Abstract:
The storage system includes a plurality of first disk devices, a plurality of second disk devices, in which a lifetime of the plurality of second disk devices is different from a lifetime of the plurality of first disk devices, and a controller coupled to the plurality of first disk devices and the plurality of second disk devices. The controller configures a first logical unit by the plurality of first disk devices and a second logical unit by the plurality of second disk devices, provides the first and the second logical units to a host computer, and manages a first remaining available time of the first logical unit and a second remaining available time of the second logical unit, on logical unit basis.

Description:
The present application is a continuation application of U.S. Ser. No. 12/076,141, filed Mar. 14, 2008 (now U.S. Pat. No. 7,925,830), which is a continuation application of U.S. Ser. No. 11/785,780, filed Apr. 20, 2007 (now U.S. Pat. No. 7,366,839), which is a continuation application of U.S. Ser. No. 10/988,495, filed Nov. 16, 2004 (now U.S. Pat. No. 7,272,686), which is a continuation of application Ser. No. 10/419,096, filed Apr. 21, 2003, (now U.S. Pat. No. 7,047,354), the contents of which are incorporated herein by reference. This application claims priority to Japanese Patent Application No. 2003-037602, filed Feb. 17, 2003. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates mainly to a control method for storage system and a storage system. 
     DESCRIPTION OF RELATED ART 
     As a kind of a storage system connected to a computer, there are disk arrays. Disk arrays are called RAID (Redundant Arrays of Inexpensive Disks). The disk array is a storage system including a plurality of disk devices arranged in an array form and a control unit for controlling them. In the disk array, read requests (data readout requests) and write requests (data write requests) are processed at high speed by parallel operation of disk devices, and redundancy is added to data. The disk arrays are classified into five levels in accordance with the kind and configuration of the added data, as disclosed in “A case for Redundant Arrays of Inexpensive Disks (RAID)”, David A. Patterson, Garth Gibson, and Randy H. Katz, Computer Science Division Department of Electrical Engineering and Computer Sciences, University of California Berkeley. By the way, disk devices are storages having a hard disk, an optical magnetic disk, or the like. 
     On the other hand, in disk devices, there are some kinds differing in interface used for connection to other devices. For example, there are disk devices (hereafter referred to as FC disk devices) each having a fibre channel (hereafter referred to as FC) interface for which standardization work is being conducted by ANSI T11, and Advanced Technology Attachment disk devices (hereafter referred to as ATA disk devices) each having an ATA (Advanced Technology Attachment) interface for which standardization work is being conducted by ANSI T13. 
     ATA disk devices are comparatively inexpensive and used in desktop computers for homes. On the other hand, FC disk devices are used in business servers of which reliability is required. As compared with the ATA disk devices, therefore, the FC disk devices have higher processing performance in data input/output (hereafter referred to as I/O) and such higher reliability that they can withstand continuous operation over 24 hours on 365 days. In the case where these disk devices are used in storage systems such as disk arrays, disk devices are used properly sometimes in accordance with the performance, price or the like required of the disk array. For example, a technique of improving the reliability of data stored in a disk array by using a disk device that is higher in performance than a data storing disk device as a disk device for storing parities, which are redundant data, is disclosed in JP-A-10-301720. 
     SUMMARY OF THE INVENTION 
     In recent years, there is a demand that a data stored in disk devices in the hosts should be consolidated into one disk array in order to decrease the cost of data management. If the disk arrays are merely collected into one disk array physically, however, flexibility is impaired as compared with the case where a plurality of disk arrays differing in kind or performance are used. Therefore, there are increased demands that a more flexible array construction should be conducted while holding down the price of the disk array, by providing disk devices having high price, high reliability, and high performance and disk devices having low price and low reliability mixedly in one disk array and properly using the disk devices according to use. 
     In the conventional technique, however, it is difficult to unitarily manage the reliability of disk devices. Therefore, it has not been considered to provide mixedly disk devices differing in reliability of disk device itself, such as, for example, device lifetime, and construct and manage a storage system, such as a disk array. 
     Therefore, the present invention provides a storage system including a plurality of storages differing in reliability of storage itself, and a control unit connected to the storages. The control unit further includes an interface to which the storages are connected, and the control unit detects information concerning the reliability of each of the storages and manages the detected information. To be concrete, it is conceivable that the control unit detects a kind of each of the storages and thereby determines a lifetime (predetermined available time given by the storage type) of the storage. Furthermore, it is also conceivable that the control unit manages the detected lifetime of each of the storages and time when the storage has been used, and thereby manages a remaining available time (remaining lifetime) of the disk device. 
     Furthermore, the control unit in the storage system according to the present invention alters a use form of each of the storages according to its remaining lifetime. For example, if the remaining lifetime of a managed storage has become shorter than a certain predetermined time, then the storage is used for obtaining backup of data, or the use of the storage is stopped and replaced. 
     Furthermore, the control unit in the storage system according to the present invention previously determines use of each of the storages according to its available time. For example, storages each having a long available time are discriminated from storages each having a short available time. A group of storages each having a long available time are designated as usually used storages, whereas a group of storages each having a short available time are designated as storages for storing backup data. 
     Furthermore, the control unit in the storage system according to the present invention controls these storages on the basis of detected kinds of the storages. For example, the control unit issues a command peculiar to a storage according to the detected kind of the storage. 
     Furthermore, the control unit in the storage system according to the present invention may have a program for identifying kinds of storages and managing different storages separately, and a drive management table that stores management information. 
     Furthermore, the storage system according to the present invention, for example, sets a lifetime of each of the drives, intentionally start/stops each of ATA disk devices, and measures accumulated operation time. 
     Furthermore, a storage management server for managing an environment including a mixture of storage systems described above may also be provided. 
     Furthermore, the storage system conducts data duplication between storage systems or within the storage system, and assigns logical storage regions that become subjects of data duplication on the basis of lifetime management. 
     By the way, both logical storages and physical storages, such as disk devices, are included in “storages.” 
     Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a system configuration diagram in a first embodiment of the invention; 
         FIG. 2  is a diagram of a drive management table in the first embodiment; 
         FIG. 3  is a configuration diagram of an input unit in the first embodiment; 
         FIG. 4  is a configuration diagram of an output unit in the first embodiment; 
         FIG. 5  is a diagram showing an example of an LU management table in the first embodiment; 
         FIG. 6  is a flow chart of a drive lifetime management operation in the first embodiment; 
         FIG. 7  is a system configuration diagram in a second embodiment of the invention; 
         FIG. 8  is a diagram of a port bypass circuit in the second embodiment; 
         FIG. 9  is a diagram of an FC-ATA conversion I/F in the second embodiment; 
         FIG. 10  is a system configuration diagram in the third embodiment of the invention; 
         FIG. 11  is a diagram showing an example of an LU pair management table in the third embodiment; 
         FIG. 12  is a diagram of a storage management server in the third embodiment; 
         FIG. 13  is a diagram showing an example of a device list in the third embodiment; 
         FIG. 14  is a diagram showing an example of an LU evaluation item table in the third embodiment; 
         FIG. 15  is a flow chart of logical unit (LU) assignment processing in the third embodiment; 
         FIG. 16  is a flow chart of host LU assignment processing in the third embodiment; 
         FIG. 17  is a flow chart of copy destination LU assignment processing in the third embodiment; 
         FIG. 18  is a flow chart of assignment candidate LU search processing in the third embodiment; 
         FIG. 19  is a diagram showing an example of an LU remaining lifetime watermark table in the third embodiment; and 
         FIG. 20  is a flow chart of LU lifetime management processing in the third embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  is a diagram showing a first embodiment of a storage system according to the present invention. A disk array  700 , which is an example of a storage system, is connected to a computer (hereafter referred to as host)  100  and a management terminal  500 . As for an interface used for connection to the host  100 , an FC or a SCSI is conceivable. The disk array  700  includes a disk array control unit  200 , an FC disk group  310 , and an ATA disk group  410 . 
