Abstract:
A computer comprises a memory, and a processor being operable to manage a relationship between an image of a virtual machine and a plurality of storage systems forming a virtual storage system, and storing the relationship in the memory. The processor is operable to create a new image of the virtual machine in a target storage system of the plurality of storage systems based on the relationship, the new image of the virtual machine to be used to deploy the virtual machine in the target storage system. When the relationship indicates that the target storage system does not have the image, the processor is operable to copy the image from another storage system of the plurality of storage system to the target storage system and to create a new image of the virtual machine in the target storage system from the copied image in the target storage system.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates generally to storage systems and, more particularly, to method and apparatus to conceal the configuration and processing of the replication (e.g., replication of virtual machine image) by virtual storage. 
         [0002]    Virtualization technology has been used extensively. All IT infrastructures are virtualized. Storage systems are also virtualized. Virtual storage subsystem technique has the following features. One virtual storage system can be created from multiple physical storage systems. In this situation, the application does not need to be aware of each physical storage system. Even if the storage system is virtualized, however, the boundary of the physical storage system still exists. For example, a snapshot cannot be taken over the multiple physical storage systems. 
         [0003]    U.S. Pat. No. 8,356,147 discloses tiered storage pool management and control for loosely coupled multiple storage environment. A system comprises a first storage system including a first storage controller, which receives input/output commands from host computers and provides first storage volumes to the host computers; and a second storage system including a second storage controller which receives input/output commands from host computers and provides second storage volumes to the host computers. A first data storing region of one of the first storage volumes is allocated from a first pool by the first storage controller. A second data storing region of another one of the first storage volumes is allocated from a second pool by the first storage controller. A third data storing region of one of the second storage volumes is allocated from the first pool by the second storage controller. A fourth data storing region of another one of the second storage volumes is allocated from the second pool by the second storage controller. 
         [0004]    US 20120272021A1 discloses management system and control method for computer system to provide a storage management technique for creating and managing, with single operation by a user, a large quantity of writable snapshots, which satisfy a requirement desired by the user, while controlling a use form of a storage apparatus not to exceed limits of the performance and the capacity of the storage apparatus. Therefore, a management computer manages configuration information and performance information of plural storage apparatuses and an operation state of a writable snapshot. When a writable snapshot is created, the management computer controls, concerning an original snapshot, a use form of the storage apparatuses not to exceed a disk performance limit and a controller performance limit and a capacity limit of a storage on the basis of the number of writable snapshots to be created and a performance requirement (IOPS) and a capacity requirement of the writable snapshot. 
       BRIEF SUMMARY OF THE INVENTION 
       [0005]    Exemplary embodiments of the invention provide a technique to conceal the limitation of the physical storage systems in the virtual storage system environment when a new virtual machine is deployed using writable snapshot technology. When the virtual storage system which includes multiple physical storage systems receives an instruction to create virtual machine, a management program decides which physical storage system should be used and then creates a writable snapshot of the image appropriately. More specifically, if the selected physical storage already has the image, writable snapshot from the image is used; otherwise, the management program copies the image from another storage system and then creates a writable snapshot. 
         [0006]    In one embodiment, the management program decides the target storage system which has enough resource to deploy the new virtual machine, then the management program checks whether the target golden image exists or not in the target storage system. Definition of the golden image in this disclosure is the original image or full copy of the original image. If the storage system has the golden image, the management program creates VM image by using writable snapshot technology. If the storage system does not have the golden image, the management program copies the golden image to the storage system, and then creates VM image by using writable snapshot technology. 
         [0007]    In accordance with an aspect of the present invention, a computer comprises a memory, and a processor being operable to manage a relationship between an image of a virtual machine and a plurality of storage systems forming a virtual storage system, and storing the relationship in the memory. The processor is operable to create a new image of the virtual machine in a target storage system of the plurality of storage systems based on the relationship, the new image of the virtual machine to be used to deploy the virtual machine in the target storage system. When the relationship indicates that the target storage system does not have the image, the processor is operable to copy the image from another storage system of the plurality of storage system to the target storage system and to create a new image of the virtual machine in the target storage system from the copied image in the target storage system. 
