Directory and file mirroring for migration, snapshot, and replication

• US 7,720,796 B2
• Filed: 01/03/2006
• Issued: 05/18/2010
• Est. Priority Date: 04/23/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: NeoPath Networks, Inc. (Cisco Systems, Inc.)
• Inventors: Wong, Thomas K., Wong, Chi M., Simpkins, Richard A., Tsirigotis, Panagiotis, Liu, Zuwei
• Primary Examiner(s): Woo; Isaac M
• Application Number:
  US11/324,845
• Publication Number:
  US 20060161746A1
• Time in Patent Office: 1,596 Days
• Field of Search: 707 1- 10, 707100-1041, 707200-206, 707600-831
• US Class Current: 707/639
• CPC Class Codes: G06F 11/1662 the resynchronized component or unit being a persistent storage device re-synchronization of failed mirror storage G06F11/2082; rebuild or reconstruction of parity RAID storage G06F11/1008
• CPC Class Codes: G06F 11/2071 using a plurality of controllers
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• 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]

Abstract

A NAS switch provides mirroring in a NAS storage network that is transparent to client. 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 mirroring of a namespace when during processes such as data migration, data replication, and data snapshot.

Claims

1. A method comprising:

receiving NAS (Network Attached Storage) file handles at a storage network switch, the NAS file handles including locations of objects on a source file server;

sending switch file handles to a client device, the switch file handles representative of the objects and independent of the locations of the objects;

mirroring at the storage network switch a namespace including the locations of the objects on the source file server, wherein the namespace is stored on the source file server and is mirrored from the source file server to a mirrored namespace on a destination file server;

replicating the objects from the source file server to the destination file server;

receiving at the storage network switch a request to modify an object associated with the namespace from the client device; and

sending at the storage network switch the request to modify the object associated with the namespace to both the source file server and the destination file server, wherein the source file server and the destination file server modify corresponding objects in the namespace and the mirrored namespace.

2. The method of claim 1, further comprising:

responsive to an inconsistency between the namespace and the mirrored namespace, reverting to the namespace as an authoritative namespace.

3. The method of claim 1, further comprising:

responsive to an inconsistency between the namespace and the mirrored namespace, repeating mirroring of the namespace.

4. The method of claim 1, wherein at least one object comprises a directory that includes another object representative of one or more of sub-directories or files.

5. The method of claim 1, wherein at least one object comprises a file.

6. The method of claim 1, further comprising:

in a migration process, redirecting requests to the destination file server once replicating the objects has completed.

7. The method of claim 1, further comprising;

in a replication process, redirecting requests to either the source file server or the destination file server depending on server loads.

8. 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.

9. The method of claim 1, wherein the request comprises a namespace access request including one from the group consisting of a create request, a delete request, a move request, a copy request, a look-up request and a rename request.

10. The method of claim 1, wherein the NAS file handle comprises one from the group consisting of a NFS (Network File System) file handle and a CIFS (Common Internet File System) file handle.

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

receiving input file handles at a storage network switch, the input file handles including locations of objects on a source file server;

sending switch file handles to a client device, the switch file handles representative of the objects and independent of the locations of the objects;

mirroring at the storage network switch a namespace including the locations of the objects on the source file server, wherein the namespace is stored on the source file server and is mirrored from the source file server to a mirrored namespace on a destination file server;

replicating the objects from the source file server to the destination file server;

receiving at the storage network switch a request to modify an object associated with the namespace from the client device; and

sending at the storage network switch the request to modify the object associated with the namespace to both the source file server and the destination file server, wherein the source file server and the destination file server modify corresponding objects in the namespace and the mirrored namespace.

12. The method of claim 11, further comprising:

responsive to an inconsistency between the namespace and the mirrored namespace, reverting to the namespace as an authoritative namespace.

13. The method of claim 11, further comprising:

responsive to an inconsistency between the namespace and the mirrored namespace, repeating mirroring of the namespace.

14. A computer program product, comprising:

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

receiving NAS (Network Attached Storage) file handles at a storage network switch, the NAS file handles including locations of objects on a source file server;

sending switch file handles to a client device, the switch file handles representative of the objects and independent of the locations of the objects;

mirroring at the storage network switch a namespace including the locations of the objects on the source file server, wherein the namespace is stored on the source file server and is mirrored from the source file server to a mirrored namespace on a destination file server;

replicating the objects from the source file server to the destination file server;

receiving at the storage network switch a request to modify an object associated with the namespace from the client device; and

sending at the storage network switch the request to modify the object associated with the namespace to both the source file server and the destination file server, wherein the source file server and the destination file server modify corresponding objects in the namespace and the mirrored namespace.

15. The method of claim 14, further comprising:

responsive to an inconsistency between the namespace and the mirrored namespace, reverting to the namespace as an authoritative namespace.

16. The method of claim 14, further comprising:

responsive to an inconsistency between the namespace and the mirrored namespace, repeating mirroring of the namespace.