     The FC disk group  310  includes a plurality of FC disk devices  301 . The ATA disk group  410  includes a plurality of ATA disk devices  401 . In the present embodiment, FC disk devices and ATA disk devices are exemplified. In application of the present invention, however, disk devices used in the disk array are not limited to these disk devices. 
     The management terminal  500  includes an input unit  510 , such as a keyboard device, used by the user when inputting setting concerning the disk array  700 , and an output unit  520 , such as a display device, for showing information concerning the disk array  700  to the user. 
     The disk array control unit  200  includes a CPU  201  for executing a program to control the disk array  700 , a memory  202 , a cache  203  for temporarily storing input and output data of the host  100 , a host FC I/F  204  for controlling data transmission and reception between the host  100  and the disk array control unit  200 , a drive FC I/F  205  for controlling data transmission and reception between the FC disk group  310  and the disk array control unit  200 , a drive ATA I/F  206  for controlling data transmission and reception between the ATA disk group  410  and the disk array control unit  200 , and a management interface (I/F)  207  for controlling information transmission and reception between the management terminal  500  and the disk array control unit  200 . These components are connected to each other via an internal bus. 
     The drive FC I/F  205  is connected to the FC disk group  310  via an FC. In the present embodiment, the fibre channel arbitration loop is used as a protocol for the FC. However, the protocol is not limited to this, but another protocol, such as the point-to-point or fabric of the FC, also may be used. 
     The drive ATA I/F  206  is connected to ATA disk devices included in the ATA disk group  410  via an ATA bus. 
     Various programs to be executed by the CPU  201  to control the disk array  700  are stored in the memory  202 . To be concrete, a RAID control program  210  for controlling the operation of the disk array  700 , and a management agent  800  for managing the configuration of the disk array  700  are stored in the memory  202 . Various kinds of information is also stored in the memory  202 . To be concrete, a drive management table  240  for recording information concerning the FC disk group  310  and the ATA disk group  410 , and an LU management table  245  for recording information concerning a logical storage region (hereafter referred to as FCLU)  320  created in the FC disk group  310  and a logical storage region (hereafter referred to as ATA LU)  420  created in the ATA disk group  410  are also stored in the memory  202 . 
     The RAID control program  210  is formed of several subprograms. To be concrete, the RAID control program  210  includes a drive command issuance program  220  to be executed by the CPU  201  when issuing a command to the FC disk group  310  or the ATA disk group  410 , a drive management program  230  to be executed to manage the FC disk group  310  and the ATA disk group  410 , and an LU management program  225  to be executed to manage logical storage regions (hereafter referred to as LU) preset in respective disk groups. 
     The management agent  800  is formed of several subprograms. To be concrete, the management agent  800  includes a drive information setting program  250  to be executed when setting information (hereafter referred to as drive information) concerning a disk device in response to an input from the management terminal  500 , a drive information notification program  260  to be executed when outputting drive information to the management terminal  500 , an array information setting program  270  to be executed when setting information (hereafter referred to as array information) concerning the disk array  700 , and an array information notification program  280  to be executed when outputting array information to the management terminal  500 . 
       FIG. 2  is a diagram showing an example of contents of the drive management table  240 . The drive management table  240  has items for registering various kinds of information for each of disk devices included in the disk array  700 . To be concrete, the drive management table  240  has a “drive No.” column  240   a  for registering a number assigned to the disk device, a “drive type” column  240   b  for registering a type of the disk device, an “array configuration” column  240   c  for registering an RAID group (a set of disk devices forming redundancy) including the disk device and its RAID level (hereafter referred to as array configu-ration), a “use” column  240   d  for registering a user&#39;s use (hereafter referred to as array use) of a RAID group including the disk device, a “start situation” column  240   e  for registering a situation as to whether the disk device is started or stopped, an “accumulated time” column  240   f  for registering accumulated operation time of the disk device, a “lifetime setting” column  240   g  for registering lifetime of the disk device, a “remaining lifetime” column  240   h  for registering a remaining lifetime of the disk device, and an “automatic migration specification” column  240   i  for registering whether data should be automatically migrated (hereafter referred to as automatic migration) to another disk device when the disk device is judged to have arrived at the lifetime. 
     To be concrete, information indicating FC or ATA is registered in the “drive kind” column  240   b . A number indicating an order in which the RAID group has been created, and information indicating the RAID level are registered in the “array configuration” column  240   c . For example, a disk device for which “(1)RAID5” has been registered is a disk device included in a RAID group having a RAID level 5 created first. In the disk array  700 , a plurality of RAID groups can be created. For example, RAID groups RAID1 and RAID5 can be created. Disk devices included in the RAID group may be all devices included in the disk array  700  or may be a part of them. 
     In the “use” column  240   d , to be concrete, information, such as DB indicating the use of the database and FS indicating the use of the file system, is registered. In the “start situation” column  240   e , information indicating ON is registered in the case where the disk device is started, and information indicating OFF is registered in the case where the disk device is stopped. In the “remaining lifetime” column  240   h , a value indicating a difference between time registered in the “lifetime setting” column  240   g  and time registered in the “accumulated time” column  240   f  is stored. In the “automatic migration specification” column  240   i,  1 is registered when setting automatic migration of data stored in the disk device, and 0 is registered when not setting automatic migration of data stored in the disk device. 
     The drive management program  230  is executed in the CPU  201 , when the disk array control unit  200  discriminates the kind of the disk device, when the disk array control unit  200  measures the operation time of the disk device, when the disk array control unit  200  controls the start and stop of the disk device, and when the disk array control unit  200  executes the automatic migration in response to arrival of the disk device at the lifetime. 
     The drive information setting program  250  is executed in the CPU  201 , when the disk array control unit  200  sets the kind of the disk device in the drive management table  240  in accordance with an input from the management terminal  500 , when the disk array control unit  200  sets the lifetime of the disk device in the drive management table  240 , and when the disk array control unit  200  sets the situation of start and stop of the disk device in the drive management table  240 . 
     The drive information notification program  260  is executed in the CPU  201 , when the disk array control unit  200  notifies the management terminal  500  of the kind of the disk device, when the disk array control unit  200  notifies the management terminal  500  of the accumulated operation time of the disk device, when the disk array control unit  200  notifies the management terminal  500  of the situation of start and stop of the disk device, when the disk array control unit  200  orders exchange of the disk device, and when the disk array control unit  200  notifies that automatic migration of data to another disk device has been conducted because of arrival of the disk device at the lifetime. 
     The array information setting program  270  is executed in the CPU  201 , when the disk array control unit  200  sets the array configuration in accordance with an input from the management terminal  500 , and when the disk array control unit  200  sets the use of the array in accordance with an input from the management terminal  500 . 
     The array information notification program  280  is executed in the CPU  201 , when the disk array control unit  200  notifies the management terminal  500  of information concerning the array configuration, and when the disk array control unit  200  notifies the management terminal  500  of information concerning the use of the array. 
