Abstract:
A power-saving computer system comprises a plurality of storage areas provided by one or more storage systems, including at least one first storage area which is always powered on and at least one second storage area which is periodically powered on and off according to a power control schedule. The at least one first storage area provides primary and secondary volumes of a first backup set that is scheduled as always paired. For a second backup set that is scheduled as normally suspended and resynchronized according to a backup schedule, a primary volume of the second backup set is included in the at least one first storage area and a secondary volume of the second backup set is included in the at least one second storage area. The at least one second storage area is powered on during every backup time for resynchronizing the second backup set according to the backup schedule.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to power-saving in storage systems and, more particularly, to methods and apparatus to provision a data storage configuration with consideration of the power control schedule of storage subsystems. 
         [0002]    Recently power consumption efficiency in information systems is gaining attention as an important issue and many enterprise organizations are committed to improving their information systems to conserve energy. Under current solutions, users can save electric power consumption by switching on and off the power supply of the entire storage apparatus or a part of the storage apparatus in their operation. For example, U.S. Patent Application Publication No. 20070079156 provides a method to control the power supply on a hard disk group basis, and to determine the time to turn on or off the hard disks based on collected system running information. Applying current solutions, it is possible to reduce power consumption by supplying electric power only when it is necessary and stopping it when it is unnecessary. For instance, users can turn on the power of the storage device that stores backup data only during the time when the backup process is running, and turn off the power after backup is done because the backup data storage is normally accessed only during a backup process except restoration. 
         [0003]    The application of current solutions, however, gives rise to a situation in which a single information system includes both storage apparatus that are always turned on and storage apparatus that are regularly turned off. This mixture of different data storage apparatus makes it difficult for users to provision a new backup configuration. If they do not locate a backup data volume properly, the new backup set cannot take advantage of the power-saving storage system. For example, if they locate a backup volume in permanently power-on storage, the backup volume keeps consuming electric power even though it is not necessary until the backup process starts. On the other hand, if they locate a backup volume in a regularly turned-off storage, they need to be sure the scheduled backup time is within the available time of the power-saving storage. 
       BRIEF SUMMARY OF THE INVENTION 
       [0004]    Embodiments of the invention provide methods and apparatus to provision appropriate configuration of data volumes in power-saving information systems. In a power-saving storage system that is periodically turned off, new backup set volumes need to be located properly with consideration of power control schedule so that they can consistently or continuously leverage the power-saving effect. The storage system includes a function that coordinates and provisions a backup configuration based on both the backup requirements and power control schedule of the storage system. If the backup set is scheduled as always running copy (paired), the primary volume and secondary volume of the backup set is located on the permanently power-on storage; and if the backup set is scheduled as normally suspended and resynchronized with regular intervals, the secondary volume is located on the power-saving storage that is operated with the power control schedule and is available during the backup (resynchronization) process. In this way, it becomes possible to provision appropriate location of backup volumes that can leverage both the existing power-saving feature and the required backup plan or schedule. 
         [0005]    In accordance with an aspect of the present invention, a power-saving computer system comprises a plurality of storage areas provided by one or more storage systems, including at least one first storage area which is always powered on and at least one second storage area which is periodically powered on and off according to a power control schedule. The at least one first storage area provides primary and secondary volumes of a first backup set that is scheduled as always paired. For a second backup set that is scheduled as normally suspended and resynchronized according to a backup schedule, a primary volume of the second backup set is included in the at least one first storage area and a secondary volume of the second backup set is included in the at least one second storage area. The at least one second storage area having the secondary volume of the second backup set is powered on according to the power control schedule during every backup time for resynchronizing the second backup set according to the backup schedule. 
         [0006]    In some embodiments, the at least one second storage area each includes one or more storage disks, the system further comprising: a power controller that switches power on or off for the one or more storage disks of each of the at least one second storage area according to the power control schedule. The at least one first storage area is provided in a first storage system and is always powered on. The at least one second storage area is provided in a second storage system and is periodically powered on or off according to the power control schedule. The second storage system includes a power controller that switches power on or off for the at least one second storage area provided therein according to the power control schedule. The second storage system includes a plurality of power controllers each corresponding to one of a plurality of the second storage areas each having at least one storage disk, and each power controller switches power on or off for the corresponding second storage area according to the power control schedule. A power controller switches power on or off for the at least one second storage area according to the power control schedule. 
