Multi-epoch method for saving and exporting file system events

• US 8,458,175 B2
• Filed: 06/17/2011
• Issued: 06/04/2013
• Est. Priority Date: 10/29/2002
• Status: Expired due to Term

• Current Assignee: EMC Corporation (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Stokes, Randall K.
• Primary Examiner(s): To, Baoquoc N
• Application Number:
  US13/163,450
• Publication Number:
  US 20110252434A1
• Time in Patent Office: 718 Days
• Field of Search: 707/793, 707/812
• US Class Current: 707/725
• CPC Class Codes: G06F 11/1451 by selection of backup contents
• CPC Class Codes: G06F 16/10 File systems; File servers
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface

Abstract

As things happen on a volume, the file system forwards events to an event list manager. The event list manager stores the events and associates them with epochs that were active at the time the event occurred. Event consumers can independently declare epochs at any time. When event consumers end an epoch, they can request events that occurred during the epoch, which are reported to the event consumer using the event list manager.

Claims

1. A computer-implemented method for using an event system, comprising:

receiving a start epoch declaration at an event request handler from a computer operated by a consumer;

beginning an epoch for the consumer at a time of receiving the start epoch declaration, including assigning a unique epoch number to the epoch for the consumer;

receiving a first event;

associating the first event with the first epoch in an event list;

ending the epoch for the consumer at a time of receiving an end epoch declaration at the event request handler from the consumer; and

reading an event associated with the first epoch from the event list after ending the first epoch and sending the associated event to the computer operated by the consumer.

2. A computer-implemented method according to claim 1, wherein the start epoch declaration comprises a first start epoch declaration, the consumer comprises a first consumer, the epoch comprises a first epoch, and the end epoch declaration comprises a first end epoch declaration, the method further comprising:

receiving a second start epoch declaration at the event request handler from a second computer operated by a second consumer;

beginning a second epoch for the second consumer at a time of receiving the second start epoch declaration, and without receiving the first end epoch declaration for the first epoch;

ending the second epoch at a time of receiving a second end epoch declaration at the event request handler from the second consumer; and

reading a second event associated with the second epoch from the event list after ending the second epoch and sending the second associated event to the second computer operated by the second consumer.

3. An apparatus for using an event system, the apparatus comprising:

an epoch storage configured to store at least one first active epoch and a second active epoch;

the first active epoch created by a first start epoch declaration and remaining active until a first end epoch declaration;

the second active epoch created by a second start epoch declaration and remaining active until a second end epoch declaration;

an event storage;

an event list manager to receive an event, store the event in the event storage, and associate the event with at least one epoch active when the event occurred;

an event request handler to receive the first start epoch declaration, the first end epoch declaration, the second start epoch declaration, and the second end epoch declaration; and

an interface with the event list manager, wherein after a user issues at least one of the first and second end epoch declarations, the interface enables the user to access the event that was associated with the corresponding active epoch while the epoch was active;

wherein the first start epoch declaration is issued at a time of the start of the first active epoch and the first end epoch declaration is issued at a time of the end of the first active epoch.

4. An apparatus according to claim 3, wherein the second start epoch declaration is issued at a time of the start of the second active epoch and the second end epoch declaration is issued at a time of the end of the second active epoch.

5. An apparatus according to claim 3, further comprising:

a volume;

a file system for the volume, configured to report the event; and

the event list manager is configured to associate a unique epoch number for each epoch active when the event occurred with the event in the event storage.

6. An apparatus according to claim 5, wherein the event list manager is configured to associate the event with at least the first active epoch in the epoch storage if the first active epoch is active when the event occurs and to associate the event with the second active epoch if the second active epoch is active when the event occurs.

7. An apparatus according to claim 6, wherein the event is associated with the unique epoch numbers for at least the first active epoch or the second active epoch.

8. An apparatus according to claim 5, wherein the event list manager is configured to assign a unique epoch number to at least one of the first and second active epochs thereby giving a user an impression of being a sole consumer of events.

