Source: http://www.google.com/patents/US20040250021?dq=5,222,134
Timestamp: 2016-10-27 13:07:29
Document Index: 370805446

Matched Legal Cases: ['art 20', 'art 22', 'art 20', 'arts 7', 'art 20', 'art 7', 'art 81', 'art 82', 'art 7', 'art 73', 'art 72', 'art 7', 'art 7', 'art 72', 'art 20', 'art 20', 'art 53', 'art 82', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 7', 'art 20', 'art 20', 'art 20']

Patent US20040250021 - Virtualization controller and data transfer control method - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsEmbodiments of the present invention are directed to systems and methods of controlling data transfer between a host system and a plurality of storage devices. One embodiment is directed to a virtualization controller for controlling data transfer between a host system and a plurality of storage devices....http://www.google.com/patents/US20040250021?utm_source=gb-gplus-sharePatent US20040250021 - Virtualization controller and data transfer control methodAdvanced Patent SearchTry the new Google Patents, with machine-classified Google Scholar results, and Japanese and South Korean patents.Publication numberUS20040250021 A1Publication typeApplicationApplication numberUS 10/882,797Publication dateDec 9, 2004Filing dateJun 30, 2004Priority dateNov 25, 2002Also published asUS7263593, US7366853, US7694104, US7877568, US8190852, US8572352, US20040103261, US20060195676, US20070162721, US20070192558, US20120297159Publication number10882797, 882797, US 2004/0250021 A1, US 2004/250021 A1, US 20040250021 A1, US 20040250021A1, US 2004250021 A1, US 2004250021A1, US-A1-20040250021, US-A1-2004250021, US2004/0250021A1, US2004/250021A1, US20040250021 A1, US20040250021A1, US2004250021 A1, US2004250021A1InventorsKiyoshi Honda, Naoko Iwami, Kazuyoshi SerizawaOriginal AssigneeHitachi, Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (99), Referenced by (67), Classifications (23), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetVirtualization controller and data transfer control method
[0154] Though the volume management information including status information for each volume is shown above, the volume management information can include different types of status information. For example, status information for each access pass (i.e., status information for a primary pass and status information for a secondary pass), which indicates whether or not a real volume can be accessed via each access pass, can be included in the volume management information. Then storage device identification processor 15 can decide which access pass can be used to access the real volume according to the status information. If the host computer has a storage device manager similar to the one which the managing unit 4 has, the host computer can maintain such status information in the volume management information. Once the abovementioned steps have been taken, even after the host computer 1 is connected with the virtualization controller 2, it can identify the real volume of the storage device using the same personal information (AAA_02) as before connection of the virtualization controller 2. Therefore, even when the virtualization controller 2 is newly introduced in the computer system and the host computer issues an access request to the virtual volume, there is no need to set new personal information on the host computer. For this reason, the host computer need not stop a process which it is performing. Embodiment 3 Plurality of Storage Devices Constitute One Virtual Volume [0155] In the first and second embodiments, one real volume constitutes one virtual volume. However, the present invention is not limited thereto and also applicable to a case that plurality of real volumes constitute one virtual volume. [0156] Referring to FIGS. 15 and 16, an explanation will be given below of the case that a plurality of real volumes constitute one virtual volume. [0157] [0157]FIG. 15 shows an example of volume mapping information 515 where the real volume identified by Port ID=P_Pid_1, Port Name=P_Pname_1, LUN=3 (5 GB) and the real volume identified by Port ID=P_Pid_2, Port Name=P_Pname_2, LUN=1 (5 GB) constitute one virtual volume identified by Port ID=P_Pid_3, Port Name=P_Pname_3, LUN=0 (10 GB). The volume management table (FIG. 15) is the same as the one shown in FIG. 12 except that two real volumes are assigned to one virtual volume and address information for the real volumes is added as an entry to the virtual volume management information 520. In the case shown in FIG. 15, the personal information of the real volume identified by Port ID=P_Pid_1, Port Name=P_Name_1, LUN=3 is used as the personal information of the virtual volume identified by Port ID=V_Pid_3, Port Name=V_Pname_3, LUN=0. [0158] [0158]FIG. 16 shows an example of a computer system in which two real volumes constitute one virtual volume. In the computer system shown in FIG. 16, the virtualization controller 2 takes the same steps to deal with data transfer and storage device monitoring as in the first and second embodiments, so only the routing process is explained below. [0159] The routing process begins when the virtualization controller 2 receives frame data from the host computer 1 or storage device 3. The routing processor 501, which has received the frame data, decides whether