System and Method for Replicating Disk Images in a Cloud Computing Based Virtual Machine File System

• US 20110022574A1
• Filed: 07/21/2009
• Published: 01/27/2011
• Est. Priority Date: 07/21/2009
• Status: Active Grant

• Current Assignee: Vmware LLC (Broadcom, Inc.)
• Original Assignee: VMware, Inc. (Broadcom, Inc.)
• Inventors: Hansen, Jacob Gorm
• Granted Patent: US 8,352,482 B2
• Time in Patent Office: Days
• US Class Current: 707/698
• CPC Class Codes: G06F 11/1484 involving virtual machines
• CPC Class Codes: G06F 11/2025 using centralised failover control functionality
• CPC Class Codes: G06F 11/2041 with more than one idle spare processing component
• CPC Class Codes: G06F 11/2048 where the redundant components share neither address space nor persistent storage
• CPC Class Codes: G06F 11/2097 maintaining the standby controller/processing unit updated initialisation or re-synchronisation thereof G06F11/1658 and subgroups
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 16/178 Techniques for file synchronisation in file systems
• CPC Class Codes: G06F 16/188 Virtual file systems
• CPC Class Codes: G06F 16/20 of structured data, e.g. relational data
• CPC Class Codes: G06F 16/23 Updating
• CPC Class Codes: G06F 2009/45583 Memory management, e.g. access or allocation
• CPC Class Codes: G06F 2009/45595 Network integration; Enabling network access in virtual machine instances
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects

Abstract

A replicated decentralized storage system comprises a plurality of servers that locally store disk images for locally running virtual machines as well as disk images, for failover purposes, for remotely running virtual machines. To ensure that disk images stored for failover purposes are properly replicated upon an update of the disk image on the server running the virtual machine, a hash of a unique value known only to the server running the virtual machine is used to verify the origin of update operations that have been transmitted by the server to the other servers storing replications of the disk image for failover purposes. If verified, the update operations are added to such failover disk images.

Claims

1. A computer system configured to replicate a log file stored in a primary server, the computer system comprising:

a local storage unit for storing a replication of the log file; and

a software module configured to receive an update operation from the primary server, wherein the update operation includes a public unique id and a private unique id from a previous update operation, obtain a previous public unique id from a last update operation stored in the replication of the log file stored in the local storage unit, generate a hash of the private unique id, compare the generated hash of the private unique id to the previous public unique id, and append the update operation to the replication of the log file upon confirmation that the generated hash of the private unique id equals the previous public unique id.

2. The computer system of claim 1, wherein the public unique id is a hash of a new private unique id generated from a master secret value stored in the primary server.

3. The computer system of claim 2, wherein the new private unique id comprises a hash of a bitwise intersection of the master secret value, the private unique id from the previous update operation, and data corresponding to the update operation.

4. The computer system of claim 1, wherein the log file comprises a list of update operations.

5. The computer system of claim 4, wherein the log file and the replication of the log file correspond to a disk image of a virtual machine running on the primary server.

6. The computer system of claim 5, wherein the update operation further includes a data portion corresponding to a write operation issued by the virtual machine and comprising a logical address of the virtual machine and data to be written to the logical address.

7. The computer system of claim 1, wherein the software module is further configured to reject the update operation upon confirmation that the generated hash of the private unique id does not equal the previous public unique id.

8. A method for updating a replication of a log file, wherein the log file is stored in a local storage unit of a primary server and the replication is stored in a local storage unit of a secondary server, the method comprising:

receiving an update operation from the primary server, wherein the update operation includes a public unique id and a private unique id from a previous update operation;

obtaining a previous public unique id from a last update operation stored in the replication of the log file stored in the local storage unit of the secondary server;

generating a hash of the private unique id;

comparing the generated hash of the private unique id to the previous public unique id; and

appending the update operation to the replication of the log file upon confirmation that the generated hash of the private unique id equals the previous public unique id.

9. The method of claim 8, wherein the public unique id is a hash of a new private unique id generated from a master secret value stored in the primary server.

10. The method of claim 9, wherein the new private unique id comprises a hash of a bitwise intersection of the master secret value, the private unique id from the previous update operation, and data corresponding to the update operation.

11. The method of claim 8, wherein the log file comprises a list of update operations.

12. The method of claim 11, wherein the log file and the replication of the log file correspond to a disk image of a virtual machine running on the primary server.

13. The method of claim 12, wherein the update operation further includes a data portion corresponding to a write operation issued by the virtual machine and comprising a logical address of the virtual machine and data to be written to the logical address.

14. The method of claim 8, further comprising rejecting the update operation upon confirmation that the generated hash of the private unique id does not equal the previous public unique id.

15. A computer-readable storage medium including instructions that, when executed by a processing unit of a secondary server having a local storage unit storing a replication of a log file stored on in a local storage unit of a primary server, causes the processing unit to update the replication by performing steps of:

receiving an update operation from the primary server, wherein the update operation includes a public unique id and a private unique id from a previous update operation;

obtaining a previous public unique id from a last update operation stored in the replication of the log file stored in the local storage unit of the secondary server;

generating a hash of the private unique id;

comparing the generated hash of the private unique id to the previous public unique id; and

appending the update operation to the replication of the log file upon confirmation that the generated hash of the private unique id equals the previous public unique id.

16. The computer readable storage medium of claim 15, wherein the public unique id is a hash of a new private unique id generated from a master secret value stored in the primary server.

17. The computer readable storage medium of claim 16, wherein the new private unique id comprises a hash of a bitwise intersection of the master secret value, the private unique id from the previous update operation, and data corresponding to the update operation.

18. The computer readable storage medium of claim 15, wherein the log file comprises a list of update operations.

19. The computer readable storage medium of claim 18, wherein the log file and the replication of the log file correspond to a disk image of a virtual machine running on the primary server.

20. The computer readable storage medium of claim 19, wherein the update operation further includes a data portion corresponding to a write operation issued by the virtual machine and comprising a logical address of the virtual machine and data to be written to the logical address.