         [0007]    In specific embodiments, a management computer maintains the backup schedule and the power control schedule, and manages powering on or off of the at least one second storage area. The management computer allocates the secondary volume of the second backup set according to the backup schedule and the power control schedule. The management computer changes the power control schedule based on the backup schedule, if necessary, so that the at least one second storage area having the secondary volume of the second backup set is powered on during every backup time for resynchronizing the second backup set according to the backup schedule. For a third backup set that is scheduled as normally suspended and resynchronized according to the backup schedule, a primary volume of the third backup set is included in the at least one first storage area and a secondary volume of the third backup set is also included in the at least one first storage area, if a backup time of the secondary volume of the third backup set does not match a time when the at least one second storage area is powered on according to the power control schedule. 
         [0008]    Another aspect of the invention is directed to a method to provide data storage for power-saving in a computer system which includes a plurality of storage areas provided by one or more storage systems, including at least one first storage area which is always powered on and at least one second storage area which is periodically powered on and off according to a power control schedule. The method comprises allocating to the at least one first storage area primary and secondary volumes of a first backup set that is scheduled as always paired; and for a second backup set that is scheduled as normally suspended and resynchronized according to a backup schedule, allocating a primary volume of the second backup set to the at least one first storage area and allocating a secondary volume of the second backup set to the at least one second storage area. The at least one second storage area having the secondary volume of the second backup set is powered on according to the power control schedule during every backup time for resynchronizing the second backup set according to the backup schedule. 
         [0009]    Another aspect of the invention is directed to a computer-readable medium storing a plurality of instructions for controlling a data processor to provide data storage for power-saving in a computer system which includes a plurality of storage areas provided by one or more storage systems, including at least one first storage area which is always powered on and at least one second storage area which is periodically powered on and off according to a power control schedule. The computer-readable medium storing the plurality of instructions comprises instructions that cause the data processor to allocate to the at least one first storage area primary and secondary volumes of a first backup set that is scheduled as always paired; and instructions that cause the data processor, for a second backup set that is scheduled as normally suspended and resynchronized according to a backup schedule, to allocate a primary volume of the second backup set to the at least one first storage area and to allocate a secondary volume of the second backup set to the at least one second storage area; 
         [0000]    wherein the at least one second storage area having the secondary volume of the second backup set is powered on according to the power control schedule during every backup time for resynchronizing the second backup set according to the backup schedule. 
         [0010]    These and other features and advantages of the present invention will become apparent to those of ordinary skill in the art in view of the following detailed description of the specific embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  illustrates the hardware configuration of a system in which the method and apparatus of the invention may be applied. 
           [0012]      FIG. 2  illustrates an example of a memory in the management computer of  FIG. 1 . 
           [0013]      FIG. 3  illustrates an example of a Power Control Schedule Table in the memory of the management computer of  FIG. 2  according to a first embodiment of the invention. 
           [0014]      FIG. 4  illustrates an example of a Backup Schedule Table in the memory of the management computer of  FIG. 2 . 
           [0015]      FIG. 5  illustrates an example of a memory in the Tier  1  storage system of  FIG. 1 . 
           [0016]      FIG. 6  illustrates an example of a copy pair in the hard disks of  FIG. 1 . 
           [0017]      FIG. 7  illustrates an example of a pair status transition in the Data Copy Program in the memory of the Tier  1  storage system of  FIG. 5 . 
           [0018]      FIG. 8  illustrates an example of a Pair Configuration Table in the memory of the Tier  1  storage system of  FIG. 5 . 
           [0019]      FIG. 9  illustrates an example of a Volume List Table in the memory of the Tier  1  storage system of  FIG. 5 . 
           [0020]      FIG. 10  illustrates an example of a Tier  2  storage system according to the first embodiment of the invention. 
           [0021]      FIG. 11  illustrates an example of a backup setting screen shown at the output device of the management computer of  FIG. 1 . 
           [0022]      FIG. 12(   a ) illustrates an example of a process flow of operation to turn on the power supply of the Tier  2  storage system. 
           [0023]      FIG. 12(   b ) illustrates an example of a process flow of operation to turn off the power supply of the Tier  2  storage system. 
           [0024]      FIG. 13  illustrates an example of an overall process flow of the backup environment setup process. 
           [0025]      FIG. 14  illustrates an example of a process flow of the Volume Allocation Program in the memory of the management computer of  FIG. 2  according to the first embodiment of the invention. 
           [0026]      FIG. 15  illustrates an example of the volume creation process executed by the Volume Management Program in the memory of the Tier  1  storage system of  FIG. 5 . 
           [0027]      FIG. 16  illustrates an example of a process flow of pair registration executed by the Volume Management Program in the memory of the Tier  1  storage system of  FIG. 5 . 
