Computer storage restoration

• US 6,990,563 B2
• Filed: 10/12/2001
• Issued: 01/24/2006
• Est. Priority Date: 02/26/1999
• Status: Expired due to Fees

• Current Assignee: Data Recovery Solutions LLC (Acacia Research Corporation)
• Original Assignee: Voom Technologies Incorporated
• Inventors: Biessener, David W., Frolik, Joseph A., Biessener, Gaston R.
• Primary Examiner(s): Padmanabhan, Mano
• Assistant Examiner(s): Namazi, Mehdi
• Application Number:
  US09/975,628
• Publication Number:
  US 20020023199A1
• Time in Patent Office: 1,565 Days
• Field of Search: 711/112, 711/162, 711/166, 711/170, 714/4, 714/7
• US Class Current: 711/162
• CPC Class Codes: G06F 11/1433 during software upgrading
• CPC Class Codes: G06F 11/1456 Hardware arrangements for backup
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence

Abstract

Restoration of a storage device for a computer, such as a hard disk drive, is provided. In one embodiment, a system includes a host device such as a processor or computer, a connection point at the host device such as a communications bus, a primary storage and a secondary storage. The primary storage has stored thereon first data, and sends this data to the host device in response to receiving a corresponding read command at the connection point. The secondary storage stores second data in response to receiving a write command including this data at the connection point, and sends the second data in response to receiving a corresponding read command at the connection point.

Claims

1. A method comprising:

storing data received from a host computer prior to a time T₀ on a primary storage;

storing data received from the host computer after time T₀ on a secondary storage;

defining a map designating corresponding logical storage units for the primary and secondary storage;

updating the map to indicate whether data has been written to the logical storage units of the secondary storage;

receiving a read command issued by the host computer;

identifying a logical storage unit designated by the read command;

accessing the map to determine whether data has been written to the secondary storage within the identified logical storage unit; and

selectively reading data from the primary storage and the secondary storage based on the determination.

2. The method of claim 1, further comprising storing the map in a computer-readable medium coupled to the host computer.

3. The method of claim 1, further comprising storing the map in a computer-readable medium of a controller coupled to the host computer via an input/output I/O bus.

4. The method of claim 1, wherein the map comprises a bitmap having a set of binary values, wherein each binary value corresponds to a respective logical storage unit, and further wherein updating the map includes changing a state of at least one of the binary values.

5. The method of claim 1, farther comprising:

reading data from the secondary storage device when data has been written within the identified logical storage unit;

reading data from the primary storage device when data has not been written within the identified logical storage unit; and

communicating the read data to the host computer.

6. The method of claim 1, further comprising initializing the map in response to a restore signal.

7. The method of claim 4, further comprising setting the binary values of the bitmap to a first state in response to a restore command.

8. The method of claim 7, further comprising receiving the restore signal from a hardware switch.

9. The method of claim 1, comprising:

receiving a reconcile command;

copying data between the primary and secondary storage devices in response to the reconcile command until the primary and secondary storages store equivalent data; and

resetting the map.

10. The method of claim 1, further comprising:

detecting free cycles for a bus in the host computer; and

copying data from the primary storage to the secondary storage during the unused bus cycles.

11. The method of claim 10, further comprising

receiving a reconcile command at a time T_R;

determining a remaining amount of data to copy from the primary storage to the secondary storage;

copying the remaining data from the primary storage to the secondary storage when the remaining amount of data is less than the data received from the host computer after time T₀; and

resetting the map.

12. The method of claim 11, further comprising storing data received from the host computer after time T_R on the primary storage.

13. A method comprising:

receiving a first reconcile command from a reconcile hardware switch at a time T₀;

establishing a T₀ state in response to the reconcile command in which data received from a host computer prior to time T₀ is stored on a primary storage and data received from the host computer alter time T₀ is stored on a secondary storage;

receiving a restore command from a restore hardware switch subsequent to time T₀; and

disregarding the data received from the host computer alter time T₀ in response to the restore command.

14. The method of claim 13, further comprising:

receiving a second reconcile command at a time subsequent to time T₀; and

establishing a new T₀ state in response to receiving a second reconcile command.

15. The method of claim 13, further comprising:

defining a map designating corresponding logical storage units for the primary and secondary storage; and

updating the map to indicate whether data has been written to the logical storage units of the secondary storage.

16. A system comprising:

a host computer;

a primary storage;

a secondary storage;

a controller to receive data from the host computer;

a first switch to generate a reconcile command upon activation; and

a second switch to generate a restore command upon activation,

wherein the controller stores data received prior to the reconcile command on the primary storage, and data received after the reconcile command on the secondary storage, and

wherein the controller discards the data stored on the secondary storage upon receiving the restore command.

17. The system of claim 16, wherein the first and second switches comprise hardware switches.

18. The system of claim 16, wherein the controller is coupled to the host computer via an input/output (I/O) bus.

19. The system of claim 16, wherein the controller includes a computer-readable medium storing a record of the data written to the secondary storage, and wherein the controller selectively reads data from the primary storage device and the secondary storage device based on the record.

20. The system of claim 16, wherein the controller defines a map designating corresponding logical storage units for the primary and secondary storage, and

updates the map to indicate whether data has been written to the logical storage units of the secondary storage.