virtualization is needed or not, using source (sender)/destination (receiver) identification information in the frame data, and if necessary, frame data type and various information (LUN, etc.) as payload in the frame. In a specific example, if the source/destination identification information (Port ID, etc.) and information in the frame payload (LUN) are registered in the virtual volume management information 520 of the volume mapping information 515, the routing processor 501 decides that virtualization is needed. [0160] If the routing processor 501 decides that virtualization is needed, the virtualization processor 505 carries out the following steps for virtualization. [0161] 1. When the received frame data is frame data addressed to a storage device from the host computer: [0162] The virtualization processor 505 decides whether the received frame data is a read/write access request or not. If the frame data is a read/write access request, the virtualization processor 505 identifies the storage device corresponding to the virtual storage device to which the frame data is addressed, according to the volume mapping information 515 and address and data length information in the access request information (payload in the received frame in particular). Then, in order to convert the received frame into a frame for the identified storage device, the destination identification information (D_ID) in the frame data and CRC are replaced by destination identification information indicating the port of the identified storage device, and CRC which is based on the new destination identification information. Furthermore, if necessary, new address information and data length information are generated as access request information. The new frame as a result of conversion is sent to the storage device 3 through a port 23 of the virtualization controller 2. If the access request is to be sent to two storage devices (request for access across address 989680h), the virtualization processor 505 generates an access request for each of the storage devices and sends the request to each storage device. [0163] If the frame data received by the virtualization controller 2 is data (write data) other than a read/write access request, the virtualization processor 505 identifies the storage device corresponding to the virtual storage device to which the frame data is addressed, according to the volume mapping information 515 and, if necessary, address and data length information as the write access request information which the virtualization controller 2 received before reception of the write data, and write data offset information. Then, in order to convert the received frame into a frame for the identified storage device, the virtualization processor 505 replaces the destination identification information (DID) in the frame data and CRC by identification information for the identified storage device, and new CRC which is based on this identification information. The virtualization controller 2 sends the frame to the identified storage device 3 through a port 23. [0164] 2. When the received frame data is frame data addressed to the host computer from a storage device mapped to a virtual storage device: [0165] The virtualization processor 505 decides whether the received frame data is a read data or not, and takes steps depending on the type of frame data. For example, if the frame data is read data, the virtualization processor 505 identifies the virtual storage device corresponding to the storage device which has sent the frame data. Then, in order to convert the received frame into a frame from the identified virtual storage device, the virtualization processor 505 replaces the source (sender) identification information (S_ID) in the frame data and CRC by identification information for the virtual storage device, and CRC which is based on the new destination identification information. The virtualization controller 2 sends the frame to the host computer 1 through a port 23. [0166] When two storage devices send read data according to one read access request simultaneously, it is desirable that until forwarding of the data received from one storage device to the host computer is completed, the virtualization controller 2 suspend forwarding of the read data received from the other storage device. For example, if the virtualization controller 2 receives read data from the storage device with the real volume identified by P_Pid_1, P_Pname_1, LUN=3 (5 GB) and the storage device with the real volume identified by P_Pid_2, P_Pname_2, LUN=1 (5 GB), the virtualization controller 2 temporarily stores the read data from the storage device with the real volume identified by P_Pid_2, P_Pname_2, LUN=1 (5 GB) to suspend forwarding of the read data. Moreover, when two storage devices send response data according to one read access request, the virtualization controller 2 generates one response data based on the two response data received from the two storage devices, and sends the generated response data to the host computer. [0167] In the abovementioned computer system in which more than one real volume constitute one virtual volume, data can be transferred between storage devices under virtualization control without revising the identification information for the volume which the host