         [0008]    In some embodiments, when the relationship indicates that the target storage system does have the image, the processor is operable to create a new image of the virtual machine in the target storage system from the image in the target storage system. The processor is operable to create a new image of the virtual machine in the target storage system based on the relationship and resource conditions of the plurality of storage systems. The processor is operable to select the target storage system which has sufficient resource to deploy the virtual machine. The processor is operable to select a volume in the target storage system which has sufficient capacity to create the new image of the virtual machine. The processor is operable to select the target storage system based on a location of the target storage system and a location of said another storage system. The image is a golden image of the virtual machine and wherein the new image is a writable snapshot or a copy of the gold image. The relationship includes information identifying which storage system has the image and which storage system, if any, has a copy of the image. 
         [0009]    Another aspect of the invention is directed to a system comprising a plurality of storage systems and a management computer. The management computer includes a memory, and a processor being operable to manage a relationship between an image of a virtual machine and the plurality of storage systems forming a virtual storage system, and storing the relationship in the memory. The processor is operable to create a new image of the virtual machine in a target storage system of the plurality of storage systems based on the relationship, the new image of the virtual machine to be used to deploy the virtual machine in the target storage system. When the relationship indicates that the target storage system does not have the image, the processor is operable to copy the image from another storage system of the plurality of storage system to the target storage system and to create a new image of the virtual machine in the target storage system from the copied image in the target storage system. 
         [0010]    In accordance with another aspect of this invention, a computer program comprises: code for managing a relationship between an image of a virtual machine and a plurality of storage systems forming a virtual storage system, and storing the relationship in a memory; code for creating a new image of the virtual machine in a target storage system of the plurality of storage systems based on the relationship, the new image of the virtual machine to be used to deploy the virtual machine in the target storage system; and code for, when the relationship indicates that the target storage system does not have the image, copying the image from another storage system of the plurality of storage system to the target storage system and creating a new image of the virtual machine in the target storage system from the copied image in the target storage system. 
         [0011]    Another aspect of the invention is directed to a computer-readable storage medium storing a plurality of instructions for controlling a data processor, the plurality of instructions comprising: instructions that cause the data processor to manage a relationship between an image of a virtual machine and a plurality of storage systems forming a virtual storage system, and store the relationship in a memory; instructions that cause the data processor to create a new image of the virtual machine in a target storage system of the plurality of storage systems based on the relationship, the new image of the virtual machine to be used to deploy the virtual machine in the target storage system; and instructions that cause the data processor, when the relationship indicates that the target storage system does not have the image, to copy the image from another storage system of the plurality of storage system to the target storage system and to create a new image of the virtual machine in the target storage system from the copied image in target storage system. 
         [0012]    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 
         [0013]      FIG. 1  illustrates an example of a hardware configuration of a system in which the method and apparatus of the invention may be applied. 
           [0014]      FIG. 2  shows an example of a logical configuration of the system of  FIG. 1 . 
           [0015]      FIG. 3  shows an example of a logical configuration of the management server. 
           [0016]      FIG. 4  shows an example of the image catalog table. 
           [0017]      FIG. 5  shows an example of the configuration table according to the first embodiment. 
           [0018]      FIG. 6  shows an example of the image management table according to the first embodiment. 
           [0019]      FIG. 7  shows the logical configuration of the system which reflects the contents of the image management table of  FIG. 6 . 
           [0020]      FIG. 8  shows an example of the GUI of the self-service portal. 
           [0021]      FIG. 9  shows an example of a flow diagram illustrating the process of the management program in the management server. 
           [0022]      FIG. 10  shows an example of a block diagram illustrating a process to create a plan under step  9050  of  FIG. 9  by the management program of the management server. 
           [0023]      FIG. 11  shows an example of the configuration table according to the second embodiment. 
