Availability and recovery of files using copy storage pools

• US 6,148,412 A
• Filed: 09/03/1997
• Issued: 11/14/2000
• Est. Priority Date: 05/23/1996
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Kaczmarski, Michael Allen, Cannon, David Maxwell, Warren, Donald Paul Jr.
• Primary Examiner(s): LE, DIEU MINH T
• Application Number:
  US08/922,496
• Time in Patent Office: 1,168 Days
• Field of Search: 714/2, 714/5, 714/6, 714/11, 714/13, 714/15, 714/41, 714/42
• US Class Current: 714/6.31
• CPC Class Codes: G06F 11/1448 Management of the data involved in backup or backup restore
• CPC Class Codes: G06F 11/1464 for networked environments
• CPC Class Codes: G06F 11/1469 Backup restoration techniques

Abstract

A data processing system using a client-server configuration provides a method and apparatus for generating and managing multiple copies of client data files. A server coupled to a plurality of client systems organizes sets of storage volumes into storage pools. Primary copies of the client data files are stored in primary storage pools while additional back-up copies of the client data files are copied to secondary storage pools, called copy storage pools. A server database maintains directory information about the original client data file and reference information about the location of the multiple file copies within the server. A storage manager provides a control center within the server, directing and coordinating the transfer of files between the various storage pools, and updating the server database with directory and reference location information.

Claims

1. In a data processing system having a plurality of client systems generating client data files, a server coupled to said plurality of client systems for generating and managing multiple copies of said client data files, said server comprising:

a first storage pool having a plurality of primary storage volumes for storing a primary copy of said client data files;

a second storage pool having a plurality of copy storage volumes for storing a back-up copy of said client data files;

a server database for maintaining directory information and reference location information linking said primary copy and said back-up copy of said client data files; and

a storage manager coupled to said first storage pool, said second storage pool, and said server database, said storage manager receiving said primary copy of said client data file from said client system and storing said primary copy of said client data file in said primary storage volume, said storage manager further generating said back-up copy of said client data file by copying said primary copy of said client data file from said primary storage volume to said copy storage volume, said storage manager updating said directory information and said reference location information in said server data base to link said primary copy and said back-up copy, said storage manager transferring said primary copy to said client system in response to a client system request for said client data file, said storage manager also periodically performing an incremental back-up operation from said first storage pool to said second storage pool such that a set of selected primary copies of client data files is copied to said copy storage volumes,

wherein in response to said client system request for said client data file, said storage manager determining that said primary copy of said client data file is unavailable, said storage manager then directly accessing said back-up copy of said client data file by using said directory information and said reference location information in said server database and transferring said back-up copy from said copy storage volume to said requesting client system, said storage manager then subsequently recovering said unavailable primary copy of said client data file by copying said back-up copy from said copy storage volume to said primary storage volume.

2. The server in claim 1 further comprising:

a first list in said server database identifying said primary copies of said client data files to be copied from said first storage pool to said second storage pool during said incremental back-up operation,

wherein said storage manager queries said directory information and said reference location information in said server database to build said first list.

3. The server in claim 2 wherein said first list identifies said primary copies of client data files stored in said first storage pool at a time subsequent to when a previous incremental back-up operation was most recently completed.

4. The server in claim 3 wherein said first list further identifies said primary copies of client data files stored in said first storage pool having corresponding damaged back-up copies in said second storage pool.

5. The server in claim 1 further comprising:

a second list in said server database identifying said unavailable primary copy of said client data files, a best back-up copy of said unavailable primary copy, and said copy storage volume containing said best back-up copy,

wherein said storage manager searches said reference location information in said server database to find said unavailable primary copy, said storage manager further determines said best back-up copy according to which said back-up copy in said second storage pool is most easily accessible to said storage manager.

6. The server in claim 5 wherein for each said copy storage volume identified in said second list, said storage manager copies said best back-up copy from said copy storage volume to said primary storage volume to recover said unavailable primary copy.

7. The server in claim 6 wherein said unavailable primary copy of said client data file is damaged or destroyed in said first storage pool.

8. The server in claim 1 wherein said storage manager synchronously generates said back-up copy of said client data file on said copy storage volume immediately after storing said primary copy of said client data file on said primary storage volume.

9. The server in claim 1 wherein said directory information in said server database for each said primary copy and each said back-up copy of said client data file further comprises:

a file name;

a client system identifier;

a file status word;

a time stamp; and

a bit-file identifier (bfid).

10. The server in claim 1 wherein said reference location information in said server database for each said primary copy and each said back-up copy of said client data file further comprises:

a storage pool identifier;

a storage volume identifier;

a storage volume offset;

a file size; and

a bit-file identifier (bfid).

11. The server in claim 1 further comprising a third storage pool coupled to said storage manager, said third storage pool for storing a back-up copy of said server database.

