Method, system, and program for migrating source data to target data

• US 20050278492A1
• Filed: 06/10/2004
• Published: 12/15/2005
• Est. Priority Date: 06/10/2004
• Status: Active Grant

• Current Assignee: International Business Machines Corporation, International Business Corporation (Kleangas Energy Technologies, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Stakutis, Christopher John, Haselton, William Robert
• Granted Patent: US 7,613,889 B2
• Time in Patent Office: Days
• US Class Current: 711/161
• CPC Class Codes: G06F 11/2082 Data synchronisation
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99955 Archiving or backup

Abstract

Provided are a method, system, and program for migrating source data to target data. A write request is received to write application data to source data not yet migrated to the target data. Information is generated for the write request indicating the source data to which the application data is written. The application data is written to the source data. A request is received to migrate source data to target data and indication is returned to retry the request to migrate in response to determining that the requested source data to migrate overlaps source data indicated in the generated information for one write request.

Claims

1. A method for migrating source data to target data, comprising:

receiving a write request to write application data to source data not yet migrated to the target data;

generating information for the write request indicating the source data to which the application data is written;

writing the application data to the source data;

receiving a request to migrate source data to target data; and

returning indication to retry the request to migrate in response to determining that the requested source data to migrate overlaps source data indicated in the generated information for one write request.

2. The method of claim 1, wherein the write request to write application data is from an application and the migration request is from a migration program.

3. The method of claim 2, wherein the application and the migration program execute in a user address space and wherein the steps of receiving the write request, generating the information, writing the requested data, determining the overlap, and returning indication to retry are performed by at least one process executing in the kernel address space.

4. The method of claim 1, wherein the generated information for one write request indicates a status of the write of the application data as pending or completed, wherein the indication to retry is returned before the source data to migrate is transferred to the target data and in response to determining that the requested source data to migrate overlaps source data indicated in generated information for one write request having pending status.

5. The method of claim 1, wherein the generated information for one write request indicates a status of the write as pending or completed, wherein the indication to retry is returned after the source data to migrate is transferred to the target data and in response to determining that the requested source data to migrate overlaps source data indicated in generated information for one write request having pending or completed status.

6. The method of claim 5, further comprising:

setting the status in the generated information for one write request to completed in response to writing the application data to the source data indicated in the generated information for the write request, wherein the operations of writing the application data to the source data for the write request and migrating the source data to the target data in response to the migrate request occur independently of one another.

7. The method of claim 1, wherein the indication to retry is returned in response to determining that the requested source data to migrate overlaps source data indicated in generated information for one write both before transferring the source data to migrate to the target data and after transferring the source data to migrate to the target data

8. The method of claim 1, wherein the generated information indicates a status of the write as pending or completed, further comprising:

removing generated information for write requests having completed status after migrating source data to target data.

9. The method of claim 8, further comprising:

removing generated information for write requests to source data preceding the source data to migrate in response to writing the source data to migrate to the target data.

10. The method of claim 1, wherein returning indication to retry the request to migrate comprises:

indicating in the response to the request to migrate that the request did not complete; and

including in the response a retry code indicating to retry the request to migrate.

11. The method of claim 10, wherein the request to migrate comprises a read request from a migration process providing a read buffer, and wherein indicating in the response that the request to migrate did not complete comprises indicating that all the requested data is not included in the read buffer, and wherein the retry code is included at a predetermined position in the read buffer returned in response to the read request.

12. A system for migrating source data to target data, comprising:

a source storage location;

a target storage location;

a memory;

circuitry enabled to communicate with the source and target storage locations and the memory, wherein the circuitry is enabled to perform;

(i) receiving a write request to write application data to source data not yet migrated to the target data;

(ii) generating information for the write request in the memory indicating the source data to which the application data is written;

(iii) writing the application data to the source data in the source storage location;

(iv) receiving a request to migrate source data to target data at the target storage location; and

(v) returning indication to retry the request to migrate in response to determining that the requested source data to migrate overlaps source data indicated in the generated information for one write request.

13. The system of claim 12, wherein the write request to write application data is from an application and the migration request is from a migration program.

14. The system of claim 13, wherein the circuitry is further enabled to perform:

generating a user address space and kernel address space, wherein the application and the migration program execute in the user address space and wherein the steps of receiving the write request, generating the information, writing the requested data, determining the overlap, and returning indication to retry are performed by at least one process executing in the kernel address space.

