Transparent file migration using namespace replication

• US 8,180,843 B2
• Filed: 01/24/2008
• Issued: 05/15/2012
• Est. Priority Date: 04/24/2003
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: NeoPath Networks, Inc. (Cisco Systems, Inc.)
• Inventors: Wong, Thomas K., Tsirigotis, Panagiotis, Iyengar, Anand, Chawla, Rajeev
• Primary Examiner(s): VU, VIET DUY
• Application Number:
  US12/019,582
• Publication Number:
  US 20080114854A1
• Time in Patent Office: 1,573 Days
• Field of Search: 709/213, 709/214, 709/215, 709/216, 709/217, 709/223, 709/224
• US Class Current: 709/214
• CPC Class Codes: G06F 16/119 Details of migration of file systems migration mechanisms in storage systems G06F3/0647
• CPC Class Codes: G06F 16/184 implemented as replicated file system
• 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

Abstract

A NAS switch provides file migrations in a NAS storage network that are transparent to the clients. A source file server exports an original NAS file handles indicative of object locations on the source file server to the NAS switch. The NAS switch modifies the original NAS file handles to an internal file system and maps the original NAS file handles to a switch file handles independent of location. The NAS switch exports the switch file handles to a client. The client looks-up objects and makes NAS requests to the source file server using switch file handles. The NAS switch performs file migration by first replicating the namespace containing data to be migrated from source file server to a destination file server. Separately, the NAS replicates data which is a relatively longer process than the namespace replication. During data replication, namespace access requests for objects are directed to the replicated namespace. After data replication, file object requests for migrated objects are redirected to the destination file server in a process that is transparent to the client.

Claims

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

receiving a NAS (Network Attached Storage) file handle for the object including a location of the object on a source file server;

sending to a client as representative of the object, a switch file handle for the object that is independent of the location of the object;

migrating the object from the location on the source file server to a location on a destination file server,

wherein the migrating comprises replicating a namespace associated with the object, the namespace located on the source file server and the replication of the namespace occurring separately from migrating data associated with the object;

receiving from the client an access request associated with the switch file handle;

mapping the switch file handle to the NAS file handle; and

sending the access request to the location on the destination file server using the NAS file handle.

2. The method of claim 1, wherein the replicated namespace is located on the destination file server.

3. The method of claim 2, wherein the migrating the object further comprises:

during migration, if the access request comprises a request to access or modify the namespace, sending the namespace access request to both the namespace and the replicated namespace during migration.

4. The method of claim 2, wherein the migrating the object further comprises:

prior to migrating object, storing a stored file handle in the location on the destination file server, the stored file handle indicative of the location of the object on the source file server.

5. The method of claim 2, wherein migrating the object further comprises:

after migrating the object, storing a stored file handle in the location on the source file server, the stored file handle indicative of the location of the object on the destination file server.

6. The method of claim 1, wherein the migrating the object comprises updating a file handle migration table with an entry for the location on the source file server and an entry for the location on the destination file server responsive to a successful migration.

7. A method for centrally accessing an object in a decentralized storage network, comprising:

receiving an input file handle for the object including a location of the object on a source file server;

sending to a client as representative of the object, a switch file handle independent of the location of the object;

migrating the object from the location on the source file server to a location on a destination file server,

wherein the migrating comprises replicating a namespace associated with the object, the namespace located on the source file server and the replication of the namespace occurring separately from migrating data associated with the object;

updating a file migration table after migration, the file migration table comprising an entry with object locations on the first and destination file servers;

receiving from the client an access request associated with the switch file handle;

mapping the switch file handle to the NAS file handle; and

redirecting the access request to the location on the destination file server using the NAS file handle.

8. The method of claim 7, wherein the first and destination file servers include file systems and the client does not include the file system.

9. A computer program product, comprising:

a computer-readable medium having computer program instructions and data embodied thereon for a method for accessing an object in a NAS (Network Attached Storage) storage network, the method comprising;

receiving a NAS (Network Attached Storage) file handle for the object including a location of the object on a source file server;

sending to a client as representative of the object, a switch file handle for the object that is independent of the location of the object;

migrating the object from the location on the source file server to a location on a destination file server,

wherein the migrating comprises replicating a namespace associated with the object, the namespace located on the source file server and the replication of the namespace occurring separately from migrating data associated with the object;

receiving from the client an access request associated with the switch file handle;

mapping the switch file handle to the NAS file handle; and

redirecting the access request to the location on the destination file server using the NAS file handle.

10. The computer program product of claim 9, wherein the replicated namespace is located on the destination file server.

11. The computer program product of claim 10, wherein the migrating the object further comprises:

during migration, sending the access request to both the namespace and the replicated namespace during migration.

12. The computer program product of claim 10, wherein the migrating the object further comprises:

prior to migrating object, storing a stored file handle in the location on the destination file server, the stored file handle indicative of the location of the object on the source file server.

13. The computer program product of claim 11, wherein the migrating the object further comprises:

after migrating the object, storing a stored file handle in the location on the source file server, the stored file handle indicative of the location of the object on the destination file server.

14. The computer program product of claim 11, wherein the migrating the object comprises updating a file handle migration table with an entry for the location on the source file server and an entry for the location on the destination file server responsive to a successful migration.

15. A NAS (Network Attached Storage) switch, comprising:

a file server interface to issue a switch file handle representative of an object in response to receiving a NAS file handle including a location of the object on a source file server, the switch file handle independent of the location of the object on the source file server;

a client server interface to send the switch file handle to a client and receive an access request from the client associated with the switch file handle;

a migration module to maintain records concerning migration of the object from the location on the source file server to a location on a destination file server, wherein the migrating comprises replicating a namespace associated with the object, the namespace located on the source file server and the replication of the namespace occurring separately from migrating data associated with the object and wherein the migration module enters the location of the object on the source file server and a location of the object on the destination file server in response to receiving an indication of successful migration; and

a redirection module, communicatively coupled to the migration module, the redirection module redirecting the access request received from the client to the location on the destination file server in part by mapping the switch file handle associated with the request to the NAS file handle.

16. The NAS switch of claim 15, wherein the replicated namespace is located on the destination file server.

17. The NAS switch of claim 16, wherein during migration, the redirection module sends the access request to both the namespace and the replicated namespace.

18. The NAS switch of claim 16, wherein prior to migrating the object, the migration module stores a stored file handle in the location on the destination file server, the stored file handle indicative of the location of the object on the source file server.

19. The NAS switch of claim 15, wherein after migrating the object, the migration module stores a stored file handle in the location on the source file server, the stored file handle indicative of the location of the object on the destination file server.

20. The NAS switch of claim 17, wherein the migration module updates a file handle migration table with an entry for the location on the source file server and an entry for the location on the destination file server responsive to a successful migration.