computer recognizes as the volume to be accessed, as in the first and second embodiments. More specifically, like the first and second embodiments, as data transfer is done between storage devices, the virtualization controller 2 updates the volume mapping information 515 and changes the real volume correlated with the virtual volume from the data transfer source real volume to the data transfer destination real volume, so the real volume mapped to the virtual volume is dynamically changed without revising the identification information for the volume which the host computer 1 recognizes as the volume to be accessed. Thus, the host computer 1 can continue its operation without knowing the data transfer which takes place between storage devices (real volumes). Embodiment 4 Intelligent Ports Provide Virtualization Control and Storage Functions [0168] In the above embodiments, the main control part 20 of the virtualization controller 20 which functions as a switch executes all processes according to the present invention. However, the present invention is not limited thereto. Alternatively, it is possible that each of the ports 23 has a processor which performs the routing task. [0169] Furthermore, the virtualization controller 2 is not limited to one which only incorporates ports 23, a path control part 22 and a main control part 20. For example, like a disk array controller in a disk array system, it is possible to control the system in a way that a host computer recognizes plural physical disk devices as a single logical storage. Another approach is that the virtualization controller 2 has a storage control function as follows: parity data as redundant data is added to the data being accessed by a host computer and the data is stored on a disk and the virtualization controller 2 has a storage control part to perform parity control and other related tasks to enable data transfer with the host computer using the parity data even if a disk device fails. It is also possible that the virtualization controller 2 has the function as a storage (storage function) by incorporating a storage control part and a storage group composed of plural storages such as disk devices. [0170] Next, referring to FIGS. 19 to 22, an explanation will be given concerning a case that the virtualization controller has a storage control part and a storage group to provide a storage function and its constituent parts or components process their respective tasks. [0171] [0171]FIG. 19 shows an example of a computer system according to the present invention. The components other than the virtualization controller 2 are the same as those shown in FIG. 1. In the virtualization controller 2, one or more port sections 8, and one or more storage control parts 7-1, 7-2, and the main control part 20 are connected through a backplane 9, and the storage control part 7-1 is connected with plural disk devices 35. Each port section 8 incorporates: an interface control part 81 (SN I/F in the figure) which controls a network 5 connected with host computers 1 or storage devices 3; an interface control part 82 (BP I/F) which controls the backplane 9 for connection with other components inside the virtualization controller 2; a memory 85 which stores programs and information (discussed hereinbelow); and a CPU 84 which executes the program using such information. The storage control part 7-1 incorporates: an interface control part 73 (hereinafter called BP I/F) which controls the backplane 9; an interface control part 72 for data transfer with plural disk devices 35 (hereinafter called “HDD I/F); a cache 71 which stores data to be transferred from/to the disk devices 35 or storage devices 3; and a CPU 70 which performs relevant tasks and executes the programs (discussed hereinbelow). The storage control part 7-2 is structurally the same as the storage control part 7-1 except that it does not have an interface control part 72 for data transfer with disk devices 35. The main control part 20 is the same as the main control part 20 shown in FIG. 1 except that it includes a management port 25 and has an interface control part 53 for control of the backplane 9. The program to be executed by the CPU 50 will be discussed hereinbelow. [0172] Although FIG. 19 shows a case in which host computers 1, storage devices 3, a management server (managing unit) 4, and port sections 8 in the virtualization controller 2 each have one port, the invention is not limited thereto. Each of them may have more than one port. Likewise, the components which constitute the virtualization controller 2 may each have more than one interface control part 82 (BP I/F) for control of the backplane 9 and in that case, it is desirable that the components should be interconnected through plural backplanes. Since the port sections 8 of the virtualization controller 2 are compatible with different network protocols, they may be used as management ports. [0173] [0173]FIG. 20 shows programs to be executed by the CPU in a component of the virtualization controller 2 and an example of management information. The programs and management information shown here are the same as those in FIG. 3 except for the following three points. Firstly, the virtualization processor 505 newly has virtualization routing control information 530. Secondly, the