       FIG. 3  is a diagram showing an example of a picture displayed on the output unit  520  of the management terminal  500  when the user or manager of the disk array  700  conducts setting of the disk array  700 . In this case, the following regions are displayed on the output unit  520 . The regions are a drive kind setting region  551  for displaying an input kind of the disk device, a drive lifetime setting region  552  for displaying an input lifetime of the disk device, a drive start/stop setting region  553  for displaying a start/stop condition of the disk device specified by the user, an array configuration setting region  571  for displaying an input array configuration, and an array use setting region  572  for displaying an input array use. While watching the picture, the user inputs necessary data via the input unit, and ascertains contents of the input data. 
       FIG. 4  shows an example of a picture displayed on the output unit  520  when the user or manager of the disk array  700  acquires information of the disk array  700  via the management terminal  500 . In this case, the following regions are displayed on the output unit  520 . 
     The regions are a drive kind display region  561  for displaying a kind of a disk device included in the disk array  700 , an operation time display region  562  for displaying accumulated operation time of a disk device included in the disk array  700 , a drive state display region  563  for displaying a start/stop situation of the disk device, an exchange order display region  564  for displaying an exchange order of the disk device, an automatic migration notification display region  565  for displaying that automatic migration of data to another disk device has been conducted because of arrival of some disk device at the lifetime, an array configuration display region  581  for displaying a preset array configuration, and an array use display region  582  for displaying a preset array use. By displaying this picture on the management terminal  500 , the manager or user can ascertain the state of the disk array  700 . 
       FIG. 5  is a diagram showing an example of contents of the LU management table  245  used by the disk array control unit  200  to manage the FCLU  320  and the ATA LU  420 . In the LU management table  245 , the following items for registering information is provided for each LU in order that the disk array control unit  200  may manage respective LUs. 
     In “LU No.” column  245   a , identifiers arbitrarily assigned to respective LUs are registered. In “host assignment situation” column  245   b , information of “presence” or “absence” indicating whether an LU has been assigned to the host  100  is registered (hereafter referred to as used if assigned, and referred to as unused if not assigned). In “SCSI ID” column  245   c , a SCSI ID number, which is assigned to a logical storage including an LU, is registered if the LU is assigned to the host  100 . In “LUN” column  245   d , a SCSI logical unit number required for the host  100  to access an LU is registered if the LU is assigned to the host  100 . 
     In “capacity” column  245   e , a storage capacity assigned to an LU is registered. In “LU kind” column  245   f , information indicating the kind as to whether the LU is the FCLU  320  or the ATA LU  420  is registered. In “LU remaining lifetime” column  245   g , remaining lifetime of the LU is registered. To be concrete, the disk array control unit  200  acquires remaining lifetime values of respective disk devices forming the LU registered in a “drive No. list” column  245   h , from the drive management table  240 , and registers a minimum value among them. 
     In the “drive No. list” column  245   h , information that indicates disk devices forming the LU is registered as a list of drive Nos. In “evaluation value” column  245   i , information indicating an evaluation value, which serves as a criterion of LU selection, is registered. A method for calculating the evaluation value will be described later. In the case of a used LU, a maximum value (+99999 in the example of  FIG. 5 ) which can be registered is registered in “evaluation value” column  245   i.    
     Hereafter, the case where the disk array control unit  200  conducts construction of the drive management table  240 , the LU management table  245 , and the RAID group in accordance with an order from the user or manager will be described. 
     When a power supply of the disk array  700  is turned on, the disk array control unit  200  executes the drive management program  230 , and makes inquiries about disk devices connected to the drive FC I/F  205  and the drive ATA I/F  206 . As an example of inquiries about the disk devices, there is an example in which a ModeSelect command is used. To be concrete, the disk array control unit  200  issues the ModeSelect command to respective disk devices. Upon receiving the ModeSelect command, the disk device transmits page information stored in the disk device to the disk array control unit  200 . Page information contains information concerning the kind of the disk device. The disk array control unit  200  discriminates the kind of the inquired disk device on the basis of page information acquired from the disk device. 
     Furthermore, the disk array control unit  200  executes the drive information setting program  250 , and registers pertinent information in the “drive No.” and the “drive kind” items of the drive management table  240  with respect to all of the detected disk devices. 
     The kind of the disk device may be input by the user via the input unit of the management terminal  500 . In this case, the disk array control unit  200  registers information in the drive management table  240  on the basis of information received from the management terminal  500 . 
     After detection or registration of the kind of the disk device has been conducted, the disk array control unit  200  sets the array configuration and array use on the basis of an order from the user. 
     First, upon receiving an acquisition order of information of “drive No.” and “drive kind” input by the user via the input unit  510  in the management terminal  500 , the disk array control unit  200  executes the drive information notification program  260 , acquires requested information from the drive management table  240 , and transfers the requested information to the management terminal  500  via the management I/F  207 . The management terminal  500  displays received information in a portion for displaying the “drive No.” and “drive kind” in the drive kind display region  561 , which is displayed on the output unit  520 . In the case where the user defines the kind of the disk device, the present processing may be omitted. 
     Thereafter, the user selects an arbitrary disk device on the basis of information displayed in the drive kind display region  561 , which is displayed on the output unit  520  of the management terminal  500 , and inputs an order for constructing a RAID group by using the selected disk device, from the input unit  510  by using the array configuration setting region  571 . Furthermore, the user inputs the use of the RAID group to be constructed. The disk array control unit  200  executes the array information setting program, and registers array information, such as the RAID group and use, received via the management I/F  207  in the “array configuration” and “use” columns of the drive management table  240 . 
     The user constructs a RAID group on the basis of the kind of the disk device displayed in the drive kind display picture  561 . At this time, however, it is possible to prevent an ATA disk device, which is low in reliability and performance, from being set for array use, which is required to be high in reliability and performance, such as array use for a database. To be concrete, in the case where “use” is specified by the user, a decision is made as to whether the lifetime of the disk device meets the use, on the basis of information concerning the lifetime of the disk device described later. And warning is given to the user in accordance with a result of the decision. 
     For example, in the case where it is attempted to set an ATA disk device for array use, which is high in reliability and performance, the management terminal  500  may issue caution or warning to the user via the output unit  520 . Furthermore, when displaying disk devices in the drive kind display picture  561 , disk devices differing in kind may have different patterns so as to be able to be discriminated from each other. 
     It is also possible to consider a method of disregarding the lifetime of the disk device when first creating a RAID group and adding the remaining lifetime of the disk device as a decision criterion for new use setting when remaking a RAID group again. 
     Upon receiving information for ordering information acquisition of “array configuration” and “use” input by the user via the input unit  510  of the management terminal  500 , the disk array control unit  200  retrieves information requested from the management terminal  500  via the management I/F  207 , from the drive management table  240  and transfers the retrieved information, by executing the array information notification program. Upon receiving the information, the management terminal  500  displays the acquired information in the array configuration display region  581  and the array use display region  582  of the output unit  520 . 
     Lifetime management of the disk device conducted by the disk array control unit  200  will now be described. As described earlier, the disk array control unit  200  controls the management of the accumulated operation time and planned start/stop of disk devices, and automatic migration of data. 
     The “lifetime” of a disk device refers to time preset by a manufacturer of the disk device on the basis of specifications, such as the mean time between failures and recommended service time, of the disk device, or time preset by the disk array manager on the basis of time preset by a manufacturer of the disk device. The “lifetime” of a disk device is defined as “time serving as a criterion of preventive maintenance for preventing a failure caused by a long time operation of the disk device.” For a disk device that has exceeded the “lifetime,” therefore, it is necessary to execute migration of stored data and the maintenance personnel must execute exchange to a new disk device. 
