Method and apparatus for restoring a corrupted data volume

• US 6,912,631 B1
• Filed: 09/25/2002
• Issued: 06/28/2005
• Est. Priority Date: 09/25/2002
• Status: Expired due to Term

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Veritas Operating Corporation (Gen Digital Inc.)
• Inventors: Kiselev, Oleg, Colgrove, John A., Karr, Ronald S., Kekre, Anand A.
• Primary Examiner(s): Elmore, Reba I.
• Application Number:
  US10/254,753
• Time in Patent Office: 1,007 Days
• Field of Search: 711/162, 711/165
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 2201/84 Using snapshots, i.e. a logical point-in-time copy of the data

Abstract

Disclosed is a method and apparatus for restoring a corrupted data volume. In one embodiment, the method includes creating a backup copy of the data volume before the data volume is corrupted. Data transactions that modify the contents of the data volume are stored in a transaction log. After detection of the data corruption, a virtual copy of the backup copy is created. Thereafter, select data transactions stored in the transaction log, are applied to the virtual copy. Data of the corrupted data volume is then overwritten with data of the backup copy and data of the virtual copy after applying data transactions to the virtual copy.

Claims

1. A method of restoring a corrupted data volume, the method comprising:

creating a backup copy of the data volume before the data volume is corrupted;

creating a virtual copy of the backup copy in response to detecting corruption of the data volume;

applying data transactions stored in a transaction log to the virtual copy,

overwriting data of the corrupted data volume with data of the backup copy and data of the virtual copy after applying data transactions to the virtual copy.

2. A method of restoring a data volume stored in a first memory, the method comprising:

copying first and second data portions of the data volume to a second memory;

modifying data of the first and second data volume portions in the first memory in response to executing first and second instructions, respectively, wherein the first and second data volume portions are copied to the second memory before data of the first and second data volume portions are modified;

copying the first data volume portion stored in the second memory to a third memory;

modifying data of the first data volume portion stored in the third memory in response to re-executing the first instruction;

overwriting the first data volume portion stored in the first memory with the first data portion stored in the third memory after modification of data of the first data volumes in the first and third memories;

overwriting the second data volume portion stored in the first memory with the second data volume portion stored in the second memory after modification of data of the second data volume in the first memory.

3. The method of claim 2 further comprising:

generating a third instruction to modify data of the first data volume portion in the first memory, wherein the first data volume portion stored in the first memory is overwritten with the first data portion stored in the third memory in response to generation of the third instruction;

wherein data of the first data volume portion stored in the first memory is modified in response to executing the third instruction, wherein the first data volume portion stored in the first memory is overwritten with the first data portion stored in the third memory before execution of the third instruction.

4. The method of claim 3 further comprising:

generating a fourth instruction to modify data of the second data volume portion in the first memory, wherein the second data volume portion stored in the first memory is overwritten with the second data portion stored in the second memory in response to generation of the fourth instruction;

wherein data of the second data volume portion stored in the first memory is modified in response to executing the fourth instruction, wherein the second data volume portion stored in the first memory is overwritten with the second data portion stored in the second memory before execution of the fourth instruction.

5. The method of claim 2 further comprising:

modifying data of the first data volume portion in response to executing a third instruction, wherein the data of the first data volume portion modified by execution of the first instruction is distinct from the data of the first data volume portion modified by execution of the third instruction, and wherein the third instruction is executed after re-execution of the first instruction.

6. A method comprising:

storing a plurality of instructions in an instruction memory;

copying data from a plurality of blocks in a first memory to a plurality of blocks, respectively, in a second memory;

modifying data in each of the plurality of first memory blocks in response to executing the plurality of instructions, wherein data in each of the first memory blocks is copied to a respective second memory block before modification;

switching the state of a plurality of first bits in memory from one of a first or second state to the other of the first or second state, wherein the plurality of first bits corresponds to the plurality of first memory blocks, respectively;

switching the state of a plurality of second bits in memory from one of the first or second states to the other of the first and second states, wherein the plurality of second bits corresponds to the plurality of second memory blocks, respectively.

7. The method of claim 6 further comprising:

copying data from one of the plurality of second memory blocks to a block of a third memory;

modifying data copied to the third memory block in response to re-executing one of the plurality of instructions.

8. The method of claim 7 further comprising:

overwriting data of one of the plurality of first memory blocks with data of a respective second memory block, and;

overwriting data of another of the plurality of first memory blocks with data of the third memory block after data of the third memory block is modified in response to re-executing one of the plurality of instructions.

9. The method of claim 6 further comprising:

copying data from a subset of the plurality of second memory blocks to respective blocks of a third memory;

modifying data copied to each of the third memory blocks in response to re-executing a subset of the plurality of instructions.