           [0028]      FIG. 17  illustrates an example of a process flow of the overall power control and backup operation of the power-saving storage system. 
           [0029]      FIG. 18  illustrates an example of a process flow of the backup operation. 
           [0030]      FIG. 19  illustrates an example of a Tier  2  storage system according to a second embodiment of the invention. 
           [0031]      FIG. 20  illustrates an example of a Power Control Schedule Table in the memory of the management computer of  FIG. 2  according to the second embodiment of the invention. 
           [0032]      FIG. 21  illustrates an example of a process flow of the Volume Allocation Program in the memory of the management computer of  FIG. 2  according to the second embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0033]    In the following detailed description of the invention, reference is made to the accompanying drawings which form a part of the disclosure, and in which are shown by way of illustration, and not of limitation, exemplary embodiments by which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. Further, it should be noted that while the detailed description provides various exemplary embodiments, as described below and as illustrated in the drawings, the present invention is not limited to the embodiments described and illustrated herein, but can extend to other embodiments, as would be known or as would become known to those skilled in the art. Reference in the specification to “one embodiment”, “this embodiment”, or “these embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, and the appearances of these phrases in various places in the specification are not necessarily all referring to the same embodiment. Additionally, in the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that these specific details may not all be needed to practice the present invention. In other circumstances, well-known structures, materials, circuits, processes and interfaces have not been described in detail, and/or may be illustrated in block diagram form, so as to not unnecessarily obscure the present invention. 
         [0034]    Furthermore, some portions of the detailed description that follow are presented in terms of algorithms and symbolic representations of operations within a computer. These algorithmic descriptions and symbolic representations are the means used by those skilled in the data processing arts to most effectively convey the essence of their innovations to others skilled in the art. An algorithm is a series of defined steps leading to a desired end state or result. In the present invention, the steps carried out require physical manipulations of tangible quantities for achieving a tangible result. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals or instructions capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, instructions, or the like. It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, as apparent from the following discussion, it is appreciated that throughout the description, discussions utilizing terms such as “processing”, “computing”, “calculating”, “determining”, “displaying”, or the like, can include the actions and processes of a computer system or other information processing device that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system&#39;s memories or registers or other information storage, transmission or display devices. 
         [0035]    Exemplary embodiments of the invention, as will be described in greater detail below, provide apparatuses, methods and computer programs to provision a data storage configuration with consideration of the power control schedule of storage subsystems. 
       First Embodiment 
       [0036]    In the first embodiment, a method to provision the primary volume and the secondary volume for the backup set is explained. It is assumed that the computer system has at least one Tier  1  storage system and at least one Tier  2  storage system and that the Tier  2  storage system is periodically turned on/off for the purpose of power-saving effect. By applying the invention in the first embodiment, it becomes possible to provision the appropriate location of backup volumes in a way that leverages both the existing power-saving feature and the required backup plan. 
         [0037]    1. System Structure 
         [0038]      FIG. 1  illustrates the hardware configuration of a system in which the method and apparatus of the invention may be applied. The computer system includes a host computer  500 , a management computer  600 , at least one Tier  1  storage system  100 , and at least one Tier  2  storage system  200 ,  300  that are connected via a data transfer network  700  and a management network  800 . 
         [0039]    The host computer  500  includes a CPU  510  that controls the operation of the host computer  500 , a cache  520  for storing data temporarily, a memory  530  for storing programs and tables read and used by the CPU  510  to manage the operation of the host computer  500 , an interface  540  that transmits data to and receives data from the networks  700 ,  800 . It includes an interface for the Ethernet network interface and an FC network interface. 
         [0040]    The management computer  600  includes a CPU  610  that controls the operation of the management computer  600 , a cache  620  for storing data temporarily, a memory  630  for storing programs and tables read and used by CPU  610  to manage the operation of the computer system, an input device  640  such as a keyboard, an output device  650  such as an LCD, and an interface  660  that transmits data to and receives data from the networks  700 ,  800 . It includes an interface for the Ethernet network interface and an FC network interface. 
         [0041]    The Tier  1  storage system  100  represents the primary storage system that holds data volumes storing Tier  1  data such as online transaction data that is frequently accessed. The Tier  1  storage system  100  includes an interface  110  providing an interface for the Ethernet network interface and an FC network interface, a cache  120  for storing data temporarily, a CPU  130  that calls the programs and tables stored in a memory  150  and executes the programs, and a disk controller  140  for controlling associated hard disks  160 . The memory  150  stores programs and tables read by the CPU  130 . There are one or more hard disks  160 . A plurality of hard disks  160  can make a RAID configuration for redundancy. The group of hard disks for a single RAID configuration is called a “parity group” and an identification number is assigned to each parity group. These groups of hard disks are used as logically separate volumes such as primary volumes and secondary volumes of a copy pair. In the Tier  1  storage system  100 , the hard disks  160  may include FC disks that enable high speed access to stored data. 
