Uniform name space referrals with location independence

• US 7,774,364 B2
• Filed: 03/09/2005
• Issued: 08/10/2010
• Est. Priority Date: 07/30/2002
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Shmueli, Boaz, Everhart, Craig F., Anderson, Owen T.
• Primary Examiner(s): Vo; Tim T.
• Assistant Examiner(s): OWYANG, MICHELLE N
• Application Number:
  US11/076,235
• Publication Number:
  US 20050149528A1
• Time in Patent Office: 1,980 Days
• Field of Search: 707 1- 10, 707/203, 709201-244
• US Class Current: 707/782
• CPC Class Codes: G06F 16/10 File systems; File servers

Abstract

Improved techniques are disclosed for accessing content in file systems, allowing file system clients to realize advantages of file system referrals even though a file access protocol used by the client is not specifically adapted for referral objects. (For example, the client may have a legacy file system protocol or a proprietary file system protocol which does not support referrals.) These advantages include a uniform name space view of content in a network file system, and an ability to locate content in a (nearly) seamless and transparent manner, even though the content may be dynamically moved from one location to another or replicated in different locations. A file system server returns a symbolic link in place of a referral, and an automated file mounting process on the client is leveraged to access the content using the link. Built-in crash recovery techniques of the file system client are leveraged to access moved content.

Claims

1. A computer-implemented method of simulating client-side file system referral capability, comprising:

receiving, at a first file system server from a legacy client, a request for a file system, wherein the legacy client does not support referral file access protocol;

determining, by the first file system server, that the requested file system is not stored at the first file system server but that the first file system server instead stores a referral for the requested file system, the referral comprising a key value uniquely associated with the requested file system;

creating, by the first file system server responsive to the determining, a symbolic reference for the requested file system, the symbolic reference comprising the key value and a predetermined text string that signifies presence of the symbolic reference; and

returning, from the first file system server to the legacy client as a response to the request, the symbolic reference instead of the requested file system, wherein presence of the predetermined text string in a path name component provided in the response thereby signals that client-side resolution is needed, the client-side resolution comprising accessing a client-side mapping that uniquely associates the key value with location information that identifies a location of the requested file system on a second file system server that is distinct from the first file system server.

2. The computer-implemented method according to claim 1, further comprising mounting the located file system on the legacy client.

3. The computer-implemented method according to claim 1, wherein the response is intercepted, at the legacy client, by a client-side automounter that performs the client-side resolution.

4. The computer-implemented method according to claim 3, further comprising mounting the located file system in an automounter directory on the legacy client.

5. The computer-implemented method according to claim 1, wherein the client-side resolution is performed by a client-side file locating component.

6. A computer-implemented method of simulating client-side file system referral capability, comprising:

requesting, by a client, a file system from a first file system server, wherein the client does not support referral file access protocol;

receiving, at the client from the first file system server as a response to the request, a symbolic reference for the requested file system instead of the requested file system, wherein the symbolic reference comprises a predetermined text string and a key value and was created at the first file system server responsive to a determination that the requested file system is not stored at the first file system server but that the first file system server instead stores a referral uniquely associated with the requested file system, the referral comprising the key value and the symbolic reference signalling that client-side resolution of the key value is needed; and

responsive to detecting, at the client, the predetermined text string in a path name component provided in the received response, performing the client-side resolution by extracting the key value from the path name component and programmatically locating the requested file system using the extracted key value to retrieve location information for the requested file system from a key-to-location mapping that uniquely associates the key value with the location information.

responsive to detecting, the client, the predetermined text

7. The computer-implemented method according to claim 6, further comprising using the retrieved location information to mount the requested file system on the client.

8. The computer-implemented method according to claim 6, wherein:

the receiving further comprises intercepting the response, at the client, by a client-side automounter; and

the automounter performs the client-side resolution.

9. The computer-implemented method according to claim 8, further comprising using the retrieved location information to mount the requested file system in an automounter directory on the client.

10. The computer-implemented method according to claim 6, wherein the client-side resolution is performed by a client-side file locating component.

11. A system for simulating client-side file system referral capability, comprising:

a computer comprising a processor; and

instructions which execute using the processor to implement functions comprising;

receiving, at a first file system server from a legacy client, a request for a file system, wherein the legacy client does not support referral file access protocol;

determining, by the first file system server, that the requested file system is not stored at the first file system server but that the first file system server instead stores a referral for the requested file system, the referral comprising a key value uniquely associated with the requested file system;

creating, by the first file system server responsive to the determining, a symbolic reference for the requested file system, the symbolic reference comprising the key value and a predetermined text string that signifies presence of the symbolic reference; and

returning, from the first file system server to the legacy client as a response to the request, the symbolic reference instead of the requested file system, wherein presence of the predetermined text string in a path name component provided in the response thereby signals that client-side resolution is needed, the client-side resolution comprising accessing a client-side mapping that uniquely associates the key value with location information that identifies a location of the requested file system on a second file system server that is distinct from the first file system server.

