VIRTUAL STORAGE MIGRATION METHOD, VIRTUAL STORAGE MIGRATION SYSTEM AND VIRTUAL MACHINE MONITOR

• US 20120137098A1
• Filed: 12/29/2011
• Published: 05/31/2012
• Est. Priority Date: 11/29/2010
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Wang, Feng, Wang, Zhikun, Yang, Xiaowei, Xu, Jianhui
• Granted Patent: US 9,411,620 B2
• Time in Patent Office: Days
• US Class Current: 711/165
• CPC Class Codes: G06F 2009/4557 Distribution of virtual machine instances; Migration and load balancing
• CPC Class Codes: G06F 2009/45579 I/O management, e.g. providing access to device drivers or storage
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0683 Plurality of storage devices
• CPC Class Codes: G06F 9/45533 Hypervisors; Virtual machine monitors

Abstract

A virtual storage migration method is provided, including: starting a data migration process, and copying, from a source storage device to a destination storage device, a data block in a virtual disk to be migrated; when a VM front-end I/O read request is received, directly reading, corresponding data from the source storage device; when a VM front-end I/O write request is received, determining whether a migration data block that corresponds to the write request is being migrated, if yes, executing a write operation that corresponds to the write request after the migration of the migration data block is completed, if no, executing a write operation that corresponds to the write request; and after all the data blocks in the virtual disk to be migrated are copied to the destination storage device, stopping the data migration, and switching the virtual disk from the source storage device to the destination storage device.

Claims

1. A virtual storage migration method, comprising:

starting a data migration process, and copying, from a source storage device to a destination storage device, a data block in a virtual disk to be migrated;

during the data migration process, when a virtual machine front-end input/output (I/O) read request is received, directly reading, from the source storage device, data that corresponds to the virtual machine front-end input/output (I/O) read request; and

when a virtual machine front-end I/O write request is received, determining whether a migration data block that corresponds to the virtual machine front-end I/O write request is being migrated, and if the migration data block that corresponds to the virtual machine front-end I/O write request is being migrated, executing a write operation that corresponds to the virtual machine front-end I/O write request after the migration of the migration data block is completed;

if the migration data block that corresponds to the virtual machine front-end I/O write request is not being migrated, executing the write operation that corresponds to the virtual machine front-end I/O write request; and

after all data blocks in the virtual disk to be migrated are copied to the destination storage device, stopping the data migration process, and switching the virtual disk managed by a virtual machine manager from the source storage device to the destination storage device.

2. The method according to claim 1, wherein the starting the data migration process and copying, from the source storage device to the destination storage device, the data block in the virtual disk to be migrated comprises:

initializing, with a chunk as granularity, a bitmap table of the data block in the virtual disk to be migrated, wherein a size of the chunk is set according to a size of the virtual disk to be migrated;

sequentially selecting the data block that corresponds to an unset chunk from the bitmap table for migration; and

setting the unset chunk in the bitmap table to represent that the data block that corresponds to the chunk has been migrated when the data block that corresponds to the unset chunk is copied from the source storage device to the destination storage device.

3. The method according to claim 2, wherein, in the data migration process, when the virtual machine front-end I/O write request is received and it is determined that the migration data block that corresponds to the virtual machine front-end I/O write request is not being migrated, the step of executing the write operation that corresponds to the virtual machine front-end I/O write request comprises:

directly writing a new write request data block carried in the virtual machine front-end I/O write request into the source storage device and the destination storage device when it is queried according to the bitmap table that the migration data block that corresponds to the virtual machine front-end I/O write request has been migrated;

copying the migration data block from the source storage device to the destination storage device, writing the new write request data block into the source storage device and the destination storage device, and setting the chunk that corresponds to the migration data block in the bitmap table, when it is queried according to the bitmap table that the migration data block that corresponds to the virtual machine front-end I/O write request is not migrated and the size of the new write request data block carried in the virtual machine front-end I/O write request is smaller than the size of the migration data block; and

directly writing the new write request data block into the source storage device and the destination storage device and setting the chunk that corresponds to the migration data block in the bitmap table to represent that the data block that corresponds to the chunk has been migrated, when it is queried according to the bitmap table that the migration data block that corresponds to the virtual machine front-end I/O write request is not migrated and the size of the new write request data block carried in the virtual machine front-end I/O write request is equal to the size of the migration data block.