         [0042]    The Tier  2  storage systems  200  and  300  represent storage systems for storing Tier  2  data such as backup data that are less critical than the data stored in the Tier  1  storage system  100 . The detailed internal structure of the Tier  2  storage systems  200 ,  300  is described below. 
         [0043]    The data transfer network  700  is used to transfer user data. For example, transaction data created by users on a host computer are transferred via the data transfer network  700  to the Tier  1  storage system  100  in order to store them. The data transfer network  700  can be either LAN or SAN, for instance. 
         [0044]    The management network  800  is used to transfer management information regarding the computer system. The host computer  500 , the management computer  600 , the Tier  1  storage system  100 , and the Tier  2  storage systems  200 ,  300  transmit and receive the management information mutually via the management network  800 . This network can be either LAN or SAN, for instance. It is also possible that the data transfer network  700  and the management network  800  are part of the same network in actual configuration. 
         [0045]      FIG. 2  illustrates an example of a memory  630  in the management computer  600  of  FIG. 1 . The memory  630  includes a Volume Allocation Program  631 , a Power Control Schedule Table  632 , a Power Control Schedule Program  633 , a Backup Management Program  634 , and a Backup Schedule Table  635 . 
         [0046]    The Volume Allocation Program  631  determines which storage is appropriate to create volumes requested by users, and then issues a volume creation command to the specified storage. When a user makes a request to add the new volume and designate the backup copy type (“always copied” or “always suspended”), this program refers to the Power Control Schedule Table  632  and finds the proper storage to create the volume. For example, the user designates “always suspended” for the backup sets and inputs the backup schedule, and the Volume Allocation Program  631  detects a storage that is scheduled to be turned on during the input backup execution time by checking the power control schedule according to the Power Control Schedule Table  632 . 
         [0047]    The Power Control Schedule Table  632  contains the information of power control schedule for each storage system in the computer system of  FIG. 1 . For example, it has a storage system ID to identify each storage system, the enabled/disabled status of the power control function, and the time when the storage system is turned on/off. The detailed contents are shown in  FIG. 3  and described below. The Power Control Schedule Program  633  issues commands to turn on or off the power supply of the storage systems in accordance with the Power Control Schedule Table  632 . 
         [0048]    The Backup Management Program  634  issues commands for acquiring backup to the storage systems in accordance with the Backup Schedule Table  635 . This table manages a schedule of backup acquisition executed by the Backup Management Program  634 . The detailed contents are shown in  FIG. 4  and described below. 
         [0049]      FIG. 3  illustrates an example of the Power Control Schedule Table  632  in the memory  630  of the management computer  600  of  FIG. 2 . It can be separated into  2  tables as seen in  FIG. 3 . The first table shown in  FIG. 3(   a ) includes columns of storage system ID  6320  and the status of power control function  6321 . The second table shown in  FIG. 3(   b ) contains the power control schedule information for each power-controlled storage system and includes columns of storage system ID  6320 , power control frequency  6322 , power-on time  6323 , and power-off time  6324 . Of course, these two tables may be merged in to one table. 
         [0050]      FIG. 4  illustrates an example of the Backup Schedule Table  635  in the memory  630  of the management computer  600  of  FIG. 2 . It contains columns of Pair ID  6350 , backup frequency  6351 , backup start time  6352 , and backup due time  6353 . The contents of this table can be updated by the Backup Management Program  634 . For example, when a user inputs a backup setting through a backup setting screen, the Backup Management Program  634  can add new backup setting information into this table based on the user&#39;s input. 
         [0051]      FIG. 5  illustrates an example of the programs and tables stored in a memory  150  in the Tier  1  storage system  100  of  FIG. 1 . They include a Data Copy Program  151 , a Pair Configuration Table  153 , a Volume Management Program  155 , and a Volume List Table  156 . 
         [0052]    The Data Copy Program  151  copies the data from the primary volumes to the secondary volumes as backup. The volume association is defined in the Pair Configuration Table  155 . The detailed copy operation is described below. The Pair Configuration Table  153  contains information regarding the definition of the copy pair referred to by Data Copy Program  151 . A detailed example is described later. The Volume Management Program  155  creates or deletes volumes in the Tier  1  storage system  100  and updates the Volume List Table  156 . It also manages the copy pair configuration by updating the Pair Configuration Table  153 . The Volume List Table  156  contains information of volumes within the Tier  1  storage system  100  to manage the volume configurations. The details are shown in  FIG. 9  and described below. 
