and a communication network  550 . Herein, the storage system  200  and the host computer  300  are the same as their respective counterparts in  FIG. 2 .  FIG. 23  shows an example of configuration of the management computer  100 A in the Second Embodiment, and a disk  120 A besides storing of programs and tables developed in the disk  120 A by the management computer  100  shown in  FIG. 3 , further stores a subprogram page relevance discovering program  1258 . 
       (2-3) Details of Actions to Discover Subprogram Page Relevance 
       [0165]    Actions of a subprogram page relevance discovering program stored in the disk  120 A by the management computer  100 A will be described in detail.  FIG. 24  is a diagram showing an example of flow chart of the subprogram page relevance discovering program  1258 . The management computer  100 A executes, periodically and for each set of event information (combination of sets of information shown in the application name column  120301 , the operation type column  120302  and the server name column  120303 ) the included in the log file management table  1203 , the subprogram page relevance discovering program  1258  with event information as the input. 
         [0166]    The CPU  150  of the management computer  100 A (hereinafter abbreviated to the management computer  100 A) first acquires every log file IO matching inputted event information from the log file IO column  120305 , and identifies the log file data  1202  matching the acquired log file  10  (step S 7005 ). Next, the management computer  100 A extracts one or more subprograms  3102  from the identified log file data group  1202  (step S 7010 ). As the processing at step S 7010  is the same as that at step S 1010 , its description is dispensed with. 
         [0167]    The management computer  100 A executes step S 7020  through step S 7050  that follow as the loop (A) once or a plurality of times for each of the subprograms  3102  extracted at step S 7010  (step S 7015 ). At step S 7020 , the management computer  100 A extracts time information matching the information regarding the subprogram  3102  chosen at step S 7015  from the subprogram column  120203  and the time column  120202  in the log file data group  1202  identified at step S 7005 . More specifically, the time information indicates the start time and end time of the subprogram  3102 . 
         [0168]    The management computer  100 A extracts from IOPS transition data  1103  IOPS transitions in the time group extracted at step S 7020 . More specifically, they are IOPS transitions from the start time till end time of the subprogram  3102 . To add, if the end time of the subprogram  3102  is not identified at step S 7020 , they are IOPS transitions until the end time stored in the log file data  1202  (step S 7025 ). 
         [0169]    The management computer  100 A executes processes at step S 7035  through step S 7045  that follow as the loop (B) once or a plurality of times for each page (step S 7030 ). The management computer  100 A determines at step S 7035  whether or not an access to the page chosen at step S 7030  occurs every time after the subprogram  3102  is executed. More specifically, it determines whether or not a failure of any IOPS for a page to surpass a threshold occurs in the IOPS transition group extracted at step S 7025  (step S 7035 ). To add, as the threshold, the IOPS value or the like for the pertinent page in state of occurrence of no event at all may be used for instance. 
         [0170]    If, as a result of determination at step S 7035 , it is found that an access to a page has occurred in every set of IOPS transition data, the management computer  100 A executes step S 7040 . The management computer  100 A determines at step S 7040  whether or not the timing of variation of access volume occurring to any page chosen at step S 7030  is constant. More specifically, the management computer  100 A calculates, for every IOPS transition group extracted at step S 7025 , the elapsed time since the execution of the subprogram  3102  until the amount of access to the page. The method of calculation may be, for instance, similar processing to that executed at S 1020 . Next, the management computer  100 A determines for each IOPS transition group whether or not there is any discrepancy in the calculated elapsed time since the execution of the subprogram  3102  until the amount of access to page to which the calculation above applies (step S 7040 ). As the method of checking any discrepancy in the elapsed time, for instance a statistical checking method utilized at step S 1010  may be used. 
         [0171]    If the result of determination at step S 7040  is affirmative, the management computer  100 A executes step S 7045  or, if negative, the management computer  100 A executes step S 7050 . At step S 7045 , the management computer  100 A stores into the subprogram page relationship table  1101  information on the event given as an input, the subprogram  3102  chosen at step S 7015  and the No. of the page chosen at step S 7030 . To add, information indicating an unoccupied column is stored into the data ID column  110105  of the subprogram page relationship table  1101 . 
         [0172]    At step S 7050 , the management computer  100 A determines whether or not processing is executed on every page covered by the loop (B). If processing is found to be executed, the management computer  100 A executes step S 7055  or, if not, the management computer  100 A returns processing to step S 7030 . At step S 7055 , the management computer  100  determines whether or not processing is executed on every subprogram  3102  covered by the loop (A). If processing is found to be executed, the management computer  100 A ends the job end time I/O analysis correction program  1257 , or if not, the management computer  100 A returns processing to step S 7030 . 
         [0173]    As hitherto described, even in an application program  3101  in which relevance between the subprogram  3102  and pages is not clear, I/O analysis can be performed by identifying pages relevant to the subprogram  3102  and updating the subprogram page relationship table  1101  in accordance with the subprogram page relevance discovering program  1258 . 