           [0024]      FIG. 12  shows an example of the image management table according to the second embodiment. 
           [0025]      FIG. 13  shows an example of an updated image management table. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0026]    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. 
         [0027]    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. 
         [0028]    The present invention also relates to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, or it may include one or more general-purpose computers selectively activated or reconfigured by one or more computer programs. Such computer programs may be stored in a computer-readable storage medium including non-transitory medium, such as, but not limited to optical disks, magnetic disks, read-only memories, random access memories, solid state devices and drives, or any other types of media suitable for storing electronic information. The algorithms and displays presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may be used with programs and modules in accordance with the teachings herein, or it may prove convenient to construct a more specialized apparatus to perform desired method steps. In addition, the present invention is not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the invention as described herein. The instructions of the programming language(s) may be executed by one or more processing devices, e.g., central processing units (CPUs), processors, or controllers. 
         [0029]    Exemplary embodiments of the invention, as will be described in greater detail below, provide apparatuses, methods and computer programs for concealing the limitation of the physical storage systems in the virtual storage system environment when a new virtual machine is deployed using writable snapshot technology. 
       EMBODIMENT 1  
       [0030]    The first embodiment discloses how the management program decides the target storage system to deploy a new virtual machine when it receives instruction to create new virtual machine. 
         [0031]      FIG. 1  illustrates an example of a hardware configuration of a system in which the method and apparatus of the invention may be applied. The system  1000  includes a management server  3000 , servers  1400 , and storage systems  2000 . The servers  1400  and storage systems  2000  are connected via a Data Network  1070 . The network is usually a WAN (Wide Area Network), but it is not limited to this. The management server  3000 , servers  1400 , and storage systems  2000  are connected via a management. network  1050 . The network is usually a WAN, but it is not limited to this. In the embodiment shown, the management network and data network are separate, but the invention is not limited to this. In the embodiment shown, the management server  3000  and servers  1400  are separate, but the invention is not limited to this. For example, any server can host a management server. In the embodiment shown, the servers  1400  and storage systems  2000  are separate, but the invention is not limited to this. For example, the server and storage system can be combined into one system. 
         [0032]      FIG. 2  shows an example of a logical configuration of the system  1000  of  FIG. 1 . Applications  1110  and OSs  1210  run on the hypervisor  1310 . The hypervisor  1310  runs on the server  1401 . Application  1120 ,  1130  and OS  1220 ,  1230  run on the hypervisor  1320 . The hypervisor  1320  runs on the server  1402 . Application  1110  uses virtual volume  2610  of the virtual storage system  01   2501 . Application  1120  uses virtual volume  2620  of the virtual storage system  01   2501 . Application  1130  uses virtual volume  2630  of the virtual storage system  01   2501 . These virtual volumes  2610 ,  2620 , and  2630  are provisioned from physical storage systems  01   2001  and  02   2002 . 
         [0033]      FIG. 3  shows an example of a logical configuration of the management server  3000 . Management interface  3010  is an interface to the management network  1050 . Input and output device  3030  is a user interface such as monitor, keyboard, and mouse. Local Disk  3040  contains management program  3100  and image catalog table  4000 . The management program  3100  is loaded to the memory  3050  and executed by the processor  3020 . The procedure of the management program  3100  is described in connection with  FIG. 9  and  FIG. 10 . The image catalog table  4000  is loaded to the memory  3050  and used by the management program  3100 . The memory  3050  contains configuration table  5000  and image management table  6000 . Each table is described below. 
         [0034]      FIG. 4  shows an example of the image catalog table  4000 . The image catalog table is referred to when the administrator provisions IT resources by using a self-service portal. This table is loaded from the local disk  3040  to the memory  3050  of the management server  3000 . Column  4010  shows the identification of the catalog. Column  4020  shows the name of the catalog. Column  4030  shows the description of the catalog. Column  4040  shows the location of this golden image. Each row ( 4210 ,  4220 ,  4230 ) shows an image catalog. For example, row  4210  shows the catalog of Linux. This catalog has the SUSE 10.0 Linux image. This image is located on volume  01  of storage system  01 . 