         [0053]      FIG. 6  illustrates an example of a copy pair in the hard disks  160  of  FIG. 1  for data copy. The hard disks  160  are configured to provide logically separate logical volumes comprised of a plurality of disks (RAID configuration). From the aspect of backup or Data Copy Program  151 , there are two types of logical volumes: the primary volume  162  and the secondary volume  163 . The primary volume  162  is for storing original data to be protected by backup technology, and the secondary volume  163  is for storing backup data copied by the Data Copy Program  151 . A set of these two types of volumes is called a copy pair  161 . 
         [0054]    In the initial copy, the Data Copy Program  151  copies the entire data in the primary volume  162  to the secondary volume  163 , while only updated data are copied after the initial copy. The copy process can be temporarily suspended because the pair association is kept unless the pair configuration is deleted. If data are written in the primary volume  162  during the suspension, the Data Copy Program  151  records the updated data address within the hard disk or logical volume. When resuming the copy process after suspension (often called resynchronization), the Data Copy Program  151  copies only updated data to the secondary volume. The detailed status changes are shown in  FIG. 7  and described below. 
         [0055]      FIG. 7  illustrates an example of a pair status transition in the Data Copy Program  151  in the memory  150  of the Tier  1  storage system  100  of  FIG. 5 . Initially, the pair volumes (primary and secondary volumes) are in the “simplex” status  1550 , which means no pair association is established. Once a pair creation is executed, all data in the primary volume  162  are copied to the secondary volume  163  and their statuses are turned into “paired”  1551 , which means the primary and the secondary data are synchronized and updated data to the primary volume  162  are copied to the secondary volume  163  as needed. When the pair volumes are suspended by the Data Copy Program  151 , the copy process is stopped and the statuses are turned to “suspended”  1552 . During the suspended status, updated data to the primary volume  162  is not copied but the data address is recorded. When the pair is requested to resynchronize, the Data Copy Program  151  copies updated data at the recorded address in the primary volume  162  to the secondary volume  163 , and the status turns to “paired”  1551  again. To clear the pair definition, it can be deleted by the Data Copy Program  151 , tuning the status back to “simplex.” 
         [0000]    When operating the power-saving storage system, the electric power for the secondary volume  163  can be turned off when it is in the Simplex or Suspended status, while it should be turned on when it is (or is changing to) the Paired status. 
         [0056]      FIG. 8  illustrates an example of the Pair Configuration Table  153  in the memory  150  of the Tier  1  storage system  100  of  FIG. 5 . The Pair Configuration Table  153  includes columns of the Pair ID  1530  which is an identifier of each copy pair and is assigned by the Data Copy Program  151 , the Storage System ID for primary volume  1531  which is an identifier for the storage system that owns the primary volume in its disks, the Primary Volume ID  1532  which is an identifier for the primary volume  162  and can be the LUN ( logical unit number) of the system that composes the RAID, the Capacity of the primary volume  1533  which is capacity information of the primary volume  162 , the Storage System ID of secondary volume  1534  which is an identifier for the storage system that owns the secondary volume in its disks, the Secondary Volume ID  1535  which is an identifier for the secondary volume  163  and can be the LUN (logical unit number) of the system that composes the RAID, and the Capacity of the secondary volume  1536  which is the capacity information of the secondary volume  163 . 
         [0057]      FIG. 9  illustrates an example of the Volume List Table  156  in the memory  150  of the Tier  1  storage system  100  of  FIG. 5 . The Volume List Table  156  includes columns of the Volume ID  1560  which is an identifier of the volumes in the Tier  1  storage system  100  and can be the LUN, the Disk Controller ID  1561  which is an identifier of the disk controller  140  in the Tier  1  storage system  100 , the Parity Group ID  1562  which is an identifier of the parity groups in the Tier  1  storage system  100 , and the Capacity  1563  which indicates a capacity of the corresponding volume. 
