LOCATING THE LATEST VERSION OF REPLICATED DATA FILES

• US 20110161335A1
• Filed: 12/30/2009
• Published: 06/30/2011
• Est. Priority Date: 12/30/2009
• Status: Active Grant

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: Kher, Vishal, Harmer, Craig, Dash, Prasanta
• Granted Patent: US 9,135,268 B2
• Time in Patent Office: Days
• US Class Current: 707/758
• CPC Class Codes: G06F 16/182 Distributed file systems

Abstract

A list of servers known to a client is compared with lists of servers stored on the servers. An instance of content (e.g., a data file) can be accessed from a server on the list if at least a simple majority of the servers have the same version of the list.

Claims

1. A computer-readable storage medium having computer-executable instructions for causing a computer system to perform a method comprising:

comparing a list comprising a plurality of servers known to said computer system with a plurality of lists of servers stored on servers on said list; and

accessing a version of an instance of content from a server on said list if at least a simple majority of said servers have the same version of said list.

2. The computer-readable storage medium of claim 1 further comprising determining whether said version of said instance of content on said server is at least as recent as any other version of said instance of content stored on any other of said servers.

3. The computer-readable storage medium of claim 1 wherein said version of said instance of content is indicated using a version number.

4. The computer-readable storage medium of claim 1 wherein said version of said instance of content is indicated using a time stamp.

5. The computer-readable storage medium of claim 1 wherein said method further comprises computing a checksum for said instance of content.

6. The computer-readable storage medium of claim 1 wherein said instance of content is replicated on multiple servers of said plurality of servers, wherein each of said multiple servers is identified in said list.

7. The computer-readable storage medium of claim 1 wherein said plurality of servers comprise a distributed file storage system and wherein said instance of content comprises a file comprising data.

8. A computer-implemented method for managing data, said method comprising:

identifying a first plurality of servers during a first phase of a search for lists of servers;

after said first phase, propagating said search through succeeding pluralities of servers, wherein each succeeding plurality of servers is selected based upon lists of servers stored on a plurality of a servers identified in a preceding phase of said search;

identifying a latest list of servers, wherein said latest list is selected from lists of servers identified during said search; and

accessing a version of said file comprising data stored on a server included in said latest list.

9. The computer-implemented method of claim 8 further comprising:

accessing a first list that identifies said first plurality of servers;

accessing said lists of servers stored on a quorum comprising at least a simple majority of said first plurality of servers;

comparing said lists stored on said quorum of servers to identify which of said lists stored on said quorum of servers is a most recent list; and

selecting a second plurality of servers from said most recent list stored on said quorum of servers.

10. The computer-implemented method of claim 9 wherein said comparing further comprises:

comparing a list comprising a plurality of servers known to a computer system with a plurality of lists of servers stored on said servers; and

accessing a version of a file comprising said data from a server on said list if at least a simple majority of said servers have the same version of said list.

11. The computer-implemented method of claim 10 further comprising determining whether said version of said file on said server is at least as recent as any other version of said file stored on any other of said servers.

12. The computer-implemented method of claim 8 wherein said version of said file is indicated using a version number.

13. The computer-implemented method of claim 8 wherein said version of said file is indicated using a time stamp.

14. The computer-implemented method of claim 8 further comprising computing a checksum of said data.

15. The computer-implemented method of claim 8 wherein said data is replicated on multiple servers, wherein each of said multiple servers is identified in said latest list.

16. A computer system comprising:

a processor; and

memory coupled to said processor and having stored therein instructions that, if executed by said computer system, cause said computer system to execute a method of managing data, said method comprising;

accessing a first list affiliated with a first data file, said first list identifying a plurality of servers on which replicas of said first data file are stored;

writing data to a set of said replicas stored on a quorum comprising at least a simple majority of said plurality of servers; and

affiliating a second list with said set of replicas that are written to, said second list comprising listings identifying said quorum of servers, wherein said second list and said replicas are stored on said quorum of servers.

17. The computer system of claim 16 wherein said method further comprises associating version information with said replicas, wherein said version information comprises a version number.

18. The computer system of claim 16 wherein said method further comprises associating version information with said replicas, wherein said version information comprises a time stamp.

19. The computer system of claim 16 wherein said method further comprises computing a checksum for each of said replicas.

20. The computer system of claim 16 wherein said plurality of servers comprise a distributed file storage system.