       Third Embodiment 
     (3-1) Outline of this Embodiment 
       [0174]    Concerning the computer system of the Third Embodiment, only the parts different from the First Embodiment will be described in the following account. In the First Embodiment, data to be used by the application program  3101  is arranged in the storage system  200 . Unlike that, in the Third Embodiment, even in the disk within the host computer, it is made possible to arrange data to be used by the application program  3101 , and page hierarchical control can be accomplished on the basis of I/O analysis at the time of performing operations on the application program  3101 . 
       (3-2) Hardware Configuration of Computer System 
       [0175]    The computer system of the Third Embodiment is configured of a management computer  100 B, a storage system  200  and a host computer  300 B, and they are connected to one another via a communication network  500  and a communication network  550 . Here, the storage system  200  is the same as what is shown in  FIG. 4 .  FIG. 25  is a diagram showing an example of configuration of the management computer  100 B in the Third Embodiment. A disk  120 B of the management computer  100 B stores the programs and tables developed in the disk  120  by the management computer  100  shown in  FIG. 3 , and a relative hierarchical storage management table  1205  is further held in the disk  120 B. As programs and tables stored in the memory  110 , the I/F for management use  130 , the data communication I/F  140 , the CPU  150  and the memory  110  of the management computer  100 B pertaining to the Third Embodiment are similar to the configuration of the management computer  100  pertaining to the First Embodiment, their description will be dispensed with. 
         [0176]    The disk  320  of the host computer  300 B stores the programs and tables the host computer  300  shown in  FIG. 5  develops in the disk  320 , and the storage system  200  shown in  FIG. 4  further holds in the disk  320  programs similar to the I/O amount monitoring program  2151  and the page allocation control program  2152  stored in a memory  210 . 
         [0177]    To add, in the computer system of the Third Embodiment, part or the whole of the data to be used by application programs the storage system  200  shown in  FIG. 4  stores in a storage region  250  can be stored not only in the storage region  250  of the storage system  200  but also in the disk  320  or stored in an external storage DAS (Direct Attached Storage), not shown, connected to the host computer  300 B. Namely, the presence of the storage system  200  is not indispensable in the Third Embodiment. Further, in the computer system of the Third Embodiment, data may be reciprocally stored in two or more host computers  300 B. 
         [0178]    As programs and tables stored in the memory  310 , the I/F for management use  330 , the data communication I/F  340 , the CPU  350  and the memory  310  of the host computer  300 B of the Third Embodiment are similar to the configuration of the host computer  300  shown in  FIG. 5 , their description is dispensed with. 
       (3-3) Details of Various Tables 
       [0179]      FIG. 26  is a diagram showing an example of relative hierarchical storage management table  1205  stored in the disk  120 B of the management computer  100 B. The relative hierarchical storage management table  1205  is information resulting from sequential arrangement of tiers held by the storage system  200  and the host computer  300 B in the order of input/output performance levels when data is accessed from the host computer  300 B. 
         [0180]    In a server name column external storage, the name of the host computer  300 B by which the application program  3101  is executed is stored. In a relative tier ID column  120502 , the Nos. of tiers which constitute a storage region accessible from the host computer  300 B that executes the application program  3101  are stored. In the relative tier ID column  120502 , the higher the tier input/output performance level as seen from the host computer  300 B that executes the application program  3101 , the smaller the No. that is assigned. In a tier-providing machine name column  120503 , the name of the storage system  200  or the host computer  300 B that actually holds tiers is stored. 
         [0181]    In a tier ID column  120504 , the tier No. of the storage system  200  or the host computer  300 B that actually holds tiers is stored. Further, in contrast to relative tiers whose Nos. are determined by the input/output performance level as seen from the host computer  300 B that executes the application program  3101 , tiers numbered by the tier ID  120504  within the storage system  200  or the host computer  300 B are expressed as absolute tiers. To add, though it was stated that in  FIG. 26  the smaller the tier No. the higher the performance level, this is not the only possibility. Further, instead of the tier No., the name of the medium constituting the tier can also be used as the tier ID. 
       (3-4) Details of Actions of Various Devices 
       [0182]    When the management computer  100 B is to reference a tier No. in a program stored in the disk  120 B, the tier No. in the relative tier ID column  120502  of the relative hierarchical storage management table  1205  is searched for. Further, when the management computer  100 B is to formulate a hierarchical control plan, a hierarchical control task is generated by differentiating absolute tiers from relative tiers on the basis of the relative hierarchical storage management table  1205  and designating absolute tiers. 
         [0183]    As hitherto described, the management computer  100 B can formulate a hierarchical control plan among all the tiers provided by the storage system  200  and the host computer  300 B on the basis of the result of I/O analysis and execute the plan. Further in a computer system in which no dedicated storage system is present, namely having a built-in server or configured only of external storages, it is possible to formulate and execute a hierarchical control plan. 
       LIST OF REFERENCE SIGNS 
       [0000]    
       
           100  . . . Management computer 
           200  . . . Storage system 
           300  . . . Host computer: 
           1101  . . . Subprogram relationship table 
           1201  . . . IOPS transition data 
           3201  . . . Log file