     For conducting the lifetime management, first, the disk array  700  conducts lifetime setting and automatic migration specification for each disk device. The present processing may be conducted together when the disk array control unit  200  conducts setting of various tables according to a user&#39;s order, or the present processing may be conducted before the disk array control unit  200  conducts setting of various tables according to a user&#39;s order. The lifetime setting and automatic migration specification for each disk device are conducted as described below. 
     Upon receiving the order for acquiring information of “drive No.” and “drive kind” input from the input unit  510  of the management terminal  500  by the user, the disk array control unit  200  transfers the requested information to the management terminal  500  via the management I/F  207 . Upon receiving the information, the management terminal  500  displays the received information concerning “drive No.” and “drive kind” in the drive kind display region  561  of the output unit  520 . 
     The user discriminates the kind of the disk device on the basis of the information displayed in the drive kind display region  561 , and conducts setting as to the lifetime of the disk device and as to whether automatic migration is necessary via the input unit  510  of the management terminal  500 . Upon receiving information concerning the lifetime of the disk device and whether automatic migration in the disk device is necessary via the management I/F  207 , the disk array control unit  200  executes the drive information setting program  252 , and registers the received information in “lifetime setting” and “automatic migration specification” columns of the drive management table  240 . The information of “lifetime setting” and “automatic migration specification” may not be specified by the user, but the disk array control unit  200  may determine the information of “lifetime setting” and “automatic migration specification” uniquely on the basis of the kind of the disk device and set the information in the drive management table  240 . For example, in the case of an FC disk device, it is considerable to predict from the beginning that the lifetime is long and set the information in the drive management table  240 . 
       FIG. 6  is a flow chart showing a procedure of the drive lifetime management conducted by the disk array control unit  200 . 
     First, the disk array control unit  200  starts measurement of the operation time of respective disk devices included in the disk array  700  and accumulates results of the measurement in the “accumulated time” of the drive management table  240 , by executing the drive management program  230 . When measuring the operation time, the disk array control unit  200  measures the operation time on the basis of a clock included in the disk array  700  (step  1003 ). Thereafter, the disk array control unit  200  compares values in the “accumulated time” and “lifetime setting” in the drive management table  240 , and determines whether the accumulated time has reached the preset lifetime. Timing for the comparison may be arbitrary timing that is asynchronous with other processing (step  1004 ). 
     If the accumulated time has not reached the lifetime, then the processing returns to the step  1003 . If the accumulated time has reached the preset life-time, then the disk array control unit  200  determines whether there is 1 registered in the “automatic migration specification” column  240   i  for the disk device (step  1005 ). If the automatic migration is not specified (i.e., the registered value is 0), then the disk array control unit  200  executes the drive information notification program  260 , and thereby notifies the management terminal  500  of a disk device that has reached in accumulated time the preset lifetime as a disk device to be exchanged, via the management I/F  207 . 
     The management terminal  500  displays the disk device that has reached in accumulated time the preset lifetime as a disk device to be exchanged, in the exchange order display region  564  of the output unit  520  (step  1006 ). If the automatic migration is specified for the disk device that has reached in accumulated time the preset lifetime (i.e., the registered value is 1), then the disk array control unit  200  executes the drive management program  230  and the RAID control program  210 , and thereby transfers data stored in the disk device that has reached in accumulated time the preset lifetime to a disk device serving as the automatic migration destination. The disk device that serves as the automatic migration destination is specified beforehand by the user or the like. In this case, one disk device may be specified as an automatic migration destination device for a plurality of disk devices (step  1010 ). 
     After the data transfer has been completed, the disk array control unit  200  notifies the management terminal  500  of information concerning the disk device designated as the automatic migration destination, via the management I/F  270  (step  1011 ). Upon being notified of the information, the management terminal  500  displays the information concerning the disk device designated as the automatic migration destination, in the automatic migration notification display region  565  on the output unit  520 . The drive management program  230  clears the “accumulated time” in the drive management table  240  concerning the drive subjected to the automatic migration (step  1012 ), and the processing returns to the step  1003 . 
     In the present embodiment, automatic migration is conducted with respect to a disk device that has reached in accumulated time the lifetime. However, automatic migration may be conducted with respect to a disk device that is less in remaining lifetime than a certain threshold. In this case, the disk array control unit  200  ascertains values registered in the “remaining lifetime”  240   h , and discriminates a disk device that is less in remaining lifetime than the threshold. 
     On the other hand, the disk array control unit  200  controls the start/stop of the operation of the disk devices in order to prevent an increase in the accumulated operation time of the disk devices. This control is conducted independently from the lifetime management shown in  FIG. 6 . 
     The disk array control unit  200  conducts start/stop of a disk device on the basis of a preset trigger. The trigger for starting/stopping a disk device may be, for example, time when user&#39;s access is completely stopped, such as nighttime. Or the fact that the remaining lifetime of some disk device has become shorter than a certain threshold may be used as a trigger of start/stop of the disk device. 
     Or the user may directly specify the start/stop of the disk device via the input unit  510  of the management terminal  500 . The management terminal  500  transmits an order concerning the start/stop of the disk device to the disk array control unit  200  via the management I/F  207 . The disk array control unit  200  controls the start/stop of the disk device on the basis of the received order. Thereafter, the disk array control unit  200  registers the start/stop situation of the disk device in the “start situation” in the drive management table  240 . Start/stop of a drive is conducted by issuing a Start/StopUnit command to the drive. 
     When acquiring the start situation and accumulated operation time of a drive, the user issues an order at the input unit  510  in the management terminal  500  to acquire information of the “start situation” and “accumulated time.” The disk array control unit  200  transfers the specified information to the management terminal  500  via the management I/F  207 . The management terminal  500  displays the received start situation of the disk device and the accumulated operation time of the disk device in the drive state display region  563  and the operation time display region  562  of the output unit  520 . 
     The user may execute disk device exchange beforehand on the basis of the displayed accumulated operation time or remaining lifetime of the drive. 
     The case where the disk array control unit  200  issues a command to a disk device having a different interface will now be described. 
     For example, the ATA disk device  401  cannot conduct processing on a command having a plurality of tags. Upon receiving a command that orders to write data from the host  100 , therefore, the disk array control unit  200  executes the drive command issuance program  220  and determines a command to be issued to a disk device. To be concrete, when issuing a command to the disk device, the disk array control unit  200  refers to the “drive kind” in the drive management table  230 , and determines whether issuance destination of the command is an FC disk device  301  or an ATA disk device  401 . In the case of an ATA disk device  401 , the disk array control unit  200  does not issue a command having a plurality of tags, but issues a single command. 
     According to the present embodiment, it becomes possible to provide disk devices differing in reliability, such as in lifetime, mixedly and manage the disk devices in the same disk array  700 . Furthermore, it is possible to determine the use of LUs by considering the reliability of disk devices that form a RAID group. Furthermore, it becomes possible to provide disk devices differing in control scheme mixedly and manage the disk devices in the same disk array. 
       FIG. 7  is a diagram showing a second embodiment of a computer system according to the present invention. Hereafter, only differences from the first embodiment will be described. In  FIG. 7 , a disk array  700 ′ includes an FC drive chassis  300  for storing an FC disk group  310 , and an ATA drive chassis  400  for storing an ATA disk drive group  410 . FC disk devices  301  stored in the FC drive chassis  300  are connected to a drive FC I/F  205  and the ATA drive chassis  400  via a port bypass circuit  330  included in the FC drive chassis  300 . Furthermore, the FC drive chassis  300  and the ATA drive chassis  400  are connected to each other by an FC loop  600 , to be concrete, a fibre cable. 
