METHOD AND SYSTEM FOR TRANSPARENTLY FAILING OVER APPLICATION CONFIGURATION INFORMATION IN A SERVER CLUSTER

• US 20010008019A1
• Filed: 04/17/1998
• Published: 07/12/2001
• Est. Priority Date: 04/17/1998
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: VERT, JOHN D., SHRIVASTAVA, SUNITA
• Granted Patent: US 6,360,331 B2
• Time in Patent Office: Days
• US Class Current: 714/1
• 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 11/203 using migration
• CPC Class Codes: G06F 11/2038 with a single idle spare processing component
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability

Abstract

A method and system for transparently failing over a legacy application from a first system to a second system of a server cluster by tracking and checkpointing changes to application configuration information stored in a system'"'"'s local registry. When an application running on the first system makes a change to the application configuration information in a subtree of the registry, the change is detected and a snapshot of the subtree'"'"'s data is taken. The snapshot is written to a storage device shared by systems of the cluster, such as a quorum disk. When the application is failed over to a second system, the snapshot for that application is retrieved from the quorum disk and written to the registry of the second system in a corresponding subtree. The application is then run on the second system using the most-recent application configuration information as modified by the other system in the cluster.

Claims

1. In a server cluster including at least two systems, a method of failing over an application from a first system to a second system of the cluster, comprising the steps of, locally maintaining application configuration information for the application on the first system, running the application on the first system, detecting a change to the application configuration information, and, in response to the change, making data representative of the change available to the second system, and running the application on the second system using the data made available thereto.

2. The method of

claim 1

wherein the application configuration information is maintained in a registry of the first system, and wherein the step of detecting a change to the application configuration information includes the step of monitoring for a change to data in at least one subtree associated with the application in the registry.

3. The method of

claim 2

wherein the step of making data representative of the change available to the second system includes the steps of making a copy of the data in each subtree having a change detected thereto.

4. The method of

claim 1

wherein the step of making data representative of the change available to the second system comprises the step of writing the data to a storage device shared by systems of the cluster.

5. The method of

claim 4

wherein the step of making data representative of the change available to the second system further comprises the step of retrieving the data from the storage device and passing the data to the second system.

6. The method of

claim 1

wherein the step of making data representative of the change available to other systems in the cluster comprises the step of storing the data in a quorum device of the cluster.

7. The method of

claim 1

wherein the step of making data representative of the change available to other systems in the cluster comprises the step communicating the data to at least one other system in the cluster.

8. The method of

claim 1

wherein the first system and the second system each locally maintain application configuration information for the application in a registry, and wherein the step of making data representative of the change available to the second system comprises the steps of, reading subtree data of the registry in the first system, writing the subtree data to a storage device shared by systems in the cluster, and retrieving the subtree data from the storage device to the registry of the second system.

9. The method of

claim 1

wherein the application has a list of subtrees associated therewith, and further comprising the step of registering each of the subtrees in the list with a notification mechanism for detecting changes thereto.

10. The method of

claim 1

further comprising the step of terminating the application on the first system.

11. The method of

claim 1

wherein the cluster includes a third system, and further comprising the steps of locally maintaining application configuration information for another application on the first system, running the other application on the first system, detecting a change to the other application configuration information, and, in response to the change, making data representative of the change available to the third system, and running the other application on the third system using the data made available thereto.

12. In a server cluster including at least two systems, a system for failing over an application from a first system to a second system of the cluster, comprising, a registry on each of the first and second systems for storing application configuration information of the application, a storage device shared by the first and second systems, a notification mechanism in the first system for detecting a change to a subtree in the registry associated with the application and providing a notification in response thereto, a snapshot mechanism in the first system responsive to the notification for reading the registry and saving subtree data to the storage device, and a restore mechanism in the second system for retrieving the subtree data from the storage device and updating the registry of the second system therewith.

13. The system of

claim 12

wherein the application has a list of subtrees associated therewith, and wherein the notification mechanism monitors each of the subtrees in the list for detecting changes thereto.

14. The system of

claim 13

wherein the list of subtrees is stored on the storage device.

15. The system of

claim 13

wherein the list of subtrees is stored in a cluster registry on the storage device.

16. The system of

claim 12

wherein the subtree data includes a name representative of a key in the registry and at least one value.

17. In a server cluster, a method of using application configuration information with an application, comprising the steps of:

locally maintaining application configuration information for the application on a system of the cluster;

determining if a cluster checkpoint of data corresponding to the application configuration information for the application is present on a storage device shared by systems in the cluster; and

if the cluster checkpoint exists,

updating the application configuration information of the local system with the data in the storage device,

running the application with the updated application configuration information, and

updating the cluster checkpoint to correspond to local changes to the application configuration information; and

if the checkpoint does not exist,

creating a cluster checkpoint on the storage device,

running the application with the locally maintained application configuration information, and

updating the cluster checkpoint to correspond to local changes to the application configuration information.

18. The method of

claim 17

wherein the application configuration information is maintained in a local registry of the system, and further comprising the step of detecting a change to the application configuration information by monitoring for a change to data of at least one subtree in the registry.

20. The method of

claim 18

wherein the application has a list of subtrees associated therewith, and further comprising the step of registering each of the subtrees in the list with a notification mechanism for detecting changes thereto.

19. In a server cluster including at least two systems, a method of failing over an application from a first system to a second system of the cluster, comprising the steps of, maintaining application configuration information for the application in a registry of the first system, running the application on the first system, detecting a change to the application configuration information in a subtree of the registry, and, in response to the change, writing data of that subtree as subtree data to a storage device shared by systems of the cluster, terminating the application on the first system, reading the subtree data, modifying a registry of the second system with the subtree data, and running the application on the second system using the application configuration information stored in the registry of the second system.

21. The method of

claim 19

wherein the cluster includes a third system, and further comprising the steps of maintaining other application configuration information for another application in the registry of the first system, running the other application on the first system, detecting a change to the other application configuration information in a subtree of the registry, and, in response to the change, writing data of that subtree as subtree data to a storage device shared by systems of the cluster, terminating the other application on the first system, reading the subtree data, modifying a registry of the third system with the subtree data, and running the other application on the third system using the other application configuration information stored in the registry of the third system.