9. An apparatus according to claim 3, wherein the interface enables the user to issue one of the start epoch declarations without issuing any end epoch declaration.

10. A computer-implemented method for using an event system, comprising:

receiving a first start epoch declaration from a first computer operated by a first consumer;

beginning a first epoch for the first consumer at a time of receiving the first start epoch declaration;

receiving a second start epoch declaration from a second computer operated by a second consumer;

beginning a second epoch for the second consumer at a time of receiving the second start epoch declaration, and without receiving an end epoch declaration;

maintaining the first epoch as active until receiving an end epoch declaration from the first consumer;

maintaining the second epoch as active until receiving an end epoch declaration from the second consumer;

receiving a first event;

storing the first event in an event list;

associating the first event with any active epochs in the event list;

ending the first epoch at a time of receiving the end epoch declaration from the first consumer;

reading an event associated with the first epoch from the event list after ending the first epoch; and

sending the associated event to the first computer operated by the first consumer.

11. A computer-implemented method according to claim 10, wherein:

receiving a first event includes receiving the first event from a file system as the first event occurs; and

associating the first event with any active epochs in the event list includes;

associating the first event with the first epoch if the first epoch is active when the first event occurs; and

associating the first event with the second epoch if the second epoch is active when the first event occurs.

12. A computer-implemented method according to claim 11, further comprising:

receiving a second event as the second event occurs, wherein the second event is a different event type than the first event;

associating the second event with the first epoch if the first epoch is active when the second event occurs; and

associating the second event with the second epoch if the second epoch is active when the second event occurs.

13. A computer-implemented method according to claim 10, wherein receiving the first start epoch declaration includes receiving the first start epoch declaration from the first consumer using non-proprietary application program interfaces (APIs).

14. A computer-implemented method according to claim 10, wherein receiving the second start epoch declaration includes receiving the second start epoch declaration from the second consumer using non-proprietary application program interfaces (APIs).

15. A computer-implemented method according to claim 10, wherein:

beginning the first epoch includes beginning the first epoch for the first consumer at a first time; and

beginning the second epoch includes beginning the second epoch for the second consumer at a second time.

16. A computer-implemented method according to claim 15, wherein:

ending the first active epoch includes ending the first active epoch for the first consumer at a third time; and

ending the second active epoch includes ending the second active epoch for the second consumer at a fourth time.

17. A computer-implemented method according to claim 10, wherein:

receiving the first event includes receiving the first event from the file system for a volume; and

storing the first event includes storing the first event in the event list on the volume.

18. A computer-implemented method according to claim 10, wherein storing the first event includes storing the first event in the event list implemented as a b-tree.

19. A computer-implemented method according to claim 10, wherein reading an event associated with the first epoch from the event list includes removing the association of the event with the first epoch.

20. A computer-implemented method according to claim 19, wherein removing the association of the event with the first epoch includes removing the event from the event list if the event is not associated with the second epoch.

21. A computer-implemented method according to claim 19, wherein removing the association of the event with the first epoch includes removing the event responsive to a message from the first consumer that the event can be removed.

22. A computer-implemented method according to claim 10, wherein reading an event associated with the first epoch includes reading the associated event from the event list using non-proprietary application program interfaces (APIs).

23. A computer-implemented method according to claim 10, further comprising processing the associated event associated with the first epoch by the first consumer.

24. A computer-implemented method according to claim 10, wherein:

the method further comprises receiving a request for the associated event associated with the first epoch from the first consumer; and

reading an event associated with the first epoch and sending the associated event associated with the first epoch are responsive to the request for the associated event.

25. A computer-implemented method according to claim 10, wherein storing the first event includes:

determining that the first event affects an object of the file system and that a second event affects the object of the file system, wherein the first event and the second event are different events;

determining that the first event and the second event are compressible; and

compressing the first event and the second event.