4. The method according to claim 1, before starting the data migration process, further comprising:

allocating a storage space in the destination storage device, and copying a virtual machine configuration file to the destination storage device, and setting a data migration flag, wherein the data migration flag is used to identify that data in the virtual disk to be migrated is currently being migrated.

5. The method according to claim 4, after the starting the data migration process, further comprising:

clearing the data migration flag, and deleting a virtual disk image that corresponds to the virtual disk in the source storage device.

6. The method according to claim 1, further comprising:

preferentially processing a virtual machine front-end I/O access request, wherein the front-end I/O access request comprises the virtual machine front-end I/O read request and the virtual machine front-end I/O write request; and

performing data migration by adopting a low-priority data migration thread when the virtual machine is idle.

7. A virtual machine monitor, comprising:

a migration module, configured to start data migration, and copy, from a source storage device to a destination storage device, a data block in a virtual disk to be migrated;

a request processing module, configured to, during a data migration process, directly read, from the source storage device, data that corresponds to a virtual machine (VM) front-end input/output (I/O) read request when the virtual machine front-end input/output (I/O) read request is received; and

determine whether a migration data block that corresponds to a virtual machine front-end I/O write request is being migrated when the VM front-end I/O write request is received, and if the migration data block that corresponds to the virtual machine front-end I/O write request is being migrated, execute a write operation that corresponds to the virtual machine front-end I/O write request after the migration of the migration data block is completed;

if the migration data block that corresponds to the virtual machine front-end I/O write request is not being migrated, execute the write operation that corresponds to the virtual machine front-end I/O write request; and

a switch module, configured to stop the data migration after all data blocks in the virtual disk to be migrated are copied to the destination storage device, and switch the virtual disk managed by a virtual machine manager from the source storage device to the destination storage device.

8. The virtual machine monitor according to claim 7, wherein the migration module comprises:

an initialization unit, configured to initialize, with a chunk as granularity, a bitmap table of a data block in the virtual disk to be migrated, wherein a size of the chunk is set according to a size of the virtual disk to be migrated;

a migration unit, configured to sequentially select a data block that corresponds to an unset chunk from the bitmap table for migration; and

a setting unit, configured to set the unset chunk in the bitmap table to represent that the data block that corresponds to the chunk has been migrated when the data block that corresponds to the unset chunk is copied from the source storage device to the destination storage device.

9. The virtual machine monitor according to claim 8, wherein the request processing module comprises:

a read request processing unit, configured to, during the data migration process, directly read, from the source storage device, data that corresponds to a virtual machine front-end I/O read request when the virtual machine front-end I/O read request is received;

a determination unit, configured to, during the data migration process, determine whether the migration data block that corresponds to a virtual machine front-end I/O write request is being migrated when the virtual machine front-end 1/0 write request is received;

a waiting unit, configured to execute a write operation that corresponds to the virtual machine front-end I/O write request after the migration of the data block is completed when a determination result of the determination unit represents that the migration data block that corresponds to the virtual machine front-end I/O write request is being migrated; and

an execution unit, configured to execute the write operation that corresponds to the virtual machine front-end I/O write request according to the bitmap table when the determination result of the determination unit represents that the migration data block that corresponds to the virtual machine front-end I/O write request is not being migrated;

wherein, the execution unit comprises;

a first execution sub-unit, configured to directly write a new write request data block carried in the virtual machine front-end I/O write request into the source storage device and the destination storage device when it is queried according to the bitmap table that the migration data block that corresponds to the virtual machine front-end I/O write request has been migrated;

a second execution sub-unit, configured to copy the migration data block from the source storage device to the destination storage device, write the new write request data block into the source storage device and the destination storage device, and set the chunk that corresponds to the migration data block in the bitmap table to represent that the migration data block that corresponds to the chunk has been migrated, when it is queried according to the bitmap table that the migration data block that corresponds to the virtual machine front-end I/O write request is not migrated and the size of the new write request data block carried in the virtual machine front-end I/O write request is smaller than the size of the migration data block; and

a third execution sub-unit, configured to directly write the new write request data block into the source storage device and the destination storage device and set the chunk that corresponds to the migration data block in the bitmap table to represent that the migration data block that corresponds to the chunk has been migrated, when it is queried according to the bitmap table that the migration data block that corresponds to the virtual machine front-end I/O write request is not migrated and the size of the new write request data block carried in the virtual machine front-end I/O write request is equal to the size of the migration data block.