         [0035]      FIG. 5  shows an example of the configuration table  5000  according to the first embodiment. This table is created in the memory  3050  by the management program  3100 . Rows  5510  to  5550  show the information of the virtual volume. Row  5510  shows the identification of the virtual volume. Row  5520  shows the identification of the physical volume. Row  5530  shows the assigned port resources to each volume. For example, 4 Gbps of port resources are assigned to volume  01 . Row  5540  shows the assigned cache resources to each volume. For example, 32 GB of cache resources are assigned to volume  01 . Row  5550  shows the assigned capacity to each volume. For example, 80 TB of capacity is assigned to volume  01 . 
         [0036]    Rows  5560  to  5590  show the information of the virtual storage system. Row  5560  shows the identification of the virtual storage system. Row  5570  shows the assigned port resources to each virtual storage system. For example, 8 Gbps of port A, B, C, D, E, F, G, and H are assigned to virtual storage  01 . Row  5580  shows the assigned cache resources to each virtual storage system. For example, 160 GB of cache C- 01 , 128 GB of cache C- 02 , 128 GB of cache C- 03 , and 32 GB of cache C- 04  are assigned to virtual storage  01 . Row  5590  shows the assigned array groups to each virtual storage system. For example, 300 TB of array group AG- 001 , 300 TB of array group AG- 002 , 200 TB of array group AG- 003 , 500 TS of array group AG- 004 , 1000 TB of array group AG- 005 , and 500 TB of array group AG- 006  are assigned to virtual storage  01 . 
         [0037]    Rows  5600  to  5630  show the information of the physical storage system. Row  5600  shows the identification of the physical storage system. Row  5610  shows the port resources in each physical storage system. For example, storage system  01  has 8 Gbps of port A, B, C, and D. Row  5620  shows the cache resources in each physical storage system. For example, storage system  01  has 160 GB of cache C- 01  and 128 GB of cache C- 02 . Row  5630  shows the array group resources in each physical storage system. For example, storage system  01  has 300 TB of array group AG- 002  and 300 TS of array group AG- 102 . Each column ( 5030  to  5140 ) shows the resource configuration of a volume. For example, column  5030  shows the resource configuration of the volume  01 . 4 Gbps of port resources, 32 Gbps of cache resources, and 80 TB of capacity are assigned to the volume  01 . This volume is provisioned from virtual storage  01  and resources are carved from physical storage  01 . 
         [0038]      FIG. 6  shows an example of the image management table  6000  according to the first embodiment. In this embodiment, an application can only use the writable snapshot image. Therefore, writable snapshot should be taken from the golden image or full copy of the golden image for the application. Columns  6010 ,  6020 , and  6030  show the information of the golden images. Column  6010  shows the identification of the image. Detailed information of this image is shown in the image catalog table  4000  in  FIG. 4 . Column  6020  shows the identification of the physical storage and physical volume which contain this image. The entry “01:01” means the physical storage identification is  01  and the physical volume identification is  01 . Column  6030  shows the status of this image. The entry “Protected” means this image is write protected. Because this is a golden image, writable snapshot should be taken from this image to be used. 
         [0039]    Columns  6040 ,  6050 , and  6060  show the information of the secondary images. Column  6040  shows the relation between the golden image and secondary image. There are two types of relations. The first one is “Copy”. In this case, the secondary image is a full copy of the golden image. The second one is “Snap”. In this case, the secondary image is a writable snapshot of the golden image. Column  6050  shows the identification of the physical storage and physical volume which contain this secondary image. Column  6060  shows the status of this image. The entry “Protected” means this image is write protected. Because this is a copy of the golden image, writable snapshot should be taken from this image to be used. The entry “In use” means this image is a writable snapshot of the golden image and it is used for the application. 
