Virtualization controller and data transfer control method

• US 7,694,104 B2
• Filed: 03/19/2007
• Issued: 04/06/2010
• Est. Priority Date: 11/25/2002
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Iwami, Naoko, Serizawa, Kazuyoshi, Honda, Kiyoshi
• Primary Examiner(s): Bragdon; Reginald G
• Assistant Examiner(s): LOONAN, ERIC T
• Application Number:
  US11/723,230
• Publication Number:
  US 20070162721A1
• Time in Patent Office: 1,114 Days
• Field of Search: None
• US Class Current: 711/202
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0649 Lifecycle management
• CPC Class Codes: G06F 3/0665 at area level, e.g. provisioning of virtual or logical volumes
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

System for controlling data transfer between a host system and storage devices. A virtualization controller implements the data transfer and includes first ports for connection with the storage devices, a second port for connection with the host system, a processor, and a memory configured to store volume mapping information which correlates first identification information used by the host system to access a first storage area in one of the storage devices, with second identification information for identifying the first storage area, the correlation being used by the processor to access the first storage area. When data stored in the first storage area is transferred to a second storage area, the processor correlates the first identification information with a third identification information for identifying the second storage area and registers the first identification information and the third identification information in the volume mapping information.

Claims

1. A virtualization system for controlling data transfer between a host computer and a plurality of storage devices, each of the plurality of storage devices including a disk controller and a plurality of disk drives related to at least one logical volume, the virtualization system comprising:

a plurality of first ports being adapted to be coupled to the plurality of storage devices;

a second port being adapted to be coupled to the host computer;

at least one of a plurality of processing circuits configured to transfer data, which are related to a first virtual volume identification information identifying a first virtual volume and are received from the host computer, to a first logical volume in a first storage device of the plurality of storage devices in reference to a first mapping information mapping the first virtual volume identification information to a first logical volume identification information identifying in the first logical volume;

at least one of a plurality of first memories configured to store the first mapping information to be referred by at least one of the plurality of processing circuits;

a control circuit configured to manage a plurality of mapping information including the first mapping information; and

a second memory configured to store the plurality of mapping information,

wherein the virtualization system is configured to transfer data, which are related to the first virtual volume identification information and are received from the host computer during a data transfer phase in which data stored in the first logical volume are transferred to a second logical volume of a second storage device of the plurality of storage devices, to the second logical volume,

wherein, based on the data transfer phase, the control circuit is configured to update the first mapping information of the plurality of mapping information in the second memory to a second mapping information, mapping the first virtual volume identification information to a second logical volume identification information identifying the second logical volume, and to update the first mapping information in the at least one of the plurality of first memories to the second mapping information, and

wherein, after the data transfer phase is completed, the second mapping information in the at least one of the plurality of first memories, instead of the first mapping information, is referred by the at least one of the plurality of processing circuits for transferring data, which are related to the first virtual volume identification information and are received from the host computer, to the second logical volume.

2. A virtualization system according to claim 1, wherein the at least one of the plurality of processing circuits is configured to transfer the data, which are related to the first virtual volume identification information and are received from the host computer during the data transfer phase, to the second logical volume of the second storage device.

3. A virtualization system according to claim 1, wherein, in data transfer phase, the at least one of the plurality of processing circuits is configured to transfer the data stored in the first logical volume to the second logical volume of the second storage device via at least one of the plurality of first ports.

4. A virtualization system according to claim 1, wherein the virtualization system is configured to transfer the data, which are related to the first virtual volume identification information and are received from the host computer during the data transfer phase, to the first logical volume of the first storage device and the second logical volume of the second storage device.

5. A virtualization system according to claim 1, wherein the control circuit is adapted to be coupled to a management computer and is configured to communicate information with the management computer.

6. A virtualization system according to claim 1, wherein the control circuit is adapted to be coupled to a computer and is configured to communicate information of the first mapping information and/or the second mapping information with the computer so that the computer can output the first mapping information and/or the second mapping information.

7. A virtualization system according to claim 1, wherein the at least one of the plurality of processing circuits is configured to communicate a status of the data transfer phase with the control circuit, and

wherein, after the control circuit receives the status of the data transfer phase from the at least one of the plurality of processing circuits, the control circuit is configured to update the first mapping information of the plurality of mapping information in the second memory to the second mapping information and to update the first mapping information in the at least one of the plurality of first memories to the second mapping information.