     ATA disk devices  401  stored in the ATA drive chassis  400  cannot be connected directly to the FC loop  600 . Therefore, the ATA drive chassis  400  includes an FC-ATA conversion I/F  430  for converting conversion between the FC interface and the ATA interface. Therefore, the ATA disk devices  401  are connected to the drive chassis  300  via the I/F  430  and the FC loop  600 . 
       FIG. 8  is a diagram showing a configuration of the port bypass circuit  330 . The port bypass circuit  330  shown in  FIG. 8  includes five ports. Furthermore, the port bypass circuit includes as many selectors  331  as ports, and thereby executes loop wiring for each port. The selector  331  forms a signal path through a port when wiring is connected to the port, and forms a signal path through an internal circuit, which does not through a port, when the port is not connected. 
       FIG. 9  is a diagram showing a configuration of the FC-ATA conversion I/F  430 . The FC-ATA conversion I/F  430  functions to connect ATA disk devices to the FC I/F. The FC-ATA conversion I/F  430  includes an FC I/F  431  serving as an interface to the FC, an ATA I/F  438  serving as an interface to the ATA, a memory  441 , a CPU  440  for executing programs stored in the memory  441 , and an internal bus  442  for connecting the FC I/F  431 , the ATA I/F  438 , the memory  441  and the CPU  440 . 
     In the memory  441 , an FC command reception program  432  to be executed when receiving a command from the FC, an FC data transfer program  433  to be executed when transmitting/receiving data to/from the FC, a command conversion program  434  to be executed when converting an FC command to a command for the ATA, a data buffer  435  for conducting data buffering between the FC and ATA, an ATA command issuance program  436  to be executed when issuing a command obtained by the conversion to the ATA side, an ATA data transfer program  437  to be executed when transmitting/receiving data to/from the ATA, and a command buffer  439  for conducting temporary buffering to hold and regenerate a command. 
     The CPU  440  executes the FC command reception program  432  to receive a command from the FC, and executes the FC data transfer program  433  to conduct data transfer between the FC I/F  431  and the data buffer  435 . Furthermore, the CPU  440  executes the command conversion program  434  to convert an FC command to a command for the ATA, and executes the ATA command issuance program  436  to issue a command obtained by the conversion to the ATA side. Furthermore, the CPU  220  executes the ATA data transfer program  437  to conduct data transfer between the ATA I/F  438  and the data buffer  435 . 
     In the present embodiment, it is possible to connect the disk array control unit  200 ′ to the ATA disk devices  401  via the FC by using the FC-ATA conversion I/F  430 . The FC-ATA conversion I/F  430  converts a command received from the disk array control unit  200 ′ to a command for ATA disk device. Furthermore, data transmitted and received between the disk array control unit  200 ′ and an ATA disk device are also converted by the FC-ATA conversion I/F  430 . 
     According to the present embodiment, it is possible to connect an ATA disk device to a fibre channel arbitrated loop, which is an interface for connecting an FC disk device. 
       FIG. 10  is a diagram showing a third embodiment of a computer system according to the present invention. Hereafter, differences from the first embodiment will be described. In addition to the configuration of the first embodiment, the computer system of the present embodiment includes another disk array  701 B connected to a disk array  701 A, a host computer  100  connected to the disk array  701 B, and a storage management server  10000 , which is a computer connected to the disk arrays  701 A and  701 B via a management network  20000 . The two disk arrays are connected to each other via a host FC I/F  204  included in each disk array and a remote copy connection  30000 . As for a method for the remote copy connection  30000 , for example, a fibre channel, an ESCON, or the like can be considered. In the present embodiment, however, a distinction is not especially made among them. Furthermore, for connection between each disk array  701  and the management network  20000 , a management I/F  207  included in each disk array  701  is used. 
     In addition to the configuration of the first embodiment, the disk array  701  in the present embodiment newly includes an LU pair management table  246  in a memory  202  in a disk array control unit  2001 . Furthermore, in a RAID control program, a program module for controlling duplication (hereafter referred to as remote copy) of data between the disk array  701 A and the disk array  701 B connected thereto, and a program module for managing duplication (hereafter referred to as intra-device replication) of data in the disk array  701 A or  701 B are newly added. As for methods for implementing the remote copy, there are variations, such as synchronous operation (in which data write request completion is not reported to a host computer until data duplication is completed) and asynchronous operation (in which data write request completion is reported to a host computer without waiting for the data duplication completion). In the present embodiment, however, a distinction is not especially made among them. 
       FIG. 11  is a diagram showing an example of the LU pair management table  246 . By using the LU pair management tables  246  registered in respective memories  202 , the disk arrays  701 A and  701 B manage a pair of LUs (hereafter referred to as LU pair) that hold the same data between disk arrays used for remote copy, or a pair of LUs that hold the same data in the disk array  701  generated by the intra-device replication. 
     The LU pair management table  246  has items of “LU pair No.”, “copy source LU information”, “copy destination LU information”, and “pair state”. 
     In an “LU pair No.” column  246   a , an identifier assigned arbitrarily to an LU pair is registered. In the present embodiment, identifiers are assigned without discriminating LU pairs between the disk arrays  701  from LU pairs in the disk array  701 . 
     The “copy source LU information” item has three sub-items described below. In an “LU pair No.” column  246   b , an LU No. assigned to an LU (hereafter referred to as copy source LU) that stores original data included in an LU pair provided with some identifier is registered. In a “pair attribute” column  246   c , information for determining whether the LU pair is an LU pair based on the remote copy or an LU pair based on the intra-device replication, to be concrete, a value indicating “remote” in the case of the remote copy or a value indicating “local” in the case of the intra-device replication is registered. In a “LU kind” column  246   d , a kind of a disk device that stores the copy source LU is registered. 
     The “copy destination LU information” item has three sub-items described below. In a “device ID” column  246   e , an identifier assigned to a disk array  701  to which an LU (hereafter referred to as copy destination LU) paired with the copy source LU belongs is registered. For example, in the case of the remote copy, an identifier assigned to a disk array  701  of the remote copy destination is registered. In the case of an intra-device replication, an identifier assigned to a disk array  701  having a copy source LU is registered. In an “LU pair No.” column  246   f , an LU No. assigned to a copy destination LU is registered. In a “LU kind” column  246   g , a kind of a disk device that holds the copy destination LU is registered. 
     In a “pair state” column  246   h , the current state of the LU pair is registered. For example, a value indicating whether the current state is a state (hereafter referred to as pair state) in which synchronization of data stored in respective LUs of the LU pair is attained and contents of data stored in the respective LUs coincide with each other, or a state (hereafter referred to as split state) in which synchronization of data is not attained between the LUs of the LU pair is registered. 
     The disk array  701  conducts the following operations by using the function of the intra-device replication. For example, the disk array  701  changes an LU pair that assumes the pair state to the split state at arbitrary time. By doing so, data held by the LU pair at arbitrary time is preserved in the copy destination LU (such processing is referred to as snapshotting). Thereafter, the host  100  reads out data from the copy destination LU, and writes the data into another storage, such as a tape device. As a result, it is possible to obtain a backup of data stored in the LU pair at time of snapshot acquisition. Furthermore, the copy destination LU itself after the snapshot has been acquired may be preserved as the backup of the data. 
     It is also possible to combine an LU pair of the remote copy with an LU pair of the intra-device replication. For example, in the case where remote copy is conducted between the disk arrays  701 A and  701 B, the copy destination LU held by the disk array  701 B is used as the copy source LU of the intra-device application to be executed by the disk array  701 B. And within the disk array  701 B, the copy destination LU that serves as an LU pair for the intra-device application may be created. The copy destination LU thus created can be used for data backup by attaining the split state as described above. 