         [0058]      FIG. 10  illustrates an example of the Tier  2  storage system  200  (or  300 ) according to the first embodiment of the invention. The Tier  2  storage system  200  includes an interface  210 , a cache  220 , a CPU  230 , a disk controller  240 , a memory  250 , hard disks  260 , and a power controller  270 . The interface  210  provides an interface for the Ethernet network interface and an FC network interface. The cache  220  is used as temporary data storage, and may be a generic semiconductor device or a plurality of such devices. The CPU  230  calls the programs and tables stored in the memory  250 , and executes the programs. In this embodiment, execution of programs is always done by the CPU. The disk controller  240  controls associated hard disks  260 . The memory  250  stores programs and tables read and used by the CPU  230 . In this embodiment, the memory  250  stores the Volume Management Program  251  and Volume List Table  252 . These can be the same as those of the Tier  1  storage system  100  ( 155 ,  156  in  FIG. 5 ). 
         [0059]    The hard disks  260  are one or a plurality of hard disks. A plurality of hard disks can make the RAID configuration for its redundancy. The group of hard disks for a single RAID configuration is called a “parity group” and an identification number is assigned to each parity group. These groups of hard disks are used as logically separate volumes such as the secondary volumes of a copy pair. In the Tier  2  storage system  200  or  300 , the hard disks  260  may include SATA disks, for example, that have lower performance than FC disks for accessing the stored data but can be provided at a low cost. 
         [0060]    The power controller  270  controls electric power supply to the extent surrounded by a rectangular  280  in  FIG. 10 . A power control command indicating turning on or off the power is sent form the management computer  600  via the management network  800  and the power controller  270  switches on or off the electric power supply in accordance with the command. When the power controller  270  switches off the power, it can run a normal shutdown process before stopping the power supply. In alternative embodiments, the power controller  270  may be located outside of the Tier  2  storage system  200 ,  300  and performs in the same way. Furthermore, the Tier  2  storage system  200 ,  300  may contain a plurality of power control units  280 , and the power is controlled on the unit basis (see, e.g.,  FIG. 19 ). 
         [0061]      FIG. 11  illustrates an example of a backup setting screen  651  shown at the output device  650  of the management computer  600  of  FIG. 1 . The backup setting screen  651  provides an interface for users to input backup volume setting. The setup window  651  contains at least the following items. Under the primary volume setting  670 , users will choose either “Existing Primary Volume” or “Create Primary Volume.” If a user wants to choose the existing volume as the primary volume, the user can enter the existing primary volume ID into the input field  658 . To create a primary volume, the input field  659  is provided for the capacity of the volume to be specified as the primary volume. For the secondary volume, the Capacity input field  652  is provided for inputting the desired volume capacity. Typically, the capacity of the secondary volume corresponds to the capacity of the primary volume. The Backup Type input field  653  has two options: “Always Copied” or “Always Suspended,” which designates the copy type for the targeted pair. The Backup Frequency field  654  is shown only when “Always Suspended” is chosen as the backup type. The Backup Start Time input field  655  is used to input the backup start time. The Backup Finish Time input field  656  is used to input the backup finish time. The Volume Create button  657  can be held down to transmit the above input information to the Volume Allocation Program  631  in the Management Computer  600 . 
         [0062]    2. Process Flows 
         [0063]      FIG. 12(   a ) illustrates an example of a process flow of operation to turn on the power supply of the Tier  2  storage system  200 ,  300 . The Power Control Schedule Program  633  in the Management Computer  600  refers to the Power Control Schedule Table  632  and issues a power-on request at the time stated in the table, to the corresponding storage system (step  1000 ). The request message contains at least the destination storage system ID and power-on command. The power controller in the destination storage system (in this case the Tier  2  storage system) receives the request via the management network  800  and executes the power-on operation to supply electric power to its CPU, memory, disk controller, and disks so that the volumes in the system become readable or writable (step  1100 ). 
         [0064]      FIG. 12(   b ) illustrates an example of a process flow of operation to turn off the power supply of the Tier  2  storage system  200 ,  300 . At the time defined as power-off time in the Power Control Schedule Table  632 , the Power Control Schedule Program  633  issues a power-off request to the destination storage (step  1200 ). The request message contains at least the destination storage system ID and power-off command. The power controller in destination storage system (in this case the Tier  2  storage system) receives the request via the management network  800  and executes power-off operation to stop supplying electric power to its CPU, memory, disk controller, and disks (step  1300 ). This step can be accompanied with a normal shutdown process of storage system such as writing cached data to the disks. 