8. A virtualization system according to claim 1, wherein the first virtual volume identification information includes a Logical Unit Number LUN) of the first virtual volume,

wherein the first logical volume identification information includes a LUN of the first logical volume, and

wherein the second logical volume identification information includes a LUN of the second logical volume.

9. A virtualization system according to claim 1, wherein the first virtual volume identification information is a LUN of the first virtual volume and corresponds to an identifier of a virtual port,

wherein the first logical volume identification information is a LUN of the first logical volume and corresponds to an identifier of one of the plurality of first ports, and

wherein the second logical volume identification information is a LUN of the second logical volume and corresponds to an identifier of another one of the plurality of first ports.

10. A virtualization system according to claim 1, wherein, based on the data transfer phase, the control circuit is configured to further update the first mapping information in at least another one of the plurality of first memories to the second mapping information.

11. A virtualization system according to claim 1, wherein the first mapping information in the at least one of the plurality of first memories is formed by a first part of the first mapping information stored in one of the plurality of first memories and a second part of the first mapping information stored in another one of the plurality of first memories,

wherein the second mapping information in the at least one of the plurality of first memories is formed by a first part of the second mapping information stored in the one of the plurality of first memories and a second part of the second mapping information stored in the another one of the plurality of first memories.

12. A virtualization system according to claim 1, wherein the data, which are related to the first virtual volume identification information and are received from the host computer before the data transfer phase, are transferred to the first logical volume after being related to the first logical volume identification information instead of the first virtual volume identification information,

wherein the data, which are related to the first virtual volume identification information and are received from the host computer during the data transfer phase, are transferred to the second logical volume after being related to the second logical volume identification information instead of the first virtual volume identification information, and

wherein, after the data transfer phase is completed, the data, which are related to the first virtual volume identification information and are received from the host computer, are transferred to the second logical volume after being related to the second logical volume identification information instead of the first virtual volume identification information.

13. A virtualization system according to claim 1, further comprising:

at least another one of the plurality of processing circuits configured to transfer data, which are related to a second virtual volume identification information identifying a second virtual volume and are received from the host computer, to a third logical volume in a third storage device of the plurality of storage devices in reference to a third mapping information mapping the second virtual volume identification information to a third logical volume identification information identifying the third logical volume; and

at least another one of the plurality of first memories configured to store the third mapping information to be referred by the at least another one of the plurality of processing circuits;

wherein the virtualization system is configured to transfer data, which are related to the third virtual volume identification information and are received from the host computer during another data transfer phase in which data stored in the third logical volume are transferred to a fourth logical volume of a fourth storage device of the plurality of storage devices, to the fourth logical volume,

wherein, based on the another data transfer phase, the control circuit is configured to update the third mapping information of the plurality of mapping information in the second memory to a fourth mapping information, mapping the second virtual volume identification information to a fourth logical volume identification information identifying the fourth logical volume, and to update the third mapping information in the at least another one of the plurality of first memories to the fourth mapping information, and

wherein, after the another data transfer phase is completed, the fourth mapping information in the at least another one of the plurality of first memories, instead of the third mapping information, is referred by the at least another one of the plurality of processing circuits for transferring data, which are related to the second virtual volume identification information and are received from the host computer, to the fourth logical volume.

14. A control part of a virtualization system, wherein the virtualization system controls data transfer between a host computer and a plurality of storage devices, each of the plurality of storage devices comprising a disk controller and a plurality of disk drives related to at least one logical volume, the virtualization system comprising:

at least one of a plurality of processing circuits configured to transfer data, which are related to a first virtual volume identification information identifying a first virtual volume and are received from the host computer, to a first logical volume in a first storage device of the plurality of storage devices in reference to a first mapping information mapping the first virtual volume identification information to a first logical volume identification information identifying the first logical volume; and

at least one of a plurality of first memories configured to store the first mapping information to be referred by the at least one of the plurality of processing circuits;

wherein the virtualization system is configured to transfer data, which are related to the first virtual volume identification information and are received from the host computer during a data transfer phase in which data stored in the first logical volume are transferred to a second logical volume of a second storage device of the plurality of storage devices, to the second logical volume of the second storage device,

wherein the control part comprises;

a control circuit configured to manage a plurality of mapping information including the first mapping information; and

a second memory configured to store the plurality of mapping information

wherein, based on the data transfer phase, the control circuit is configured to update the first mapping information of the plurality of mapping information in the second memory to a second mapping information, mapping the first virtual volume identification information to a second logical volume identification information identifying the second logical volume, and to update the first mapping information in the at least one of the plurality of first memories to the second mapping information, and

wherein, after the data transfer phase is completed, the second mapping information in the at least one of the plurality of first memories, instead of the first mapping information, is referred by the at least one of the plurality of processing circuits for transferring data, which are related to the first virtual volume identification information and are received from the host computer, to the second logical volume of the second storage device.

