Stored memory recovery system

• US 7,337,360 B2
• Filed: 06/11/2003
• Issued: 02/26/2008
• Est. Priority Date: 10/19/1999
• Status: Expired due to Term

• Current Assignee: Xylon LLC (Intellectual Ventures LLC)
• Original Assignee: Idocrase Investments LLC (Intellectual Ventures LLC)
• Inventors: Jian, Zhang, Sun, Hanxiang, Murray, Timothy John, Vohariwatt, Janet, Shen, Andrew W.
• Primary Examiner(s): Beausoliel; Robert
• Assistant Examiner(s): Mehrmanesh; Elmira
• Application Number:
  US10/460,778
• Publication Number:
  US 20040153718A1
• Time in Patent Office: 1,721 Days
• Field of Search: 714/8, 714/15, 714 19- 20, 711/152, 711/163, 711/202, 711/208, 711/209, 711/221, 707/702
• US Class Current: 714/20
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 11/2087 with a common controller

Abstract

Various embodiments of systems and methods for preserving saved memory states to which a computer system can be restored are disclosed. In certain embodiments, the systems and methods intercept write operations to protected memory locations and redirect them to alternate memory locations. Embodiments of the systems and methods include creation of a table for each memory state. Certain embodiments additionally include a recovery capability, by which the protected memory in the computer system is capable of being restored or recovered to a recovery point that represents a saved memory state. Further embodiments relate to systems and methods for preventing protected memory locations from being overwritten that utilize a plurality of memory state values.

Claims

1. A method for accessing a group of memory locations in a computer system, the method comprising:

maintaining, for said group of memory locations, a first data structure that has a plurality of entries, the plurality of entries including one or more entries dedicated to each memory status type in a set of two or more memory status types, wherein the one or more entries dedicated to a given memory status type include an indication of any and all memory locations in said group of memory locations that currently have a status corresponding to the given memory status type;

receiving a write request to a first memory location within said group of memory locations;

reading from a first group of one or more entries within said first data structure to determine whether said first memory location is indicated as having a protected memory status, wherein the first group of one or more entries are dedicated to one or more memory status types indicative of a protected memory status; and

redirecting said write request to a second memory location if said one or more entries indicate that said first memory location has a protected memory status, wherein said redirecting preserves the contents of the first memory location for a first recovery point.

2. The method of claim 1, further comprising redirecting a read request to said first memory location to said second memory location, wherein the contents of said second memory location are returned in response to said read request to said first memory location.

3. The method of claim 1, wherein the group of memory locations is accessed via a network.

4. The method of claim 1, wherein said first memory location has a protected memory status, and wherein said first memory location includes operating system data of the computer system.

5. The method of claim 1, wherein said first recovery point corresponds to a configuration of the computer system.

6. The method of claim 1, further comprising:

redirecting a subsequent write request to said second memory location to a third memory location such that the contents of said second memory location are preserved for a second recovery point.

7. The method of claim 6, further comprising redirecting a read request to said second memory location to said third memory location, wherein the contents of said third memory location are returned in response to said read request to said second memory location.

8. The method of claim 1, further comprising establishing said first recovery point.

9. The method of claim 8, wherein said first data structure is maintained after said establishing said first recovery point.

10. The method of claim 9, further comprising establishing a second recovery point subsequent to said first recovery point, wherein said establishing said second recovery point includes saving the contents of the first data structure and creating a second data structure.

11. The method of claim 1, wherein said first data structure has a first entry indicating one or more memory locations that have a first memory status type, wherein accesses to the one or more memory locations within the first entry are currently redirected to other memory locations.

12. The method of claim 11, wherein said one or more memory locations were added to said first entry after said first recovery point was established.

13. The method of claim 1, wherein said first data structure has a first entry indicating one or more memory locations that have a first memory status type, wherein accesses to the one or more memory locations in the first entry were previously redirected to other memory locations.

14. The method of claim 13, wherein said one or more memory locations indicated by the first entry are associated with recovery points established before said first recovery point.

15. The method of claim 1, wherein said first data structure has a first entry indicating one or more memory locations that have a protected memory status.

16. The method of claim 15, wherein said one or more memory locations indicated by the first entry were written before said first recovery point was established.

17. The method of claim 15, wherein said one or more memory locations indicated by the first entry were written after said first recovery point was established.

18. The method of claim 1, wherein said first data structure has a first entry indicating one or more memory locations that have a first memory status type, wherein the one or more locations indicated by said first entry were written after said first recovery point was established.

19. The method of claim 18, wherein said first memory status type is indicative of a non-protected memory status.

20. The method of claim 1, wherein said first data structure includes a first entry corresponding to a free memory status.

21. The method of claim 1, wherein the first data structure includes one or more entries indicative of protected memory locations and one or more entries indicative of non-protected memory locations.

22. The method of claim 21, wherein the one or more entries indicative of protected memory locations include a first set of entries dedicated to a first memory status type and a second set of entries dedicated to a second memory status type.

23. The method of claim 21, wherein each of the plurality of entries, if populated, includes information indicating memory locations having only the memory status type that the entry is dedicated to.