virtualization routing program 517 has a program for transfer of command frames (command transfer program) 531, a program for transfer of response frames (response transfer program) 532, and a program for transfer of other frame data (other transfer program) 533. Thirdly, the virtualization controller 2 newly has an internal storage access processor 506 which holds internal storage configuration management information 508 as information on the configuration of storage devices 35 in the virtualization controller 2, and an internal storage access control program 507 for actually transferring frame data. [0174] It is desirable that the internal storage access processor 506 should control the system in a way that a host computer recognizes plural physical disk devices as a single logical storage device, and also by adding parity data as redundant data to the data being accessed by the host computer and storing it on a disk, the internal storage access processor 506 can perform parity control and other related tasks to enable data transfer with the host computer using the parity data even if a disk device fails. However, this is not directly related to the present invention and a detailed explanation thereof is omitted here. Details of the virtualization routing control information 530, command transfer program 531, response transfer program 532 and other transfer program 533 will be given later. [0175] In FIG. 3 and FIG. 20, a program or the like for initialization of the virtualization controller 2 is not shown. The virtualization controller 2 may have at least an initialization program to initialize various management information upon turning on the power or a group of programs which initialize the system or carry out diagnosis according to an instruction from the managing unit (management server) 4 or the like. [0176] [0176]FIG. 21 shows three major types of access path between a host computer and a storage device. In connection with the figure, a storage group 34 as a component of the virtualization controller 2 is referred to as an internal storage, and storage devices 3 which are connected through the network 5 with the virtualization controller 2 as external storages; and the port section 8 connected with the host computer 1 is called In Port and the port section 8 connected with external storage devices 3 is called Out Port. The first type of access path is a route which connects the host computer 1 with the internal storage 34 through the port section 8 (In Port) and the storage control part 7-1. The second type of access path is a route which connects the host computer 1 with an external storage 3 through the port section 8 (In Port), the storage control part 7-2 and the port section 8 (Out Port). The third type of access path is a route which connects the host computer 1 with an external storage 3 through the port section 8 (In Port) and the port section 8 (Out Port). [0177] [0177]FIG. 22 is a table showing an example of volume mapping information 515 which is used in this embodiment. The difference from the table in FIG. 4 is that this table newly includes virtualization module management information 523 which manages information for identifying the component performing the virtualization process (discussed hereinbelow), and external volume connection module management information 254 which, when a real volume exists in an external storage 3, manages the identifier for the port for connection with the external storage 3. In FIG. 22, “Storage Control part #1” refers to the identification for the storage control part 7-1 in FIG. 19, and “Storage Control part #2” refers to the identification for the storage control part 7-2 in FIG. 19. In FIG. 22, Size (volume state information) and Status information are omitted here, but it is desirable to manage such information. In addition, since the internal storage configuration management information 507 contains detailed real volume management information concerning the internal storage 34, an explanation thereof is omitted here. In this embodiment, it is not necessary for each component of the virtualization controller 2 to hold and manage all information as elements of volume mapping information 515; rather, it is desirable for each component to hold and manage only information that it needs to carry out the task assigned to it. [0178] [0178]FIG. 23 is a table showing an example of virtualization routing control information 530 which is managed by each component of the virtualization controller 2. The virtualization routing control information 530 is generated, referenced or updated when each component of the virtualization controller 2 performs the frame data transfer process as mentioned later. It has source management information 534 (which includes source identification and source-specified command identification) and destination management information 535 (which includes destination identification and self-specified command identification). The command identification is information which is added to individual frame data in order to identify which command is relevant to the frame data being transferred between the source and destination. Although a detailed explanation of the composition of frame data is not given here, frame data at least contains information for identifying the source (sender)/destination (receiver) of the frame data (source/destination identification), frame data type information, and header information including command identification, and payload information including access request information or status information or data. FIG. 23 suggests, as an example of virtualization routing control information 530 which is held and managed by the port section 8 (In Port) connected with the host computer 1, that the port section 8 has received three commands identified by Host_Tag_1, Host_Tag_2, and Host_Tag_3 from the host computer identified by Host_Pid_1 and respectively has added command identifiers InPort_Tag_1, InPort_Tag 2, and InPort_Tag_3 (which it has specified) to the commands and respectively has sent them to the storage control part 7-1 (SC#1 in FIG. 23), storage control part 7-2 (SC#2 in FIG. 23) and port section 8 (Out Port in FIG. 23). [0179] [0179]FIG. 24 shows an example of the frame data transfer process which is performed by a component of the virtualization controller 2. This means that the process can be performed by a port section 8, the storage control part 7-1, or the storage control part 7-2. This process begins when frame data is received from the host computer 1 or internal storage 34 or external storage device 3, or when a component of the virtualization controller 2 receives frame data from another component. Next, the frame data transfer process according to this embodiment will be explained as an example, referring to FIG. 24. When a component of the virtualization controller 2 receives frame data, first of all it decides whether virtualization is needed or not (130) (discussed hereinbelow). The following is a concrete example of conditions of frame data which should be decided as needing virtualization. [0180] (1) The destination identification in the frame data is registered in the virtual volume management information 520 of the volume mapping information 515. [0181] (2) The source identification in the frame data is registered in the real volume management information 521 of the volume mapping information 515. [0182] (3) The command identification in the frame data is registered in the source management information 534 or destination management information 535 of the virtualization routing control information 530. [0183] The above conditions for decision on the necessity for virtualization are mere examples and do not limit the invention. The real routing process (131) which is to be performed if it is decided that virtualization is not needed is the same as the process shown in FIG. 9 and an explanation thereof is omitted here. Next, if it is decided that virtualization is needed, the component concerned detects the type of frame data using frame data type information included in the frame data. [0184] Command Frame [0185] If the received frame data is found to be a command frame (132), the command transfer program 531 takes the following steps for transfer of the command frame. [0186] 1. Decision on Necessity for Command Conversion (133) [0187] Using the frame data destination identification included in the received frame data, and if necessary, various information included in the payload of the received frame data (destination LUN, etc.) and volume mapping information 515, the command transfer program 531 decides whether it should perform the after-mentioned command conversion process or not. For example, if the destination Port ID or LUN is registered in the virtual volume management information 520 of the volume mapping information 515, and the information for identifying it is registered in the virtualization module management information 523, then the program decides that the command needs conversion by it. [0188] 2. Command Conversion (134) [0189] If the command transfer program 531 decides that command conversion by it is needed, it performs the command conversion process as follows: using the virtual volume management information 520 and real volume management information 521 of the volume mapping information 515, it replaces the destination identification included in the received frame data by identification corresponding to a real volume, and the source identification by its identification, and access request (command) information (LUN, etc) by access request information (LUN, etc) corresponding to a real volume. If it is decided at step 133 that command conversion is not needed, the step of command conversion (134) is not taken and the sequence proceeds to step 135. [0190] 3. Detection of Command Frame Destination (135) [0191] If it is decided that command conversion is not needed, or after the above command conversion process is performed, the command transfer program 531 detects the destination to which the command frame is to be transferred, using the virtualization module management information 523 (for In Port), or the external volume connection module management information 524 (for the storage controller), or the real volume management information 521 (for Out Port) in the volume mapping information 515. [0192] 4. Registration of Virtualization Routing Control Information (136) [0193] Next, the command transfer program 531 registers the source identification and command identification included in the received command frame, the destination identification for identifying