21. A system comprising:

a connector adapted to provide an interface to a computer;

primary storage connected to the connector, wherein the primary storage is adapted to store first data;

secondary storage connected to the connector, wherein the secondary storage is adapted to store second data;

a restoration switch; and

a reconcile switch,

wherein the first data is data stored prior to time T₀;

wherein the second data is data stored after T₀;

wherein after time T₀ and in response to a read command for the first data being received at the connector, the first data is sent from the primary storage to the computer;

wherein after time T₀ and in response to a read command for the second data being received at the connector, the second data is sent from the secondary storage to the computer;

wherein actuating the restoration switch disregards the second data; and

wherein actuating the reconcile switch establishes a new T₀.

22. The storage device of claim 21, wherein the restoration switch includes a hardware switch.

23. The storage device of claim 21, wherein the restoration switch includes a virtual switch implemented via software such that actuation of the restoration switch comprises receiving a command at the connector.

24. The storage device of claim 21, further comprising a controller for controlling the primary storage and the secondary storage, the controller including a map for tracking the second data received at the connection point and stored on the secondary storage.

25. The storage device of claim 21, wherein the reconcile switch includes a hardware switch.

26. The storage device of claim 21, wherein the reconcile switch includes a virtual switch implemented via software such that actuation of the reconcile switch comprises receiving a command at the connector.

27. The storage device of claim 21, wherein the new T₀ is established by copying the second data from the secondary storage to the primary storage.

28. The storage device of claim 21, wherein the new T₀ is established by copying the first data from the primary storage to the secondary storage during free bus cycles before the reconcile switch is actuated, and copying any of the first data from the primary storage to the secondary storage that has not already been copied to the secondary storage when the reconcile switch is actuated.

29. A storage device for a computer, comprising:

a connector adapted to provide an interface to the computer;

a single computer-readable medium, including;

primary storage connected to the connector, wherein the primary storage is adapted to store first data; and

secondary storage connected to the connector, wherein the secondary storage is adapted to store second data; and

a reconcile switch,

wherein the first data is data stored prior to time T₀;

wherein the second data is data stored after T₀;

wherein after time T₀ and in response to a read command for the first data being received at the connector, the first data is sent from the primary storage to the computer;

wherein after time T₀ and in response to a read command for the second data being received at the connector, the second data is sent from the secondary storage to the computer; and

wherein actuating the reconcile switch establishes a new T₀ state.

30. The storage device of claim 29, further comprising a restoration switch, wherein actuating the restoration switch places the secondary storage in a T₀ state.

31. The storage device of claim 29, further comprising a controller for controlling the primary storage and the secondary storage, the controller including a map for tracking the second data received at the connection point and stored on the secondary storage.

32. A method, comprising:

in response to receiving a read command regarding first data after time T₀, reading the first data from primary storage, wherein the first data is data stored prior to T₀;

in response to receiving a write command after T₀, storing second data to secondary storage;

in response to receiving a read command regarding the second data, reading the second data from secondary storage; and

in response to a reconcile command, establishing a new T₀;

wherein establishing a new T₀ includes establishing a new T₀ in response to actuating a reconcile switch.

33. The method of claim 32, further comprising in response to actuating a restoration switch, disregarding the second data.

34. The method of claim 32, wherein establishing a new T₀ includes copying second data from the secondary storage to the primary storage.

35. The method of claim 32, wherein establishing a new T₀ state includes:

prior to actuating a reconcile switch, copying first data from the primary storage to the secondary storage during free cycles; and

in response to actuating a reconcile switch, copying any of the first data from the primary storage to the secondary storage that has not already been copied to the secondary storage.

36. An apparatus comprising:

a computer-readable medium with primary storage for storing first data and secondary storage for storing second data, wherein the first data is data stored prior to time T₀ and the second data is data stored after T₀;

a restoration switch for disregarding the second data; and

a reconcile switch for establishing a new T₀.

37. The apparatus of claim 36, wherein the computer-readable medium comprises a fixed computer-readable medium.

38. The apparatus of claim 36, wherein the computer-readable medium comprises a single computer-readable medium.

39. The apparatus of claim 36, wherein the computer-readable medium includes no more than one computer-readable medium.

40. The apparatus of claim 36, further comprising a controller for storing the first data to the primary storage prior to time T₀, for storing the second data to the secondary storage after T₀, for reading the first data from primary storage in response to receiving a read command regarding the first data, for reading the second data from secondary storage in response to receiving a reed command regarding the second data, and for establishing a new time T₀ in response to an actuated reconcile switch.

41. A method comprising:

storing data received from a host computer prior to a time T₀ on a primary storage;

storing data received from the host computer after time T₀ on a secondary storage;

maintaining a record of the data written to the secondary storage; and

selectively reading data from the primary storage and the secondary storage based on the record;

wherein the record comprises a bitmap having a set of binary values,

wherein each binary value corresponds to a respective logical storage unit, and wherein

updating the record includes changing a state of at least one of the binary values.

42. The method of claim 41, further comprising setting the binary values of the bitmap to a first state in response to a restore command.

43. The method of claim 42, further comprising receiving the restore signal from a hardware switch.

44. A method comprising:

receiving a first reconcile command from a reconcile hardware switch at a time T₀;

establishing a T₀ state in response to the reconcile command in which data received from the host computer prior to time T₀ is stored on a primary storage and data received from the host computer after time T₀ is stored on a secondary storage;

receiving a second reconcile command at a time subsequent to time T₀; and

establishing a new T₀ state in response to receiving a second reconcile command.

45. A method comprising:

in response to receiving a read command regarding first data alter time T₀, reading the first data from primary storage, wherein the first data is data stored prior to T₀;

in response to receiving a write command after T₀, storing second data to secondary storage;

in response to receiving a read command regarding the second data, reading the second data from secondary storage;

in response to a reconcile command, establishing a new T₀; and

in response to actuating a restoration switch, disregarding the second data.