         [0065]      FIG. 13  illustrates an example of an overall process flow of the backup environment setup process. It describes the case in which the primary volume is created in the Tier  1  storage system  100 , and the secondary volume is created in the Tier  2  storage system  200 ,  300  as a result of the calculation of the Volume Allocation Program  631 . At first, the management computer  600  receives a volume creation request from a user input through a management screen (step  2000 ). The input information is transmitted to the Volume Allocation Program  631 , and it calculates and determines the destination storage system to create a volume using an after-mentioned scheme of  FIG. 14  (step  2100 ). Then the management computer  600  issues a volume creation request to the target storage system (step  2200 ). Receiving the request via the management network  800 , the Tier  1  and Tier  2  storage systems  100 ,  200 ,  300  each create a volume according to the information in the request message (step  2300 ) and returns completion of the process with the created volume ID. After that, the management computer  600  issues a pair registration command to the Tier  1  storage system  100  (step  2400 ). The Tier  1  storage system registers a pair (step  2500 ). 
         [0066]    If the Volume Allocation Program  631  determines that the primary volume and the secondary volume are to be allocated in the Tier  1  storage system in step  2200 , the volume creation request is simply sent to only the Tier  1  storage system, and the Volume Management Program in the Tier  1  storage system creates the primary and the secondary volumes. 
         [0067]    It is also possible that the user issues a request to create volume only for the secondary volume  200 ,  300  that is paired to an existing primary volume  100 , and the Volume Allocation Program  631  issues a volume creation request to either the Tier  1  storage system or the Tier  2  storage system. 
         [0068]      FIG. 14  illustrates an example of a process flow of the Volume Allocation Program  631  in the memory  630  of the management computer  600  of  FIG. 2 . First, it receives a volume creation request from a user input through the input screen shown in  FIG. 11  and described above (step  3000 ). If the existing volume is selected as the primary volume (step  3700  yes), it proceeds to step  3100 . If primary volume is to be created (step  3700  no), the Volume Allocation Program  631  finds the permanently on storage system (step  3800 ), and then issues a volume creation command to the found storage system (step  3900 ). If the backup requirement is “Always Paired” or “Always Copied” (step  3100 ), the program finds a storage system that is permanently turned on using the Power Control Schedule Table  632 , and designates the storage as a secondary volume location (step  3200 ). Then the program issues a volume creation request for the primary volume and the secondary volume to the target storage system (step  3300 ). The location of the primary volume will be a Tier  1  storage system in this embodiment. If the backup requirement is “Always Suspended” (step  3100 ), the program also refers to the backup schedule input by the user (step  3400 ), and finds a Tier  2  storage system that will be turned on during the backup window (step  3500 ). Then, the program issues a volume creation request for both primary and the secondary volumes (step  3600 ). 
         [0069]    In step  3500 , if no Tier  2  storage system matches the backup schedule, the following two options can be applied. The first option is to locate the secondary volume on the permanently turned on storage. The second option is to change the power on/off schedule for one of the Tier  2  storage systems by updating the Power Control Schedule Table  632 . In this case, the earlier of the backup start time and existing power on time will be the new power on time for the Tier  2  storage system. On the other hand, the later of the backup due time and existing power off time will be the new power off time for the Tier  2  storage system. 
         [0070]    When either the power control schedule or the backup schedule is changed in operation, the Volume Allocation Program  631  can be called and it can recalculate the appropriate location of volumes that are related to the change. 
         [0071]      FIG. 15  illustrates an example of the volume creation process executed by the Volume Management Program  155  in the memory  150  of the Tier  1  storage system  100  of  FIG. 5 . At first, the Tier  1  storage system  100  receives a volume creation command from the management computer  600  and the command is transferred to the Volume Management Program  155  (step  4000 ). This command contains information of the destination storage ID and volume capacity. The Volume Management Program  155  searches the availability of needed capacity in the storage (step  4100 ). If it has the available disks or parity groups that satisfy the capacity demand (step  4200  yes), it creates a volume and updates the volume list table  156  (step  4300 ). If it does not have the available disks or parity groups that satisfy the capacity demand (step  4200  no), it returns an error message (step  4400 ). The error message can include a suggestion for users to add a particular amount of capacity or a particular number of disks. 
         [0072]      FIG. 16  illustrates an example of a process flow of pair registration executed by the Volume Management Program  155  in the memory  150  of the Tier  1  storage system  100  of  FIG. 5 . At first, the Tier  1  storage system  100  receives a pair registration request from the management computer  600  and the request is transferred to the Volume Management Program  155  (step  5000 ). This command contains information of the destination storage ID and volume ID for both primary and secondary volumes of a copy pair. The program registers the pair configuration by updating the Pair Configuration Table  153  as specified in the received request (step  5100 ). The program then returns a completion message to the management computer  600  (step  5200 ). 