the command frame destination, and the command identification generated by it, as the source management information 534 and destination management information 535 of the virtualization routing control information 530. [0194] 5. Command Transfer (137) [0195] The command transfer program 531 replaces the command identification included in the received command frame by the command identification which it has generated and sends the latter to the above detected command frame destination (137). This concludes the whole command frame transfer process. [0196] Response Frame [0197] If the received frame data is found at step 132 to be not a command frame but a response frame (138), the response transfer program 532 takes the following steps for transfer of the response frame. [0198] 1. Decision on Necessity for Response Generation (139) [0199] Using the command identification included in the received response frame and volume mapping information 515, the response transfer program 532 decides whether it should perform the response generation process or not. For example, if the source identification included in the received response frame is registered in the real volume management information 521 of the volume mapping information 515, and its identification is registered in the virtualization module management information 523, then it decides that the response frame is frame data which needs response generation by it. [0200] 2. Response Generation (140) [0201] If the response transfer program 532 decides that response generation is needed, it performs the response generation process as follows: using the virtual volume management information 520 of the volume mapping information 515, it replaces the source identification included in the received response frame by identification corresponding to a virtual volume, and the destination identification by identification for the corresponding host computer, and if necessary, generates new status information according to the status information included in the received response frame and replaces the old status information by the new one. [0202] 3. Detection of Response Frame Destination (141) [0203] Then, the response transfer program 532 detects the destination to which the response frame is to be transferred, using the command identification included in the received frame data and the virtualization routing control information 530. For example, it detects the command management information in the destination management information 535 of the virtualization routing control information 530 which agrees with the command identification included in the received frame data and recognizes the source identification in the source management information 534 corresponding to the command management information, as representing the destination for the response frame. [0204] 4. Response Transfer (142) [0205] Next, the response transfer program 532 replaces the command identification included in the received response frame by the corresponding source command identification in the source management information 534 of the virtualization routing control information 530, and sends it to the response frame destination detected at step 141. [0206] 5. Updating the Virtualization Routing Control Information (143) [0207] Then, the response transfer program 532 deletes the corresponding entry (destination/source management information) in the virtualization routing control information 530 according to the command identification included in the received response frame and concludes the whole response frame transfer process. [0208] Other Frame [0209] If the received frame data is found to be a frame (e.g., data) other than a command frame and a response frame, the other transfer program 533 takes the following steps for transfer of the frame data. [0210] 1. Decision on Necessity for Virtualization (144) [0211] Using the frame data destination/source identification and command identification included in the received frame data, volume mapping information 515 and virtualization routing control information 530, the other transfer program 533 decides whether it should perform the virtualization process or not. For example, if the destination or source identification is registered in the real volume management information 521 or virtual volume management information 520 of the volume mapping information 515, and its identification is registered in the virtualization module management information 523, then the other transfer program 533 decides that it is frame data which needs virtualization by it. [0212] 2. Virtualization (Source/Destination Identification Conversion) (145) [0213] If the other transfer program 533 decides that virtualization by it (source/destination identification conversion) is needed, it performs the virtualization process as follows: using the virtual volume management information 520 and real volume management information 521 of the volume mapping information 515, it replaces the source or destination identification included in the received frame data by virtual or real volume identification information. For example, if the destination identification included in the received frame data agrees with virtual volume identification information (from a host computer to the virtualization controller), the other transfer