Method for generating and reconstructing in-place delta files

• US 6,018,747 A
• Filed: 11/26/1997
• Issued: 01/25/2000
• Est. Priority Date: 11/26/1997
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Long, Darrell D. E., Burns, Randal Chilton
• Primary Examiner(s): HOMERE, JEAN RAYMOND
• Application Number:
  US08/978,550
• Time in Patent Office: 790 Days
• Field of Search: 707/203, 707/10, 707/204, 707/202, 395/712
• US Class Current: 1/1
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: G06F 8/654 using techniques specially adapted for alterable solid state memories, e.g. for EEPROM or flash memories
• CPC Class Codes: G06F 8/658 Incremental updates; Differential updates
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99954 Version management

Abstract

The present invention discloses a method, apparatus, and article of manufacture for generating, transmitting, replicating, and rebuilding in-place reconstructible software updates to a file from a source computer to a target computer updates to a file from a source computer to a target computer. The present invention stores the first version of the file and the updates to the first version of the file in the memory of the source computer. The first version is also stored in the memory of the target computer. The updates are then transmitted from the memory of the source computer to the memory of the target computer. The present invention uses these updates at the target computer to build the second version of the file in-place.

Claims

1. A method for generating in-place reconstructible delta files on a source computer and reconstruction the in-place delta files on a target computer, comprising the following steps:

creating an in-place reconstructible delta file on the source computer, wherein the in-place reconstructible delta file comprises a plurality of changes made between a prior version of a file and a new version of a file and a plurality of read and write commands and wherein the source computer discards the prior version of the file and the new version of the file after generating the in-place reconstructible delta file;

storing the prior version of the file in a memory of the target computer; and

at the target computer, using the in-place reconstructible delta file from the source computer to rebuild the new version of the file in-place by building the new version in a same region of the memory of the target computer in which the prior version resides.

2. The method of claim 1, further comprising the following steps:

creating a plurality of copies of the in-place reconstructible delta file; and

transmitting the copies to a plurality of servers, the servers being source computers for the in-place reconstructible delta file.

3. The method of claim 1, further comprising the following step:

detecting one or more conflicts in at least one region of the in-place reconstructible delta file where the in-place reconstructible delta file may be first written to and then later read from.

4. The method of claim 3, further comprising the following step:

rearranging an order of the read and write commands such that the in-place reconstructible delta file is first read from and then later written to.

5. The method of claim 4, wherein the rearranging step further comprises the following step:

converting the in-place reconstructible delta file into a revised in-place reconstructible delta file that lacks conflicts.

6. The method of claim 3, further comprising the following step:

converting copy commands to add commands.

7. The method of claim 3, further comprising the following steps:

performing a copy command in an overlapping data region starting from a left region and ending at a right region.

8. The method of claim 3, further comprising the following step:

performing copy commands in an overlapping data region starting from a right region and ending at a left region.

9. The method of claim 1, further comprising the following steps:

maintaining a progress counter at the target computer to track the number of executed read and write commands;

re-transmitting the in-place reconstructible delta files after a system failure;

counting read and write commands until the counted value matches the progress counter;

discarding the counted read and write commands; and

using the in-place reconstructible delta file at the target computer to rebuild the new version of the file in-place by building the new version in a same region of the memory of the target computer in which the prior version resides.

10. An apparatus for generating in-place reconstructible delta files on a source computer and reconstructing the in-place delta files on a target computer, comprising:

(a) a computer;

(b) means performed by the computer, for;

creating an in-place reconstructible delta file on the source computer, wherein the in-place reconstructible delta file comprises a plurality of changes made between a prior version of a file and a new version of a file and a plurality of read and write commands and wherein the source computer discards the prior version of the file and the new version of the file after generating the in-place reconstructible delta file;

storing the prior version of the file in a memory of the target computer; and

at the target computer, using the in-place reconstructible delta file from the source computer to rebuild the new version of the file in-place by building the new version in a same region of the memory of the target computer in which the prior version resides.