     The user can freely combine the FCLU  320  and the ATA-LU  420 , and set the copy source LU and the copy destination LU (hereafter referred to as LU pair). Especially, the user can set the assignment of the LU pair with due regard to features of respective LUs via the storage management server  10000  described later. For example, it is possible to set the LU kind to the feature, and assign the fibre channel LU  320  using a FC disk device of high performance and high reliability to the copy source LU and assign the ATA-LU  420  using an ATA disk device of low price to the copy destination LU. Furthermore, it is possible to set the LU remaining time to the feature, and conduct setting so as not to select an LU having a disk device that is short in remaining lifetime as a subject of assignment, or use the LU having a disk device that is short in remaining lifetime, only for the copy destination of the intra-device replication. 
     The storage management server  10000  will now be described. FIG.  12  is a diagram showing a configuration of the storage management server  10000 . 
     The storage management server  10000  includes a CPU  11000 , a main memory  12000 , a storage unit  13000 , a management I/F  14000  for connection to a management network  20000 , an output unit  15000 , and an input unit  16000 . These components are connected to each other via a communication line, such as a bus. In the storage unit  13000 , a storage manager  13100  serving as a program executed by the CPU  11000 , a storage repository  13200  serving as a region for storing information collected from the disk array  701 , a device list  13300  for holding a list of the disk array  700  to be managed by the storage manager  13100 , an LU evaluation item table  13400 , and an LU remaining lifetime watermark table  13500  for managing the remaining lifetime of the LU. 
     In the storage repository  13200 , information stored in the drive management table  240 , the LU management table  245 , and the LU pair management table  246 , which are included in the disk arrays  701 A and  701 B, is periodically collected, and duplications of these tables are created. Furthermore, the device list  13300 , the LU evaluation item table  13400 , and the LU remaining lifetime watermark table  13500  are created by execution of the storage manager  13100  conducted by the storage management server  10000  on the basis of a user&#39;s order. 
       FIG. 13  is a diagram showing an example of the device list  13300 . The device list  13300  is used by the storage management server  10000  to ascertain the disk array  701  to be managed by the storage management server  10000  itself and refer to information required to communicate with the disk array  701 . In a “subject device No.” column  13300   a , an identifier assigned arbitrarily to the disk array  701 , which is managed by the storage management server  10000 , is registered. In a “device ID” column  13300   b , a peculiar identifier assigned to the disk array  701  is registered. In an “IP address” column  13300   c , information required for the storage management server  10000  to communicate with the disk array  701 , such as information concerning an IP address assigned to the disk array  700  in the case where an IP network is used as the management network  20000 , is registered. 
       FIG. 14  is a diagram showing an example of the LU evaluation item table  13400 . In the LU evaluation item table  13400 , items to be considered when selecting LUs of the LU pair and evaluation contents in the items are registered beforehand. When retrieving an LU that meets a user&#39;s order, the storage management server  1000  evaluates respective LUs with respect to items registered in the LU evaluation item table  13400 , and registers evaluation contents specified by the table in the item of the evaluation value  245   i  in the duplication (hereafter referred to as LU management table  245 ′) of the LU management table  245 . Thereafter, the storage management server  10000  selects a suitable LU, and exhibits the selected LU to the user. 
     In an “evaluation item” column  13400   a , evaluation items at the time of LU specification which can be selected by the user are registered. In an “evaluation subject LU management table column” column  13400   b , an item in the LU management table  245 , such as the LU kind  245   f , which becomes the evaluation subject in the evaluation item, is registered. In an “input condition reading with expression changed” column  13400   c , it is registered whether reading a condition input by the user, while changing its expression is needed when evaluating LUs registered in the LU management table  245 ′. In a “penalty at the time of condition satisfaction” column  13400   d , a value to be added to the value of the “evaluation value” column  245   i  in the LU management table  245 ′ when the condition input by the user agrees with a content registered in an item of the LU management table  245 ′ to be evaluated is stored. In a “penalty at the time of condition unsatisfaction” column  13400   e , a value to be added to the value of the “evaluation value” column  245   i  in the LU management table  245 ′ when the condition input by the user does not agree with a content registered in the column of the LU management table  245 ′ to be evaluated is registered. A concrete LU evaluation method will be described later. 
       FIG. 19  is a diagram showing an example of the LU remaining lifetime watermark table  13500 . The LU remaining lifetime watermark table  13500  is used when the storage management server  10000  manages the remaining lifetimes of LUs included in respective disk arrays  701 . To be concrete, the LU remaining lifetime watermark table  13500  has the following items for registering information. 
     In a “watermark No.” column  13500   a , an identifier assigned arbitrarily to each of a plurality of preset watermarks is registered. In a “device ID” column  13500   b , an identifier assigned to a disk array  701  to be managed in remaining lifetime is registered. In a “monitoring subject LU list” column  13500   c , information indicating an LU that is included in LUs of the disk array  701  to be managed and that is actually managed in remaining lifetime is registered. In a “remaining lifetime watermark” column  13500   d , information that indicates a watermark corresponding to the identifier is registered. 
     In the present embodiment, the storage management server  10000  ascertains the remaining lifetime of the LU registered as the management subject, and if the ascertained remaining lifetime becomes shorter than a preset watermark, the storage management server  10000  outputs a warning to the user. According to circumstances, the storage management server  10000  urges the user to set the LU migration or issues an automatic migration order to the disk array device. In the case where the importance of data stored in the LU is low, the lifetime of disk devices included in the LU may be used as a decision criterion instead of using the lifetime as the decision criterion. In this case, however, fast exchange of disk devices becomes necessary. 
     In the present embodiment, the user can consider parameters concerning performance and reliability of disk devices, when creating LUs of the disk array  701  including a mixture of disk devices having different input/output I/Fs by using the storage management server  10000 . Hereafter, this processing is referred to as LU assignment processing. Unless otherwise stated, processing described hereafter with reference to a flow chart is processing conducted by execution of the storage manager  13100  effected by the storage management server  10000 . 
       FIG. 15  is a flow chart showing a procedure of LU assignment processing  2000 . First, on the basis of an order from the user, the storage management server  10000  determines whether processing to be executed is processing of assigning the copy source LU to the host  100  or processing of assigning the copy destination LU in the remote copy or the intra-device replication (step  2100 ). 
     If the processing to be executed is judged to be processing of assigning the copy source LU to the host  100  at the step  2100 , then the storage management server  10000  conducts processing of assigning an LU to the host. Details of the present processing will be described later (step  2200 ). Thereafter, the storage management server  10000  inquires of the user whether a copy destination LU should be assigned. To be concrete, display for inquiring whether processing should be conducted is output to the output unit  15000  (step  2300 ). 
     If the copy destination LU assignment is ordered by the user at the step  2100 , or if the copy destination LU assignment is ordered by the user at the step  2300 , then the storage management server  10000  conducts copy destination LU assignment processing. As for the present processing as well, details will be described later (step  2400 ). Thereafter, the storage management server  10000  finishes the LU assignment processing. If the copy destination LU assignment processing is judged at the step  2300  to be unnecessary, then the storage management server  10000  finishes the LU assignment processing immediately. 
       FIG. 16  is a flow chart showing a detailed procedure of the processing of assigning an LU to the host executed at the step  2200  shown in  FIG. 15 . The storage management server  10000  receives a condition (hereafter referred to as parameters) required of the copy source LU, from the user. In addition to basic information required for LU creation, such as a subject device in which an LU is created, a storage capacity of the LU, a host FC I/F, a SCSI ID, and a LUN, the parameters include information concerning evaluation items registered in the “item” column of the LU evaluation item table  13400  (step  2210 ). 
