Quorum Establishment Based On A Vote From A Voting Device

• US 20070294363A1
• Filed: 05/18/2006
• Published: 12/20/2007
• Est. Priority Date: 05/18/2006
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Friedrich, Kurt Lawrence, Dion, David Allen, Das, Rajsekhar, Thiel, Gregory I.
• Granted Patent: US 7,644,305 B2
• Time in Patent Office: Days
• US Class Current: 709/217
• CPC Class Codes: G06F 2209/505 Clust
• CPC Class Codes: G06F 9/5061 Partitioning or combining of resources
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1034 Reaction to server failures by a load balancer
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

A cluster system including as few as two cluster nodes and a plurality of links, each one of the plurality of links coupling one of the cluster nodes to a voting device wherein a single surviving cluster node obtain a vote from the voting device. A method of establishing quorum in a cluster system including as few as two cluster nodes, the method comprising determining a single surviving cluster node of the as few as two cluster nodes, obtaining a vote from a voting device, and establishing quorum such that cluster operations are continued by the single surviving cluster node. A method for preventing a partition-in-time quorum establishment problem in a cluster system including as few as two cluster nodes, the method comprising determining that a revived cluster node is also a sole active cluster node of the cluster system, checking a last-surviving flag of the sole active cluster node, and if the last-surviving flag is set to FALSE, not restarting cluster operations.

Claims

1. A cluster system comprising:

as few as two cluster nodes; and

a plurality of links, each one of the plurality of links coupling one of the as few as two cluster nodes to a voting device wherein a single surviving cluster node of the as few as two cluster nodes can obtain a vote from the voting device.

2. The cluster system of claim 1 wherein each of the as few as two cluster nodes includes a last-surviving flag, the single surviving node being indicated by the last-surviving flag being set to TRUE.

3. The cluster system of claim 1 wherein the voting device is unrelated to the cluster system other than by being able to communicate with the as few as two cluster nodes and provide the vote.

4. The cluster system of claim 1 wherein the voting device is one or more devices within a safe zone.

5. The cluster system of claim 1 wherein the single surviving cluster node continues cluster operations after obtaining the vote from the voting device.

6. The cluster system of claim 1 wherein the vote is a response from the voting device responsive to a contact attempt by the single surviving cluster node.

7. The cluster system of claim 1 wherein the as few as two cluster nodes are geographically distributed.

8. A method of establishing quorum in a cluster system including as few as two cluster nodes, the method comprising:

determining a single surviving cluster node of the as few as two cluster nodes;

obtaining a vote from a voting device; and

establishing quorum such that cluster operations are continued by the single surviving cluster node.

9. The method of claim 8 further comprising setting a last-surviving flag of the single surviving cluster node to TRUE;

10. The method of claim 8 wherein the voting device is unrelated to the cluster system other than by being able to communicate with the as few as two cluster nodes and provide the vote.

11. The method of claim 8 wherein the vote is a response from the voting device responsive to a contact attempt by the single surviving cluster node.

12. The method of claim 8 wherein the voting device is one or more devices within a safe zone.

13. The method of claim 8 wherein the as few as two cluster nodes are geographically distributed.

14. The method of claim 8 wherein the voting device is a web server.

15. The method of claim 8 wherein the vote is obtained using a uniform resource locator associated with the voting device.

16. The method of claim 8 embodied as computer-executable instructions on computer-readable media.

17. The method of claim 8 wherein the as few as two cluster nodes are coupled to the voting device via the Internet.

18. A method for preventing a partition-in-time quorum establishment problem in a cluster system including as few as two cluster nodes, the method comprising:

determining that a revived cluster node is also a sole active cluster node of the cluster system;

checking a last-surviving flag of the sole active cluster node; and

if the last-surviving flag is set to FALSE, not restarting cluster operations.

19. The method of claim 18 embodied as computer-executable instructions on computer-readable media.

20. The method of claim 18 further comprising joining the revived cluster node to cluster operations after a second cluster node of the as few as two cluster nodes, the second cluster node including a last-surviving flag previously set to TRUE, restarts cluster operations.