         [0040]    Columns  6070 ,  6080 , and  6090  show the information of the third images. Column  6070  shows the relation between the secondary image and third image. There are two types of relations. The first one is “Copy”. In this case, the third image is a full copy of the secondary image. The second one is “Snap”. In this case, the third image is a writable snapshot of the secondary image. Column  6080  shows the identification of the physical storage and physical volume which contain this third image. Column  6090  shows the status of this image. The entry “Protected” means this image is write protected. Because this is a copy of the golden image, writable snapshot should be taken from this image to be used. The entry “In use” means this image is a writable snapshot of the golden image and it is used for the application. 
         [0041]    Each row ( 6510 - 6540 ) shows the relation for a volume. For example, row  6530  shows that the golden image of the image  001  is stored in volume  01 , a full copy of this image is stored in volume  05 , and a writable snapshot of this image is stored in volume  08 . This figure contains up to the third level, but it is not limited to this. Fourth, fifth, and more levels can be added. 
         [0042]    In the above description, the application only can use the writable snapshot image, but the invention is not limited to this. The application can use the full copy of the golden image. Writable snapshot is quick to deploy but it is difficult to balance the I/O workload. Therefore, it is possible to use the full copy image instead of the writable snapshot. 
         [0043]      FIG. 7  shows the logical configuration of the system  1000  which reflects the contents of the image management table  6000  of  FIG. 6 . This figure is almost the same as  FIG. 2 . Logical data placement is as follows. In the virtual storage system layer, the golden image  001  is stored in volume  01  of the virtual storage system  01  and full copy of the golden image is stored in volume  05  of the virtual storage system  01 . Three writable snapshots of the golden image  001  are stored in volume  03 ,  07 , and  08  of the virtual storage system  01 . Physical data placement is as follows. In the physical storage system layer, the golden image  001  is stored in volume  01  of the storage system  01  and full copy of the golden image is stored in volume  01  of the storage system  02 . One writable snapshot of the golden image  001  in volume  01  of the storage system  01  is stored in volume  03  of the storage system  01 . Two writable snapshots of the golden image  001  in volume  01  of the storage system  02  are stored in volumes  07  and  08  of the storage system  02 . 
         [0044]      FIG. 8  shows an example of the GUI (Graphical User Interface)  8000  of the self-service portal. This self-service portal GUI is used when the administrator wants to provision virtual machine resources and its storage resources. The administrator selects the application type  8010  (e.g., “MySQL”). Candidates are displayed based on the image catalog name  4020  of the image catalog table  4000 . When he/she selects the VM type, description is displayed by referring to the description  4030  in the image catalog table  4000 . The administrator checks a “quick deployment checkbox”  8040 , if he/she wants to deploy a virtual machine quickly. This checkbox is optional. Then, he/she inputs a VM name  8020  (e.g., “MySQL-A”). If the “Cancel” button  8120  is pressed, the management program  3100  cancels the provisioning process. If the “OK” button  8110  is pressed, the management program  3100  issues a “Create VM” instruction. How to process this instruction is described below by using the flow diagram  9000  of  FIG. 9 . 
         [0045]      FIG. 9  shows an example of a flow diagram illustrating the process of the management program  3100  in the management server  3000 . The program starts at Step  9010 . In Step  9020 , the program initializes. The management program  3100  creates the configuration table  5000  and image management table  6000  in the memory  3050 . Then, the management program  3100  loads the image catalog table  4000  from the local disk  3040  to the memory  3050  in the management server  3000 . Next, the virtual storage system is created by the administrator. The administrator configures the port, cache, and capacity of the virtual storage system. This result is reflected in the configuration table  5000 . Then, the virtual volumes are created by the administrator. The administrator configures the port, cache, and capacity of each virtual volume. This result is reflected in the configuration table  5000 . 
