Systems and methods for distributed system scanning

• US 20070094269A1
• Filed: 10/21/2005
• Published: 04/26/2007
• Est. Priority Date: 10/21/2005
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Schack, Darren, Anderson, Robert, Dire, Nathan, Mikesell, Paul, Godman, Peter
• Granted Patent: US 7,788,303 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 16/134 Distributed indices
• CPC Class Codes: G06F 16/1834 implemented based on peer-to-peer networks, e.g. gnutella p2p communication protocols H04L67/104

Abstract

Systems and methods are provided for scanning files and directories in a distributed file system on a network of nodes. The nodes include metadata with attribute information corresponding to files and directories distributed on the nodes. In one embodiment, the files and directories are scanned by commanding the nodes to search their respective metadata for a selected attribute. At least two of the nodes are capable of searching their respective metadata in parallel. In one embodiment, the distributed file system commands the nodes to search for metadata data structures having location information corresponding to a failed device on the network. The metadata data structures identified in the search may then be used to reconstruct lost data that was stored on the failed device.

Claims

1. A method for scanning files and directories in a distributed file system on a network having a plurality of nodes, at least a portion of the nodes including metadata with attribute information for one or more files striped across the distributed file system, the method comprising commanding at least a subset of the nodes to search their respective metadata for a selected attribute and to perform an action in response to identifying the selected attribute in their respective metadata, the subset of nodes being capable of searching their respective metadata in parallel.

2. The method of claim 1, wherein the metadata comprises location information for at least one of a content data block, a metadata data block, and a protection data block.

3. The method of claim 2, wherein the metadata further comprises location information for at least one directory.

4. The method of claim 1, wherein the selected attribute comprises one or more attributes selected from the group comprising file size, file name, file type, file extension, file creation time, file access time, file modification time, file version, file permission, file protection scheme, and file location.

5. The method of claim 1, wherein the action comprises one or more file system functions selected from the group comprising writing data, reading data, copying data, backing up data, reconstructing lost data blocks, restriping data blocks, generating parity data blocks, updating metadata, sending a message to one or more of the plurality of nodes, and executing instructions.

6. The method of claim 1, wherein the action comprises returning a unique identifier for a metadata data structure corresponding to a file comprising the selected attribute.

7. The method of claim 6, further comprising:

receiving the response from at least one of the nodes in the subset of nodes; and

accessing the metadata data structure to determine location information for the file comprising the selected attribute.

8. The method of claim 7, wherein the selected attribute comprises having one or more data blocks stored on a failed node, the method further comprising:

recovering the one or more data blocks stored on the failed node; and

restriping the file comprising the selected attribute across the distributed file system.

9. The method of claim 8, wherein recovering the one or more data blocks stored on the failed node comprises:

accessing the metadata data structure to determine the location of at least one accessible content data block and at least one accessible parity data block corresponding to the file comprising the selected attribute;

reading the at least one accessible content data block and the at least one accessible parity data block from their respective locations on the distributed file system; and

processing the at least one accessible content data block and the at least one accessible parity data block to generate the one or more data blocks stored on the failed node.

10. The method of claim 9, wherein processing the at least one accessible content data block and the at least one accessible parity data block comprises performing an exclusive-or (XOR) operation on the at least one accessible content data block and the at least one accessible parity data block.

11. The method of claim 8, wherein recovering the one or more data blocks stored on the failed node comprises:

accessing the metadata data structure to determine the location of at least one accessible copy of the one or more data blocks stored on the failed node; and

reading the at least one accessible copy.

12. A distributed file system comprising:

a plurality of nodes configured to store data blocks corresponding to files striped across the plurality of nodes;

metadata data structures stored on at least a portion of the plurality of nodes, the metadata data structures including attribute information for the files;

wherein at least two of the plurality of nodes are configured to search, at substantially the same time, their respective metadata data structures for a selected attribute.

13. The distributed file system of claim 12, wherein the data blocks comprise at least one of a content data block, a metadata data block, and a protection data block.

14. The distributed file system of claim 13, wherein the metadata data structures comprise location information for corresponding data blocks.

15. The distributed file system of claim 12, wherein the selected attribute comprises one or more attributes selected from the group comprising file size, file name, file type, file extension, file creation time, file access time, file modification time, file version, file permission, file protection scheme, and file location.

16. The distributed file system of claim 12, wherein the plurality of nodes are configured to generate a list of unique identification numbers for corresponding metadata data structures that comprise the selected attribute.

17. The distributed file system of claim 16, wherein at least one node is configured to restripe one or more files corresponding to the unique identification numbers.

18. A method for recovering from a failure in a distributed file system, the method comprising:

storing metadata corresponding to one or more files on one or more nodes in a network, the metadata pointing to data blocks stored on the one or more nodes;

detecting a failed device in the distributed file system;

commanding the nodes to search their respective metadata for location information corresponding to the failed device;

receiving responses from the nodes, the responses identifying metadata data structures corresponding to information stored on the failed device; and

accessing the identified metadata data structures to reconstruct the information stored on the failed device.

19. The method of claim 18, wherein the location information comprises a list of devices used corresponding to the metadata data structure.

20. The method of claim 18, wherein accessing the identified metadata data structures comprises reading pointers to at least one of file content data blocks, metadata data blocks, and protection data blocks stored on the failed device.