15. A control part of the virtualization system according to claim 14, wherein the data, which are related to the first virtual volume identification information and are received from the host computer during the data transfer phase, are transferred, by the at least one of the plurality of processing circuits, to the second logical volume of the second storage device.

16. A control part of the virtualization system according to claim 14, wherein, in data transfer phase, the data stored in the first logical volume are transferred, by the at least one of the plurality of processing circuits, to the second logical volume of the second storage device.

17. A control part of the virtualization system according to claim 14, wherein the data, which are related to the first virtual volume identification information and are received from the host computer during the data transfer phase, are transferred to the first logical volume of the first storage device and the second logical volume of the second storage device.

18. A control part of the virtualization system according to claim 14, wherein the control circuit is adapted to be coupled to a management computer and is configured to communicate information with the management computer.

19. A control part of the virtualization system according to claim 14, wherein the control circuit is adapted to be coupled to a computer and is configured to communicate information of the first mapping information and/or the second mapping information with the computer so that the computer can output the first mapping information and/or the second mapping information.

20. A control part of the virtualization system according to claim 14, wherein, after the control circuit receives a status of the data transfer phase from the at least one of the plurality of processing circuits, the control circuit is configured to update the first mapping information of the plurality of mapping information in the second memory to the second mapping information and to update the first mapping information in the at least one of the plurality of first memories to the second mapping information.

21. A control part of the virtualization system according to claim 14, wherein the first virtual volume identification information includes a Logical Unit Number LUN) of the first virtual volume,

wherein the first logical volume identification information includes a LUN of the first logical volume, and

wherein the second logical volume identification information includes a LUN of the second logical volume.

22. A control part of the virtualization system according to claim 14, wherein the first virtual volume identification information is a LUN of the first virtual volume and corresponds to an identifier of a virtual port,

wherein the first logical volume identification information is a LUN of the first logical volume and corresponds to an identifier of one of a plurality of ports of the virtualization system, and

wherein the second logical volume identification information is a LUN of the second logical volume and corresponds to an identifier of another one of the plurality of ports of the virtualization system.

23. A control part of the virtualization system according to claim 14, wherein, based on the data transfer phase, the control circuit is configured to further update the first mapping information in at least another one of the plurality of first memories to the second mapping information.

24. A control part of the virtualization system according to claim 14, wherein the first mapping information in the at least one of the plurality of first memories is formed by a first part of the first mapping information stored in one of the plurality of first memories and a second part of the first mapping information stored in another one of the plurality of first memories, and

wherein the second mapping information in the at least one of the plurality of first memories is formed by a first part of the second mapping information stored in the one of the plurality of first memories and a second part of the second mapping information stored in the another one of the plurality of first memories.

25. A control part of the virtualization system according to claim 14, wherein the data, which are related to the first virtual volume identification information and are received from the host computer before the data transfer phase, are transferred to the first logical volume after being related to the first logical volume identification information instead of the first virtual volume identification information,

wherein the data, which are related to the first virtual volume identification information and are received from the host computer during the data transfer phase, are transferred to the second logical volume after being related to the second logical volume identification information instead of the first virtual volume identification information, and

wherein, after the data transfer phase is completed, the data, which are related to the first virtual volume identification information and are received from the host computer, are transferred to the second logical volume after being related to the second logical volume identification information instead of the first virtual volume identification information.