24. The method of claim 1, wherein the set of memory status types includes one or more types indicative of a protected memory status, and wherein the first data structure is arranged to permit a determination of any and all memory locations within the group of memory locations that currently have a status corresponding to a particular memory status type by accessing only those one or more entries dedicated to the particular memory status type.

25. A method of storing a group of memory locations in a computer system, the method comprising:

maintaining, for said group of memory locations, a first data structure that has a plurality of entries, the plurality of entries including one or more entries dedicated to each memory status type in a set of two or more memory status types, wherein the one or more entries dedicated to a given memory status type include an indication of any and all memory locations in said group of memory locations that currently have a status corresponding to the given memory status type;

selecting a first addressable memory location within said group of memory locations as part of a first recovery point, wherein said first memory location is indicated as having a protected memory status in said first data structure;

receiving a write request to said first addressable memory location; and

redirecting said write request to a second addressable memory location within said group of memory locations.

26. The method of claim 25, further comprising redirecting a read request to said first addressable memory location to said second addressable memory location, thereby returning the contents of said second addressable memory location in response to said read request to said first addressable memory location.

27. The method of claim 25, wherein said first recovery point corresponds to a configuration of an operating system loaded on the computer system.

28. The method of claim 25, further comprising:

selecting said second addressable memory location as part of a second recovery point, wherein said second memory location is indicated as having a protected memory status in a second data structure; and

redirecting a subsequent write request to said second addressable memory location to a third addressable memory location within said group of memory locations.

29. The method of claim 28, further comprising redirecting a read request to said second addressable memory location to said third addressable memory location, such that the contents of said third addressable memory location are returned in response to said read request to said second addressable memory location.

30. The method of claim 28, further comprising creating said second recovery point is in response to a timer event.

31. The method of claim 28, further comprising creating said second recovery point in response to pre-determined criteria.

32. The method of claim 25, wherein the set of memory status types includes one or more types indicative of a protected memory status, and wherein the first data structure is arranged to permit a determination of any and all memory locations within the group of memory locations that currently have a particular memory status type by accessing only those one or more entries dedicated to the particular memory status type.

33. A method of protecting a group of memory locations in a computer system from being overwritten, the method comprising:

maintaining, for said group of memory locations, a first data structure that has a plurality of entries, the plurality of entries including one or more entries dedicated to each memory status type in a set of two or more memory status types, wherein the one or more entries dedicated to a given memory status type include an indication of any and all memory locations in said group of memory locations that currently have a status corresponding to the given memory status type;

receiving a write request to a first memory location within said group of memory locations;

reading from one or more entries within said first data structure to determine whether said first memory location is indicated as having a protected memory status, wherein the one or more entries are dedicated to one or memory status types indicative of a protected memory status;

redirecting said write request to a second memory location if said one or more entries indicate that said first memory location has a protected memory status;

writing to a first entry within said first data structure to indicate that said second memory location has a protected memory status;

redirecting a write request to said second memory location to a third memory location; and

writing to a second entry within said first data structure to indicate that said second memory location has a protected memory status;

wherein the set of memory status types includes two or more memory status types.

34. The method of claim 33, further comprising redirecting a read request to said first memory location to said second memory location, thereby returning the contents of said second memory location in response to said read request to said first memory location.

35. The method of claim 33, further comprising redirecting a read request to said second memory location to said third memory location, thereby returning the contents of said third memory location in response to said read request to said second memory location.

36. The method of claim 33, wherein the set of memory status types includes one or more types indicative of a protected memory status, and wherein the first data structure is arranged to permit a determination of any and all memory locations within the group of memory locations that currently have a status corresponding to a particular memory status type by accessing only those one or more entries dedicated to the particular memory status type.

37. A computer, comprising:

a processor; and

a memory coupled to the processor, wherein the memory stores instructions executable by the processor to;

maintain a first data structure indicating the current memory status types of each of a group of memory locations, wherein the first data structure includes one or more entries dedicated to each memory status type in a set of two or more memory status types, wherein the one or more entries dedicated to a given memory status type include an indication of any and all memory locations in said group of memory locations that currently have a status corresponding to the given memory status type;

receive one or more write requests to the group of memory locations;

update said first data structure in response to the one or more write requests to the group of memory locations.

38. The computer of claim 37, wherein the group of memory locations is accessed via a network.

39. The computer of claim 37, wherein the first data structure includes one or more entries indicative of protected memory locations and one or more entries indicative of non-protected memory locations.

40. The computer of claim 39, wherein the one or more entries indicative of protected memory locations include a first set of entries dedicated to a first memory status type and a second set of entries dedicated to a second memory status type.

41. The computer of claim 39, wherein each of the plurality of entries, if populated, includes information indicating memory locations having only the memory status type that the entry is dedicated to.

42. The computer of claim 37, wherein the memory stores program instructions executable by the processor to:

receive a write request to a first memory location within said group of memory locations;

determine, from a first entry within the first data structure, whether said first memory location has a protected status;

if said first memory location has a protected status, find, from a second entry within said first data structure, a second memory location that has a status of not used;

update said first data structure so that a third entry indicates that said second memory location has a status of used;

redirect said write request from said first memory location to said second memory location; and

update said first data structure so that a fourth entry indicates that said first memory location is currently redirected to said second memory location.