10. The method of claim 9 further comprising:

overwriting data of a first subset of the plurality of first memory blocks with data of respective second memory blocks, and;

overwriting data of a second subset of the plurality of first memory blocks with data of respective third memory blocks after data of the respective third memory blocks are modified.

11. The method of claim 9 further comprising:

switching the state of third bits in memory from one of the first or second states to the other of the first or second states, wherein the third bits correspond to the third memory blocks, respectively.

12. The method of claim 11 further comprising:

overwriting data in first memory blocks with data of respective third memory blocks if third memory bits corresponding to the respective third memory blocks were switched from one of the first or second states to the other of the first or second states.

13. The method of claim 12 further comprising:

overwriting data of first memory blocks with data of respective second memory blocks for each first memory block having (1) data which is not overwritten by data of a respective third memory block and (2) a corresponding first bit switched from one of the first or second states to the other of the first or second states.

14. An apparatus comprising:

a first memory for storing a data volume;

a second memory;

a third memory;

a computer system in data communication with the first, second and third memories;

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;

the computer system copying first and second data portions of the data volume to the second memory;

the computer system modifying data of the first and second data volume portions in the first memory in response to the computer system executing first and second instructions, respectively, wherein the computer system copies the first and second data volume portions to the second memory before the computer system modifies data of the first and second data volume portions;

the computer system copying the first data volume portion stored in the second memory to a third memory;

the computer system modifying data of the first data volume portion stored in the third memory in response to re-executing the first instruction;

the computer system overwriting the first data volume portion stored in the first memory with the first data portion stored in the third memory after the computer system modifies data of the first data volumes in the first and third memories;

the computer system overwriting the second data volume portion stored in the first memory with the second data volume portion stored in the second memory after the computer system modifies data of the second data volume in the first memory.

15. An apparatus comprising:

a first memory for storing a data volume;

a second memory;

a third memory;

means for copying first and second data portions of the data volume to the second memory;

means for modifying data of the first and second data volume portions in the first memory in response to execution of first and second instructions, respectively, wherein the first and second data volume portions are copied to the second memory before data of the first and second data volume portions are modified;

means for copying the first data volume portion stored in the second memory to a third memory;

means modifying data of the first data volume portion stored in the third memory in response to re-execution of the first instruction;

means for overwriting the first data volume portion stored in the first memory with the first data portion stored in the third memory after modification of data of the first data volumes in the first and third memories;

means for overwriting the second data volume portion stored in the first memory with the second data volume portion stored in the second memory after modification of data of the second data volume in the first memory.

16. A computer readable medium storing instructions executable by a computer system, wherein the computer system performs a method of restoring a data volume in a first memory in response to executing the instructions, the method comprising:

copying first and second data portions of the data volume to a second memory;

modifying data of the first and second data volume portions in the first memory in response to executing first and second instructions, respectively, wherein the first and second data volume portions are copied to the second memory before data of the first and second data volume portions are modified;

copying the first data volume portion stored in the second memory to a third memory;

modifying data of the first data volume portion stored in the third memory in response to re-executing the first instruction;

overwriting the first data volume portion stored in the first memory with the first data portion stored in the third memory after modification of data of the first data volumes in the first and third memories;

overwriting the second data volume portion stored in the first memory with the second data volume portion stored in the second memory after modification of data of the second data volume in the first memory.

17. The computer readable medium of claim 16 wherein the method further comprises:

generating a third instruction to modify data of the first data volume portion in the first memory, wherein the first data volume portion stored in the first memory is overwritten with the first data portion stored in the third memory in response to generation of the third instruction;

wherein data of the first data volume portion stored in the first memory is modified in response to executing the third instruction, wherein the first data volume portion stored in the first memory is overwritten with the first data portion stored in the third memory before execution of the third instruction.

18. The computer readable medium of claim 17 wherein the method further comprises:

generating a fourth instruction to modify data of the second data volume portion in the first memory, wherein the second data volume portion stored in the first memory is overwritten with the second data portion stored in the second memory in response to generation of the fourth instruction;

wherein data of the second data volume portion stored in the first memory is modified in response to executing the fourth instruction, wherein the second data volume portion stored in the first memory is overwritten with the second data portion stored in the second memory before execution of the fourth instruction.

19. The computer readable medium of claim 16 wherein the method further comprises:

modifying data of the first data volume portion in response to executing a third instruction, wherein the data of the first data volume portion modified by execution of the first instruction is distinct from the data of the first data volume portion modified by execution of the third instruction, and wherein the third instruction is executed after re-execution of the first instruction.