SYSTEMS AND METHODS FOR ATTACHING A VIRTUAL MACHINE VIRTUAL HARD DISK TO A HOST MACHINE

• US 20090235358A1
• Filed: 05/26/2009
• Published: 09/17/2009
• Est. Priority Date: 12/10/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Tolba, Ahmed M.
• Granted Patent: US 8,312,212 B2
• Time in Patent Office: Days
• US Class Current: 726/24
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/0676 Magnetic disk device

Abstract

Various embodiments of the present invention are directed to systems and methods for “attaching” a virtual hard drive to the physical computer hardware by implementing a specialized disk controller driver for the host operating system that is recognized by the host operating system as a disk controller driver but which in fact also emulates the virtual hard disk it is “attached” to. When the host operating system sends requests to read and write sectors from the virtual hard drive, the specialized driver (the “virtual hard drive controller driver”) directly accesses and manipulates the back-end file mentioned above. Thus the virtual disk is “attached” and recognizable by the host operating system and can be manipulated thereby (and applications executing thereon).

Claims

1. A method for accessing a virtual file on a virtual hard drive comprising:

running a host operating system, the host operating system including a hard driver disk controller configured to control a physical hard drive;

managing, by the host operating system a virtual machine, wherein the virtual machine includes a virtual hard drive;

running, by the host operating system, a virtual hard drive disk controller, wherein the virtual hard drive disk controller is configured to control the virtual hard drive of the virtual machine;

receiving, from an application, a request to access a virtual file stored in the virtual hard drive of the virtual machine; and

accessing, by the host operating system using the virtual disk controller to interface with the hard drive disk controller, a file on a physical hard drive, said file corresponding to said virtual file stored in the virtual hard drive.

2. The method of claim 1 wherein accessing the file includes modifying code of a guest operating system stored in the virtual hard drive.

3. The method of claim 1, wherein accessing the file includes scanning the contents of the file for a computer virus.

4. The method of claim 1, wherein receiving from an application a request further comprises:

receiving a request from an application that is executed by a second virtual machine.

5. The method of claim 1, wherein receiving from an application a request further comprises:

receiving a request from an application executing on a remote computer system.

6. The method of claim 1, wherein said file comprises a plurality of files.

7. A computer system, comprising:

a processor coupled to a computer readable storage medium, the computer readable storage medium comprising;

instructions for controlling, by a privileged process, a first and second virtual machine, wherein the second virtual machine includes a virtual hard drive;

instructions for receiving, by the privileged process, a request to access a virtual file on said virtual hard drive, the request received from the first virtual machine;

instructions for determining, by the privileged process, that the virtual file corresponds to a file stored on a physical hard drive;

instructions for accessing, by the privileged process, the file on the physical hard drive; and

instructions for sending, by the privileged process, information related to the file to the first virtual machine.

8. The computer system of claim 7, wherein the request includes a request to access the virtual file to scan the contents of the virtual file for a computer virus.

9. The computer system of claim 7, wherein the request includes a request to patch a guest operating system stored in the virtual hard drive.

10. The computer system of claim 7, wherein said request includes a request to read said virtual file.

11. The computer system of claim 7, wherein said request includes a request to write to said virtual file.

12. The computer system of claim 7, wherein the privileged processes includes a hypervisor.

13. The computer system of claim 7, wherein the privileged processes is effectuated by a host operating system.

14. A computer readable storage medium including processor executable instructions, the computer readable storage medium comprising:

instructions for determining that a virtual file stored in a virtual hard drive of a virtual machine corresponds to a file stored on a physical hard drive, wherein the virtual hard drive is stored on the physical hard drive; and

instructions for accessing the physical file without running the virtual machine.

15. The computer readable storage medium of claim 14, wherein the virtual machine is an online virtual machine.

16. The computer readable storage medium of claim 14, wherein accessing the physical file without running the virtual machine includes accessing the physical file without executing a virtual processor associated with the virtual machine.

17. The computer readable storage medium of claim 14, wherein accessing the physical file without running the virtual machine includes accessing the physical file without executing a guest operating system of the virtual machine.

18. The computer readable storage medium of claim 14, further comprising:

instructions for receiving a request to access the physical file from a second virtual machine.

19. The computer readable storage medium of claim 14, further comprising:

instructions for receiving a request to access the physical file from a remote networked computer system.

20. The computer readable storage medium of claim 14, wherein accessing the physical file includes scanning the contents of the physical file for a computer virus.