43. The computer of claim 42, wherein the memory stores instructions executable by the processor to redirect a read request to said first memory location to said second memory location so that the contents of said second memory location are returned in response to said read request to said first memory location.

44. The computer of claim 37, wherein the set of memory status types includes one or more types indicative of a protected memory status, and wherein the first data structure is arranged to permit a determination of any and all memory locations within the group of memory locations that cuffently have a status coffesponding to a particular memory status type by accessing only those one or more entries dedicated to the particular memory status type.

45. A method for creating a plurality of recovery points for a computer system having a group of memory locations, the method comprising:

creating an initial data structure indicating an original state of said group of memory locations, wherein said initial data structure corresponds to an initial recovery point for said computer system;

receiving information identifying a new recovery point for said computer system, wherein said new recovery point is subsequent in time to said initial recovery point;

creating a new data structure corresponding to said new recovery point, wherein said creating includes using states of said group of memory locations indicated by said initial data structure to indicate states of said group of memory locations within said new data structure, and wherein said creating includes;

if said initial data structure indicates that one or more of said group of memory locations were unused at said initial recovery point but in use at said new recovery point, indicating in said new data structure that said one or more memory locations are protected;

wherein both said initial data structure and said new data structure have a plurality of entries, each of the data structures having one or more entries dedicated to each memory status type of a set of two or more memory status types, wherein the one or more entries dedicated to a given memory status type include an indication of any and all memory locations in said group of memory locations that currently have a status corresponding to the given memory status type.

46. The method of claim 45, wherein said information identifying the new recovery point is received from an enterprise manager executing on a remote computer system that is connected to the computer system via a network.

47. The method of claim 45, wherein said new recovery point is identified in response to a timer event.

48. The method of claim 45, wherein said new recovery point is identified in response to satisfaction of a pre-determined condition.

49. The method of claim 45, wherein said protected memory locations contain operating system data of the computer system.

50. The method of claim 45, wherein said initial recovery points corresponds to an initial configuration of the computer system.

51. The method of claim 45, further comprising removing said initial recovery point, wherein said removing comprises deleting the initial data structure.

52. The method of claim 51, wherein said removing further comprises releasing memory locations of the deleted initial data structure and memory locations no longer needed after removal of said initial recovery point, wherein the released memory locations are made available for use by the computer system.

53. The method of claim 45, further comprising removing said new recovery point, wherein said removing comprises deleting the new data structure.

54. The method of claim 45, wherein the set of memory status types includes one or more types indicative of a protected memory status, and wherein both the initial and new data structures are arranged to permit a determination of any and all memory locations within the group of memory locations that currently have a status corresponding to a particular memory status type by accessing only those one or more entries dedicated to the particular memory status type.

55. A computer readable storage medium including program instructions for accessing a group of memory locations in a computer system, wherein said program instructions are executable to:

maintain, for said group of memory locations, a first data structure that has a plurality of entries, the plurality of entries including one or more entries dedicated to each memory status type in a set of two or more memory status types, wherein the one or more entries dedicated to a given memory status type include an indication of any and all memory locations in said group of memory locations that currently have a status corresponding to the given memory status type;

receive a write request to a first memory location within said group of memory locations;

read from one or more entries within said first data structure to determine whether said first memory location is indicated as having a protected memory status, wherein the one or more entries are dedicated to one or more memory status types indicative of a protected memory status; and

redirect said write request to a second memory location if said one or more entries indicate that said first memory location has a protected memory status, wherein said write request is redirected such that the contents of the first memory location are preserved for a first recovery point.

56. The computer readable storage medium of claim 55, the method further comprising redirecting a read request to said first memory location to said second memory location, thereby returning the contents of said second memory location in response to said read request to said first memory location.

57. The computer readable storage medium of claim 55, wherein said first memory location has a protected memory status, and wherein said first memory location includes operating system data of the computer system.

58. The computer readable storage medium of claim 55, further including program instructions executable to:

redirect a subsequent write request to said second memory location to a third memory location such that the contents of said second memory location are preserved for a second recovery point.

59. The computer readable storage medium of claim 55, wherein the first data structure includes one or more entries indicative of protected memory locations and one or more entries indicative of non-protected memory locations.

60. The computer readable storage medium of claim 59, wherein the one or more entries indicative of protected memory locations include a first set of entries dedicated to a first memory status type and a second set of entries dedicated to a second memory status type.

61. The computer readable storage medium of claim 59, wherein each of the plurality of entries, if populated, includes information indicating memory locations having only the memory status type associated with that entry.

62. The computer readable storage medium of claim 55, wherein the set of memory status types includes one or more types indicative of a protected memory status, and wherein the first data structure is arranged to permit a determination of any and all memory locations within the group of memory locations that currently have a status corresponding to a particular memory status type by accessing only those one or more entries dedicated to the particular memory status type.