11. The apparatus of claim 10, farther comprises:

(c) means, performed by the computer, for;

creating a plurality of copies of the in-place reconstructible delta file; and

transmitting the copies to a plurality of servers, the servers being source computers for the in-place reconstructible delta file.

12. The apparatus of claim 10, further comprises:

means, performed by the computer, for detecting one or more conflicts in at least one region of the in-place reconstructible delta file where the in-place reconstructible delta file may be first written to and then later read from.

13. The apparatus of claim 12, further comprises:

means, performed by the computer, for rearranging an order of the read and write commands such that the in-place reconstructible delta file is first read from and then later written to.

14. The apparatus of claim 13, wherein the means of rearranging further comprises converting the in-place reconstructible delta file into a revised in-place reconstructible delta file that lacks conflicts.

15. The apparatus of claim 12, further comprises means, performed by the computer, for converting copy commands to add commands.

16. The apparatus of claim 12, further comprises means, performed by the computer, for performing a copy command in an overlapping data region starting from a left region and ending at a right region.

17. The apparatus of claim 12, further comprising means, performed by the computer, for performing copy commands in an overlapping data region starting from a right region and ending at a left region.

18. The apparatus of claim 10, further comprises:

(c) means, performed by the computer for;

maintaining a progress counter at the target computer to track the number of executed read and write commands;

re-transmitting the in-place reconstructible delta files after a system failure;

counting read and write commands until the counted value matches the progress counter;

discarding the counted read and write commands; and

using the in-place reconstructible delta file at the target computer to rebuild the new version of the file in-place by building the new version in a same region of the memory of the target computer in which the prior version resides.

19. An article of manufacture comprising a program storage medium readable by a computer, the medium tangibly embodying one or more programs of instructions executable by the computer to perform method steps for generating in-place reconstructible delta files on a source computer and reconstructing the in-place delta files on a target computer, the method comprising the steps of:

creating an in-place reconstructible delta file on the source computer, wherein the in-place reconstructible delta file comprises a plurality of changes made between a prior version of a file and a new version of a file and a plurality of read and write commands and wherein the source computer discards the prior version of the file and the new version of the file after generating the in-place reconstructible delta file;

storing the prior version of the file in a memory of the target computer; and

at the target computer, using the in-place reconstructible delta file from the source computer to rebuild the new version of the file in-place by building the new version in a same region of the memory of the target computer in which the prior version resides.

20. The article of manufacture of claim 19, further comprising the following steps:

creating a plurality of copies of the in-place reconstructible delta file; and

transmitting the copies to a plurality of servers, the servers being source computers for the in-place reconstructible delta file.

21. The article of manufacture of claim 19, further comprising the following step:

detecting one or more conflicts in at least one region of the in-place reconstructible delta file where the in-place reconstructible delta file may be first written to and then later read from.

22. The article of manufacture of claim 21, further comprising the following step:

converting copy commands to add commands.

23. The article of manufacture of claim 21, further comprising the following steps:

performing a copy command in an overlapping data region starting from a left region and ending at a right region.

24. The article of manufacture of claim 21, further comprising the following step:

performing copy commands in an overlapping data region starting from a right region and ending at a left region.

25. The article of manufacture of claim 21, further comprising the following step:

rearranging an order of the read and write commands such that the in-place reconstructible delta file is first read from and then later written to.

26. The article of manufacture of claim 25, wherein the rearranging step further comprises the following step:

converting the in-place reconstructible delta file into a revised in-place reconstructible delta file that lacks conflicts.

27. The article of manufacture of claim 19, further comprising the following steps:

maintaining a progress counter at the target computer to track the number of executed read and write commands;

re-transmitting the in-place reconstructible delta files after a system failure;

counting read and write commands until the counted value matches the progress counter;

discarding the counted read and write commands; and

using the in-place reconstructible delta file at the target computer to rebuild the new version of the file in-place by building the new version in a same region of the memory of the target computer in which the prior version resides.