         [0046]    In Step  9030  the management program  3100  checks whether a “Create VM” instruction has arrived or not. If the “Create VM” instruction has arrived, the program goes to step  9050 ; otherwise, it goes to step  9040 . In Step  9040 , the program waits for a while, and then goes back to Step  9030 . In Step  9050 , the management program  3100  tries to create a plan. How to create a plan is described in the flow diagram  10000  of FOG.  10 . If the program succeeds in creating a plan, the program goes to step  9070 ; otherwise, it goes to step  9060 . Step  9060  involves an alert. Because the management program  3100  cannot create a plan, it notifies an alert to the administrator. The program then ends at step  9110 . If the management program  3100  succeeds in creating a plan, it logs the created plan in Step  9070 . In Step  9080 , the program executes the created plan. Based on the executed plan, configuration will change. Therefore, the configuration table  5000  is updated in Step  9090 . In Step  9100 , the program checks whether there is a termination indication by the user. If a termination indication exists, the program ends at step  9110 ; otherwise, it goes back to step  9040 . 
         [0047]      FIG. 10  shows an example of a block diagram illustrating a process to create a plan under step  9050  of  FIG. 9  by the management program  3100  of the management server  3000 . The program starts at Step  10010 , when the management program receives “create new virtual machine” instruction. In Step  10020 , the program selects a storage system. If the administrator checks the “quick deployment checkbox”  8040  in the self-service portal GUI  8000 , management program  3100  selects one physical storage system which has enough resource to deploy the new virtual machine and contains specified and “Protected” image by referring to the image catalog table  6000 . If the management program  3100  cannot find a storage system that satisfies the above condition, the management program  3100  selects a physical storage system which has enough resource to deploy the new virtual machine by referring to the image catalog table  6000 . If the administrator does not check the “quick deployment checkbox”  8040  in the self-service portal GUI  8000 , the management program  3100  selects a physical storage system which has enough resource to deploy the new virtual machine. If there is no physical storage which has enough storage resources, then the management program  3100  goes to step  9060  (notify alert). 
         [0048]    In Step  10030 , the management program  3100  selects a volume which has enough capacity to create a writable snapshot of the specified image. If management program  3100  cannot find a volume which satisfies the above condition, then the management program  3100  goes back to step  10020 . In Step  10040 , the management program  3100  checks whether the physical storage system which contains the selected volume has enough resources to provision the new VM. If the selected volume does not have enough resources, then the management program  3100  goes back to step  10020 . If the selected volume has enough resources, the management program  3100  creates a writable snapshot of the specified image. If selected storage system has a protected image, the management program  3100  only creates a writable snapshot from the protected image. If selected storage system does not have a protected image, the management program  3100  copies the protected image from another storage system, and then creates a writable snapshot from the copied image. For example, it is assumed that Linux image (ID= 001 ) is selected at application type  12010  in provisioning GUI  8000  and storage system  03  is selected in step  10020 . In this case, the storage system  03  does not have a Linux image, and hence the management program  3100  copies the image from another storage system (e.g., storage system  01 ), and then creates a writable snapshot from the copied image. 
         [0049]    In this embodiment, the management program receives a “create new virtual machine” instruction, and then the management program decides the target storage system which has enough resource to deploy the new virtual machine, and then the management program checks whether the target golden image exists or not in the target storage system. If the storage system has the golden image, the management program creates a VM image by using writable snapshot technology. If the storage system does not have golden image, the management program copies the golden image to the storage system, and then creates a VM image by using writable snapshot technology. By doing this, the management program can conceal the limitation of the physical storage systems in the virtual storage system environment when the new virtual machine is deployed using writable snapshot technology. 
       EMBODIMENT 2  
       [0050]    Copy performance among physical storage systems may differ, especially in a multi-site environment. In embodiment 2, how to select the optimal physical storage system pair is disclosed. 
         [0051]      FIG. 11  shows an example of the configuration table  5001  according to the second embodiment. This table  5001  is almost the same as the configuration table  5000  of the first embodiment shown in  FIG. 5 . Only the differences are described. In  FIG. 11 , row  11010  is added. Row  11011  shows the identification of the site of the physical storage system. For example, physical storage system  01  is located in site  01  and physical storage systems  02  and  03  are located in site  02 . How to create a plan accordingly to the second embodiment is disclosed next. 
