File consistency protocols and methods for carrying out the protocols

• US 6,687,716 B1
• Filed: 09/13/2000
• Issued: 02/03/2004
• Est. Priority Date: 09/13/2000
• Status: Expired due to Fees

• Current Assignee: Independent Storage Corporation
• Original Assignee: Radiant Data Corporation
• Inventors: Bradley, Mark W.
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): GODDARD, BRIAN D
• Application Number:
  US09/662,368
• Time in Patent Office: 1,238 Days
• Field of Search: 707/201, 707/8, 707/200, 707/203, 709/213
• US Class Current: 707/822
• CPC Class Codes: G06F 16/1767 Concurrency control, e.g. optimistic or pessimistic approaches
• CPC Class Codes: Y10S 707/99938 Concurrency, e.g. lock management in shared database
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users

Abstract

Methods for maintaining consistent data and attributes for files sharable by two or more consumers are provided. One exemplary method includes initially defining a set of consistency bits that are implemented by a file consistency protocol. Once the consistency bits are defined and implemented by a file system managing the shared files, the method receives indication that a change was made to a file associated with the file system. The method then sets a bit of the set of consistency bits on each instance file to reflect the change performed to the file. An update is then messaged to each instance file such that the instance files contain the change made to the file. The messaging can be performed by way of a pulling protocol or a push protocol, which transfers the updates to the instances to maintain the consistency.

Claims

1. A method for maintaining file consistency, a file being associated with a file system, the method comprising:

integrating a file consistency protocol with an operating system (O/S), wherein the file consistency protocol maintains file consistency between instances of the file associated with the file system using a set of consistency bits;

checking the file for an exclusive bit setting of true;

failing an opening of another instance of the file if the exclusive bit of the file was determined to be set to true;

opening another instance of the file if the exclusive bit of the file was determined to be set to false;

changing the file;

setting a bit of the set of consistency bits on the instance file to reflect the change performed to the file, the change being made in accordance with the file consistency protocol that operates based on the settings of the set of consistency bits; and

updating the instance file such that the instance file contains the change made to the file using the file consistency protocol.

2. A method for maintaining file consistency, a file being associated with a file system as recited in claim 1, the operation of updating the instance file further comprising:

pushing the change to the instance file from the file.

3. A method for maintaining file consistency, a file being associated with a file system as recited in claim 1, wherein the instance file pulls the change from the file in order to update the instance file.

4. A method for maintaining file consistency, a file being associated with a file system as recited in claim 1, further comprising:

determining a type of change to be performed on the file before the change to the file is performed.

5. A method for maintaining file consistency, a file being associated with a file system as recited in claim 4, wherein the type is a data change.

6. A method for maintaining file consistency, a file being associated with a file system as recited in claim 4, wherein the type is an attribute change.

7. A method for maintaining file consistency, a file being associated with a file system as recited in claim 1, wherein the set of consistency bits comprises an “

M”

bit, an “

A”

bit, an “

E”

bit, a “

S”

bit and an “

I”

bit.

8. A method for maintaining file consistency, a file being associated with a file system as recited in claim 7, wherein the “

M”

bit, the “

A”

bit, the “

E”

bit, the “

S”

bit and the “

I”

bit are set by changing the “

M”

bit, the “

A”

bit, the “

E”

bit, the “

S”

bit and the “

I”

bit from a first state to a second state and are reset back to the first state.

9. A method for maintaining file consistency, a file being associated with a file system as recited in claim 1, the method further comprising:

closing the file and the instance file after all changes are made to the file and the instance file.

10. A method for maintaining file consistency, a file being associated with a file system as recited in claim 8, wherein the first state is a “

0”

state and the second state is a “

1”

state.

11. A method for maintaining file consistency, a file being associated with a file system as recited in claim 7, the method further comprising:

setting a file bit in the set of consistency bits when the file is changed.

12. A method for maintaining file consistency, a file being associated with a file system as recited in claim 11, wherein the “

M”

bit is set in the file when the data in the file is modified such that the “

M”

bit is the file bit that is set in the set of consistency bits.

