DISCARDABLE FILES

• US 20100153352A1
• Filed: 12/22/2009
• Published: 06/17/2010
• Est. Priority Date: 12/16/2008
• Status: Active Grant

• Current Assignee: Western Digital Israel Limited (Western Digital Corporation)
• Original Assignee: SanDisk IL Ltd. (Western Digital Corporation)
• Inventors: Jagannadha, Baddireddi Kalyan Venkannadora, Subramanian, Natarajanja Raja, Hahn, Judah Gamliel
• Granted Patent: US 8,375,192 B2
• Time in Patent Office: Days
• US Class Current: 707/704
• CPC Class Codes: G06F 16/11 File system administration, e.g. details of archiving or snapshots file system backup G06F11/14
• CPC Class Codes: G06F 16/125 characterised by the use of retention policies retention policies for HSM systems G06F16/185

Abstract

The present application includes methods and system for managing a storage device. In one implementation, a storage allocator that is present in a host or a storage device receives a request to store a file in a storage area of the storage device. The storage allocator marks the file as discardable in a file system structure associated with the storage device and updates a primary file allocation table (“FAT”) to associate a cluster chain that is allocated to the file with the file. The storage allocator additionally updates a discardable FAT or a database to reflect a physical location of the file, or may generate one or more location files that store the physical location of the file. The storage allocator then manages the storage area device based on the FAT and a discardable FAT, database, or one more location files indicating the physical location of the file.

Claims

1-16. -16. (canceled)

17. A method for managing a storage device, the method comprising:

in a storage device operatively coupled to a host;

receiving a request to store a first file in a storage area of the storage device, wherein the storage device contains a primary file allocation table (“

FAT”

) and, in addition, a discardable FAT;

marking the first file as discardable, the marking of the first file being done in a file system structure associated with the storage device;

updating the primary FAT to associate a cluster chain that is allocated to the first file with the first file;

updating the discardable FAT to reflect a physical location of the first file in the storage device; and

managing the storage area of the storage device in accordance with the discardable FAT.

18. The method of claim 17, wherein the cluster chain masks at least the physical location of the first file.

19. The method of claim 17, further comprising:

enabling an attribute associated with the first file to prevent a host operating system from accessing the first file.

20. The method of claim 17, further comprising:

receiving a request to store a second file in the storage area of the storage device;

marking the second file as discardable, the marking of the second file being done in the file system structure associated with the storage device;

updating the primary FAT to associate the cluster chain with the second file, wherein the cluster chain is associated with the first file and the second file; and

updating the discardable FAT to reflect a physical location of the second file.

21. The method of claim 20, wherein the cluster chain masks the physical location of the first file and the second file.

22. The method of claim 17, further comprising:

receiving a request to store a second file in the storage area of the storage device;

marking the second file as discardable, the marking of the second file being done in the file system structure associated with the storage device;

updating the primary FAT to associate a second cluster chain that is allocated to the second file with the second file; and

updating the discardable FAT to reflect the physical location of the second file.

23. The method of claim 17, further comprising:

marking the first file as a non-discardable file, the marking of the first file being done in the file system structure associated with the storage device;

updating the primary FAT to reflect the physical location of the first file; and

updating the discardable FAT to remove the physical location of the first file.

24. The method of claim 23, further comprising:

identifying a value of a conversion lock identifier associated with the first file to determine whether the first file may be converted from a discardable file to a non-discardable file;

wherein the first file is marked as a non-discardable file after determining the value of the conversion lock identifier associated with the first file indicates that the first file is not locked.

25. The method of claim 17, further comprising:

identifying a value of a conversion lock identifier associated with the first file to determine whether the first file may be converted from a discardable file to a non-discardable file; and

prohibiting the marking of the first file as non-discardable after determining the value of the convert lock associated with the first file indicates that the first file is locked.

26. The method of claim 17, further comprising:

identifying file permissions associated with a user ID and a preview file associated with the first file; and

managing access to the preview file associated with the first file based on the identified file permissions.

27. The method of claim 17, wherein the user ID is a shared user ID.

28. The method of claim 17, wherein the cluster chain of the primary FAT points to a location in the discardable FAT.

29. The method of claim 17, wherein marking the first file as discardable comprises:

assigning a discarding priority level to the first file.

30. The method of claim 29, wherein assigning the discarding priority level to the first file comprises at least one of:

setting a corresponding value to m most significant bits in the primary FAT entry corresponding to the first file;

or

setting a corresponding value to a data field in a file system entry corresponding of the first file.

31. The method of claim 29, wherein the discarding priority level is assigned to the first file according to any one of:

anticipated usage of the first file;

anticipated revenue associated with using the file;

a type of file of the first file;

a size of the first file;

a location of the first file in the storage device; and

an age of the first file.

32. The method of claim 17, wherein managing the storage area of the storage device in accordance with the discardable FAT comprises any one or a combination of:

restoring a storage usage safety margin by selectively removing one or more files marked as discardable;

freeing a storage area by removing all files marked as discardable; and

remapping clusters of the first file to a lower-performance storage module.

33. A storage allocator for managing a storage device, comprising:

a communication interface to interface a storage device and a host of the storage device;

a storage unit for storing a file system associated with the storage device;

a processor for managing the file system associated with the storage device; and

wherein the processor is configured to;

receive a request to store a first file in a storage area of the storage device, wherein the storage device contains a primary file allocation table (“

FAT”

) and, in addition, a discardable FAT;

mark the first file as discardable, the marking of the first file being done in a file system structure associated with the storage device;

cause the storage device to update the primary FAT to associate a cluster chain that is allocated to the first file with the first file;

cause the storage device to update the discardable FAT to reflect a physical location of the first file in the storage device; and

manage the storage area of the storage device in accordance with the discardable FAT.

