Transparent file replication using namespace replication

• US 7,587,422 B2
• Filed: 04/23/2004
• Issued: 09/08/2009
• Est. Priority Date: 04/24/2003
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: NeoPath Networks, Inc. (Cisco Systems, Inc.)
• Inventors: Wong, Thomas K., Chawla, Rajeev, Tsirigotis, Panagiotis, Iyengar, Anand
• Primary Examiner(s): Wong; Leslie
• Application Number:
  US10/831,701
• Publication Number:
  US 20040267752A1
• Time in Patent Office: 1,964 Days
• Field of Search: 707/10, 707/104.1, 707/200, 707/204, 707/E17.01, 707/E17.032, 709/214, 709/215, 709/217, 709/223, 709/226, 709/201, 709/207, 711/161, 711/162
• US Class Current: 1/1
• CPC Class Codes: G06F 16/10 File systems; File servers
• 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
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing
• CPC Class Codes: Y10S 707/99948 Application of database or data structure, e.g. distributed, multimedia, or image
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A NAS switch, in the data path of a client and a NAS file server on the storage network, provides a centralized point of reconfiguration after a network change that alleviates the need for reconfiguration of each connected client. The client uses a NAS request to access a storage object to the NAS switch using a switch file handle that is independent of object location and that can be used to locate the primary and its replica storage objects if the object is subsequently replicated. A replication module replicates a namespace separately from data contained therein. Afterwards, synchronicity module looks-up the switch file handle in a file handle replication table to determine if the object has been replicated and, if so, sends one of the replica NAS file handles. The synchronicity module also maintains synchronicity between the primary and replica file servers through critical NAS requests that modify objects such as create, delete, and the like.

Claims

1. A method for accessing an object in a storage network, the method comprising:

at a NAS (Network Attached Storage) switch, mapping a switch file handle that is independent of a location of an object to a first NAS file handle that is indicative of the location of the object on a primary NAS file server;

providing the switch file handle to a client;

at the NAS switch, replicating the object on the primary NAS file server to a replica object on a replica NAS file server, the replicating comprising;

replicating a namespace containing the object, wherein on the replica NAS file server a directory associated with the object is separately replicated from replicating data associated with the object; and

mapping the switch file handle to a second NAS file handle that is indicative of a location of the replica object on the replica NAS file server.

2. The method of claim 1, wherein the object comprises a directory having objects representative of sub-directories and files.

3. The method of claim 1, wherein the object comprises a file.

4. The method of claim 1, further comprising receiving the switch file handle with a corresponding operation.

5. The method of claim 1, further comprising submitting the switch file handle including the NAS request to the replica NAS file server.

6. The method of claim 1, wherein the replicating the object comprises:

during the replicating, sending critical requests involving the object to both the primary NAS file server and the replica NAS file server, each critical request comprising a create request, a delete request, a move request or a copy request.

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

prior to replicating the object, storing a file handle in the location on the replica NAS file server, the stored file handle indicative of the location of the object on the primary NAS file server.

8. The method of claim 1, wherein the replicating the object comprises updating a file handle replication table with an entry for the location on the primary NAS file server and an entry for the location on the replica NAS file server responsive to a successful migration.

9. The method of claim 1, further comprising:

receiving the switch file handle with a request from a client;

looking-up the second NAS file handle in the file handle replication table with the switch file handle; and

sending the request to the location on the replica NAS file server.

10. The method of claim 1, further comprising:

receiving a request concerning a non-replicated object;

looking-up the non-replicated object in the file replication table with a non-replicated file handle; and

responsive to failing to find an entry for the non-replicated object in the file handle replication table, sending the second request to a second location on the primary NAS file server.

11. The method of claim 1, wherein the request comprises a read request or a write request.

12. The method of claim 1, wherein the request comprises a create request, a delete request, a move request, or a copy request.

13. The method of claim 1, wherein the NAS file handle comprises a NFS (Network File System) file handle or a CIFS (Common Internet File System) file handle.