15. The system of claim 12, wherein the generated information for one write request indicates a status of the write of the application data as pending or completed, wherein the indication to retry is returned before the source data to migrate is transferred to the target data and in response to determining that the requested source data to migrate overlaps source data indicated in generated information for one write request having pending status.

16. The system of claim 12, wherein the generated information for one write request indicates a status of the write as pending or completed, wherein the indication to retry is returned after the source data to migrate is transferred to the target data and in response to determining that the requested source data to migrate overlaps source data indicated in generated information for one write request having pending or completed status.

17. The system of claim 16, wherein the circuitry is further enabled to perform:

setting the status in the generated information for one write request to completed in response to writing the application data to the source data indicated in the generated information for the write request, wherein the operations of writing the application data to the source data for the write request and migrating the source data to the target data in response to the migrate request occur independently of one another.

18. The system of claim 12, wherein the indication to retry is returned in response to determining that the requested source data to migrate overlaps source data indicated in generated information for one write both before transferring the source data to migrate to the target data and after transferring the source data to migrate to the target data

19. The system of claim 12, wherein the generated information indicates a status of the write as pending or completed, wherein the circuitry is further enabled to perform:

removing generated information for write requests having completed status after migrating source data to target data.

20. The system of claim 19, wherein the circuitry is further enabled to perform:

removing generated information for write requests to source data preceding the source data to migrate in response to writing the source data to migrate to the target data.

21. The system of claim 12, wherein returning indication to retry the request to migrate comprises:

indicating in the response to the request to migrate that the request did not complete; and

including in the response a retry code indicating to retry the request to migrate.

22. The system of claim 21, wherein the request to migrate comprises a read request from a migration process providing a read buffer, and wherein indicating in the response that the request to migrate did not complete comprises indicating that all the requested data is not included in the read buffer, and wherein the retry code is included at a predetermined position in the read buffer returned in response to the read request.

23. An article of manufacture for migrating source data to target data, wherein the article of manufacture causes operations to be performed, the operations comprising:

receiving a write request to write application data to source data not yet migrated to the target data;

generating information for the write request indicating the source data to which the application data is written;

writing the application data to the source data;

receiving a request to migrate source data to target data; and

returning indication to retry the request to migrate in response to determining that the requested source data to migrate overlaps source data indicated in the generated information for one write request.

24. The article of manufacture of claim 23, wherein the write request to write application data is from an application and the migration request is from a migration program.

25. The article of manufacture of claim 24, wherein the application and the migration program execute in a user address space and wherein the steps of receiving the write request, generating the information, writing the requested data, determining the overlap, and returning indication to retry are performed by at least one process executing in the kernel address space.

26. The article of manufacture of claim 23, wherein the generated information for one write request indicates a status of the write of the application data as pending or completed, wherein the indication to retry is returned before the source data to migrate is transferred to the target data and in response to determining that the requested source data to migrate overlaps source data indicated in generated information for one write request having pending status.

27. The article of manufacture of claim 23, wherein the generated information for one write request indicates a status of the write as pending or completed, wherein the indication to retry is returned after the source data to migrate is transferred to the target data and in response to determining that the requested source data to migrate overlaps source data indicated in generated information for one write request having pending or completed status.

28. The article of manufacture of claim 27, wherein the operations further comprise:

setting the status in the generated information for one write request to completed in response to writing the application data to the source data indicated in the generated information for the write request, wherein the operations of writing the application data to the source data for the write request and migrating the source data to the target data in response to the migrate request occur independently of one another.

29. The article of manufacture of claim 23, wherein the indication to retry is returned in response to determining that the requested source data to migrate overlaps source data indicated in generated information for one write both before transferring the source data to migrate to the target data and after transferring the source data to migrate to the target data

30. The article of manufacture of claim 23, wherein the generated information indicates a status of the write as pending or completed, wherein the operations further comprise:

removing generated information for write requests having completed status after migrating source data to target data.

31. The article of manufacture of claim 30, wherein the operations further comprise:

removing generated information for write requests to source data preceding the source data to migrate in response to writing the source data to migrate to the target data.

32. The article of manufacture of claim 23, wherein returning indication to retry the request to migrate comprises:

indicating in the response to the request to migrate that the request did not complete; and

including in the response a retry code indicating to retry the request to migrate.

33. The article of manufacture of claim 32, wherein the request to migrate comprises a read request from a migration process providing a read buffer, and wherein indicating in the response that the request to migrate did not complete comprises indicating that all the requested data is not included in the read buffer, and wherein the retry code is included at a predetermined position in the read buffer returned in response to the read request.