Systems and methods for a snapshot of data

• US 7,680,842 B2
• Filed: 08/18/2006
• Issued: 03/16/2010
• Est. Priority Date: 08/18/2006
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Isilon Systems Incorporated (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:
  US11/506,591
• Publication Number:
  US 20080046475A1
• Time in Patent Office: 1,306 Days
• Field of Search: 707/200, 707/204, 707/2, 707/8, 707/102
• US Class Current: 1/1
• 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 processor-accessible data storage system for the storage of data representing a file system with a root-accessible directory-level snapshot structure comprising:

at least one computer processor;

at least one storage device;

a file system stored on the at least one storage device and accessible by the at least one computer processor, the file system comprising multiple metadata nodes, each metadata node comprising information about a file or directory stored on the at least one storage device;

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

receive a request to take a snapshot of a file or directory, the file or directory associated with a target metadata node;

access a parent metadata node of the target metadata node, the parent metadata node comprising a reference to the target metadata node and one or more references to one or more metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory; and

create a copy of the parent metadata node, the copy of the parent metadata node comprising a reference to the target metadata node and no reference to any of the metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory.

2. The data storage system of claim 1, wherein the at least one executable software module is further configured to:

access a grandparent metadata node of the target metadata node, the grandparent metadata node comprising a reference to the parent metadata node and one or more references to one or more metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory; and

create a copy of the grandparent metadata node, the copy of the grandparent metadata node comprising a reference to the parent metadata node and no reference to any of the metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory.

3. The data storage system of claim 1, wherein the at least one executable software module is further configured to:

access at least one ancestor metadata node of the target metadata node and the parent metadata node, each of the at least one ancestor metadata node comprising a reference to one or more ancestors of the target metadata node and one or more references to one or more metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory; and

create a copy of each of the at least one ancestor metadata node, each copy of each of the at least one ancestor metadata node comprising a reference to one or more ancestors of the target metadata node and no reference to any of the metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory.

4. The data storage system of claim 3, wherein the at least one ancestor metadata node comprises all ancestors of the parent metadata node on a path between the parent metadata node and a root metadata node corresponding to a root of the file system.

5. The data storage system of claim 4, wherein the at least one ancestor metadata node further comprises the root metadata node.

6. The data storage system of claim 3, wherein each copy of each of the at least one ancestor metadata node does not store any information unrelated to accessing the file or directory associated with the target metadata node.

7. The data storage system of claim 1, wherein the copy of the parent metadata node does not store any information unrelated to accessing the file or directory associated with the target metadata node.

8. The data storage system of claim 1, wherein the at least one executable software module is further configured to receive a request to access the file or directory associated with the target metadata node and to perform the accessing and copying in response to the request to access.

9. A method of maintaining path-accessibility for partial snapshots of a hierarchical structure comprising:

receiving a request to take a snapshot of a file or directory, the file or directory associated with a target metadata node in the hierarchical structure, the hierarchical structure comprising multiple metadata nodes, each metadata node, including the target metadata node, comprising information about a file or directory;

accessing, by a computer processor, a parent metadata node of the target metadata node, the parent metadata node comprising a reference to the target metadata node and one or more references to one or more metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory; and

creating, by the computer processor, a copy of the parent metadata node, the copy of the parent metadata node comprising a reference to the target metadata node and no reference to any of the metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory.

10. The method of claim 9, further comprising:

accessing, by the computer processor, a grandparent metadata node of the target metadata node, the grandparent metadata node comprising a reference to the parent metadata node and one or more references to one or more metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory; and

creating, by the computer processor, a copy of the grandparent metadata node, the copy of the grandparent metadata node comprising a reference to the parent metadata node and no reference to any of the metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory.

11. The method of claim 9, further comprising:

accessing, by the computer processor, at least one ancestor metadata node of the target metadata node and the parent metadata node, each of the at least one ancestor metadata node comprising a reference to one or more ancestors of the target metadata node and one or more references to one or more metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory; and

creating, by the computer processor, a copy of each of the at least one ancestor metadata node, each copy of each of the at least one ancestor metadata node comprising a reference to one or more ancestors of the target metadata node and no reference to any of the metadata nodes associated with files or directories which are not governed by the snapshot of the file or directory.

12. The method of claim 11, wherein the at least one ancestor metadata node comprises all ancestors of the parent metadata node on a path between the parent metadata node and a root metadata node corresponding to a root of the hierarchical structure.

13. The method of claim 12, wherein the at least one ancestor metadata node further comprises the root metadata node.

14. The method of claim 11, wherein each copy of each of the at least one ancestor metadata node does not store any information unrelated to accessing the file or directory associated with the target metadata node.

15. The method of claim 9, wherein the copy of the parent metadata node does not store any information unrelated to accessing the file or directory associated with the target metadata node.

16. The method of claim 9, further comprising receiving a request to access the file or directory associated with the target metadata node, wherein the accessing and the creating are in response to the request to access.