14. A method for accessing an object in a decentralized storage network, the method comprising:

at a centralizing switch, mapping a switch file handle that is independent of a location of an object to a first NAS file handle that is indicative of the location of the object on a primary NAS file server;

providing the switch file handle to a client;

at the centralizing switch, replicating the object on the primary NAS file server to a replica object on a replica NAS file server, the replicating comprising;

replicating a namespace containing the object, wherein on the replica NAS file server a directory associated with the object is separately replicated from replicating data associated with the object; and

mapping the switch file handle to a second server file handle that is indicative of a location of the replica object on the replica NAS file server.

15. A NAS (Network Attached Storage) switch to access an object in a storage network, comprising:

a file server interface to map a switch file handle that is independent of a location of an object to a first NAS file handle that is indicative of the location of the object on a primary NAS file server; and

a replication module to copy the object on the primary NAS file server to a replica object on a replica NAS file server, wherein the replicating module replicates a namespace containing the object, wherein on the replica NAS file server a directory associated with the object is separately replicated from replicating data associated with the object; and

wherein the file server interface maps the switch file handle to a second NAS file handle that is indicative of a location of the replica object on the replica NAS file server.

16. The NAS switch of claim 15, wherein the object comprises a directory having objects representative of sub-directories and files.

17. The NAS switch of claim 15, wherein the object comprises a file.

18. The NAS switch of claim 15, further comprising a client module to receive the switch file handle, with a corresponding operation, from a client.

19. The NAS switch of claim 17, wherein the file server module submits the second file handle including the NAS request to the replica NAS file server.

20. The NAS switch of claim 15, wherein a client module receives the switch file handle with a request from a client;

a synchronization module looks-up the second NAS file handle in a file handle replication table with the switch file handle; and

responsive to finding an entry in the file handle replication table, the server module also sends the request to the location on the replica NAS file server.

21. The NAS switch of claim 15 wherein a client module receives a request concerning a non-replicated object;

a synchronization modules looks-up the non-replicated object in the file replication table with a non-replicated file handle; and

responsive to failing to find an entry for the non-replicated object in the file handle replication table, the file server module sends the non-replicated request to the primary NAS file server location using the first NAS file handle.

22. The NAS switch of claim 15, wherein the request comprises a read request or a write request.

23. The NAS switch of claim 15, wherein the request comprises a create request, a delete request, a move request, or a copy request.

24. The NAS switch of claim 15, wherein the NAS file handle comprises a NFS (Network File System) file handle or a CIFS (Common Internet File System) file handle.

25. A computer program product, comprising a computer-readable storage medium having computer program instructions and data embodied thereon in a NAS (Network Attached Storage) switch, for accessing an object in a storage network, comprising:

program code for mapping at the NAS switch a switch file handle that is independent of a location of an object to a first NAS file handle that is indicative of the location of the object on a primary NAS file server;

program code for providing the switch file handle to a client;

program code for replicating at the NAS switch the object on the NAS primary file server to a replica object on a NAS replica file server, wherein the replicating the object comprises replicating a namespace containing the object, wherein on the replica NAS file server a directory associated with the object is separately replicated from replicating data associated with the object; and

program code for mapping the switch file handle to a second NAS file handle that is indicative of a location of the replica object on the replica NAS file server.

26. The computer program product of claim 25, wherein the object comprises a directory having objects representative of sub-directories and files.

27. The computer program product of claim 25, wherein the object comprises a file.

28. The computer program product of claim 25, further comprising program code for receiving the switch file handle with a corresponding operation.

29. The computer program product of claim 25, further comprising program code for submitting the switch file handle including the NAS request to the replica NAS file server.

30. The computer program product of claim 25, further comprising:

program code for receiving the switch file handle with a request from a client;

program code for looking-up the second NAS file handle in the file handle replication table with the switch file handle; and

program code for sending the request to the location on the replica NAS file server.

31. The computer program product of claim 25, further comprising:

program code for receiving a request concerning a non-replicated object;

program code for looking-up the non-replicated object in the file replication table with a non-replicated file handle; and

program code for responsive to failing to find an entry for the non-replicated object in the file handle replication table, sending the second request to a second location on the primary NAS file server.

32. The computer program product of claim 25, wherein the request comprises a read request or a write request.

33. The computer program product of claim 25, wherein the request comprises a create request, a delete request, a move request, or a copy request.

34. The computer program product of claim 25, wherein the NAS file handle comprises a NFS (Network File System) file handle or a CIFS (Common Internet File System) file handle.