System, method, and program for determining if write data overlaps source data within a data migration scheme

• US 7,613,889 B2
• Filed: 06/10/2004
• Issued: 11/03/2009
• Est. Priority Date: 06/10/2004
• Status: Expired due to Fees

• 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
• Primary Examiner(s): Elmore; Stephen C
• Assistant Examiner(s): SAVLA, ARPAN P
• Application Number:
  US10/865,625
• Publication Number:
  US 20050278492A1
• Time in Patent Office: 1,972 Days
• Field of Search: 711/161, 711/162, 711/165, 707/204
• US Class Current: 711/162
• 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:

using, by a migration manager, a map indicating source data to migrate to target data;

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

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

writing the application data for the write requests to the source data;

issuing, by the migration manager, migration requests to migrate source data to target data indicated in the map as not yet migrated;

receiving, by a migration function, a migration request from the migration manager to migrate source data indicated in the map as not yet migrated to target data as part of a migration operation to mirror source data to target data;

returning, by the migration function, indication to retry the migration request to the migration manager in response to the migration request and in response to determining that the requested source data to migrate as part of the migration request overlaps source data indicated in the generated information for one of the write requests; and

returning, by the migration function, indication to retry the migration request to migrate to the migration manager in response to migrating the source data to the target data for the migration request and in response to determining that the migrated source data overlaps source data indicated in the generated information for one of the write requests.

2. The method of claim 1, wherein the write requests to write application data are from an application.

3. The method of claim 2, wherein the application and the migration program execute in a user address space and wherein the migration function executes in a kernel address space.

4. The method of claim 1, wherein the generated information for the write requests 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 of the write requests having pending status.

5. The method of claim 1, wherein the generated information for write requests indicates a status of the write requests 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 of the write requests having pending or completed status.

6. The method of claim 5, further comprising:

setting the status in the generated information for the write requests to completed in response to writing the application data for the write request to the source data indicated in the generated information for the write request.

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 of the write requests 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 request as pending or completed, further comprising:

removing generated information for write requests having completed status in response to 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 from the migration manager comprises a read request and 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; and

circuitry that communicates with the source and target storage locations and the memory, wherein the circuitry implements a migration manager and performs operations, the operations comprising;

using, by the migration manager, a map indicating source data to migrate to target data;

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

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

writing the application data for the write requests to the source data;

issuing, by the migration manager, migration requests to migrate source data to target data indicated in the map as not yet migrated;

receiving, by a migration function, a migration request from the migration manager to migrate source data indicated in the map as not yet migrated to target data as part of a migration operation to mirror source data to target data;

returning, by the migration function, indication to retry the migration request to the migration manager in response to the migration request and in response to determining that the requested source data to migrate as part of the migration request overlaps source data indicated in the generated information for one of the write requests; and

returning, by the migration function, indication to retry the migration request to migrate to the migration manager in response to migrating the source data to the target data for the migration request and in response to determining that the migrated source data overlaps source data indicated in the generated information for one of the write requests.

13. The system of claim 12, wherein the write requests to write application data are from an application.

14. The system of claim 13, wherein the application and the migration program execute in a user address space and wherein the migration function executes in a kernel address space.

15. The system of claim 12, wherein the generated information for the write requests 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 of the write requests having pending status.

16. The system of claim 12, wherein the generated information for write requests indicates a status of the write requests 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 of the write requests having pending or completed status.

17. The system of claim 16, wherein the operations further comprise:

setting the status in the generated information for the write requests to completed in response to writing the application data for the write request to the source data indicated in the generated information for the write request.

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 of the write requests 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 request as pending or completed, wherein the operations further comprise:

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

20. The system of claim 19, 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.

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 from the migration manager comprises a read request and 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 comprising at least one of a hardware device including hardware logic and computer readable storage including code operable for performing operations to migrate source data to target data, wherein the code includes a migration manager and causes operations to be performed, the operations comprising:

using, by the migration manager, a map indicating source data to migrate to target data;

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

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

writing the application data for the write requests to the source data;

issuing, by the migration manager, migration requests to migrate source data to target data indicated in the map as not yet migrated;

receiving, by a migration function, a migration request from the migration manager to migrate source data indicated in the map as not yet migrated to target data as part of a migration operation to mirror source data to target data;

returning, by the migration function, indication to retry the migration request to the migration manager in response to the migration request and in response to determining that the requested source data to migrate as part of the migration request overlaps source data indicated in the generated information for one of the write requests; and

returning, by the migration function, indication to retry the migration request to migrate to the migration manager in response to migrating the source data to the target data for the migration request and in response to determining that the migrated source data overlaps source data indicated in the generated information for one of the write requests.

24. The article of manufacture of claim 23, wherein the write requests to write application data are from an application.

25. The article of manufacture of claim 24, wherein the application and the migration program execute in a user address space and wherein the migration function executes in a kernel address space.

26. The article of manufacture of claim 23, wherein the generated information for the write requests 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 of the write requests having pending status.

27. The article of manufacture of claim 23, wherein the generated information for write requests indicates a status of the write requests 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 of the write requests 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 the write requests to completed in response to writing the application data for the write request to the source data indicated in the generated information for the write request.

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 of the write requests 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 request as pending or completed, wherein the operations further comprise:

removing generated information for write requests having completed status in response to 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 from the migration manager comprises a read and 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.