Virtual Machine Smart Migration

• US 20090007106A1
• Filed: 06/29/2007
• Published: 01/01/2009
• Est. Priority Date: 06/29/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Araujo, Nelson Sampaio JR., Michael, Michael L., Fries, Robert M.
• Granted Patent: US 8,806,480 B2
• Time in Patent Office: Days
• US Class Current: 718/1
• CPC Class Codes: G06F 2009/4557 Distribution of virtual machine instances; Migration and load balancing
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects
• CPC Class Codes: G06F 9/54 Interprogram communication

Abstract

Migration mechanisms are disclosed herein that smartly transfer data among virtual machines, minimizing the down time of migration of such machines but maximizing the consistent state of data stored thereon. Specifically, data can be classified into three types: low volatility data (such as hard disk data), high volatility data (such a random access memory data), and immutable data (such as read only data). This data can be migrated from a source virtual machine to a target virtual machine by sending the immutable data along with the low volatility data first—before the source virtual machine has stopped itself for the migration process. Then, after the source virtual machine has stopped, high volatility data and (again) low volatility data can be sent from the source to the target. In this latter case, only differences between the low volatility data may be sent (or alternatively, new low volatility data may be sent).

Claims

1. A system that migrates a plurality of virtual machines among servers, wherein said plurality of virtual machines include data that is classified into a plurality of data types, comprising:

a first data of a first data type that is classified according to a first predetermined standard;

a second data of a second data type that is classified according to a second predetermined standard;

a third data of a third data type that is read-only data; and

data migration mechanism that sends said first data and said third data from a source virtual machine to a target virtual machine when said source virtual machine is running, and wherein said data migration mechanism sends said first data and said second data when said source virtual machine has stopped running.

2. The system according to claim 1, wherein said first data type is representative of low volatility data, such as hard disk data.

3. The system according to claim 1, wherein said second data type is representative of high volatility data, such as random access memory data.

4. The system according to claim 1, wherein said data migration mechanism additionally sends said second data when said source virtual machine is running, if said second data is present on said source virtual machine.

5. The system according to claim 4, wherein said data migration mechanism sends said first data and said second data after said source virtual machine has stopped running, wherein said data migration mechanism uses one of (a) a full data transfer mechanism between said source virtual machine and said target virtual machine, and (b) a differential data transfer mechanism.

6. The system according to claim 1, wherein said data migration mechanism sends said first data when said source virtual machine has stopped running by using a full data transfer of said first data from said source virtual machine to said target virtual machine.

7. The system according to claim 1, wherein said data migration mechanism sends said first data when said source virtual machine has stopped running by using a partial differential data transfer of said first data type from said source virtual machine to said target virtual machine, wherein said partial differential transfer only sends data that has changed since said first data type was sent when said source virtual machine was running.

8. The system according to claim 1, wherein said data migration mechanism migrates said virtual machine according to a predetermined virtual machine down-time constraint.

9. A method that provides for the migration of virtual machines and associated data, comprising:

sending a first set of data based on a plurality of data types from a source server to a target server when said source server is running, wherein said first set of data contains at least two different data types;

sending a second set of data based on said plurality of data types from said source server to said target server when said source server has stopped running, wherein said second set of data contains at least two different data types; and

wherein said first set of data and said second set of data has at least one data type in common.

10. The method according to claim 9, wherein said at least one data type in common corresponds to non-immutable data that is subject to change between the time when said source server has started running and when said source server has stopped running.

11. The method according to claim 9, further comprising pre-caching said first set of data in a plurality of servers and then migrating said second set of data to at least one of said plurality of servers.

12. The method according to claim 9, further comprising sending in said first set of data and in said second set of data read and write data, and further comprising sending in said first set of data at least read only data.

13. The method according to claim 9, further comprising sending in said first set of data of a type different from said at least two different data types.

14. The method according to claim 13, wherein said sending in said first set of data of a type different from said at least two different data types occurs only if said data of said type different is present on said source server.

15. The method according to claim 9, wherein in said second data set, at least one data subset of said set is transferred as a full subset or a differential subset.

16. The method according to claim 9, further comprising migrating said virtual machines according to a predetermined virtual machine time constraint.

17. A computer readable medium storing thereon computer executable instructions for migrating data among a plurality of virtual machines, comprising:

an instruction configured to migrate an immutable data to a target device;

an instruction configured to migrate a first part of a non-immutable data to said target device;

an instruction configured to migrate a second part of said non-immutable data to said target device; and

an instruction configured to decide whether to migrate at least one of said first part and said second part of said non-immutable data to said target device based on at least one criterion.

18. The computer readable medium according to claim 17, wherein said at least one criterion is based on information regarding the data size of said at least one of said first part and said second part of said non-immutable data.

19. The computer readable medium according to claim 17, wherein said at least one criterion is based on information regarding the down time of a source device from which data is being transferred to said target device.

20. The computer readable medium according to claim 17, further comprising an instruction that migrates said at least one of said first part and said second part of said non-immutable data before a source device has stopped running and after said source device has stopped.