Method for protecting history in a file system

• US 7,293,027 B2
• Filed: 09/30/2005
• Issued: 11/06/2007
• Est. Priority Date: 02/26/2003
• Status: Expired due to Term

• Current Assignee: Red Hat, Inc. (International Business Machines Corporation)
• Original Assignee: Burnside Acquisition, LLC
• Inventors: Margolus, Norman H.
• Primary Examiner(s): Truong; Cam Y
• Assistant Examiner(s): Ehichioya; Fred I.
• Application Number:
  US11/240,829
• Publication Number:
  US 20060026220A1
• Time in Patent Office: 767 Days
• Field of Search: 707 1- 10, 707/100, 707/200, 707/203, 707/204, 707/206, 709/213, 709/229, 382/116, 382/125, 713165-168
• US Class Current: 1/1
• CPC Class Codes: G06F 16/122 using management policies backup systems G06F11/1446; file migration policies for HSM systems G06F16/185
• CPC Class Codes: G06F 16/125 characterised by the use of retention policies retention policies for HSM systems G06F16/185
• CPC Class Codes: G06F 16/2358 Change logging, detection, and notification replication G06F16/27
• CPC Class Codes: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99936 Pattern matching access
• CPC Class Codes: Y10S 707/99937 Sorting
• CPC Class Codes: Y10S 707/99939 Privileged access
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99952 Coherency, e.g. same view to multiple users
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A method for protecting history in a file system in which rules governing which versions of files must be retained, and for how long, are enforced by one or more storage systems attached to a network, the method comprising associating with a storage system a time standard configured to prevent the accuracy of the time standard from being manipulated over the network, storing file information in the storage system, with files stored as objects adapted for separate retrieval in any order, storing, in the storage system, directory information which is sufficient to allow files to be retrieved starting from file system pathnames, marking at least some versions of files as archival file versions not subject to further change, and assigning an expiration time to each of at least some of the archival file versions, preventing storage system clients from deleting archival file versions before their expiration times, and allowing individual archival file versions that have passed their expiration times to be deleted and their storage space reused, with the decision to delete a particular archival file version being capable of being made separately and independently from the decision to delete other archival file versions.

Claims

1. A method for protecting history in a file system in which rules governing which versions of files of the file system must be retained, and for how long, are enforced by one or more storage systems attached to a network, the method comprising:

associating with a storage system a time standard configured to prevent the accuracy of the time standard from being manipulated over the network;

storing versions of the files in the storage system, with each of the versions recording a state of one of the files, and with the versions of the files stored in a manner adapted to allow separate retrieval of versions of different ones of the files in any order;

storing, in the storage system, directory information which is sufficient to allow a version of each of the files to be retrieved starting from a file system pathname;

marking at least some of the versions of the files as archival file versions not subject to modification, and assigning an expiration time to each of the archival file versions;

comparing the time standard with the expiration time assigned to an archival file version that is one of the archival file versions and, based at least in part on this comparison, preventing a storage system clients from deleting the archival file version before the expiration time assigned to it has passed; and

allowing the storage system client to delete the archival file version after the expiration time assigned to it has passed;

wherein no action taken by the storage system client can cause the expiration time assigned to the archival file version to be changed to an earlier time;

wherein after the archival file version is deleted, storage space that was used to store it in the storage system is reused; and

wherein, when deletion is allowed, the storage system client can delete the archival file version separately and independently from any others of the archival file versions regardless of the expiration times assigned to them.

2. The method of claim 1 in which, after the archival file version has passed its expiration time, it is retained until it is deleted by the storage system client.

3. The method of claim 1 in which the storage system client is allowed to extend the expiration time of the archival file versions separately and independently from the expiration times of any others of the archival file versions, regardless of the expiration times assigned to them.

4. The method of claim 1 in which the expiration time assigned to a second of the archival file versions has passed and the second of the archival file versions is automatically deleted by the storage system.

5. The method of claim 1 in which no storage system client is allowed to delete the archival file version before its expiration time.

6. The method of claim 1 in which a specially privileged storage system client is allowed to delete the archival file version before its expiration time.

7. The method of claim 1 in which, before an action of a file system client operating through a standard file system interface, only a single version of a file that is one of the files is stored in the storage system, and the single version is not marked as being archival and is not assigned an expiration time.

8. The method of claim 7 in which the archival file version is marked as archival as a result of the action of the file system client operating through the standard file system interface, and after the action the single version of the file is the archival version.

9. The method of claim 1 in which the storage system client stores the archival file version in the storage system.

10. The method of claim 1 in which a version of a one of the files is not marked as being archival and the version cannot be modified and cannot be deleted from the storage system until after it is marked as being archival and assigned an expiration time, before which time both modification and deletion continue to be prohibited and after which time deletion is allowed.

