Remote Shared Virtual Disk Snapshot Creation

• US 20170068469A1
• Filed: 09/03/2015
• Published: 03/09/2017
• Est. Priority Date: 09/03/2015
• Status: Abandoned Application

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Shankar, Vinod, Sekar, Balaji, Burch, Adam, Grebur, Brendan, Kurjanowicz, Matthew David
• Application Number:
  US14/844,958
• Publication Number:
  US 20170068469A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0683 Plurality of storage devices

Abstract

A storage system creates a snapshot of a virtual hard disk by switching an I/O request target for the virtual hard disk. A requestor may issue requests to the storage system requesting that specific operations of the process should be performed. A request may specify that more than one operation should be performed in one operation. After initializing a new virtual hard disk file, I/O requests directed to a target virtual hard disk file are held for later deliver. The I/O request target is switched from the target to the new virtual hard disk file. I/O requests are unblocked and the stored requests are delivered to the new virtual hard disk file. Additional I/O requests sent to the target virtual hard disk file may be redirected to the new virtual hard disk file.

Claims

1. A system for creating a snapshot of a virtual hard disk, comprising:

at least one processor; and

memory, operatively connected to the at least one processor and containing instructions that, when executed by the at least one processor, perform a method, the method comprising;

opening a handle to a virtual hard disk set file;

accessing the virtual hard disk using the handle, wherein the virtual hard disk comprises a first virtual hard disk file, and wherein accessing the virtual hard disk comprises writing at least a first sector of data to the virtual hard disk;

requesting creation of a snapshot of the virtual hard disk file, wherein the snapshot comprises the first sector of data;

after the snapshot of the virtual hard disk is created, accessing the virtual hard disk using the handle, wherein accessing the virtual hard disk comprises writing at least a second sector of data to the virtual hard disk.

2. The system of claim 1, wherein the method further comprises:

requesting a list of snapshots; and

receiving a list of snapshots.

3. The system of claim 2, wherein the list of snapshots is requested using the handle to the virtual hard disk set file.

4. The system of claim 1, wherein a second virtual hard disk file is created in response to the request to create the snapshot.

5. The system of claim 4, wherein the second sector of data is written to the second virtual hard disk file.

6. The system of claim 4, wherein the snapshot comprises the first hard disk file.

7. The system of claim 1, wherein the method further comprises:

requesting creation of a second snapshot; and

after requesting creation of the second snapshot, writing at least a third sector of data to the virtual hard disk using the handle, wherein the third sector of data is written to a third virtual hard disk.

8. The system of claim 1, wherein accessing the virtual hard disk and writing the first and second sectors are via a Tunnel Operation SCSI pass through request.

9. The system of claim 1, wherein, as a result of creating the snapshot, access requests issued for the virtual hard disk are redirected from the first virtual hard disk file to a second virtual hard disk file.

10. A method for creating a snapshot of a virtual hard disk, the method comprising:

initializing a second virtual hard disk, wherein initializing comprises creating an empty virtual hard disk file, initializing file headers, and receiving an indication that periodic snapshots should be created;

blocking I/O requests, wherein blocking I/O requests comprises holding I/O requests directed to the first virtual hard disk and instead storing the I/O requests in a data store for later delivery;

switching the target of I/O requests from the first virtual hard disk to the second virtual hard disk;

unblocking I/O requests, wherein unblocking I/O requests comprises delivering I/O requests from the data store to the second virtual hard disk and allowing subsequent I/O requests directed to the second virtual hard disk; and

finalizing the second virtual hard disk, wherein finalizing comprises cleaning up temporary data that was stored while creating the snapshot.

11. The method of claim 10, further comprising:

after a predetermined period of time, initializing a third virtual hard disk, blocking I/O requests, switching the target of I/O requests from the second virtual hard disk to the third virtual hard disk, unblocking I/O requests, and finalizing the third virtual hard disk.

12. The method of claim 10, wherein receiving an indication comprises receiving a log file name.

13. The method of claim 12, further comprising:

logging snapshot creation progress to a log file indicated by the log file name.

14. The method of claim 10, wherein initializing further comprises updating a virtual hard disk set file to point to the second virtual hard disk file.

15. The method of claim 10, wherein initializing further comprises adding an entry to the virtual hard disk set file to indicate that the snapshot is being created.

16. The method of claim 10, wherein blocking I/O requests further comprises blocking I/O requests for the entire virtual hard disk.

17. The method of claim 10, wherein switching the target of I/O requests further comprises redirecting I/O requests from the first virtual hard disk file to the second virtual hard disk file.

18. The method of claim 10, wherein unblocking I/O requests further comprises redirecting I/O requests from the first virtual hard disk file to the second virtual hard disk file.

19. The method of claim 10, wherein a single operation may comprise two or more stages selected from the group consisting of initializing the second virtual hard disk file, blocking I/O requests, switching the target of I/O request, unblocking I/O requests, and finalizing the snapshot creation process.

20. A system comprising:

initialization means for initializing a snapshot of a first virtual hard disk;

blocking means for blocking I/O requests directed to the first virtual hard disk;

target switching means for switching a target of an I/O request from the first virtual hard disk to a second virtual hard disk;

unblocking means for unblocking subsequent I/O requests; and

finalization means for finalizing the second virtual hard disk.