program 533 replaces the destination identification by real volume identification information; or if the source identification included in the received frame data agrees with real volume identification information (from the virtualization controller to a host computer), it replaces the source identification by virtual volume identification information. [0214] 3. Detection of Other Frame Data Destination (146) [0215] Then, the other transfer program 533 detects the destination to which the frame data is to be transferred, using the command identification included in the received frame data and the virtualization routing control information 530. For example, the other transfer program 533 detects the command management information in the source management information 534 of the virtualization routing control information 530 which agrees with the command identification included in the received frame data and recognizes the destination identification in the destination management information 535 corresponding to the command management information, as representing the destination for the frame data. [0216] 4. Transfer of Frame Data (147) [0217] Next, the other transfer program 533 replaces the command identification included in the received frame data by the corresponding source command identification in the source management information 534 of the virtualization routing control information 530, and sends it to the frame data destination detected at step 156. [0218] For simplification, the above explanation assumes that the external port identification (which is used with a host computer or storage device) is the same as the internal one (which is used with another internal component of the virtualization controller). However, the present invention is not limited thereto. When the internal and external port identifications are different, it may be sufficient for the virtualization controller 2 to have information which defines the relation between them. [0219] Next, an explanation will be given of the data transfer process in this embodiment where different access paths between a host computer and a storage device offering a real volume are available. In this embodiment, a port section 8 or the storage control part 7-1 or storage control part 7-2 performs the data transfer process and, upon completion of data transfer, updates the volume mapping information 515. Which component is to perform this process is determined according to the virtualization module management information 523 of the volume mapping information 515. In other words, the component registered as a virtualization module in the virtualization module management information 523 performs the data transfer process for the corresponding virtual volume and updates the volume mapping information 515. For example, if the volume mapping information 515 is as shown in FIG. 22, the storage control part 7-2 performs the data transfer process for the virtual volume identified by Port ID=V_Pid_2, Port Name=V_Pname_2, LUN=0 and updates the volume mapping table. The sequences for data transfer and volume mapping table updating are the same as in the first embodiment. [0220] In this embodiment, the virtualization module may be changed. Next is an explanation of a data transfer process involving change of the virtualization module. A data transfer process involving change of the virtualization module is classified into two cases: in one case, the access path type (first, second or third access path) is changed; and in the other case, the access path is constant but the virtualization module is changed. The following is an explanation of a case that the access path is changed from the second access path type to the third one. [0221] [0221]FIG. 25 shows an example of volume mapping information 515 which is held by the port section 8 (In Port) of the virtualization controller 2 before the data transfer process; FIG. 26 shows an example of volume mapping information 515 which is held by the storage control part 7-2 before the data transfer process; and FIG. 27 shows an example of real volume mapping information 515 which is held by the port section 8 (Out Port) of the virtualization controller 2 before the data transfer process. [0222] As shown in FIG. 25, V_Pid_1, V_Pid_2, and V_Pid_3 are registered as virtual volume management information managed by the port section 8 (In Port). This indicates that the port section 8 (In Port) constitutes an access path for three virtual volumes (V_Pid_1, V_Pid_2, and V_Pid_3) which the virtualization controller 2 offers to the host computer. Likewise, FIG. 26 indicates that the storage control part 7-2 constitutes an access path for the virtual volume V_Pid_2; and FIG. 27 indicates that the port section 8 (Out Port) constitutes an access path for two virtual volumes (V_Pid_2 and V_Pid_3). In addition, the virtualization module management information in FIGS. 25, 26 and 27 indicates that the storage control part 7-1 (SC#1), storage control part 7-2 (SC#2), and Out Port perform virtualization of the virtual volumes identified by V_Pid_1, V_Pid_2, and V_Pid_3, respectively. [0223] Therefore, the access path between the virtual volume V_Pid_1 and the host is of the first type, namely a path which leads from In Port through the backplane 9 to the storage control part 7-1 in