11. The method of claim 1 in which a file that is one of the files is assigned a version retention policy which governs the expiration times that will be assigned by the storage system to versions of the file stored in the storage system when they are marked as archival.

12. The method of claim 11 in which storage system objects corresponding to each of the files can individually be assigned separate and independent version retention policies.

13. The method of claim 11 in which each of a plurality of storage systems that collectively store the files independently enforces a coordinated set of version retention policies applying to the files.

14. The method of claim 11 in which the storage system stores a hash representative of the version retention policy.

15. The method of claim 1 in which the storage system monitors or controls the deposit times associated with the versions of the files that are stored in it.

16. The method of claim 15 in which some of the versions of the files are deposited before the storage system begins monitoring or controlling the deposit time associated with the versions of the files stored in it.

17. The method of claim 1 in which, once the time standard is initialized, it cannot be influenced over the network.

18. The method of claim 1 in which, once the time standard is initialized, the rate at which the time setting of the time standard can be adjusted over the network is constrained.

19. The method of claim 1 in which the storage system breaks the archival file version up into blocks of content and computes a content fingerprint that is a cryptographic hash for each of the blocks of content.

20. The method of claim 19 in which each of the blocks of content is stored at a location that depends, at least in part, on its content fingerprint.

21. The method of claim 19 in which the content fingerprints are used to share storage for identical blocks of content that are independently deposited as constituents of versions of different ones of the files.

22. The method of claim 19 in which a one of the blocks of content is encrypted using a key based on the content of the block.

23. The method of claim 1 in which a storage system object identifier is derived at least in part by computing hashes that depend on the components of a file system pathname of the archival file version.

24. The method of claim 1 in which it is the storage system client that marks the archival file version as being archival and assigns the expiration time to the archival file version.

25. The method of claim 1 in which the storage system client causes the expiration time assigned to the archival file version to be changed to a later time.

26. The method of claim 1 in which the storage system client causes a value to be assigned to the expiration time of the archival file version.

27. The method of claim 1 in which no action taken by any storage system client that only communicates with the storage system over a wide area network can cause the expiration time assigned to the archival file version to be changed to an earlier time.

28. The method of claim 7 in which the action of the file system client is a file or directory operation affecting only the file that is one of the files.

29. The method of claim 10 in which, for an interval of more than a year, the version of the one of the files is stored in the storage system and is not marked as archival.

30. The method of claim 10 in which the storage system client marks the version of the one of the files as being archival and the expiration time assigned to the version is assigned by the storage system.

31. The method of claim 30 in which the value of the expiration time assigned to the version by the storage system is determined based on rules or parameters that were associated with the version by the storage client at the time that the version was stored into the storage system.

32. The method of claim 1 in which the storage system client is a program that communicates with the storage system over the network.

33. The method of claim 1 in which the network is a wide area network.

34. The method of claim 1 in which the most current version of the versions of a one of the files is modified or replaced by a new version and the superseded most current version is not retained by the storage system.

35. The method of claim 1 in which the most current version of the versions of a one of the files is replaced by a new version and the superseded most current version is marked as archival by the storage system and becomes the archival file version.

36. The method of claim 1 in which assigning the expiration time to the archival file version comprises assigning a status that indicates that the archival file version will never expire;

wherein if the archival file version had been assigned a status that indicated that the archival file version would expire after a finite time, then the storage client would have been allowed to delete the archival file version after the finite time;

wherein the storage client cannot affect the assigned status that indicates that the archival file version will never expire; and

wherein, as long as the archival file version is assigned the status that indicates that it will never expire, no action taken by the storage client can cause the archival file version to be deleted.

37. The method of claim 1 in which the file system is separate from the storage system and the versions of the files are copied from the file system into the storage system.

38. The method of claim 1 in which the file system is not separate from the storage system and the storage client is a program that provides a file system interface to the storage system for file system clients.

39. The method of claim 1 in which the archival file version is one of a plurality of the archival file versions that are all versions of a single one of the files and each one of the plurality is associated with an interval of times during which the state recorded in the one of the plurality was the same as the state of the single one of the files.

40. The method of claim 39 in which the expiration time assigned to the archival file version depends at least in part upon the length of the interval of times associated with it.

41. The method of claim 39 in which the expiration time assigned to the archival file version depends at least in part on whether or not a specified moment of time is part of the interval of times associated with the archival file version.

42. The method of claim 1 or 31 in which the expiration time assigned to the archival file version is based on adding a prescribed period of time to a time stamp associated with the archival file version or to the time at which the expiration time is assigned.

43. The method of claim 1 in which a record of the state of a one of the files comprises a copy of the contents of the one of the files at the time of the recording.

44. The method of claim 13 in which a block of content that is a constituent of the archival file version is stored in more than one of the plurality of storage systems.

45. The method of claim 1 in which the expiration time assigned to each of the archival file versions is separate from the expiration times assigned to any others of the archival file versions and can be assigned a value independently of the others.