10. The virtual machine monitor according to claim 7, further comprising:

an allocation module, configured to allocate a storage space in the destination storage device before a data migration thread is started, and copy a virtual machine configuration file to the destination storage device, and set a data migration flag, wherein the data migration flag is used to identify that data is currently being migrated.

11. The virtual machine monitor according to claim 10, further comprising:

a deletion module, configured to clear the data migration flag and delete a virtual disk image that corresponds to the virtual disk in the source storage device, after the data migration is stopped.

12. The virtual machine monitor according to claim 7, further comprising:

a preferential processing module, configured to preferentially process a virtual machine front-end I/O access request, wherein the I/O access request comprises the virtual machine front-end I/O read request and the virtual machine front-end I/O write request; and

performing data migration by adopting a low-priority data migration thread when the virtual machine is idle.

13. A virtual storage migration system, comprising at least one virtual machine, a source storage device, a destination storage device and a virtual machine monitor, wherein the virtual machine monitor is configured to:

start a data migration process, and copy, from the source storage device to the destination storage device, a data block in a virtual disk to be migrated;

during the data migration process, when a virtual machine front-end input/output (I/O) read request is received, directly reading, from the source storage device, data that corresponds to the virtual machine front-end input/output (I/O) read request; and

when a virtual machine front-end I/O write request is received, determine whether a migration data block that corresponds to the virtual machine front-end I/O write request is being migrated, and if the migration data block that corresponds to the virtual machine front-end I/O write request is being migrated, execute a write operation that corresponds to the virtual machine front-end I/O write request after the migration of the migration data block is completed;

if the migration data block that corresponds to the virtual machine front-end I/O write request is not being migrated, execute the write operation that corresponds to the virtual machine front-end I/O write request; and

after all data blocks in the virtual disk to be migrated are copied to the destination storage device, stop the data migration process, and switch the Virtual disk managed by a virtual machine manager from the source storage device to the destination storage device.

14. The system according to claim 13, wherein the virtual machine monitor is further configured to:

allocate a storage space in the destination storage device, and copy a virtual machine configuration file to the destination storage device, and setting a data migration flag, wherein the data migration flag is used to identify that data in the virtual disk to be migrated is currently being migrated.

15. The system according to claim 14, wherein the virtual machine monitor is further configured to:

clear the data migration flag, and delete a virtual disk image that corresponds to the virtual disk in the source storage device.

16. The system according to claim 13, wherein the virtual machine monitor is further configured to:

preferentially process a virtual machine front-end I/O access request, wherein the front-end I/O access request comprises the virtual machine front-end I/O read request and the virtual machine front-end I/O write request; and

perform data migration by adopting a low-priority data migration thread when the virtual machine is idle.

17. A computer-readable medium having computer executable instructions for performing a virtual storage migration method comprising:

starting a data migration process, and copying, from a source storage device to a destination storage device, a data block in a virtual disk to be migrated;

during the data migration process, when a virtual machine front-end input/output (I/O) read request is received, directly reading, from the source storage device, data that corresponds to the virtual machine front-end input/output (I/O) read request; and

when a virtual machine front-end I/O write request is received, determining whether a migration data block that corresponds to the virtual machine front-end I/O write request is being migrated, and if the migration data block that corresponds to the virtual machine front-end I/O write request is being migrated, executing a write operation that corresponds to the virtual machine front-end I/O write request after the migration of the migration data block is completed;

if the migration data block that corresponds to the virtual machine front-end I/O write request is not being migrated, executing the write operation that corresponds to the virtual machine front-end I/O write request; and

after all data blocks in the virtual disk to be migrated are copied to the destination storage device, stopping the data migration process, and switching the virtual disk managed by a virtual machine manager from the source storage device to the destination storage device.