Systems and methods for reclaiming storage space from virtual machine disk images

• US 8,881,144 B1
• Filed: 11/22/2011
• Issued: 11/04/2014
• Est. Priority Date: 11/22/2011
• Status: Active Grant

• Current Assignee: Veritas Technologies, LLC (Whitehouse Group Ltd.)
• Original Assignee: Symantec Corporation (NortonLifeLock Inc.)
• Inventors: Banerjee, Anindya, Mukherjee, Anirban
• Primary Examiner(s): Truong, Camquy
• Application Number:
  US13/302,813
• Time in Patent Office: 1,078 Days
• US Class Current: 718/1
• CPC Class Codes: G06F 11/1484 involving virtual machines
• CPC Class Codes: G06F 12/0253 Garbage collection, i.e. reclamation of unreferenced memory
• CPC Class Codes: G06F 16/1727 Details of free space management performed by the file system saving storage space on storage systems G06F3/0608; management of blocks in storage devices G06F3/064
• CPC Class Codes: G06F 16/188 Virtual file systems
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0662 Virtualisation aspects
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD
• CPC Class Codes: G06F 9/461 Saving or restoring of program or task context

Abstract

A computer-implemented method for reclaiming storage space from virtual machine disk images may include (1) identifying a virtual machine that uses a virtual machine disk image as a virtual disk for storage, the virtual machine disk image being stored on a thin-provisioned volume within a host file system, (2) determining that a portion of the virtual machine disk image represents a portion of the virtual disk that is unused by a file system of the virtual machine, (3) based on determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine, marking the portion of the virtual machine disk image for reclamation from the thin-provisioned volume, and (4) reclaiming the marked portion of the virtual machine disk image from the thin-provisioned volume. Various other methods, systems, and computer-readable media are also disclosed.

Claims

1. A computer-implemented method for reclaiming storage space from virtual machine disk images, at least a portion of the method being performed by a computing device comprising at least one processor, the method comprising:

identifying a virtual machine that uses a virtual machine disk image as a virtual disk for storage, the virtual machine disk image being stored on a thin-provisioned volume within a host file system;

pausing the virtual machine;

after pausing the virtual machine, determining that a portion of the virtual machine disk image represents a portion of the virtual disk that is unused by a file system of the virtual machine, wherein determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine comprises querying a virtualization system that implements the virtual machine for information identifying at least one portion of the virtual disk that is used by the file system of the virtual machine;

based on determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine, marking the portion of the virtual machine disk image for reclamation from the thin-provisioned volume, wherein marking the portion of the virtual machine disk image for reclamation from the thin-provisioned volume comprises punching a hole within the virtual machine disk image within the host file system;

reclaiming the marked portion of the virtual machine disk image from the thin-provisioned volume;

resuming the virtual machine after reclaiming the marked portion.

2. The computer-implemented method of claim 1, further comprising:

identifying an attempt to read from the marked portion of the virtual machine disk image;

fulfilling the attempt with null data based on the marked portion being marked.

3. The computer-implemented method of claim 1, further comprising:

identifying an additional portion of the virtual machine disk image that represents a portion of the virtual disk that was used by the file system of the virtual machine to store a file that was subsequently deleted;

based on determining that the additional portion is unused by the file system of the virtual machine, marking the additional portion of the virtual machine disk image for reclamation from the thin-provisioned volume;

reclaiming the marked additional portion of the virtual machine disk image from the thin-provisioned volume.

4. The computer-implemented method of claim 1, wherein determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine comprises receiving a communication from an agent running within the virtual machine identifying the portion of the virtual disk as unused by the file system of the virtual machine.

5. The computer-implemented method of claim 1, wherein determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine is performed in response to identifying a reclamation request received by the host file system.

6. The computer-implemented method of claim 1, wherein determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine comprises parsing the virtual machine disk image to locate unused portions based on a format of the virtual machine disk image.

7. The computer-implemented method of claim 1, further comprising taking a snapshot of the virtual machine disk image before determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine.