12. The system according to claim 11, wherein the functions further comprise mounting the located file system on the legacy client.

13. The system according to claim 11, wherein the response is intercepted, at the legacy client, by a client-side automounter that performs the client-side resolution.

14. The system according to claim 13, wherein the instructions further comprise mounting the located file system in an automounter directory on the legacy client.

15. A system for simulating client-side file system referral capability, comprising:

a computer comprising a processor; and

instructions which execute using the processor to implement functions comprising;

requesting, by a client, a file system from a first file system server, wherein the client does not support referral file access protocol;

receiving, at the client from the first file system server as a response to the request, a symbolic reference for the requested file system instead of the requested file system, wherein the symbolic reference comprises a predetermined text string and a key value and was created at the first file system server responsive to a determination that the requested file system is not stored at the first file system server but that the first file system server instead stores a referral uniquely associated with the requested file system, the referral comprising the key value and the symbolic reference signalling that client-side resolution of the key value is needed; and

responsive to detecting, at the client, the predetermined text string in a path name component provided in the received response, performing the client-side resolution by extracting the key value from the path name component and programmatically locating the requested file system using the extracted key value to retrieve location information for the requested file system from a key-to-location mapping that uniquely associates the key value with the location information.

16. The system according to claim 15, wherein the instructions further comprise using the retrieved location information to mount the requested file system on the client.

17. The system according to claim 15, wherein:

the receiving further comprises intercepting the response, at the client, by a client-side automounter; and

the automounter performs the client-side resolution.

18. The system according to claim 17, wherein the instructions further comprise using the retrieved location information to mount the requested file system in an automounter directory on the client.

19. A computer program product for simulating client-side file system referral capability, the computer program product embodied on at least one computer-usable storage media and comprising computer-usable program code for:

receiving, at a first file system server from a legacy client, a request for a file system, wherein the legacy client does not support referral file access protocol;

determining, by the first file system server, that the requested file system is not stored at the first file system server but that the first file system server instead stores a referral for the requested file system, the referral comprising a key value uniquely associated with the requested file system;

creating, by the first file system server responsive to the determining, a symbolic reference for the requested file system, the symbolic reference comprising the key value and a predetermined text string that signifies presence of the symbolic reference; and

returning, from the first file system server to the legacy client as a response to the request, the symbolic reference instead of the requested file system, wherein presence of the predetermined text string in a path name component provided in the response thereby signals that client-side resolution is needed, the client-side resolution comprising accessing a client-side mapping that uniquely associates the key value with location information that identifies a location of the requested file system on a second file system server that is distinct from the first file system server.

20. The computer program product according to claim 19, further comprising computer-usable program code for mounting the located file system on the legacy client.

21. The computer program product according to claim 19, wherein the response is intercepted, at the legacy client, by a client-side automounter that performs the client-side resolution.

22. The computer program product according to claim 21, further comprising computer-usable program code for mounting the located file system in an automounter directory on the legacy client.

23. A computer program product for simulating client-side file system referral capability, the computer program product embodied on at least one computer-usable storage media and comprising computer-usable program code for:

requesting, by a client, a file system from a first file system server, wherein the client does not support referral file access protocol;

receiving, at the client from the first file system server as a response to the request, a symbolic reference for the requested file system instead of the requested file system, wherein the symbolic reference comprises a predetermined text string and a key value and was created at the first file system server responsive to a determination that the requested file system is not stored at the first file system server but that the first file system server instead stores a referral uniquely associated with the requested file system, the referral comprising the key value and the symbolic reference signalling that client-side resolution of the key value is needed; and

responsive to detecting, at the client, the predetermined text string in a path name component provided in the received response, performing the client-side resolution by extracting the key value from the path name component and programmatically locating the requested file system using the extracted key value to retrieve location information for the requested file system from a key-to-location mapping that uniquely associates the key value with the location information.

24. The computer program product according to claim 23, further comprising computer-usable program code for using the retrieved location information to mount the requested file system on the client.

25. The computer program product according to claim 23, wherein:

the receiving further comprises intercepting the response, at the client, by a client-side automounter; and

the automounter performs the client-side resolution.

26. The computer program product according to claim 25, further comprising computer-usable program code for using the retrieved location information to mount the requested file system in an automounter directory on the client.