System and method for transparently accessing a virtual disk using a file-based protocol

• US 20070100792A1
• Filed: 11/30/2006
• Published: 05/03/2007
• Est. Priority Date: 04/25/2003
• Status: Active Grant

• Current Assignee: Arthur Lent, Brian Pawlowski, Jeffrey Kimmel, Mohan Srinivasan, Vijayan Rajan
• Original Assignee: Arthur Lent, Brian Pawlowski, Jeffrey Kimmel, Mohan Srinivasan, Vijayan Rajan
• Inventors: Pawlowski, Brian, Srinivasan, Mohan, Rajan, Vijayan, Lent, Arthur, Kimmel, Jeffrey
• Granted Patent: US 7,904,482 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: Y10S 707/99932 Access augmentation or optimizing

Abstract

A system and method enabling transparent access to blocks, such as virtual disks, stored on a storage system using a file-based protocol. The system and method traps in-coming file-based protocol open commands to check for a predetermined modification to the file name. If the system and method detects the predetermined modification, then the virtual disk associated with the file name is exported to the client issuing the open command and the client receives a response from the storage system. The client, in response to receiving the response to the open command, creates a new device instantiation for reading and writing raw data to the virtual disk.

Claims

1. A method for a client of a storage system to transparently access a virtual disk on the storage system using a file-based protocol, the method comprising the steps of:

sending, a file open command, from the client to the storage system, the file open command including a modified file name;

checking, for the modified file name;

at the storage system, and

in response to detecting the modified file name, performing a transparent open process.

2. The method of claim 1 wherein the modified file name comprises a predetermined prefix to the file name.

3. The method of claim 1 wherein the modified file name comprises a predetermined suffix to the file name.

4. The method of claim 1 wherein the transparent open process further comprises the steps of:

mapping the virtual disk for a file to the client;

mapping, by the client, an exported logical unit number;

sending, by the client, a device identification to the storage system;

responding, by the storage system, to the open command issued by the client;

creating a new instance of a device using the device identification; and

returning a file descriptor to an application that issued the open command.

5. The method of claim 4 wherein the step of mapping the virtual disk for the file to the client further comprises the steps of:

determining if the file comprises the virtual disk;

converting, in response to determining that the file does not comprise the virtual disk, the file to the virtual disk; and

exporting the virtual disk to the client.

6. The method of claim 4 wherein the device identification further comprises a major number and a minor number.

7. The method of claim 4 wherein the step of exporting the virtual disk to the client further comprises the step of setting an appropriate lun mask so that the client may access the virtual disk.

8. The method of claim 4 wherein the step of mapping the exported logical unit number by the client further comprises the steps of:

determining if the logical unit number is already mapped;

rescanning, in response to determining that the logical unit number is not already mapped, a device bus to locate the logical unit number; and

creating a device identification associated with the logical unit number.

9. The method of claim 8 wherein the device bus further comprises a small computer system interface bus.

10. The method of claim 8 wherein the device identification further comprises a major number and a minor number.

11. The method of claim 1 wherein the virtual disk comprises an encapsulated data container embodied as a special file.

12. The method of claim 1 further comprising the step of transparently performing, by the client, input/output operations to the virtual disk.

13. The method of claim 12 wherein the input/output operations are directed to a character device associated with the virtual disk.

14. A method for a client of a storage system to access transparently a virtual disk on the storage system using a file-based protocol, the method comprising the steps of:

sending, by the client to the storage system, a modified file open command;

checking, by the storage system for the modified file open command;

mapping in response to detecting the modified file open command, a virtual disk for the file to the client;

mapping, by the client, an exported logical unit number;

sending, by the client, a device identification to the storage system;

responding, by the storage system, to the open command issued by the client;

creating a new instance of a device using the device identification; and

returning a file descriptor to an application that issued the open command.

15. The method of claim 14 wherein the step of mapping the exported logical unit number by the client further comprises the steps of:

determining if the logical unit number is already mapped;

rescanning, in response to determining if the logical unit number is not already mapped, a device bus to locate the logical unit number; and

creating a device identification associated with the logical unit number.

16. The method of claim 15 wherein the device bus further comprises a small computer system interface bus.

17. The method of claim 15 wherein the device identification further comprises a major number and a minor number.

18. A network storage system comprising:

a storage appliance executing a storage operating system having a file-based protocol proxy layer adapted to identify incoming file open requests that contain a modified file name; and

a client operatively interconnected with the storage appliance via a file-based transport medium and a block-based transport medium, the client including a mount daemon adapted to interact with the proxy layer to enable a file to be opened using a file-based protocol command and to perform input/output operations to a virtual disk embodying the file using the block-based transport medium.

19. A network storage system comprising:

means for identifying files to be opened using a block-based protocol transport medium and a file-based protocol namespace;

means for exporting an identified file as a virtual disk to a requesting client; and

a client containing means for generating a new device instantiation associated with the exported virtual disk, wherein the new device instantiation enables the client to direct input/output operations to the virtual disk.

20. A computer readable media, including program instructions executing on a computer, for transparently accessing a virtual disk using a file-based protocol, the program instructions including instructions for performing the steps of:

sending, by the client to the storage system, a file open command, the file open command including a modified file name;

checking, by the storage system, for the modified file name;

performing, in response to detecting the modified file name, a transparent open process.