26. A control part of the virtualization system according to claim 14, wherein at least another one of the plurality of processing circuits is configured to transfer data, which are related to a second virtual volume identification information identifying a second virtual volume and are received from the host computer, to a third logical volume in a third storage device of the plurality of storage devices in reference to a third mapping information mapping the second virtual volume identification information to a third logical volume identification information identifying the third logical volume;

wherein at bust another one of the plurality of first memories is configured to store the third mapping Information to be referred by the at least another one of the plurality of processing circuits;

wherein the virtualization system is configured to transfer data, which are related to the second virtual volume Identification information and are received from the host computer during another data transfer phase in which data stored In the third logical volume are transferred to a fourth logical volume of a fourth storage device of the plurality of storage devices, to the fourth logical volume,

wherein, based on the another data transfer phase, the control circuit is configured to update the third mapping information of the plurality of mapping information In the second memory to a fourth mapping Information, mapping the second virtual volume identification information to a fourth logical volume identification Information identifying the fourth logical volume, and to update the third mapping Information in the at bust another one of the plurality of first memories to the fourth mapping information, and

wherein, after the another data transfer phase is completed, the fourth mapping information in the at least another one of the plurality of first memories, Instead of the third mapping information, is referred by the at least another one of the plurality of processing circuits for transferring data, which are related to the second virtual volume identification Information and are received from the host computer, to the fourth logical volume of the fourth storage device.

27. A computer program stored in a computer readable storage medium and implemented in a control part of a virtualization system,

wherein the virtualization system controls data transfer between a host computer and a plurality of storage devices, each of the plurality of storage devices comprising a disk controller and a plurality of disk drives related to at least one logical volume, the virtualization system comprising:

at least one of a plurality of processing circuits configured to transfer data, which are related to a first virtual volume identification information identifying a first virtual volume and are received from the host computer, to a first logical volume in a first storage device of the plurality of storage devices in reference to a first mapping information mapping the first virtual volume identification information to a first logical volume identification information identifying the first logical volume; and

at least one of a plurality of first memories configured to store the first mapping information to be referred by the at least one of the plurality of processing circuits;

wherein the virtualization system is configured to transfer data, which are related to the first virtual volume identification information and are received from the host computer during a data transfer phase in which data stored in the first logical volume are transferred to a second logical volume of a second storage device of the plurality of storage devices, to the second logical volume,

wherein the control part comprises;

a control circuit configured to manage a plurality of mapping information including the first mapping information; and

a second memory configured to store the plurality of mapping information

the computer program comprising;

a code, based on the data transfer phase, for updating the first mapping information of the plurality of mapping information in the second memory to a second mapping information, mapping the first virtual volume identification information to a second logical volume identification information identifying the second logical volume, and for updating the first mapping information in the at least one of the plurality of first memories to the second mapping information,

wherein, after the data transfer phase is completed, the second mapping information in the at least one of the plurality of first memories, instead of the first mapping information, is referred by the at least one of the plurality of processing circuits for transferring data, which are related to the first virtual volume identification information and are received from the host computer, to the second logical volume.

28. A computer program according to claim 27, wherein the data, which are related to the first virtual volume identification information and are received from the host computer during the data transfer phase, are transferred, by the at least one of the plurality of processing circuits, to the second logical volume of the second storage device.

29. A computer program according to claim 27, wherein, in data transfer phase, the data stored in the first logical volume are transferred, by the at least one of the plurality of processing circuits, to the second logical volume of the second storage device.

30. A computer program according to claim 27, wherein the data, which are related to the first virtual volume identification information and are received from the host computer during the data transfer phase, are transferred to the first logical volume of the first storage device and the second logical volume of the second storage device.

31. A computer program according to claim 27, wherein the control circuit is adapted to be coupled to a management computer,

wherein the computer program further comprises:

a code for communicating information with the management computer.

32. A computer program according to claim 27, wherein the control circuit is adapted to be coupled to a computer,

wherein the computer program further comprises:

a code for communicating information of the first mapping information and/or the second mapping information with the computer so that the computer can output the first mapping information and/or the second mapping information.

33. A computer program according to claim 27, wherein the code for, after the control circuit receives a status of the data transfer phase from the at least one of the plurality of processing circuits, updating the first mapping information of the plurality of mapping information in the second memory to the second mapping information and to update the first mapping information in the at least one of the plurality of first memories to the second mapping information.

34. A computer program according to claim 27, wherein the first virtual volume identification information includes a Logical Unit Number (LUN) of the first virtual volume,

wherein the first logical volume identification information includes a LUN of the first logical volume, and

wherein the second logical volume identification information includes a LUN of the second logical volume.

35. A computer program according to claim 27, wherein the first virtual volume identification information is a LUN of the first virtual volume and corresponds to an identifier of a virtual port,

wherein the first logical volume identification information is a LUN of the first logical volume and corresponds to an identifier of one of a plurality of ports of the virtualization system, and

wherein the second logical volume identification information is a LUN of the second logical volume and corresponds to an identifier of another one of the plurality of ports of the virtualization system.

