Data copying method and apparatus in a thin provisioned system

• US 20060224844A1
• Filed: 03/29/2005
• Published: 10/05/2006
• Est. Priority Date: 03/29/2005
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yamamoto, Akira, Kano, Yoshiki
• Granted Patent: US 7,162,600 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 11/2087 with a common controller
• CPC Class Codes: G06F 12/02 Addressing or allocation; Relocation program address sequencing G06F9/00; arrangements for selecting an address in a digital store G11C8/00
• CPC Class Codes: G06F 12/0223 User address space allocation, e.g. contiguous or non contiguous base addressing
• CPC Class Codes: G06F 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• 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

Data migration includes copying between normal volumes and thin provisioned volumes. Data in a normal volume can be copied to a thin provisioned volume. Alternatively, data structures can be provided to facilitate converting a normal volume into a thin provisioned volume without actual copying of data. Copying from a thin provisioned volume to a normal volume is also disclosed.

Claims

1. A data migration method in a storage system comprising:

receiving a designation of a source volume, the source volume comprising data for which the data migration will be performed;

receiving a designation of a target volume, the target volume comprising one or more storage segments allocated from a disk device; and

for each logical block address in the source volume, if the logical block address designates an area on the source volume that contains production data, then copying the production data to the target volume,

the copying comprising;

allocating a free storage segment from the disk device to the target volume if the logical block address does not designate a storage segment that has been allocated to the target volume; and

associating the logical block address with the allocated free storage segment, the logical block address thereby designating the allocated free storage segment,

wherein the allocating and the associating are performed automatically without user involvement.

2. The method of claim 1 wherein the data is data created by an application executing on a host machine and stored on the source volume.

3. The method of claim 1 wherein the data is data created by an operating system executing on a host machine to manage a file system and stored on the source volume.

4. The method of claim 1 wherein the source volume comprises data blocks located on one or more physical drives, the method further comprising, when a write request targets the source volume, steps of:

obtaining the logical block address associated with the write request; and

storing data at one or more data blocks comprising a storage area identified by the logical block address.

5. The method of claim 4 further comprising accessing information which identifies for each of the data blocks whether the data block contains production data or not in order to determine if the logical block address designates an area on the source volume that contains production data.

6. The method of claim 5 wherein the information is in the form of a bitmap, where each bit in the bitmap corresponds to a logical block address, wherein the value of the bit indicates whether or not the area on the source volume designated by the corresponding logical block address contains production data.

7. The method of claim 5 further comprising inspecting the source volume in order to create the information.

8. The method of claim 7 wherein the information is in the form of a bitmap, where each bit corresponds to a logical block address, wherein the value of the bit indicates whether or not the area on the source volume designated by the corresponding logical block address contains production data.

9. The method of claim 1 wherein the source volume comprises one or more storage segments allocated from the disk device, each storage segment being referenced by a logical block address, the method further comprising, when a write request targets the source volume, a step of allocating a free storage segment from the disk device if the target logical block address does not reference a storage segment comprising the source volume, wherein the allocating is performed automatically without user involvement.

10. The method of claim 9 further comprising associating the target logical block address with the storage segment obtained from the allocating step.

11. A storage system comprising a plurality of physical storage devices, the storage system having a controller operable to perform the method steps of claim 1, wherein the physical storage devices constitute the source volume and the target volume.

12. A data migration method in a storage system comprising:

receiving a designation of a source volume, the source volume comprising a plurality of data blocks, each data block having an associated logical block address, some of the data blocks storing data on which the data migration will be performed;

receiving a designation of a target volume;

defining a plurality of segments on the source volume, each segment comprising one or more of the data blocks;

if a segment includes a data block that contains data, then associating the segment with the logical block address of one of its associated data blocks and associating the segment with the target volume, whereby the target volume comprises one or more of the segments, each segment being associated with a logical block address and comprising data; and

if a segment does not include a data block that contains data, then associating the segment with a list of free segments.

13. The method of claim 12 wherein the data includes one of data created by an application executing on a host machine and stored on the source volume or data created by an operating system executing on the host machine to manage a file system and stored on the source volume.

14. The method of claim 12 further comprising:

receiving a write request directed to the target volume, the write request being associated with a target logical block address;

allocating a free segment from the list of free segments, if the target logical block address does not identify a segment that comprises the target volume; and

associating the logical block address with the allocated free segment,

wherein data associated with the write request is written to the allocated free segment.

15. The method of claim 14 wherein the allocating is performed automatically without user involvement.

16. The method of claim 12 further comprising generating use information which identifies for each of the data blocks of the source volume whether the data block contains data or not, the use information being used to determine whether a data block contains data or not.

17. The method of claim 16 wherein the use information is generated at or about the same time that write operations targeting the source volume are serviced.

18. The method of claim 17 wherein the use information is in the form of a bitmap, where each bit corresponds to a logical block address, wherein the value of the bit indicates whether or not a data block contains data.

19. The method of claim 16 wherein the use information is generated in response to a command sent by a user.

20. The method of claim 12 wherein each segment comprises exactly one data block.

21. The method of claim 12 wherein each segment comprises N data blocks, N being 4 or more.

22. The method of claim 12 as performed in a storage system comprising a plurality of physical devices and a controller, the controller comprising a data processing unit and program code, the data processing unit executing the program code to perform the method.

23. A method for a storage system comprising:

receiving from a host system a write request directed to a first volume;

allocating a storage segment from a physical storage device, if the storage segment designated by the logical block address associated with the write request does not exist on the first volume, wherein the determining and the allocating are performed automatically without user involvement;

associating the logical block address with the allocated storage segment, wherein data associated with the write request is written to the allocated storage segment;

receiving from the host system a designation of a target volume, the target volume being the destination of a migration operation of data stored in the first volume; and

for each storage segment in the first volume, copying data from the storage segment to a location on the target device that is identified by the logical block address associated with the storage segment.

24. The method of claim 23 further comprising filling locations on the target device with NULL characters which do not correspond to any storage segments in the first volume.

25. The method of claim 23 wherein the copying includes copying data in the storage segment to exactly one data block of the target volume.

26. The method of claim 23 wherein the copying includes copying data in the storage segment to N data blocks of the target volume, where N is greater than one.

27. The method of claim 23 wherein the target volume comprises physical storage devices contained in an external storage system separate from the storage system, wherein the target volume is identified by the host system by a first identifier, wherein the target volume is identified in the external storage system by a second identifier, the method further comprising consulting mapping information that maps the first identifier to the second identifier, wherein the copying uses the second identifier to access the target volume.

28. A storage system comprising a plurality of physical storage devices and a controller, the controller configured to perform the method of claim 23.