         [0052]      FIG. 12  shows an example of the image management table  6001  according to the second embodiment. This table is the same as the image management table  6000  of the first embodiment shown in  FIG. 6 . Only the contents are different, as shown in rows  12510 - 12540  instead of rows  6510 - 6540  of  FIG. 6 . It is assumed that physical storage  01  and  02  do not have enough resources to deploy a new VM and physical storage  03  has enough resources to deploy a new VM. It is assumed that the management program  3100  receives a “Create VM” instruction of image  002 . In this case, the management program  3100  should copy image  002  to physical storage system  03 . Candidates of the copy source include volume  01  of the physical storage  01  and volume  06  of the physical storage  02 . Physical storage system  01  is in site  01  and physical storage systems  02  and  03  are in site  02 . Because physical storage system  02  is in the same site as physical storage system  03 , the management program  3100  selects physical storage  02  as a copy source. As a result, image  002  is copied from volume  06  of the physical storage  02  to volume  09  of the physical storage  03 , and then writable snapshot is created in volume  11  of the physical storage  03  from image  002  in volume  09  of the physical storage  03 . 
         [0053]      FIG. 13  shows an example of an updated image management table  6002 . This table is updated from the image management table of  FIG. 12  according to Step  9090  of  FIG. 9 . New row  13550  is added. It shows a copy relation between secondary image in volume 02:06 and third image in volume 03:09 which is protected, and snapshot relation between the image in volume 03:09 and the image in volume 03:11 which is in use. 
         [0054]    In the second embodiment, the management program  3100  selects the optimal copy source and target storage systems by using site information, but the invention is not limited to this. For example, the management program  3100  gets distance information among the storage systems, and then selects the nearest pair that can be used. In another example, the management program  3100  gets the turnaround time among the storage systems, and then selects the shortest time pair that can be used. 
         [0055]    This invention discloses how to decrease the cost to execute the application, especially in the cloud environment. The management program provides the recommended plan to decrease the cost. 
         [0056]    Of course, the system configuration illustrated in  FIG. 1  is purely exemplary of information systems in which the present invention may be implemented, and the invention is not limited to a particular hardware configuration. The computers and storage systems implementing the invention can also have known I/O devices (e.g., CD and DVD drives, floppy disk drives, hard drives, etc.) which can store and read the modules, programs and data structures used to implement the above-described invention. These modules, programs and data structures can be encoded on such computer-readable media. For example, the data structures of the invention can be stored on computer-readable media independently of one or more computer-readable media on which reside the programs used in the invention. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include local area networks, wide area networks, e.g., the Internet, wireless networks, storage area networks, and the like. 
         [0057]    In the description, numerous details are set forth for purposes of explanation in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that not all of these specific details are required in order to practice the present invention. It is also noted that the invention may be described as a process, which is usually depicted as a flowchart, a flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged. 
         [0058]    As is known in the art, the operations described above can be performed by hardware, software, or some combination of software and hardware. Various aspects of embodiments of the invention may be implemented using circuits and logic devices (hardware), while other aspects may be implemented using instructions stored on a machine-readable medium (software), which if executed by a processor, would cause the processor to perform a method to carry out embodiments of the invention. Furthermore, some embodiments of the invention may be performed solely in hardware, whereas other embodiments may be performed solely in software. Moreover, the various functions described can be performed in a single unit, or can be spread across a number of components in any number of ways. When performed by software, the methods may be executed by a processor, such as a general purpose computer, based on instructions stored on a computer-readable medium. If desired, the instructions can be stored on the medium in a compressed and/or encrypted format. 
         [0059]    From the foregoing, it will be apparent that the invention provides methods, apparatuses and programs stored on computer readable media for concealing the limitation of the physical storage systems in the virtual storage system environment when a new virtual machine is deployed using writable snapshot technology. 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.