Method for creating a virtual data copy of a volume being restored

• US 6,978,354 B1
• Filed: 12/20/2002
• Issued: 12/20/2005
• Est. Priority Date: 12/20/2002
• Status: Active Grant

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Veritas Operating Corporation (Gen Digital Inc.)
• Inventors: Kiselev, Oleg, Colgrove, John A., Kekre, Anand A.
• Primary Examiner(s): Padmanabhan, Mano
• Assistant Examiner(s): BAKER, PAUL A
• Application Number:
  US10/327,536
• Time in Patent Office: 1,096 Days
• Field of Search: 711/161, 711/162, 707/202
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

In one embodiment of the method, first and second data volumes are created. Thereafter, a first data portion of the first data volume is overwritten with a first data portion of the second data volume. A second data portion of the first data volume is overwritten with a second data portion of the second data volume. In one embodiment, the first and second data portions of the first data volume are overwritten with the first and second data portions of the second data volume, respectively, in response to a command to restore or synchronize the data contents of the first data volume to the data contents of the second data volume. A virtual point-in-time (PIT) copy of the first data volume is created after overwriting the first data portion but before overwriting the second data portion.

Claims

1. A method comprising:

(a) creating a first data volume;

(b) creating a second data volume;

(c) overwriting a first data portion of the first data volume with a first data portion of the second data volume;

(d) overwriting a second data portion of the first data volume with a second data portion of the second data volume;

(e) creating a virtual point-in-time (PIT) copy of the first data volume, wherein (e) occurs after (c) but before (d).

2. The method of claim 1 further comprising:

(f) modifying data of a third data portion of the first data volume after (c) but before (d).

3. The method of claim 1 further comprising:

(f) modifying data of a third data portion of the first data volume, wherein (f) occurs after (c) but before (d), and wherein (e) occurs after (f).

4. The method of claim 3 further comprising:

(g) allocating memory to store data of the virtual PIT copy;

(h) copying the third data portion to the memory allocated in (g) before (f).

5. The method of claim 1 wherein (c) and (d) occur in response to generation of a command to synchronize the data contents of the first data volume to the data contents of the second data volume.

6. The method of claim 1 further comprising:

(i) modifying data of the first and second data portions of the first data volume, wherein (i) occurs before (c) and (d);

wherein the second data volume is created as virtual PIT copy of the first data volume in (b), and wherein (b) occurs before (i).

7. The method of claim 1 further comprising:

(j) generating a write-data transaction for modifying data of the second data portion of the first data volume, wherein (j) occurs after (e) but before (d);

(k) copying the first data portion of the second data volume to memory allocated to the virtual PIT copy, wherein (k) occurs after (j) but before (d).

8. A computer readable medium comprising instructions executable by a computer system, wherein the computer system implements a method in response to executing the instructions, the method comprising:

(a) creating a first data volume;

(b) creating a second data volume;

(c) overwriting a first data portion of the first data volume with a first data portion of the second data volume;

(d) overwriting a second data portion of the first data volume with a second data portion of the second data volume;

(e) creating a virtual point-in-time (PIT) copy of the first data volume, wherein (e) occurs after (c) but before (d).

9. The computer readable medium of method of claim 8 wherein the method further comprises:

(f) modifying data of a third data portion of the first data volume after (c) but before (d).

10. The computer readable medium of method of claim 8 wherein the method further comprises:

(f) modifying data of a third data portion of the first data volume, wherein (f) occurs after (c) but before (d), and wherein (e) occurs after (f).

11. The computer readable medium of method of claim 10 wherein the method further comprises:

(g) allocating memory to store data of the virtual PIT copy;

(h) copying the third data portion to the memory allocated in (g) before (f).

12. The computer readable medium of claim 8 wherein (c) and (d) occur in response to generation of a command to synchronize the data contents of the first data volume to the data contents of the second data volume.

13. The computer readable medium of method of claim 8 wherein the method further comprises:

(i) modifying data of the first and second data portions of the first data volume, wherein (i) occurs before (c) and (d);

wherein the second data volume is created as a virtual PIT copy of the first data volume in (b), and wherein (b) occurs before (i).

14. The computer readable medium of method of claim 8 wherein the method further comprises:

(j) generating a write-data transaction for modifying data of the second data portion of the first data volume, wherein (j) occurs after (e) but before (d);

(k) copying the first data portion of the second data volume to memory allocated to the virtual PIT copy, wherein (k) occurs after (j) but before (d).

22. The computer readable medium of method of claim 8 wherein the method further comprises:

(i) modifying data of the first and second data portions of the first data volume, wherein (i) occurs before (c) and (d);

wherein the second data volume is created as a real PIT copy of the first data volume in (b), and wherein (b) occurs before (i).

15. An apparatus comprising:

a primary memory for storing a primary data volume;

a computer system in data communication with the primary memory, the computer system comprising a computer readable medium for storing instructions executable by the computer system, wherein the computer system implements a method in response to executing the instructions, the method comprising;

(a) creating a primary data volume in the primary memory;

(b) creating a second data volume;

(c) overwriting a first data portion of the first data volume with a first data portion of the second data volume;

(d) overwriting a second data portion of the first data volume with a second data portion of the second data volume;

(e) creating a virtual point-in-time (PIT) copy of the first data volume, wherein (e) occurs after (c) but before (d).

16. The apparatus of claim 15 wherein the method further comprises:

(f) modifying data of a third data portion of the first data volume, wherein (f) occurs after (c) but before (d), and wherein (e) occurs after (f).

17. The apparatus of claim 16 wherein the method further comprises:

(g) allocating memory to store data of the virtual PIT copy;

(h) copying the third data portion to the memory allocated in (g) before (f).

18. The apparatus of claim 15 wherein (c) and (d) occur in response to generation of a command to synchronize the data contents of the first data volume to the data contents of the second data volume.

20. The apparatus of claim 16 wherein the primary memory may take form in any one or more of magnetic disc, optical disc, solid state disc, non-volatile RAM including battery backed and flash memory.

19. An apparatus comprising:

a primary memory for storing a primary data volume;

means for creating a primary data volume in the primary memory;

means for creating a second data volume;

means for overwriting a first data portion of the first data volume with a first data portion of the second data volume;

means overwriting a second data portion of the first data volume with a second data portion of the second data volume;

means creating a virtual point-in-time (PIT) copy of the first data volume, wherein the virtual PIT copy is created after overwriting the first data portion but before overwriting the second data portion.

21. A circuit comprising:

a first sub-circuit for creating first and second data volumes;

a second sub-circuit for overwriting a first data portion of the first data volume with a first data portion of the second data volume;

a third sub-circuit for overwriting a second data portion of the first data volume with a second data portion of the second data volume;

a fourth sub-circuit for creating a virtual point-in-time (PIT) copy of the first data volume, wherein the fourth sub-circuit creates the virtual PIT copy after the second sub-circuit overwrites the first data portion, and wherein the fourth sub-circuit creates the virtual PIT copy before the third sub-circuit overwrites the second data portion.