         [0073]      FIG. 17  illustrates an example of a process flow of the overall power control and backup operation of the power-saving storage system. In this case, the power-saving storage system is a Tier  2  storage system  200 ,  300 . In the operation, the Tier  2  storage system  200  or  300  is turned on in accordance with the schedule (step  7000 ), and then the backup process is executed as explained below in connection with  FIG. 18  (step  7100 ). After the backup process is completed, the Tier  2  storage system is turned off (step  7200 ). Steps  7000  to  7200  are repeated according to the operation schedule. 
         [0074]      FIG. 18  illustrates an example of a process flow of the backup operation. First, the Backup Management Program  634  in the management computer  600  issues a backup request to the Tier  1  storage system  100  at a time defined by the Backup Schedule Table  635  (step  8000 ). This request or command includes at least a Pair ID. Upon receiving the request, the Data Copy Program  151  of the Tier  1  storage system  100  resynchronizes the copy pair (step  8100 ). This step may include a process to wait for completion of the resynchronization. After completion of the resynchronization, the Data Copy Program  151  suspends the pair again (step  8200 ) and returns the message that informs the management computer  600  of the completion of the backup process (step  8300 ). 
       Second Embodiment 
       [0075]    In the second embodiment, the power-saving unit is different from that in the first embodiment. In the second embodiment, a method to provision the primary volume and the secondary volume for a backup set is provided. It is assumed that the computer system has Tier  1  storage and Tier  2  storage systems and that a certain unit of the hard disks in the Tier  2  storage system is periodically turned on/off for the purpose of power-saving effect. 
         [0076]      FIG. 19  illustrates an example of a Tier  2  storage system  200  according to the second embodiment. The difference between the first embodiment ( FIG. 10 ) and the second embodiment ( FIG. 19 ) is the power-control unit. The other components of the system will be the same as those of the first embodiment. In the second embodiment, it becomes possible to control the electric power supply with a unit of group of hard disks such as a parity group, by spinning up or down them. Each group has a corresponding power controller  270 . In this case, the power controller  270  receives a request to spin up/down with the specific Disk Controller ID  1561  and Parity Group ID  1562  from the management server  600  and executes spinning up/down as the power control. This power control system can also be applied to the Tier  1  storage system  100 . 
         [0077]      FIG. 20  illustrates an example of a Power Control Schedule Table  632  in the memory  630  of the management computer  600  of  FIG. 2 . The difference between the first embodiment ( FIG. 3 ) and the second embodiment ( FIG. 20 ) is that the second embodiment further includes the Disk Controller ID column  6391  and the Parity Group ID column  6392 , in addition to the storage subsystem ID  6390 , the power control frequency  6393 , the power-on time  6394 , and the power-off time  6395 . 
         [0078]      FIG. 21  illustrates an example of a process flow of the Volume Allocation Program  631  in the memory  630  of the management computer  600  of  FIG. 2  according to the second embodiment. First, the program receives a volume creation request from a user input through the input screen shown in  FIG. 11  and described above (step  3001 ). If the existing volume is selected as the primary volume (step  3701  yes), it proceeds to step  3101 . If the primary volume is to be created, the Volume Allocation Program  631  finds a permanently on storage system or a parity group (step  3801 ), and then issues a volume creation command to the specified storage system (step  3901 ). If the backup requirement is “Always Paired” (step  3101 ), the program finds a parity group that is permanently turned on by referring to the Power Control Schedule Table  632 , and designates the parity group as a secondary volume location (step  3201 ). Then the program issues a volume creation request for the primary volume and the secondary volume to the target storage systems (step  3301 ). The location of the primary volume will be in the permanently turned-on parity group in this embodiment. If the backup requirement is “Always Suspended” (step  3101 ), the program also refers to the backup schedule input by the user (step  3401 ), and finds a Tier  2  storage system and the parity group that will be turned on during the backup window (step  3501 ). Then, the program issues a volume creation request for both primary and secondary volumes (step  3600 ). The second embodiment ( FIG. 21 ) differs from the first embodiment ( FIG. 14 ) in that the parity group is involved in steps  3201 ,  3301 , and  3501 . 
         [0079]    From the foregoing, it will be apparent that the invention provides methods, apparatuses and programs stored on computer readable media for provisioning appropriate configuration of data volumes in power-saving information systems. Additionally, while specific embodiments have been illustrated and described in this specification, those of ordinary skill in the art appreciate that any arrangement that is calculated to achieve the same purpose may be substituted for the specific embodiments disclosed. This disclosure is intended to cover any and all adaptations or variations of the present invention, and it is to be understood that the terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with the established doctrines of claim interpretation, along with the full range of equivalents to which such claims are entitled.