13. A method for maintaining file consistency, a file being associated with a file system as recited in claim 11, wherein the “

I”

bit is set in the instance file when data in the file is modified such that the “

I”

bit is the bit set in the set of consistency bits on the instance file.

14. A method for maintaining file consistency, a file being associated with a file system as recited in claim 11, wherein the “

A”

bit is set in the file and the instance file when the attributes of the file associated with the file system is modified, such that the “

A”

bit is the bit set in the set of consistency bits on the instance file and the “

A”

bit is the file bit set in the set of consistency bits on the file.

15. A method for maintaining file consistency, a file being associated with a file system as recited in claim 11, wherein the “

E”

bit is the bit set in the set of consistency bits on the instance file and the file when the instance file is opened exclusively, such that no other users may access the file while the instance file is opened exclusively.

16. A method for maintaining file consistency, a file being associated with a file system as recited in claim 11, wherein the “

S”

bit is the bit set in the instance file and the “

S”

bit is the file bit set in the file when the file is opened in a open shared mode.

17. A method for maintaining file consistency, a file being associated with a file system as recited in claim 16, wherein the open shared mode allows other users to access the instance file while the file is opened in the open shared mode.

18. A method for maintaining file consistency, a file being associated with a file system as recited in claim 6, the method further comprising:

ascertaining if a list or a write is requested to attributes of the file; and

determining what attributes a user may access.

19. A method for maintaining file consistency, a file being associated with a file system as recited in claim 18, wherein file attributes are listed when the list is requested.

20. A method for maintaining file consistency, a file being associated with a file system as recited in claim 18, wherein when the write is requested, the method further comprises:

changing file attributes of the file and updating the instance file such that attributes of the instance file are consistent with the file attributes of the file.

21. A method for maintaining file consistency, a file being associated with a file system as recited in claim 1, wherein the file consistency protocol is configured to maintain consistent data in the file and the instance file, such that as data is modified in the file or the instance file, the modification to the data in the file or the instance file is made to data in the instance file or the file.

22. A method for maintaining file consistency, a file being associated with a file system as recited in claim 1, the method further comprising:

communicating the change in the file to a processing entity having an instantiation of the file and the consistency protocol.

23. A method for maintaining file consistency, a file being associated with a file system as recited in claim 6, wherein changing the file attributes further comprises:

listing the file attributes of the file without increasing protocol overhead.

24. A method for maintaining file consistency between multiple instances of a file, the method comprising:

associating a file consistency protocol with an operating system (O/S), the file consistency protocol maintaining file consistency between multiple instances of the file associated with a file system using a set of file consistency protocol bits;

checking the file for an exclusive bit setting of true;

failing an opening of another instance of the file if the exclusive bit of the file was determined to be set to true;

opening another instance of the file if the exclusive bit of the file was determined to be set to false;

performing an action on the file to change the file;

determining the type of action being performed on the file;

if the another instance of the file is opened, setting a bit in the set of file consistency protocol bits in the another instance of the file such that the set bits reflect the action performed on the file; and

messaging an update to the another instance of the file having the set bit such that the another instance of the file contains the change performed on the file.

25. A method for maintaining file consistency, a file being associated with a file system as recited in claim 24, wherein the determining the type of action further comprises:

determining if data within the file is to be changed; and

determining if attributes within the file are to be changed.

26. A method for maintaining file consistency, a file being associated with a file system as recited in claim 25, wherein the action further comprises:

modifying data within the file.

27. A method for maintaining file consistency, a file being associated with a file system as recited in claim 25, wherein the action further comprises:

listing attributes of the file.

28. A method for maintaining file consistency, a file being associated with a file system as recited in claim 24, wherein the action comprises:

opening the file in an open exclusive mode if it is determined that no other instance of the file has any of its set of file consistency bits set to “

1”

.

29. A method for maintaining file consistency, a file being associated with a file system as recited in claim 24, wherein the action further comprises:

opening the file in an open shared mode.

30. A method for maintaining file consistency, a file being associated with a file system as recited in claim 27, wherein the action further comprises:

changing attributes of the file.

