CONSISTENT CLUSTER OPERATIONAL DATA IN A SERVER CLUSTER USING A QUORUM OF REPLICAS

• US 20110238813A1
• Filed: 06/08/2011
• Published: 09/29/2011
• Est. Priority Date: 03/26/1999
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: MASSA, MICHAEL T., Lomet, David B., Dion, David A., Das, Rajsekhar, Nishanov, Gor N., Shrivastava, Sunita, Gamache, Rod N., Jain, Rohit, Doshi, Rushabh A., Bernstein, Philip A.
• Granted Patent: US 8,850,007 B2
• Time in Patent Office: Days
• US Class Current: 709/223
• CPC Class Codes: G06F 11/1425 by reconfiguration of node membership
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• CPC Class Codes: G06F 11/1479 Generic software techniques for error detection or fault masking
• CPC Class Codes: G06F 11/1482 by means of middleware or OS functionality
• CPC Class Codes: G06F 11/1662 the resynchronized component or unit being a persistent storage device re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008
• CPC Class Codes: G06F 11/181 Eliminating the failing redundant component
• CPC Class Codes: G06F 11/182 based on mutual exchange of the output between redundant processing components
• CPC Class Codes: G06F 11/2023 Failover techniques
• CPC Class Codes: G06F 11/2035 without idle spare hardware
• CPC Class Codes: G06F 11/2058 using more than 2 mirrored copies
• CPC Class Codes: G06F 16/27 Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor
• CPC Class Codes: G06F 2201/82 Solving problems relating to consistency

Abstract

A method and system for increasing server cluster availability by requiring at a minimum only one node and a quorum replica set of replica members to form and operate a cluster. Replica members maintain cluster operational data. A cluster operates when one node possesses a majority of replica members, which ensures that any new or surviving cluster includes consistent cluster operational data via at least one replica member from the immediately prior cluster. Arbitration provides exclusive ownership by one node of the replica members, including at cluster formation, and when the owning node fails. Arbitration uses a fast mutual exclusion algorithm and a reservation mechanism to challenge for and defend the exclusive reservation of each member. A quorum replica set algorithm brings members online and offline with data consistency, including updating unreconciled replica members, and ensures consistent read and update operations.

Claims

1. A method comprising maintaining a cluster that includes an independent replica that comprises a storage device that is not an element of any node of the cluster and that is configured to be online in the cluster regardless of how many of the any nodes are operational in the cluster.

2. The method of claim 1 further comprising operating the cluster in response to one of the nodes of the cluster possessing a majority of independent replicas of the cluster.

3. The method of claim 1 wherein the maintaining does not include a requirement that a majority of the nodes of the cluster be operational.

4. The method of claim 1 wherein the cluster further includes a local replica that comprises a storage device that is integral to one node of the cluster.

5. The method of claim 4 wherein other nodes of the cluster communicate with the local replica via the one node of the cluster.

6. The method of claim 1 wherein the cluster is configured to include any number of independent replicas.

7. The method of claim 1 wherein the cluster is configured to operate with only independent replicas and without any local replicas, wherein an independent replica comprises a storage device that is not an element of any node of the cluster and that is configured to be online in the cluster regardless of how many of the any nodes are operational in the cluster, and wherein a local replica comprises a storage device that is integral to one node of the cluster.

8. At least one computer-readable media storing computer-executable instructions that, when executed by the computer cause the computer to perform a method comprising maintaining a cluster that includes an independent replica that comprises a storage device that is not an element of any node of the cluster and that is configured to be online in the cluster regardless of how many of the any nodes are operational in the cluster.

9. The at least one computer-readable media of claim 8, the method further comprising operating the cluster in response to one of the nodes of the cluster possessing a majority of independent replicas of the cluster.

10. The at least one computer-readable media of claim 8 wherein the maintaining does not include a requirement that a majority of the nodes of the cluster be operational.

11. The at least one computer-readable media of claim 8 wherein the cluster further includes a local replica that comprises a storage device that is integral to one node of the cluster.

12. The at least one computer-readable media of claim 11 wherein other nodes of the cluster communicate with the local replica via the one node of the cluster.

13. The at least one computer-readable media of claim 8 wherein the cluster is configured to include any number of independent replicas.

14. The at least one computer-readable media of claim 8 wherein the cluster is configured to operate with only independent replicas and without any local replicas, wherein an independent replica comprises a storage device that is not an element of any node of the cluster and that is configured to be online in the cluster regardless of how many of the any nodes are operational in the cluster, and wherein a local replica comprises a storage device that is integral to one node of the cluster.

15. A system comprising a computer configured for maintaining a cluster that includes an independent replica that comprises a storage device that is not an element of any node of the cluster and that is configured to be online in the cluster regardless of how many of the any nodes are operational in the cluster.

16. The system of claim 15 further comprising the computer further configured for operating the cluster in response to one of the nodes of the cluster possessing a majority of independent replicas of the cluster.

17. The system of claim 15 wherein the maintaining does not include a requirement that a majority of the nodes of the cluster be operational.

18. The system of claim 15 wherein the cluster further includes a local replica that comprises a storage device that is integral to one node of the cluster, and wherein other nodes of the cluster communicate with the local replica via the one node of the cluster.

19. The system of claim 15 wherein the cluster is configured to include any number of independent replicas.

20. The system of claim 15 wherein the cluster is configured to operate with only independent replicas and without any local replicas, wherein an independent replica comprises a storage device that is not an element of any node of the cluster and that is configured to be online in the cluster regardless of how many of the any nodes are operational in the cluster, and wherein a local replica comprises a storage device that is integral to one node of the cluster.