Using a data protection server to backup and restore data on virtual servers

• US 20060225065A1
• Filed: 04/01/2005
• Published: 10/05/2006
• Est. Priority Date: 04/01/2005
• Status: Active Grant

• Current Assignee: ServiceNow Incorporated
• Original Assignee: Microsoft Corporation
• Inventors: Chandhok, Nikhil Vijay, Michael, Michael L., Fries, Robert M.
• Granted Patent: US 7,899,788 B2
• Time in Patent Office: Days
• US Class Current: 717/168
• CPC Class Codes: G06F 11/1458 Management of the backup or restore process
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 11/1469 Backup restoration techniques
• CPC Class Codes: G06F 11/1471 involving logging of persistent data for recovery
• 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 2201/815 Virtual middleware or OS functionality using virtual machines to implement generic software techniques for error detection or fault masking G06F11/1484
• CPC Class Codes: G06F 9/455 Emulation; Interpretation; Software simulation, e.g. virtualisation or emulation of application or operating system execution engines

Abstract

A method and system for backing up and restoring data of virtual machines. A virtual machine may be discovered through a directory service or via an agent that is installed on the host operating system that is running the virtual machine. If the agent is installed on the virtual machine, the agent monitors changes to a set of protected volumes on the virtual machine. If the agent is installed on the host, the agent monitors changes to the protected volumes, which may contain one or more virtual servers on the host. Periodically, these changes from the host or the virtual server are sent to a data protection server. The data protection server updates its replicas of protected volumes with the sent changes. Versions of files on a data protection server corresponding to a volume of a virtual server may be restored to the virtual machine, to another machine, or may be viewed from the data protection server.

Claims

1. A computer-readable medium having computer-executable instructions, comprising:

obtaining a replica of a volume of a virtual machine;

storing the replica on a data protection server;

receiving an update that includes changes to the volume that occurred after the replica was obtained; and

updating the replica on the data protection server with the update.

2. The computer-readable medium of claim 1, further comprising:

discovering that the virtual machine exists by querying a directory service; and

installing an agent on the virtual machine that periodically sends changes to the volume to the data protection server.

3. The computer-readable medium of claim 1, wherein the agent tracks changes to the volume by monitoring updates to the volume via a file system filter and creating a log file that includes the updates.

4. The computer-readable medium of claim 3, wherein updating the replica on the data protection server with the update comprises modifying the replica as indicated in the log file.

5. The computer-readable medium of claim 1, wherein a physical host machine upon which the virtual machine resides creates a differencing disk that maintains changes to the volume, and wherein the agent forwards the differencing disk to the data protection server.

6. The computer-readable medium of claim 5, wherein updating the replica on the data protection server with the update comprises merging the differencing disk with a parent disk stored on the data protection server to create a new replica.

7. A method for backing up and restoring data, comprising:

installing an agent on a host machine that hosts a virtual machine that stores data on a volume;

monitoring changes to the volume; and

sending the changes to a data protection server.

8. The method of claim 7, wherein monitoring changes to the volume comprises monitoring changes by a file system filter that has an opportunity to view each modification caused by the virtual machine that affects the volume and wherein the file system filter writes the changes to a log file.

9. The method of claim 8, further comprising:

pausing the virtual machine;

inserting a checkpoint record into the log file; and

unpausing the virtual machine after the record is inserted;

forwarding data in the log file up to the record to the data protection server; and

flushing data of the log file up to the record.

10. The method of claim 7, wherein installing an agent on a host machine comprises installing the agent to execute in the virtual machine.

11. The method of claim 7, wherein installing an agent on a host machine comprises installing the agent to execute in the host machine and not as a process inside the virtual machine.

12. The method of claim 11, further comprising:

discovering, by the agent, all virtual machines that are hosted in the host machine; and

providing a list of all the virtual machines to the data protection server.

13. The method of claim 12, wherein the agent monitors changes for each virtual machine for which data is stored on the host machine.

14. The method of claim 7, further comprising selecting data on the virtual machine to restore and sending the data from the data protection server to the agent to restore the data to the virtual machine.

15. The method of claim 7, further comprising:

accessing a directory service that includes a mapping that maps the virtual machine to the data protection server and obtaining a name of the data protection server therefrom;

obtaining a list of shadow copies corresponding to versions of a file from the data protection server, wherein the versions of the file correspond to versions of the file that existed on the virtual machine; and

selecting one of the versions.

16. The method of claim 15, further comprising restoring the one of the versions to the virtual machine.

17. The method of claim 15, further comprising restoring the one of the versions to a machine other than the host machine and the virtual machine.

18. A system for backing up and restoring data, comprising:

a host machine arranged to provide an environment in which virtual machines execute, the host machine including virtual server software and a file system;

a virtual machine arranged to execute in the environment, the virtual machine having a volume that is represented as a file in the file system; and

an agent arranged to monitor changes to the volume and to forward the changes to a data protection server.

19. The system of claim 18, wherein the agent is further arranged to monitor changes to volumes associated with other virtual machines and to forward these changes to the data protection server.