8. A system for reclaiming storage space from virtual machine disk images, the system comprising:

an identification module programmed to identify a virtual machine that uses a virtual machine disk image as a virtual disk for storage, the virtual machine disk image being stored on a thin-provisioned volume within a host file system;

a determination module programmed to;

pause the virtual machine;

after pausing the virtual machine, determine that a portion of the virtual machine disk image represents a portion of the virtual disk that is unused by a file system of the virtual machine, wherein determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine comprises querying a virtualization system that implements the virtual machine for information identifying at least one portion of the virtual disk that is used by the file system of the virtual machine;

a marking module programmed to, based on determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine, mark the portion of the virtual machine disk image for reclamation from the thin-provisioned volume, wherein marking the portion of the virtual machine disk image for reclamation from the thin-provisioned volume comprises punching a hole within the virtual machine disk image within the host file system;

a reclamation module programmed to;

reclaim the marked portion of the virtual machine disk image from the thin-provisioned volume;

resume the virtual machine after reclaiming the marked portion;

at least one hardware processor configured to execute the identification module, the determination module, the marking module, and the reclamation module.

9. The system of claim 8, further comprising a fulfillment module programmed to:

identify an attempt to read from the marked portion of the virtual machine disk image;

fulfill the attempt with null data based on the marked portion being marked.

10. The system of claim 8, wherein:

the identification module is further programmed to identify an additional portion of the virtual machine disk image that represents a portion of the virtual disk that was used by the file system of the virtual machine to store a file that was subsequently deleted;

the determination module is further programmed to, based on determining that the additional portion is unused by the file system of the virtual machine, mark the additional portion of the virtual machine disk image for reclamation from the thin-provisioned volume;

the reclamation module is further programmed to reclaim the marked additional portion of the virtual machine disk image from the thin-provisioned volume.

11. The system of claim 8, wherein the determination module is programmed to determine that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine by receiving a communication from an agent running within the virtual machine identifying the portion of the virtual disk as unused by the file system of the virtual machine.

12. The system of claim 8, wherein the determination module is programmed to determine that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine in response to identifying a reclamation request received by the host file system.

13. The system of claim 8, wherein the determination module is programmed to determine that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine by parsing the virtual machine disk image to locate unused portions based on a format of the virtual machine disk image.

14. The system of claim 8, wherein the determination module is further programmed to take a snapshot of the virtual machine disk image before determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine.

15. A non-transitory computer-readable-storage medium comprising one or more computer-executable instructions that, when executed by at least one processor of a computing device, cause the computing device to:

identify a virtual machine that uses a virtual machine disk image as a virtual disk for storage, the virtual machine disk image being stored on a thin-provisioned volume within a host file system;

pause the virtual machine;

after pausing the virtual machine, determine that a portion of the virtual machine disk image represents a portion of the virtual disk that is unused by a file system of the virtual machine, wherein determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine comprises querying a virtualization system that implements the virtual machine for information identifying at least one portion of the virtual disk that is used by the file system of the virtual machine;

based on determining that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine, mark the portion of the virtual machine disk image for reclamation from the thin-provisioned volume, wherein marking the portion of the virtual machine disk image for reclamation from the thin-provisioned volume comprises punching a hole within the virtual machine disk image within the host file system;

reclaim the marked portion of the virtual machine disk image from the thin-provisioned volume;

resume the virtual machine after reclaiming the marked portion.

16. The computer-readable-storage medium of claim 15, wherein the one or more computer-executable instructions further cause the computing device to:

identify an attempt to read from the marked portion of the virtual machine disk image;

fulfill the attempt with null data based on the marked portion being marked.

17. The computer-readable-storage medium of claim 15, wherein the one or more computer-executable instructions further cause the computing device to:

identifying an additional portion of the virtual machine disk image that represents a portion of the virtual disk that was used by the file system of the virtual machine to store a file that was subsequently deleted;

based on determining that the additional portion is unused by the file system of the virtual machine, marking the additional portion of the virtual machine disk image for reclamation from the thin-provisioned volume;

reclaiming the marked additional portion of the virtual machine disk image from the thin-provisioned volume.

18. The computer-readable-storage medium of claim 15, wherein the one or more computer-executable instructions cause the computing device to determine that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine by causing the computing device to receive a communication from an agent running within the virtual machine identifying the portion of the virtual disk as unused by the file system of the virtual machine.

19. The computer-readable-storage medium of claim 15, wherein the one or more computer-executable instructions cause the computing device to determine that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine in response to identifying a reclamation request received by the host file system.

20. The computer-readable-storage medium of claim 15, wherein the one or more computer-executable instructions cause the computing device to determine that the portion of the virtual machine disk image represents the portion of the virtual disk that is unused by the file system of the virtual machine by causing the computing device to parse the virtual machine disk image to locate unused portions based on a format of the virtual machine disk image.