Methods, systems, and computer program products for optimized copying of logical units (LUNs) in a redundant array of inexpensive disks (RAID) environment using buffers that are larger than LUN delta map chunks

• US 20070156956A1
• Filed: 01/03/2006
• Published: 07/05/2007
• Est. Priority Date: 01/03/2006
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Misra, Pawan
• Granted Patent: US 7,634,617 B2
• Time in Patent Office: Days
• US Class Current: 711/114
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 11/2087 with a common controller
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

Disclosed are methods, systems, and computer program products for optimized copying of logical units (LUNs) in a redundant array of inexpensive disks (RAID) environment using buffers that are larger than delta map chunks. According to one method, a delta map is provided including delta indicators for tracking locations of changes to data stored in a plurality of source delta map chunks representing partitions of storage in physical disks of a redundant array of inexpensive disks (RAID) array. A first buffer of a buffer size larger than a delta map chunk size is provided. An amount of data is sequentially copied to fill the first buffer beginning at an address in the delta map chunk corresponding to a first change indicated by a delta indicator in the delta map.

Claims

1. A method for optimized copying of logical units (LUNs) in a redundant array of inexpensive disks (RAID) environment using buffers that are larger than delta map chunks, the method comprising:

(a) providing a delta map including delta indicators for tracking locations of changes to data stored in a plurality of source delta map chunks representing partitions of storage in physical disks of a redundant array of inexpensive disks (RAID) array;

(b) providing a first buffer of a buffer size larger than a delta map chunk size; and

(c) sequentially copying an amount of data to fill the first buffer beginning at an address in the delta map chunk corresponding to a first change indicated by a delta indicator in the delta map.

2. The method of claim 1 comprising providing a buffer descriptor for tracking a start address, a starting delta map chunk number, and a range of buffer copy in a RAID array for the first buffer.

3. The method of claim 2 comprising updating the buffer descriptor associated with the first buffer prior to sequentially copying the amount of data.

4. The method of claim 1 comprising providing a plurality of destination delta map chunks.

5. The method of claim 4 comprising incrementing a reference counter associated with each of the plurality of source delta map chunks that are at least partially copied to the first buffer.

6. The method of claim 5 comprising decrementing the reference counter associated with each of the plurality of source delta map chunks that are at least partially copied to the first buffer when the amount of data is written to the plurality of destination delta map chunks.

7. The method of claim 1 comprising providing a collision map including collision indicators for tracking locations of collisions represented by changes to data stored in a plurality of destination delta map chunks prior to a write operation of the amount of data from the first buffer to the plurality of destination delta map chunks.

8. The method of claim 7 comprising abandoning the write operation to the plurality of destination delta map chunks corresponding to collision indicators in the collision map set in response to a collision.

9. The method of claim 8 comprising setting delta indicators in the delta map corresponding to delta map chunks associated with collision indicators in the collision map and clearing the collision indicators.

10. The method of claim 1 comprising providing a collision map including collision indicators for tracking locations of collisions represented by changes to data stored in the plurality of source delta map chunks during the sequential copying of the amount of data to fill the first buffer.

11. The method of claim 10 comprising setting delta indicators in the delta map corresponding to delta map chunks associated with collision indicators in the collision map and clearing the collision indicators.

12. The method of claim 11 comprising aligning the first buffer at a second address in the delta map chunk corresponding to a second change indicated by a delta indicator in the delta map and sequentially copying an amount of data to fill the first buffer beginning at the second address.

13. The method of claim 1 comprising clearing delta indicators associated with the plurality of source delta map chunks that are completely written to a plurality of destination delta map chunks.

14. A system for optimized copying of logical units (LUNs) in a redundant array of inexpensive disks (RAID) environment using buffers that are larger than delta map chunks, the system comprising:

(a) a redundant array of inexpensive disks (RAID) array including a plurality of delta map chunks representing partitions of storage in physical disks of the RAID array; and

(b) a copy engine, including a delta map having delta indicators for tracking locations of changes to data stored in the plurality of delta map chunks, the copy engine being adapted to;

(i) provide a first buffer of a buffer size larger than a delta map chunk size; and

(ii) sequentially copy an amount of data to fill the first buffer beginning at an address in the delta map chunk corresponding to a first change indicated by a delta indicator in the delta map.

15. The system of claim 14 wherein the copy engine is adapted to provide a buffer descriptor for tracking a start address, a starting delta map chunk number, and a range of buffer copy in a RAID array for the first buffer.

16. The system of claim 15 wherein the copy engine is adapted to update the buffer descriptor associated with the first buffer prior to sequentially copying the amount of data.

17. The system of claim 14 comprising a plurality of destination delta map chunks.

18. The system of claim 17 wherein the copy engine is adapted to increment a reference counter associated with each of the plurality of source delta map chunks that are at least partially copied to the first buffer.

19. The system of claim 18 wherein the copy engine is adapted to decrement the reference counter associated with each of the plurality of source delta map chunks that are at least partially copied to the first buffer when the amount of data is written to the plurality of destination delta map chunks.

20. The system of claim 14 wherein the copy engine is adapted to provide a collision map including collision indicators for tracking locations of collisions represented by changes to data stored in a plurality of destination delta map chunks prior to a write operation of the amount of data from the first buffer to the plurality of destination delta map chunks.

21. The system of claim 20 wherein the copy engine is adapted to abandon the write operation to the plurality of destination delta map chunks corresponding to collision indicators in the collision map set in response to a collision.

22. The system of claim 21 wherein the copy engine is adapted to set delta indicators in the delta map corresponding to delta map chunks associated with collision indicators in the collision map and to clear the collision indicators.

23. The system of claim 14 wherein the copy engine is adapted to provide a collision map including collision indicators for tracking locations of collisions represented by changes to data stored in the plurality of source delta map chunks during the sequential copying of the amount of data to fill the first buffer.

24. The system of claim 23 wherein the copy engine is adapted to set delta indicators in the delta map corresponding to delta map chunks associated with collision indicators in the collision map and to clear the collision indicators.

25. The system of claim 24 wherein the copy engine is adapted to align the first buffer at a second address in the delta map chunk corresponding to a second change indicated by a delta indicator in the delta map and to sequentially copy an amount of data to fill the first buffer beginning at the second address.

26. The system of claim 14 wherein the copy engine is adapted to clear delta indicators associated with the plurality of source delta map chunks that are completely written to a plurality of destination delta map chunks.

27. A computer program product comprising computer-executable instructions embodied in a computer-readable medium for performing steps comprising:

(a) providing a delta map including delta indicators for tracking locations of changes to data stored in a plurality of source delta map chunks representing partitions of storage in physical disks of a redundant array of inexpensive disks (RAID) array;

(b) providing a first buffer of a buffer size larger than a delta map chunk size; and

(c) sequentially copying an amount of data to fill the first buffer beginning at an address in the delta map chunk corresponding to a first change indicated by a delta indicator in the delta map.