31. A method for maintaining file consistency, a file being associated with a file system as recited in claim 30, wherein the action further comprises:

closing the file after making the attribute changes, if changes were made when the file was open.

32. A method for maintaining file consistency, a file being associated with a file system as recited in claim 24, wherein the set of file consistency protocol bits comprises:

a “

M”

bit, an “

A”

bit, an “

E”

bit, a “

S”

bit and an “

I”

bit.

33. A method for maintaining file consistency, a file being associated with a file system as recited in claim 32, wherein the “

M”

bit is set in the file when the data is modified in the file, and the “

I”

bit is set in the multiple instances.

34. A method for maintaining file consistency, a file being associated with a file system as recited in claim 32, wherein the “

A”

bit is set for the file and the multiple instances of the file when the attributes of the file are changed.

35. A method for maintaining file consistency, a file being associated with a file system as recited in claim 32, wherein the “

E”

bit is set in the file and the multiple instances of the file when the file is opened in the open exclusive mode, wherein none of the multiple instances of the file are able to have further access to data or attributes except for the file that set the “

E”

bit.

36. A method for maintaining file consistency, a file being associated with a file system as recited in claim 32, wherein the “

I”

bit is set in the multiple instances of the file when the data is modified in the file.

37. A method for maintaining file consistency, a file being associated with a file system as recited in claim 32, wherein the “

S”

bit is set in the file and the multiple instances of the file when the file is opened in the open shared mode.

38. A method for maintaining file consistency, a file being associated with a file system as recited in claim 32, wherein the “

I”

bit is set in the multiple instances of the file when the attributes of the file are changed.

39. A method for maintaining file consistency, a file being associated with a file system as recited in claim 32, wherein the “

M”

bit is set in the multiple instances of the file when the attributes of the file are changed.

40. A file consistency process for maintaining file consistency of files managed by a file system, the file consistency process being associated with an operating system, the file consistency process including:

a set of file consistency bits which correspond to actions performed on a file managed by the file system, the set of file consistency bits being configured to be set when one of the actions is to be performed on the file, the set of file consistency bits including an exclusive bit, wherein the exclusive bit being set to true causes an opening of another instance of the file to fail;

a plurality of instances of the file being instantiated when the exclusive bit of the file is set to false, the set of file consistency bits being set for each of the plurality of instances of the file so as to cause each of the instances to be updated when the actions change the file.

41. A file consistency process for maintaining file consistency of files managed by a file system as recited in claim 40, the set of file consistency bits comprising:

a “

M”

bit, an “

A”

bit, an “

E”

bit, a “

S”

bit and an “

I”

bit.

42. A file consistency process for maintaining file consistency of files managed by a file system as recited in claim 40, wherein the actions comprise:

listing attributes of the file;

opening the file in an open shared mode;

opening the file in an open exclusive mode; and

closing the file.

43. A file consistency process for maintaining file consistency of files managed by a file system as recited in claim 40, wherein the actions that change the file further comprise:

modifying data in the file; and

changing attributes in the file.

44. A method for maintaining consistent file data for shared files, comprising:

defining a set of consistency bits, wherein the set of consistency bits includes an exclusive bit;

checking a file for an exclusive bit setting of true;

failing an opening of another instance of the file if the exclusive bit of the file was determined to be set to true;

opening another instance of the file if the exclusive bit of the file was determined to be set to false;

changing the file;

setting a bit of the set of consistency bits on the instance file to reflect the change performed to the file; and

communicating an update to the instance file such that the instance file contains the change made to the file.

45. A method for maintaining file consistency between multiple copies of a file, the method comprising:

integrating a set of file consistency protocol bits with a file system that manages the file and the multiple copies of the file;

checking the multiple copies of the file for an exclusive bit setting of true;

failing an opening of the file if the exclusive bit of at least one of the multiple copies of the file was determined to be set to true;

opening the file if the exclusive bit of each of the multiple copies of the file was determined to be set to false;

performing an action on the file to change the file;

setting a bit of the set of file consistency protocol bits in the multiple copies of the file such that the set bits reflect the action performed on the file; and

messaging an update to the multiple copies of the file having the set bit such that the multiple copies of the file contain the change performed on the file.