which virtualization is performed. The access path between the virtual volume V_Pid_2 and the host is of the second type, namely a path which leads from In Port through the backplane 9 to the storage control part 7-2 in which virtualization is performed, and then (after virtualization) leads through Out Port and reaches an external storage. The access path between the virtual volume V_Pid_3 and the host is of the third type, namely a path which leads from In Port through the backplane 9 to Out Port 7-1 in which virtualization is performed, skipping the storage control parts. [0224] FIGS. 28 to 30 show examples of volume mapping information 515 which are respectively held by the port section 8 (In Port), storage control part 7-2, and port section 8 (Out Port) after the access path to the virtual volume (V_Pid_2) shown in FIGS. 25 to 27 has been changed from the second type to the third type and data transfer between external storages 3 (data transfer from the real volume identified by P_Pid_2 and LUN 0 to the real volume identified by P_Pid_3 and LUN 1) has been made. [0225] [0225]FIG. 28 and FIG. 30 respectively show volume mapping information which is held by the port section 8 (In Port) and the port section 8 (Out Port) respectively. As indicated by FIG. 28 and FIG. 30, the identification for the real volume corresponding to the virtual volume identified by V_Pid_2 is replaced by P_Pid_3, P_Pname_3, LUN 1, which is destination real volume identification, and the virtualization module management information is replaced by “Out Port” which represents the port section to perform virtualization in the new access path (third type access path). FIG. 29 shows volume mapping information which is held by the storage control part 7-2. In the third type access path, the storage control part does not constitute an access path which is used to offer a virtual volume to the host computer. Therefore, the entry for the virtual volume identified by V_Pid_2 is deleted here. [0226] A detailed explanation of the data transfer process according to this embodiment is omitted because the process is achieved when an adequate component of the virtualization controller 2 (for example, a component which performs virtualization before data transfer) follows the abovementioned data transfer process according to the above (first to third) embodiments., [0227] It is desirable that volume mapping information 515 should be updated by the components of the virtualization controller 2 synchronously. Therefore, it is desirable that as in the above embodiments, its updating should be made through the main control part 20 of the virtualization controller 2 upon completion of data transfer between storages. In other words, it is desirable that a component which performs the process for data transfer between storages should notify the main control part 20 of completion of data transfer and the main control part 20 thus notified should update the relevant volume mapping information 515. The same applies to the procedure for updating volume mapping information 515 in a case that only the access path is changed and data transfer between storages is not made. [0228] The above explanation assumes that the port section (In Port) connected with the host computer 1 and the port section (Out Port) connected with an external storage 3 are different port sections. However, the present invention is not limited thereto. It is also possible, for example, that a port section 8 is connected with a host computer 1 and an external storage 3 at the same time. Furthermore, the above explanation assumes that Port ID and Port Name as information for identifying a virtual volume are identifiers assigned to a virtual port offered to the host computer 1 by the virtualization controller 2. However, the invention is not limited thereto. According to this embodiment in particular, the actual identifiers assigned to port sections 8 of the virtualization controller 2 may be used as virtual volume management information. [0229] According to the present invention, data can be transferred between storage devices without revising the identification information which a host computer uses to identify the volume to be accessed. As a consequence, data transfer takes place without stopping operation of the host computer. [0230] Furthermore, according to the present invention, even when a virtualization controller is newly introduced or replaced in a computer system, a host computer can access data without revising the information for identifying the volume to be accessed. As a consequence, it is possible to introduce or replace a virtualization controller in the computer system without stopping operation of the host computer. [0231] It is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents. 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G06F12/08Cooperative ClassificationG06F3/0689, G06F3/0649, G06F3/067, G06F3/0605, G06F3/061, G06F3/0617, G06F3/0613, G06F3/0665, G06F3/0647European ClassificationG06F3/06A6L4R, G06F3/06A2P4, G06F3/06A4V4, G06F3/06A4H2L, G06F3/06A2R4, G06F3/06A4H2, G06F3/06A2P, G06F3/06A2A2, G06F3/06A6DLegal EventsDateCodeEventDescriptionSep 14, 2011FPAYFee paymentYear of fee payment: 4Oct 14, 2015FPAYFee paymentYear of fee payment: 8RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services