36. A computer program according to claim 27, the code for, based on the data transfer phase, further updating the first mapping information in at least another one of the plurality of first memories to the second mapping information.

37. A computer program according to claim 27, wherein the first mapping information in the at least one of the plurality of first memories is formed by a first part of the first mapping information stored in one of the plurality of first memories and a second part of the first mapping information stored in another one of the plurality of first memories, and

wherein the second mapping information in the at least one of the plurality of first memories is formed by a first part of the second mapping information stored in the one of the plurality of first memories and a second part of the second mapping information stored in the another one of the plurality of first memories.

38. A computer program according to claim 27, wherein the data, which are related to the first virtual volume identification information and are received from the host computer before the data transfer phase, are transferred to the first logical volume after being related to the first logical volume identification information instead of the first virtual volume identification information,

wherein the data, which are related to the first virtual volume identification information and are received from the host computer during the data transfer phase, are transferred to the second logical volume after being related to the second logical volume identification information instead of the first virtual volume identification information, and

wherein, after the data transfer phase is completed, the data, which are related to the first virtual volume identification information and are received from the host computer, are transferred to the second logical volume after being related to the second logical volume identification information instead of the first virtual volume identification information.

39. A computer program according to claim 27, wherein at least another one of the plurality of processing circuits is configured to transfer data, which are related to a second virtual volume identification information identifying a second virtual volume and are received from the host computer, to a third logical volume in a third storage device of the plurality of storage devices in reference to a third mapping information mapping the second virtual volume identification information to a third logical volume identification information identifying the third logical volume;

wherein at least another one of the plurality of first memories is configured to store the third mapping information to be referred by the at least another one of the plurality of processing circuits;

wherein the virtualization system is configured to transfer data, which are related to the second virtual volume identification information and are received from the host computer during another data transfer phase in which data stored in the third logical volume are transferred to a fourth logical volume of a fourth storage device of the plurality of storage devices, to the fourth logical volume,

wherein the code for, based on the another data transfer phase, updating the third mapping information of the plurality of mapping information in the second memory to a fourth mapping information, mapping the second virtual volume identification information to a fourth logical volume identification information identifying the fourth logical volume, and to update the third mapping information in the at least another one of the plurality of first memories to the fourth mapping information, and

wherein, after the another data transfer phase is completed, the fourth mapping information in the at least another one of the plurality of first memories, instead of the third mapping information, is referred by the at least another one of the plurality of processing circuits for transferring data, which are related to the second virtual volume identification information and are received from the host computer, to the fourth logical volume of the fourth storage device.

40. A virtualization system for controlling data transfer between a plurality of computers and a plurality of storage devices, each of the plurality of storage devices comprising a disk controller and a plurality of disk drives related to at least one logical volume, the virtualization system comprising:

at least one first port being adapted to be coupled to the plurality of storage devices;

at least one second port being adapted to be coupled to the plurality of computers;

at least one of a plurality of processing circuits configured to transfer data, which are related to a first virtual volume identification information identifying a first virtual volume and are received from at least one of the plurality of computers, to a first logical volume in a first storage device of the plurality of storage devices in reference to a first mapping information mapping the first virtual volume identification information to a first logical volume identification information identifying the first logical volume;

at least one of a plurality of first memories configured to store the first mapping information to be referred by the at least one of the plurality of processing circuits;

a control circuit configured to communicate information of at least one of the plurality of mapping information with at least one of the plurality of computers; and

a second memory configured to store the plurality of mapping information including the first mapping information

wherein the virtualization system is configured to transfer data, which are related to the first virtual volume identification information and are received from at least one of the plurality of computers during a data transfer phase in which data stored in the first logical volume are transferred to a second logical volume of a second storage device of the plurality of storage devices, to the second logical volume,

wherein, based on the data transfer phase, the control circuit is configured to update the first mapping information of the plurality of mapping information in the second memory to a second mapping information, mapping the first virtual volume identification information to a second logical volume identification information identifying the second logical volume, and to update the first mapping information in the at least one of the plurality of first memories to the second mapping information, and

wherein, after the data transfer phase is completed, the second mapping information in the at least one of the plurality of first memories, instead of the first mapping information, is referred by the at least one of the plurality of processing circuits for transferring data, which are related to the first virtual volume identification information and are received from at least one of the plurality of computers, to the second logical volume.