26. A computer-implemented method according to claim 25, wherein the object is one of a file, a directory, and the volume.

27. A computer-implemented method according to claim 25, wherein determining that the first event and the second event are compressible includes:

determining that the first epoch was active when the first event occurred; and

determining that the second event is associated with the first active epoch.

28. A computer-implemented method according to claim 25, wherein compressing the first event and the second event includes discarding the first event.

29. A computer-implemented method according to claim 25, wherein compressing the first event and the second event further includes storing additional information about the first event with the first epoch associated with the second event before discarding the first event.

30. A computer-implemented method according to claim 10, further comprising:

receiving a third start epoch declaration from the first consumer;

beginning a third epoch for the first consumer; and

maintaining the third epoch as active until receiving a third end epoch declaration from the first consumer.

31. A computer-implemented method according to claim 30, wherein receiving the first end epoch declaration from the first consumer includes receiving the first end epoch declaration before receiving the third start epoch declaration from the first consumer.

32. A computer-implemented method according to claim 30, wherein reading an event associated with the first epoch includes reading the event associated with the first epoch after beginning the third epoch for the first consumer.

33. A computer-implemented method according to claim 10, further comprising removing the association of the event with the first epoch.

34. A computer-implemented method according to claim 10, wherein ending the first epoch includes changing a state of the first epoch to in-use after ending the first epoch.

35. A computer-implemented method according to claim 10, further comprising changing a state of the first epoch to a not-in-use status if no events are associated with the first epoch.

36. An apparatus for using an event system, the apparatus comprising:

a volume;

a file system for the volume, configured to report an event as the event occurs;

an event storage;

an epoch storage configured to store a first active epoch and a second active epoch, the first active epoch created by a first start epoch declaration and remaining active until a first end epoch declaration, the second active epoch created by a second start epoch declaration and remaining active until a second end epoch declaration;

an event list manager configured to receive the event from the file system, store the event in the event storage, associate the event with the first active epoch in the epoch storage if the first active epoch is active when the event occurs, and associate the event with the second active epoch if the second active epoch is active when the event occurs; and

an interface with the event list manager, wherein after a user issues at least one of the first and second end epoch declarations, the interface enables the user to access the event that was associated with the corresponding active epoch while the epoch was active,

wherein a state of the first epoch is changed to in-use and maintained in the epoch storage responsive to the first end epoch declaration, and wherein a state of the second epoch is changed to in-use and maintained in the epoch storage responsive to the second end epoch declaration.

37. An article drawn from the set including floppy disks, optical disks, fixed disks, random access memory, read-only memory, or flash memory, comprising a machine-accessible medium having associated instructions that, when executed, results in a machine:

receiving a first start epoch declaration from a first computer operated by a first consumer;

beginning a first epoch for the first consumer at a time of receiving the first start epoch declaration;

receiving a second start epoch declaration from a second computer operated by a second consumer;

beginning a second epoch for the second consumer at a time of receiving the second start epoch declaration, and without receiving an end epoch declaration;

maintaining the first epoch as active until receiving an end epoch declaration from the first consumer;

maintaining the second epoch as active until receiving an end epoch declaration from the second consumer;

receiving a first event;

storing the first event in an event list;

associating the first event with any active epochs in the event list;

ending the first epoch at a time of receiving the end epoch declaration from the first consumer;

changing a state of the first epoch to in-use after ending the first epoch;

ending the second epoch at a time of receiving the end epoch declaration from the second consumer;

reading an event associated with the first epoch from the event list after ending the first epoch; and

sending the associated event to the first computer operated by the first consumer.

38. An article according to claim 37, wherein:

receiving a first event includes receiving the first event from a file system as the first event occurs; and

receiving a second event includes receiving the second event from the file system as the second event occurs.

39. An article according to claim 38, the machine-accessible medium having further associated data that, when accessed, result in the machine removing the association of the first event with the first epoch.