Data storage with snapshot-to-snapshot recovery

1. A method for data storage comprising:

deleting a corrupted node under a first meta-volume node in a hierarchical tree structure, wherein the hierarchical tree structure further comprises a source node under the first meta-volume node, the corrupted node and the source node each comprise a respective set of local pointers, and the corrupted node and the source node represent respective copies of a logical volume;

reconfiguring the source node to become a second meta-volume node having the same set of local pointers as the source node;

creating a first new node under the second meta-volume node in the hierarchical tree structure to represent the corrupted node;

configuring the first new node to have no local pointers;

creating a second new node under the second meta-volume node in the hierarchical tree structure to represent the source node; and

configuring the second new node to have no local pointers.

2. The method according to claim 1 , further comprising:

creating the corrupted node; and

creating the source node.

3. The method according to claim 2 , wherein the creating of the source node is based on the creating of the corrupted node.

4. The method according to claim 1 , wherein the creating of the first new node comprises updating a list indicating respective numbers of those nodes whose pointers point to physical storage locations in which data used by the copies is stored.

5. The method according to claim 4 , further comprising maintaining a use-count of physical partitions associated with the physical storage locations.

6. The method according to claim 1 , further comprising determining if the corrupted node and the source node represent snapshot copies of the respective logical volume.

7. The method according to claim 1 , wherein the creating of the first new node and the creating of the second new node comprise communicating with a host computer over a Storage Area Network (SAN).

8. An apparatus for data storage, comprising:

an interface configured to communicate with a host computer to receive data for storage that is addressed to a logical volume assigned on a storage device; and

a processor coupled to the interface and adapted to:

delete a corrupted node under a first meta-volume node in a hierarchical tree structure, wherein the hierarchical tree structure further comprises a source node under the first meta-volume node, the corrupted node and the source node each comprise a respective set of local pointers, and the corrupted node and the source node represent respective copies of a logical volume;

reconfigure the source node to become a second meta-volume node having the same set of local pointers as the source node;

create a first new node under the second meta-volume node in the hierarchical tree structure to represent the corrupted node;

configure the first new node to have no local pointers;

create a second new node under the second meta-volume node in the hierarchical tree structure to represent the source node; and

configure the second new node to have no local pointers.

9. The apparatus according to claim 8 , wherein the processor is further adapted to:

create the corrupted node; and

create the source node.

10. The apparatus according to claim 9 , wherein the creating of the source node is based on the creating of the corrupted node.

11. The apparatus according to claim 8 , wherein the creating of the first new node comprises updating a list indicating respective numbers of those nodes whose pointers point to physical storage locations in which data used by the copies is stored.

12. The apparatus according to claim 11 , wherein the processor is further adapted to maintain a use-count of physical partitions associated with the physical storage locations.

13. The apparatus according to claim 8 , wherein the processor is further adapted to determine if the corrupted node and the source node represent snapshot copies of the respective logical volume.

14. The apparatus according to claim 8 , wherein the creating of the first new node and the creating of the second new node comprise communicating with a host computer over a Storage Area Network (SAN).

15. A computer software product for data storage, the product comprising a non-transitory computer-readable medium, in which program instructions are stored, the program instructions comprising:

a first executable portion for deleting a corrupted node under a first meta-volume node in a hierarchical tree structure, wherein the hierarchical tree structure further comprises a source node under the first meta-volume node, the corrupted node and the source node each comprise a respective set of local pointers, and the corrupted node and the source node represent respective copies of a logical volume;

a second executable portion for reconfiguring the source node to become a second meta-volume node having the same set of local pointers as the source node;

a third executable portion for creating a first new node under the second meta-volume node in the hierarchical tree structure to represent the corrupted node;

a fourth executable portion for configuring the first new node to have no local pointers;

a fifth executable portion for creating a second new node under the second meta-volume node in the hierarchical tree structure to represent the source node; and

a sixth executable portion for configuring the second new node to have no local pointers.

16. The product according to claim 15 , wherein the program instructions further comprise:

a seventh executable portion for creating the corrupted node; and

an eighth executable portion for creating the source node.

17. The product according to claim 16 , wherein the creating of the source node is based on the creating of the corrupted node.

18. The product according to claim 17 , wherein the creating of the first new node comprises updating a list indicating respective numbers of those nodes whose pointers point to physical storage locations in which data used by the copies is stored.

19. The product according to claim 18 , wherein the program instructions further comprise a ninth executable portion for maintaining a use-count of physical partitions associated with the physical storage locations.

20. The product according to claim 15 , wherein the program instructions further comprise a seventh executable portion for determining if the corrupted node and the source node represent snapshot copies of the respective logical volume.