41. A virtualization system according to claim 40, wherein the at least one of the plurality of processing circuits is configured to transfer the data, which are related to the first virtual volume identification information and are received during the data transfer phase, to the second logical volume.

42. A virtualization system according to claim 40, wherein, in data transfer phase, the at least one of the plurality of processing circuits is configured to transfer the data stored in the first logical volume to the second logical volume via the at least one first port.

43. A virtualization system according to claim 40, wherein the virtualization system is configured to transfer the data, which are related to the first virtual volume identification information and are received during the data transfer phase, to the first logical volume and the second logical volume.

44. A virtualization system according to claim 40, wherein the control circuit is configured to communicate information of the first mapping information and/or the second mapping information with at least one of the plurality of computers so that at least one of the plurality of computers can output the first mapping information and/or the second mapping information.

45. A virtualization system according to claim 40, wherein the at least one of the plurality of processing circuits is configured to communicate a status of the data transfer phase with the control circuit, and

wherein, after the control circuit receives the status of the data transfer phase from the at least one of the plurality of processing circuits, the control circuit is configured to update the first mapping information of the plurality of mapping information in the second memory to the second mapping information and to update the first mapping information in the at least one of the plurality of first memories to the second mapping information.

46. A virtualization system according to claim 40, wherein the first virtual volume identification information includes a Logical Unit Number LUN) of the first virtual volume,

wherein the first logical volume identification information includes a LUN of the first logical volume, and

wherein the second logical volume identification information includes a LUN of the second logical volume.

47. A virtualization system according to claim 40, wherein the first virtual volume identification information is a LUN of the first virtual volume and corresponds to an identifier of a virtual port,

wherein the first logical volume identification information is a LUN of the first logical volume and corresponds to an identifier of one of the at least one first port, and

wherein the second logical volume identification information is a LUN of the second logical volume and corresponds to an identifier of another one of the at least one first port.

48. A virtualization system according to claim 40, wherein, based on the data transfer phase, the control circuit is configured to further update the first mapping information in at least another one of the plurality of first memories to the second mapping information.

49. A virtualization system according to claim 40, wherein the first mapping information in the at least one of the plurality of first memories is formed by a first part of the first mapping information stored in one of the plurality of first memories and a second part of the first mapping information stored in another one of the plurality of first memories,

wherein the second mapping information in the at least one of the plurality of first memories is formed by a first part of the second mapping information stored in the one of the plurality of first memories and a second part of the second mapping information stored in the another one of the plurality of first memories.

50. A virtualization system according to claim 40, wherein the data, which are related to the first virtual volume identification information and are received before the data transfer phase, are transferred to the first logical volume after being related to the first logical volume identification information instead of the first virtual volume identification information,

wherein the data, which are related to the first virtual volume identification information and are received during the data transfer phase, are transferred to the second logical volume after being related to the second logical volume identification information instead of the first virtual volume identification information, and

wherein the data, which are related to the first virtual volume identification information and are received after the data transfer phase, are transferred to the second logical volume after being related to the second logical volume identification information instead of the first virtual volume identification information.

51. A virtualization system according to claim 40, further comprising:

at least another one of the plurality of processing circuits configured to transfer data, which are related to a second virtual volume identification information identifying a second virtual volume and are received from at least one of the plurality of computers, to a third logical volume in a third storage device of the plurality of storage devices in reference to a third mapping information mapping the second virtual volume identification information to a third logical volume identification information identifying the third logical volume; and

at least another one of the plurality of first memories configured to store the third mapping information to be referred byte at least another one of the plurality of processing circuits;

wherein the virtualization system is configured to transfer data, which are related to the third virtual volume identification information and are received from at east one of the plurality of computers during another data transfer phase in which data, stored in the third logical volume are transferred to a fourth logical volume of a fourth storage device of the plurality of storage devices, to the fourth logical volume,

wherein, based on the another data transfer phase, the control circuit is configured to update the third Mapping information of the plurality of mapping information In the second memory to a fourth mapping information, mapping the second virtual volume identification Information to a fourth logical volume identification information identifying the fourth logical volume, and to update the third mapping information in the at least another one of the plurality of first memories to the fourth mapping information, and

wherein, after the another data transfer phase Is completed, the fourth mapping Information in the at least another one of the plurality of first memories, instead of the third mapping information, is referred by the at least another one of the plurality of processing circuits for transferring data, which are related to the second virtual volume identification information and are received from at least one of the plurality of computers, to the fourth logical volume.