     Thereafter, the storage management server  10000  conducts assignment candidate LU search process-ing of selecting a suitable LU as a candidate of the copy source LU on the basis of the parameters given by the user. Details of the present processing will be described later (step  2220 ). Thereafter, the storage management server  10000  exhibits the selected LU candidate to the user, and requests user&#39;s ascertain-ment (step  2230 ). 
     If the user has admitted the exhibited LU candidate as the copy source LU at the step  2230 , then the storage management server  10000  updates the LU management table  245  stored in the disk array  701  having the admitted LU, and its duplication  245 ′. To be concrete, with respect to the LU management table  245 ′ stored in the storage repository  13200 , the storage management server  10000  first alters the “host assignment situation” column  245   b  for the admitted LU to “present”, and registers values of parameters given by the user in the “SCSI ID” column  245   c  and the “LUN” column  245   d . Thereafter, the storage management server  10000  orders the disk array  701  having the admitted LU to reflect update contents of the LU management table  245 ′ in the LU management table  245  (step  2240 ). 
     Thereafter, the storage management server  10000  orders the disk array control unit  200  to execute the LU management on the basis of the LU management table  245  in which update has been reflected, and finishes the processing of assigning an LU to the host (step  2250 ). 
     If the exhibited LU is rejected by the user at the step  2230 , then the storage management server  10000  discontinues the processing of assigning an LU to the host (step  2260 ). In order to achieve automatization of the processing, processing of setting the selected LU as the copy source LU may be conducted without exhibiting the selected LU to the user. 
       FIG. 17  is a flow chart showing a detailed procedure of the copy destination LU assignment processing indicated by the step  2400  in  FIG. 15 . 
     The storage management server  10000  receives parameters for selecting the copy destination LU from the user. The parameters are the information described above with reference to the copy source LU (step  2410 ). 
     Thereafter, the storage management server  10000  conducts assignment candidate LU search processing for selecting a candidate that can become the copy destination LU on the basis of the parameters given by the user. Details of the present processing will be described later (step  2420 ). Thereafter, the storage management server  10000  exhibits the candidate of the copy destination LU selected at the step  2420  to the user, and requests ascertainment of use of the selected LU (step  2430 ). 
     If the user admits the exhibited LU as the copy destination LU at the step  2430 , then the storage management server  10000  updates the LU pair management table  246 , the LU pair management table  245 , and their duplications  246 ′ and  245 ′. Furthermore, the storage management server  10000  orders the disk array  701  that stores the selected LU to reflect the updated contents in respective tables. To be concrete, with respect to the LU pair management table  246 ′, the storage management server  10000  newly creates an LU pair entry for the selected copy destination LU, and registers parameters specified by the user and information of the selected copy destination LU. With respect to the LU management table  245 ′, the storage management server  10000  alters the “host assignment situation” column  245   b  of the selected LU to “present”, and registers parameter values in the “SCSI ID” column  245   c  and the “LUN” column  245   d  (step  2440 ). 
     Thereafter, the storage management server  10000  orders the disk array control unit  200  in the disk array  701  having a copy source LU paired with the selected copy destination LU to execute remote copy processing or intra-device replication processing on the basis of the pair LU management table  246  obtained after the update, and finishes the copy destination LU assignment processing (step  2450 ). 
     If the storage management server  10000  has rejected the exhibited copy destination LU at the step  2430 , then it discontinues the copy destination LU assignment processing, and finishes the copy destination LU assignment processing (step  2460 ). In order to achieve the automatization of the processing, processing of setting the selected LU as the copy destination LU may be conducted without exhibiting the selected LU to the user. 
       FIG. 18  is a flow chart showing a detailed procedure of the assignment candidate LU search processing shown in the step  2220  in  FIG. 16  and the step  2420  in  FIG. 17 . 
     First, the storage management server  10000  extracts an LU that is not being used by the host  100  from the LU management table  245 ′ stored in the storage repository  13200 . To be concrete, an LU having “present” registered in the “host assignment situation” column  245   b  in the LU management table  245 ′ is judged to have been already used, and a maximum value (+99999 in  FIG. 9 ) is registered in the evaluation value. An LU having “absent” registered in the “host assignment situation” column  245   b  is judged to have not been used yet, and the evaluation value is reset to 0 (step  3020 ). 
     Subsequently, the storage management server  10000  gives an evaluation value to every unused LU extracted at the step  3020 , with respect to each of items registered in the LU evaluation item table  1340 . A concrete example will be described later (step  3030 ). 
     Thereafter, the storage management server  10000  outputs an LU that is minimum in the value of the “evaluation value” column  245   i  and that is included in all LUs registered in the LU management table  245 ′ as a candidate for the copy source LU or the copy destination LU (step  3040 ). 
     The evaluation values registered in the LU management table  245 ′ are updated together when the storage management server  10000  orders each disk array  701  to update the LU management table  245  (steps  2240  and  2440 ). 
     Hereafter, four concrete examples of the step  3030  will be described. 
     As a first example, evaluation conducted when the user has specified the “kind” as “FC” will now be described. By ascertaining the “evaluation subject LU management table” column  13400   b , the storage management server  10000  ascertains that a column in the LU management table  245 ′ to be compared with the user&#39;s specification value “FC” is the “LU kind” column. Thereafter, the storage management server  10000  selects one of extracted unused LUs, and ascertains the content of the “LU kind” column in the LU management table  245 ′ that corresponds to the LU. If information registered in the “LU kind” column is “FC”, then the condition specified by the user is met, and the storage management server  10000  adds 0 to the evaluation value column  245   i  in the LU management table  245 ′ with respect to the unused LU, in accordance with a value that is registered in the “penalty at the time of condition satisfaction” column  13400   d  and that corresponds to the “kind” item. If information registered in the “LU kind” column is “ATA”, then the condition input by the user is not met, and consequently the storage management server  10000  adds +100 to the evaluation value column  245   i  in the LU management table  245 ′ with respect to the unused LU, in accordance with a value that is registered in the “penalty at the time of condition unsatisfaction” column  13400   e  and that corresponds to the “kind” item. 
     The storage management server  10000  repeats the processing described above, i.e., processing of making a decision as to whether the condition specified by the user is met from item to item, and adding a predetermined value to the evaluation value column  245   i  in the LU management table  245 ′ as an evaluation value in accordance with a result of the decision, until evaluation of all items shown in the LU evaluation item table  13400  has been applied to all extracted unused LUs. As a result of the present processing, the values of the evaluation value column  245   i  in the LU manage-ment table  245 ′ for all unused LUs are determined. It is shown in this concrete example that the storage management server  10000  can provide an LU including FC disk devices as a candidate as a result of selection of the kind of the disk device as “FC” conducted by the user. 
     As a second example, evaluation conducted when the user creates an LU for backup operation will now be described. In the operation form in which the data backup is held over a plurality of generations, it is conceivable to use an LU formed of inexpensive disk devices or an LU formed of disk devices that are hardly usable for ordinary business operation because of their short remaining lifetime, as the LU for backup. For the sake of such a case, an evaluation item “LU operation” as shown in  FIG. 14  is defined in the present example. The present evaluation item is an item for evaluating an LU so that the storage management server  10000  may provide an LU that is “ATA” in “LU kind” and “1000 hours or less” in “LU remaining lifetime” preferentially as a candidate when the user has specified “backup” as “LU operation.” The evaluation procedure is the same as that in the first example. Owing to this evaluation item, the storage management server  10000  can exhibit an LU candidate more suitable for backup use to the user. 