34. The storage allocator of claim 33, wherein the cluster chain masks a physical location of the first file.

35. The storage allocator of claim 33, wherein the processor is further configured to:

receive a request to store a second file in the storage area of the storage device;

mark the second file as discardable, the marking of the second file being done in the file system structure associated with the storage device;

cause the storage device to update the primary FAT to associated the cluster chain with the second file, wherein the cluster chain is associated with the first file and the second file; and

cause the storage device to update the second FAT to reflect a physical location of the second file;

wherein the discardable cluster chain masks the physical location of the first file and the second file.

36. The storage allocator of claim 33, wherein the processor is further configured to:

receive a request to store a second file in the storage area of the storage device;

mark the second file as discardable, the marking of the second file being done in the file system structure associated with the storage device;

cause the storage device to update the primary FAT to associate a second cluster chain that is allocated to the second file with the second file; and

cause the storage device to update the discardable FAT to reflect a physical location of the second file.

37. The storage allocator of claim 33, wherein the processor is further configured to:

mark the first file as a non-discardable file, the marking of the first file being done in the file system structure associated with the storage device;

cause the storage device to update the primary FAT to reflect the physical location of the first file; and

cause the storage device to update the discardable FAT to remove the physical location of the first file.

38. The storage allocator of claim 37, wherein the processor is further configured to:

identify a value of a conversion lock identifier associated with the first file to determine whether the first file may be converted from a discardable file to a non-discardable file; and

wherein the first file is marked as a non-discardable file after determining the value of the conversion lock identifier associated with the first file indicates that the first file is not locked.

39. The storage allocator of claim 33, wherein the processor is further configured to:

identify a value of a conversion lock identifier associated with the first file to determine whether the first file may be converted from a discardable file to a non-discardable file; and

prohibit the marking of the first file as non-discardable after determining the value of the conversion lock identifier associated with the first file indicates that the first file is locked.

40. The storage allocator of claim 33, wherein the processor is further configured to:

identify file permissions associated with a user id and a preview file associated with the first file; and

manage access to the preview file associated with the first file based on the identified file permissions.

41. The storage allocator of claim 33, wherein the cluster chain of the first FAT points to a location in the second FAT.

42-50. -50. (canceled)

51. A method for managing a storage device, the method comprising:

in a storage device operatively coupled to a host;

receiving a request to store a first file in a storage area of the storage device;

marking the first file as discardable, the marking of the first file being done in a file system structure associated with the storage device;

updating a file allocation table (“

FAT”

) to associate a cluster chain that is allocated to the first file with the first file;

updating a database to reflect a physical location of the first file in the storage device; and

managing the storage area of the storage device in accordance with the FAT and the database.

52-54. -54. (canceled)

55. A method for managing a storage device, the method comprising:

in storage device that is coupled to a host;

receiving a request to store a first file in a storage area of the storage device;

marking the first file as discardable, the marking of the first file being done in a file system structure associated with the storage device;

updating a file allocation table (“

FAT”

) to associate a cluster chain that is allocated to the first file with the first file;

updating a location file to reflect a physical location of the first file in the storage device; and

managing the storage area of the storage device in accordance with the FAT and the location file.

56-60. -60. (canceled)

61. A method for managing a storage device, the method comprising:

in a storage device that is coupled to a host;

receiving a request to store a first file in a storage area of the storage device;

marking the first file as discardable, the marking of the first file being done in a file system structure associated with the storage device;

updating a file allocation table (“

FAT”

) to associate a cluster chain that is allocated to the first file with the first file;

scrambling an order of two or more clusters of the cluster chain that are associated with the first file within the FAT;

creating a first range file in the FAT which comprises at least one cluster of the cluster chain that is associated with the first file; and

managing the storage area of the storage device in accordance with the FAT and the first range file.

62. The method of claim 61, further comprising:

receiving a request to store a second file in the storage area of the storage device;

marking the second file as discardable, the marking of the second file being done in the file system structure associated with the storage device;

updating the FAT to associate the cluster chain with the second file, wherein the cluster chain is associated with the first file and the second file; and

scrambling an order of two or more clusters of the cluster chain that are associated with the second file within the FAT.

63. The method of claim 61, further comprising:

updating the first range file in the FAT to comprise at least one cluster of the cluster chain associated with the second file.

64. The method of claim 61, further comprising:

receiving a request to store a second file in the storage area of the storage device;

marking the second file as discardable, the marking of the second file being done in the file system structure associated with the storage device;

updating the FAT to associate a second cluster chain that is allocated to the second file with the second file;

scrambling an order of two or more clusters of the second cluster chain that are associated with the second file within the FAT;

creating a second range file in the FAT which comprise at least one cluster of the cluster chain associated with the second file; and

wherein managing the storage area of the storage device in accordance with the FAT and the first range file comprises;

managing the storage area of the storage device in accordance with the FAT, the first range file and the second range file.

65. The method of claim 61, further comprising:

creating a second range file in the FAT that comprises at least one cluster of the cluster chain that is associated with the first file that does not comprise the first range file;

wherein managing the storage area of the storage device in accordance with the FAT and the first range file comprises;

managing the storage area of the storage device in accordance with the FAT, the first range file, and the second range file.

66-94. -94. (canceled)