12. The server in claim 1 wherein said primary storage volumes are direct access storage devices (DASDs).

13. The server in claim 1 wherein said primary storage volumes are magnetic tape cartridges.

14. The server in claim 1 wherein said primary storage volumes are optical disks.

15. The server in claim 1 wherein said copy storage volumes are magnetic tape cartridges.

16. The server in claim 1 wherein said copy storage volumes are optical disks.

17. In a data processing system having a plurality of client systems generating client data files, and a server coupled to said plurality of client systems, a method in said server for generating and managing multiple copies of said client data files comprising steps of:

receiving said client data file from said client system, and storing a primary copy of said client data file in a first storage pool, said first storage pool having a plurality of primary storage volumes;

generating a back-up copy of said client data file by copying said primary copy to a second storage pool, said second storage pool having a plurality of copy storage volumes;

maintaining directory information and reference location information in a server database to link said primary copy stored in said primary storage volume and said back-up copy stored in said copy storage volume;

in response to a client system request for said client data file which is determined to have an available primary copy, transferring said available primary copy from said primary storage volume to said requesting client system; and

in response to a client system request for said client data file which is determined to have an unavailable primary copy, accessing said back-up copy of said client data file using said directory information and said reference location information in said server database, transferring said back-up copy of said client data file directly from said copy storage volume to said requesting client system, and then subsequently recovering said unavailable primary copy of said client data file by copying said back-up copy from said copy storage volume to said primary storage volume.

18. The method of claim 17 further comprising:

periodically performing an incremental back-up operation from said first storage pool to said second storage pool by selecting a set of primary copies of client data files stored on said primary storage volumes, and copying said selected primary copies from said primary storage volumes to said copy storage volumes.

19. The method of claim 18 wherein said selecting step further comprises:

querying said directory information and said reference location information in said server database to build a first list identifying said set of primary copies.

20. The method of claim 19 wherein said first list identifies said primary copies stored in said first storage pool at a time subsequent to when a previous incremental back-up operation was most recently completed.

21. The method of claim 20 wherein said first list further identifies said primary copies stored in said first storage pool having corresponding damaged back-up copies in said second storage pool.

22. The method of claim 19 further comprising steps of:

maintaining a second list in said server database, said second list identifying a sequence of ordered primary copies of said client data files on a sequential primary storage volume, said sequence of ordered primary copies having been copied as said back-up copies to said second storage pool during a previous incremental back-up operation.

23. The method of claim 22 wherein said first list identifies said primary copies positioned on said sequential primary storage volume after said sequence of ordered primary copies.

24. The method of claim 17 wherein said recovering step further comprises:

searching said reference location information in said server database to find said unavailable primary copy of said client data file;

determining a best back-up copy of said client data file corresponding to said unavailable primary copy;

building a third list in said server database identifying said copy storage volume containing said best back-up copy such that said copy storage volume is entered in said third list only if said copy storage volume was previously entered; and

for each said copy storage volume identified in said third list, copying each said best back-up copy of said client data file stored therein to said primary storage volume.

25. The method of claim 24 wherein said best back-up copy is located on said copy storage volume that is currently most easily accessible in said server.

26. The method of claim 24 wherein said unavailable primary copy of said client data file is damaged or destroyed in said first storage pool.

27. The method of claim 17 wherein said generating step is accomplished synchronously within the server.

28. The method of claim 17 wherein said directory information in said server database for each said primary copy and each said back-up copy of said client data file further comprises:

a file name;

a client system identifier;

a file status word;

a time stamp; and

a bit-file identifier (bfid).

29. The method of claim 17 wherein said reference location information in said server database for each said primary copy and each said back-up copy of said client data file further comprises:

a storage pool identifier;

a storage volume identifier;

a storage volume offset;

a file size; and

a bit-file identifier (bfid).

30. An article of manufacture for use in a data processing system having a plurality of client systems generating client data files, and a server coupled to said plurality of client systems for generating and managing multiple copies of said client data files,

said article of manufacture comprising a computer-readable storage medium tangibly embodying a program of executable computer instructions which may cause said server to execute steps comprising:

receiving said client data file from said client system and storing a primary copy of said client data file in a first storage pool, said first storage pool having a plurality of primary storage volumes;

generating a back-up copy of said client data file by copying said primary copy to a second storage pool, said second storage pool having a plurality of copy storage volumes;

maintaining directory information and reference location information in a server database to link said primary copy stored in said primary storage volume and said back-up copy stored in said copy storage volume;

periodically performing an incremental back-up operation from said first storage pool to said second storage pool by selecting a set of primary copies of said client data files stored in said primary storage volumes and copying said selected primary copies from said primary storage volumes to said copy storage volumes;

in response to a client system request for a client system data file which is determined to have an available primary copy, transferring said available primary copy from said primary storage volume to said requesting client system; and

in response to a client system request for said client data file which is determined to have an unavailable primary copy, accessing said back-up copy of said client data file using said directory information and said reference location information in said server database, transferring said back-up copy of said client data file directly from said copy storage volume to said requesting client system, and then subsequently recovering said unavailable primary copy of said client data file by copying said back-up copy from said copy storage volume to said primary storage volume.

31. The article of manufacture of claim 30 wherein said program of executable computer instructions may cause said server to execute steps further comprising:

querying said directory information and said reference location information to build a first list in said server database, said first list identifying said set of primary copies; and

maintaining a second list in said server database, said second list identifying a sequence of ordered primary copies of said client data files on a sequential primary storage volume, said sequence of ordered primary copies having been copied as said back-up copies to said second storage pool during a previous incremental back-up operation.

32. The article of manufacture of claim 30 wherein said program of executable computer instructions may cause said server to execute steps further comprising:

searching said reference location information in said server database to collect entries corresponding to said back-up copies linked to said unavailable primary copy of said client data file;

determining a best back-up copy of said unavailable primary copy from said collected entries of said reference location information;

building a third list in said server database identifying said copy storage volume storing said best back-up copy of said unavailable primary copy; and

for each said copy storage volume identified in said third list, copying said best back-up copy of said unavailable primary copy stored therein to said primary storage volume.