     As a third example, evaluation for effecting LU creation according to the reliability requested by the user will now be described. In such a case, it is defined that “LU remaining lifetime” is evaluated in an evaluation item “reliability” as shown in  FIG. 14 . The present evaluation item is an item for evaluating each LU so that the storage management server  10000  may provide an LU that is “at least 30000 hours” in “LU remaining lifetime” preferentially as a candidate when the user has specified “high” as “reliability.” Owing to this evaluation item, the storage management server  10000  can evaluate the remaining lifetime by using a predefined evaluation criterion and provide a suitable LU candidate. 
     As a fourth example, evaluation for conducting LU creation according to the number of copy destinations preset by the user will now be described. In some cases, a large number of copy destinations are created by utilizing the function of the remote copy or the intra-device replication in order to hold data over a plurality of generations as described with reference to the second example. In such a case, it is defined that “LU kind” is evaluated in an evaluation item “the number of copy destinations” as shown in  FIG. 14 . The present evaluation item is an item for evaluating each LU so that the storage management server  10000  may preferentially search an inexpensive ATA LU and exhibit it to the user as a candidate when the user has specified a large number of copy destinations. Owing to the present evaluation item, the storage management server  10000  can evaluate the LU kind by using a predefined evaluation criterion, on the basis of the number of copy destinations specified by the user, and provide a suitable copy destination LU candidate. 
     In the present embodiment, the storage management server  10000  implements lifetime management in the LU level in a disk array  701  that includes a mixture of disk devices differing in input and output I/Fs. Hereafter, this processing will be referred to as LU lifetime management processing. Unless otherwise stated, each processing is effected by execution of the storage manager  13100  conducted by the CPU  11000  in the storage management server  10000 . 
       FIG. 20  is a flow chart showing a procedure of LU remaining lifetime management processing. 
     The storage management server  10000  periodically monitors the LU remaining lifetime by using information in the LU management tables  245 ′ respectively of the disk arrays  701 A and  701 B, which is periodically updated by the storage repository  13200 . To be concrete, with respect to each LU specified in the “device ID” column  13500   b  and “monitoring subject LU list” column  13500   c  in the LU remaining life watermark table  13500 , the storage management server  10000  compares a value registered in the “LU remaining lifetime” column  245   g  in the LU management table  245 ′ corresponding to each LU with a watermark preset in each LU (a value registered in “remaining lifetime watermark” column  13500   d  corresponding to each LU). If a plurality of watermarks can be applied to one LU according to the situation preset in the “monitoring subject LU list” column  13500   c , then such a watermark as to maximize the value in the “remaining lifetime watermark” column  13500   d  is applied (step  4010 ). 
     If as a result of the comparison the remaining lifetime of each LU is less than the value registered in the “remaining lifetime watermark” column  13500   d , then the storage management server  10000  judges that LU to be an LU that needs a warning output (step  4020 ). 
     If an LU that becomes a subject of warning does not exist at the step  4020 , then the storage management server  10000  returns to the processing in the step  4010  and continues the LU remaining lifetime management. 
     If an LU that becomes a subject of warning exists at the step  4020 , then the storage management server  10000  discriminates a disk device that is less in remaining lifetime than the watermark, with respect to the LU that needs the pertinent warning output, and determines whether automatic migration has been specified for that disk device. To be concrete, with respect to all disk devices stated in the “drive No. list” column  245   h  in the LU management table  245 ′ to which the LU that is less in remaining lifetime than the watermark belongs, the storage management server  10000  examines the “remaining lifetime” column  240   h  in the drive management table  240 ′, discriminates disk devices that are less in remaining lifetime than the watermark, and ascertains the “automatic migration specification” column  249  (step  4030 ). 
     If automatic migration is specified in all disk devices included in an LU that is less in remaining lifetime than the watermark at the step  4030 , then the storage management server  10000  outputs only a warning. If the disk array device does not start the automatic migration operation, then the storage management server  10000  orders the disk array device to conduct automatic migration. As concrete examples of the warning content, “monitoring time”, “device ID in disk array”, “LU No.”, “drive No. that is less in remaining lifetime than watermark”, and “device ID and LU No. in the related copy source or copy destination LU” can be mentioned. 
     When outputting the “device ID and LU No. in the related copy source or copy destination LU”, information in the LU pair management table  246  held in the storage repository  13200  is used. By outputting “device ID and LU No. in the related copy source or copy destination LU”, the user can immediately recognize the possibility that the LU that has become the warning subject will affect another copy source or copy destination, and in some cases the user can execute manual alteration of LU pair caused by excess of remaining lifetime (step  4040 ). 
     If automatic migration is not specified for even one of disk devices included in an LU that is less in remaining lifetime than the watermark at the step  4030 , then the storage management server  10000  outputs a warning to the user, and outputs a message for urging the migration specification or the drive exchange order. As concrete examples of the warning content, “drive Nos. which become candidates of migration destination” can be mentioned, besides the contents stated in the step  4040 . 
     In determining “drive Nos. which become candidates of migration destination”, the storage management server  10000  determines that unused disk devices that are the same in drive kind and that are not preset in array configuration should be searched by using the information in the drive management table  240 ′ held in the storage repository  13200 . By using the output of “drive Nos. which become candidates of migration destination”, the user can reduce the burden of searching for an automatic migration destination for conducting migration specification. Since the disk array automatically determines the automatic migration destination of the disk device, the output of the “drive Nos. which become candidates of migration destination” may be omitted (step  4050 ). 
     According to the present embodiment, when creating LUs of a disk array including a mixture of disk drives differing in input and output I/Fs and reliability, LUs can be created while considering the performance and reliability of the disk drive, on the basis of characteristics ordered by the user. Furthermore, in the case where the disk array has a function of the remote copy or intra-device replication, the copy destination LU can also be automatically determined while considering the performance and reliability of the disk drive, on the basis of characteristics ordered by the user. In addition, lifetime management of disk devices in a disk array, which is hard for the user to be conscious of, can be conducted in the level of LU, which is a logical volume. 
     Even if the disk array  700  has the configuration of the second embodiment, the storage management server  10000  in the present embodiment can conduct the LU creation and the lifetime management in the LU level while considering the performance and reliability of a disk device. 
     The lifetime management conducted by the storage management server  10000  while taking an LU as the unit in the present embodiment may be executed by the control unit  200  in the disk array  700  in the first embodiment. In this case, the parameters in the lifetime management conducted in the first embodiment while taking a disk device as the unit should be altered to LU remaining lifetime. If an LU that is less in LU remaining life than some watermark is found, disk devices included in the LU should be detected and processing of determining whether automatic migration is present should be conducted for each of the disk devices. 
     According to the present invention, it becomes possible to provide a mixture of disk devices differing in, for example, lifetime and remaining lifetime, and manage them in the same disk array. Furthermore, it is possible to determine the user&#39;s use of a volume while considering the reliability of the disk devices included in the array. Furthermore, it is possible to determine the user&#39;s use of a volume while considering the performance of the disk devices included in the array. Furthermore, it becomes possible to provide a mixture of disk devices differing in control scheme, and manage them in the same disk array. 
     Furthermore, there is an effect that an ATA disk device can be connected to a fibre channel arbitrated loop, which is an interface for connecting a fibre channel disk device. 
     In addition, it becomes possible to provide automatic creation of LUs and lifetime management in the LU level with due regard to the performance and reliability of disk devices, and reduce the user&#39;s burden of management in the storage system. 
     It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.