Remote File Virtualization in a Switched File System

• US 20090094252A1
• Filed: 05/23/2008
• Published: 04/09/2009
• Est. Priority Date: 05/25/2007
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Attune Systems, Inc. (F5 Incorporated)
• Inventors: Vogel, Ron S., Wong, Thomas K.
• Granted Patent: US 8,682,916 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 16/1824 implemented using Network-attached Storage [NAS] architecture distributed or networked storage systems G06F3/067; protocols for distributed storage of data in a network H04L67/1097
• CPC Class Codes: G06F 16/1865 Transactional file systems
• CPC Class Codes: H04L 67/06 specially adapted for file transfer, e.g. file transfer protocol [FTP]
• CPC Class Codes: H04L 67/1095 Replication or mirroring of data, e.g. scheduling or transport for data synchronisation between network nodes

Abstract

A plurality of network file manager switches interoperate to provide remote file virtualization. Copies of file data and/or metadata are maintained at a central site and at one or more remote sites. The network file manager switch at the remote site may satisfy certain client requests locally without having to contact the network file manager switch at the central site. A global namespace is maintained and is communicated to all network file manager switches.

Claims

1. A switched file system comprising:

a central network file manager; and

at least one remote network file manager in communication coupled to the central network file manager via a communication network, wherein the central network file manager manages reference copies of data and metadata and wherein the remote network file managers maintain mirrored copies of data and metadata for use in servicing client requests without having to communicate with the central network file manager.

2. A switched file system according to claim 1, wherein the central network file manager and the at least one remote network file manager maintain a common global namespace.

3. A switched file system according to claim 1, wherein metadata is mirrored from the central network file manager to the at least one remote network file manager using a lazy mirroring technique.

4. A switched file system according to claim 3, wherein the central network file manager pushes metadata to the at least one remote network file manager.

5. A switched file system according to claim 4, wherein, after pushing metadata to a remote network file manager, the central network file manager verifies that the metadata has not changed since being pushed and notifies the remote network file manager that the metadata is valid.

6. A switched file system according to claim 4, wherein the central network file manager maintains statistics regarding access patterns by remote clients and pushes the metadata to the at least one remote network file manager based on the statistics.

7. A switched file system according to claim 3, wherein a remote network file manager pulls metadata from the central network file manager.

8. A switched file system according to claim 7, wherein, after receiving metadata from the central network file manager, the remote network file manager requests confirmation from the central network file manager that the metadata is still valid.

9. A switched file system according to claim 7, wherein the remote network file manager maintains statistics regarding access patterns by clients and pulls the metadata from the central network file manager based on the statistics.

10. A switched file system according to claim 3, wherein the metadata is mirrored in a breadth-first fashion.

11. A switched file system according to claim 3, wherein the metadata is mirrored in a depth-first fashion.

12. A switched file system according to claim 3, wherein, when metadata is updated at a remote network file manager, the remote network file manager communicates the updated metadata to the central network file manager, and the central network file manager notifies the remote network file managers that the remote site metadata is unsynchronized so that the remote network file managers do not use the unsynchronized metadata.

13. A switched file system according to claim 1, wherein data is mirrored from the central network file manager to the at least one remote network file manager using a lazy mirroring technique.

14. A switched file system according to claim 13, wherein, when a file is updated at a remote network file manager, the remote network file manager communicates the updated data to the central network file manager, and the central network file manager notifies the remote network file managers that the remote site data is unsynchronized so that the remote network file managers do not use the unsynchronized data.

15. A switched file system according to claim 13, wherein at least one of the central network file manager and the remote network file managers maintain statistics regarding client accesses, and wherein the data for such data mirroring is selected based on the statistics.

16. A switched file system according to claim 1, wherein the remote network file managers pass oplock requests from client devices through to the central network file manager.

17. A switched file system according to claim 1, wherein the remote network file managers handle oplock breaks and pass oplock breaks through to the client devices.

18. A switched file system according to claim 1, wherein the remote network file managers flush cached contents back to the central network file manager, and wherein the central network file manager notifies all remote network file managers to break file mirrors for the file.

19. A switched file system according to claim 1, wherein the data and metadata is copied from the central network file manager to the at least one remote network file manager according to a set of rules.

20. A switched file system according to claim 1, wherein the remote network file manager disallows access to mirrored copies of data and metadata when the remote network file manager is unable to communicate with the central network file manager over the communication network.

21. A switched file system according to claim 1, wherein the remote network file manager disallows modification of mirrored copies of data and metadata when the remote network file manager is unable to communicate with the central network file manager over the communication network.

22. A network file manager that operates as a client to file server nodes and as a server to client nodes and interacts with both the client nodes and the file server nodes using the standard network file protocols, wherein the network file manager implements SMB signing on communications with the file server nodes including SMB signing on messages used to pre-fetch data from the file server nodes.

23. A network file manager according to claim 22, wherein the network file manager further implements data compression on communications with the file server nodes.

24. A WAN optimization appliance that operates as a client to file server nodes, wherein the appliance implements SMB signing on communications with the file server nodes including SMB signing on messages used to pre-fetch data from the file server nodes.

25. A WAN optimization appliance according to claim 24, wherein the appliance further implements data compression on communications with the file server nodes.

26. A WAN optimization appliance comprising a broadcast service for delivering mirror break messages reliably and in priority from the central site to the remote sites.

27. A WAN optimization appliance comprising a file transfer service for pre-positioning files from a central site to a number of remote sites.

28. A WAN optimization appliance according to claim 27, wherein the appliance obtains optimal fingerprints from a set of files to be pre-positioned and pre-positions these fingerprints to remote devices.

29. A WAN optimization appliance according to claim 27, wherein the appliance obtains fingerprints from file objects in a global namespace for fingerprint preloading at remote sites.