Method and apparatus for managing access to volumes of storage

• US 7,076,690 B1
• Filed: 04/15/2002
• Issued: 07/11/2006
• Est. Priority Date: 04/15/2002
• Status: Expired due to Term

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: EMC Corporation (Dell Technologies Inc.)
• