LOOSE SYNCHRONIZATION OF VIRTUAL DISKS

• US 20090240904A1
• Filed: 03/20/2008
• Published: 09/24/2009
• Est. Priority Date: 03/20/2008
• Status: Active Grant

• Current Assignee: Vmware LLC (Broadcom, Inc.)
• Original Assignee: VMware, Inc. (Broadcom, Inc.)
• Inventors: AUSTRUY, Maxime, LEROY, Christian, DESAI, Asit, CZEZATKE, Christian, CHAMCHAM, Jad
• Granted Patent: US 8,291,180 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• 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 11/2094 Redundant storage or storage space G06F11/2056 takes precedence

Abstract

Computer implemented methods, computer program products and computer systems synchronize copies of a virtual disk. A record of blocks that are modified during an access session of a copy of the virtual disk is maintained. For each partition of the virtual disk, a file system level indication of currently relevant blocks is obtained. Only those blocks that were modified during the access session and are currently relevant are copied to at least one additional copy of the virtual disk.

Claims

1. A computer implemented method for synchronizing copies of a virtual disk, the method comprising the steps of:

maintaining a record of blocks of a copy of a virtual disk that are modified during an access session;

for each partition of the virtual disk, obtaining a file system level indication of currently relevant blocks; and

copying blocks that were modified during the access session and are currently relevant to at least one additional copy of the virtual disk.

2. The method of claim 1 wherein maintaining a record of blocks of a virtual disk that are modified during an access session further comprises:

maintaining a bitmap in which each block of the virtual disk is represented by at least one bit, wherein the default value of each at least one bit indicates that the corresponding block has not been modified; and

responsive to a block of the virtual disk being modified during the access session, updating the value of the corresponding at least one bit to so indicate.

3. The method of claim 1 wherein obtaining a file system level indication of relevant blocks further comprises:

obtaining an internal file system maintained bitmap in which blocks of the virtual disk are represented by bits, wherein the values of the bits indicate usage statuses of corresponding blocks.

4. The method of claim 1 wherein obtaining a file system level indication of relevant blocks for each partition of the virtual disk, further comprises:

for each partition of the virtual disk, obtaining an internal file system maintained bitmap, in which blocks of the partition are represented by bits, wherein the values of the bits indicate usage statuses of corresponding blocks.

5. The method of claim 4 further comprising:

merging at least two obtained internal file system maintained bitmaps into a single bitmap.

6. The method of claim 1 wherein obtaining a file system level indication of relevant blocks further comprises:

for each partition of the virtual disk;

mounting a corresponding file system at a host level;

calling an operating system to request internal file system maintained block usage data;

responsive to the request, receiving internal file system maintained data indicating use statuses of blocks of the partition of the virtual disk; and

un-mounting the corresponding file system at a host level.

7. The method of claim 1 wherein copying blocks to at least one additional copy of the virtual disk further comprises performing at least one step from a group of steps consisting of:

copying the blocks to a copy of the virtual disk on a separate physical computer on which a user runs an associated virtual machine; and

copying the blocks to a backup copy of the virtual disk.

8. At least one computer readable medium containing a computer program product for synchronizing copies of a virtual disk, the computer program product comprising:

program code for maintaining a record of blocks of a copy of a virtual disk that are modified during an access session;

program code for, for each partition of the virtual disk, obtaining a file system level indication of currently relevant blocks; and

program code for copying blocks that were modified during the access session and are currently relevant to at least one additional copy of the virtual disk.

9. The computer program product of claim 8 wherein the program code for maintaining a record of blocks of a virtual disk that are modified during an access session further comprises:

program code for maintaining a bitmap in which each block of the virtual disk is represented by at least one bit, wherein the default value of each at least one bit indicates that the corresponding block has not been modified; and

program code for, responsive to a block of the virtual disk being modified during the access session, updating the value of the corresponding at least one bit to so indicate.

10. The computer program product of claim 8 wherein the program code for obtaining a file system level indication of relevant blocks further comprises:

program code for obtaining an internal file system maintained bitmap in which blocks of the virtual disk are represented by bits, wherein the values of the bits indicate usage statuses of corresponding blocks.

11. The computer program product of claim 8 wherein the program code for obtaining a file system level indication of relevant blocks for each partition of the virtual disk, further comprises:

program code for, for each partition of the virtual disk, obtaining an internal file system maintained bitmap, in which blocks of the partition are represented by bits, wherein the values of the bits indicate usage statuses of corresponding blocks.

12. The computer program product of claim 11 further comprising:

program code for merging at least two obtained internal file system maintained bitmaps into a single bitmap.

13. The computer program product of claim 8 wherein the program code for obtaining a file system level indication of relevant blocks further comprises:

program code for, for each partition of the virtual disk;

mounting a corresponding file system at a host level;

calling an operating system to request internal file system maintained block usage data;

responsive to the request, receiving internal file system maintained data indicating use statuses of blocks of the partition of the virtual disk; and

un-mounting the corresponding file system at a host level.

14. The computer program product of claim 8 wherein the program code for copying blocks to at least one additional copy of the virtual disk further comprises program code for performing at least one step from a group of steps consisting of:

copying the blocks to a copy of the virtual disk on a separate physical computer on which a user runs an associated virtual machine; and

copying the blocks to a backup copy of the virtual disk.

15. A computer system for synchronizing copies of a virtual disk, the computer system comprising:

means for maintaining a record of blocks of a copy of a virtual disk that are modified during an access session;

means for, for each partition of the virtual disk, obtaining a file system level indication of currently relevant blocks; and

means for copying blocks that were modified during the access session and are currently relevant to at least one additional copy of the virtual disk.

16. The computer system of claim 15 wherein the means for maintaining a record of blocks of a virtual disk that are modified during an access session further comprise:

means for maintaining a bitmap in which each block of the virtual disk is represented by at least one bit, wherein the default value of each at least one bit indicates that the corresponding block has not been modified; and

means for, responsive to a block of the virtual disk being modified during the access session, updating the value of the corresponding at least one bit to so indicate.

17. The computer system of claim 15 wherein the means for obtaining a file system level indication of relevant blocks further comprise:

means for obtaining an internal file system maintained bitmap in which blocks of the virtual disk are represented by bits, wherein the values of the bits indicate usage statuses of corresponding blocks.

18. The computer system of claim 15 wherein the means for obtaining a file system level indication of relevant blocks for each partition of the virtual disk further comprise:

means for, for each partition of the virtual disk, obtaining an internal file system maintained bitmap, in which blocks of the partition are represented by bits, wherein the values of the bits indicate usage statuses of corresponding blocks.

19. The computer system of claim 15 wherein the means for obtaining a file system level indication of relevant blocks further comprise:

means for, for each partition of the virtual disk;

mounting a corresponding file system at a host level;

calling an operating system to request internal file system maintained block usage data;

responsive to the request, receiving internal file system maintained data indicating use statuses of blocks of the partition of the virtual disk; and

un-mounting the corresponding file system at a host level.

20. The computer system of claim 15 wherein the means for copying blocks to at least one additional copy of the virtual disk further comprise means for performing at least one step from a group of steps consisting of:

copying the blocks to a copy of the virtual disk on a separate physical computer on which a user runs an associated virtual machine; and

copying the blocks to a backup copy of the virtual disk.

21. A computer implemented method for synchronizing copies of a virtual disk, the method comprising the steps of:

shutting down an active session of a first virtual machine, said first virtual machine being associated with a first copy of a virtual disk;

copying blocks of the virtual disk that were modified during the active session and are currently relevant to a second copy of the virtual disk, said second copy of the virtual disk being associated with a second virtual machine; and

starting said second virtual machine, such that said second virtual machine accesses said second copy of the virtual disk.

22. At least one computer readable medium containing a computer program product for synchronizing copies of a virtual disk, the computer program product comprising:

program code for shutting down an active session of a first virtual machine, said first virtual machine being associated with a first copy of a virtual disk;

program code for copying blocks of the virtual disk that were modified during the active session and are currently relevant to a second copy of the virtual disk, said second copy of the virtual disk being associated with a second virtual machine; and

program code for starting said second virtual machine, such that said second virtual machine accesses said second copy of the virtual disk.