Systems and methods for a snapshot of data

• US 8,010,493 B2
• Filed: 03/04/2010
• Issued: 08/30/2011
• Est. Priority Date: 08/18/2006
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Schack, Darren P., Passey, Aaron J., Lemar, Eric M., Anderson, Robert J., Fachan, Neal T., Richards, David W.
• Primary Examiner(s): Trujillo; James
• Assistant Examiner(s): Moser; Bruce M
• Application Number:
  US12/717,840
• Publication Number:
  US 20100161556A1
• Time in Patent Office: 544 Days
• Field of Search: 707/204, 707/999.204, 707/638, 707/639, 707/203, 707/999.203, 707/797, 707/829
• US Class Current: 707/638
• CPC Class Codes: G06F 16/128 Details of file system snapshots on the file-level, e.g. snapshot creation, administration, deletion use of snapshots for error detection or correction G06F11/14, G06F11/16
• CPC Class Codes: G06F 16/174 Redundancy elimination performed by the file system management of the data involved in backup or backup restore using de-duplication of the data G06F11/14
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

In one embodiment, a user or client device is connected to a distributed file system comprised of one or more physical nodes. The data on each of the physical nodes store metadata about files and directories within the file system. Some of the embodiments permit a user to take a snapshot of data stored on the file system. The snapshot may include a single file, a single directory, a plurality of files within a directory, a plurality of directories, a path on the file system that includes nested files and subdirectories, or more than one path on the file system that each includes nested files and directories. In one embodiment, the metadata comprises mini-snapshots for directories representing a path from the root of the file system to the root of the snapshot. The mini-snapshots serve as stand-ins for portions of the file system which are not included in the snapshot, but which permit access to the snapshot data in an intuitive way.

Claims

1. A data storage system for providing intuitive access to previous versions of files or directories, the system comprising:

at least one computer processor;

at least one memory;

a file system stored on the at least one memory, the file system comprising multiple data structures logically arranged hierarchically, each data structure comprising a file or directory, the multiple data structures including;

a root data structure;

a target data structure which is an ancestor of the root data structure; and

a set of directory data structures which comprise an access path between the root data structure and the target data structure, wherein at least one directory in the set of directory data structures has one or more additional child data structures that are not part of the access path between the root data structure and the target data structure; and

at least one executable software module executed by the at least one computer processor and configured to;

generate a snapshot version of the target data structure; and

generate a mini-snapshot version of the set of directory data structures, wherein the mini-snapshot version of the set of directory data structures provides an access path from the root data structure to the snapshot version of the target data structure, and wherein the mini-snapshot version of the set of directory data structures does not include access paths to the one or more additional child data structures.

2. The data storage system of claim 1, wherein the file system is a distributed file system, the at least one memory comprises a plurality of memories, and the multiple data structures are stored across the plurality of memories.

3. The data storage system of claim 1, wherein the root data structure is a root of the file system.

4. The data storage system of claim 1, wherein the root data structure is not a root of the file system.

5. The data storage system of claim 1, wherein the at least one executable software module is further configured to store the mini-snapshot version of the set of data structures as a descendant of the root data structure.

6. The data storage system of claim 1, wherein the at least one executable software module is further configured to access the snapshot version of the target data structure using the mini-snapshot version of the set of data structures.

7. The data storage system of claim 1, wherein the at least one executable software module is configured to generate the mini-snapshot version of the set of data structures as a result of a request to access the snapshot version of the target data structure.

8. The data storage system of claim 7, wherein the mini-snapshot version of the ancestor subset of data structures is not previously stored in the file system.

9. The data storage system of claim 7, wherein the snapshot version of the target data structure is accessed using a virtual directory.

10. The data storage system of claim 1, wherein the multiple data structures comprise multiple root data structures and multiple target data structures, and the at least one executable software module is configured to generate a mini-snapshot version of an ancestor subset of data structures in an access path between any one of the root data structures and a snapshot version of any one of the multiple target data structures.

11. The data storage system of claim 10, wherein the multiple root data structures comprise the directories in the file system, including the root directory of the file system.

12. A method of providing intuitive access to previous versions of files or directories, the method comprising:

generating, by a computer processor, a snapshot version of a target data structure in a file system, the file system comprising multiple data structures logically arranged hierarchically, each data structure comprising a file or directory, the multiple data structures comprising;

a root data structure;

the target data structure which is an ancestor of the root data structure; and

a set of directory data structures which comprise an access path between the root data structure and the target data structure, wherein at least one directory in the set of directory data structures has one or more additional child data structures that are not part of the access path between the root data structure and the target data structure; and

generating, by the computer processor, a mini-snapshot version of the set of directory data structures, the mini-snapshot version of the set of directory data structures providing an access path from the root data structure to the snapshot version of the target data structure and not including access paths to the one or more additional child data structures.

13. The method of claim 12, wherein the file system is a distributed file system, the at least one memory comprises a plurality of memories, and the multiple data structures are stored across the plurality of memories.

14. The method of claim 12, wherein the root data structure is a root of the file system.

15. The method of claim 12, wherein the root data structure is not a root of the file system.

16. The method of claim 12, further comprising storing the mini-snapshot version of the set of data structures as a descendant of the root data structure.

17. The method of claim 12, further comprising accessing the snapshot version of the target data structure using the mini-snapshot version of the set of data structures.

18. The method of claim 12, further comprising receiving a request to access the snapshot version of the target data structure, wherein the generating a mini-snapshot version of the set of data structures is performed after the request is received.

19. The method of claim 18, wherein the generating a mini-snapshot version of the set of data structures is performed as a result of the received request.

20. A data storage system for providing access to a snapshot version of files or directories, the system comprising:

at least one computer processor;

at least one memory;

a file system stored on the at least one memory, the file system comprising multiple data structures logically arranged hierarchically, each data structure comprising a file or directory, the multiple data structures comprising;

a target data structure;

a parent directory data structure that is the logical parent of at least two child data structures, the parent directory data structure comprising information about the at least two child data structures, the at least two child data structures including the target data structure and one or more non-target data structures; and

at least one executable software module executed by the at least one computer processor and configured to;

generate a snapshot version of the target data structure; and

generate a mini-snapshot version of the parent directory data structure such that the mini-snapshot version of the parent directory comprises information about the target data structure and does not include information about the one or more non-target data structures.

21. The data storage system of claim 20, wherein the at least one executable software module is further configured to access the snapshot version of the target data structure using the mini-snapshot version of the parent directory data structure.

22. The data storage system of claim 20, wherein the at least one executable software module is configured to generate the mini-snapshot version of the parent directory data structure as a result of a request to access the snapshot version of the target data structure.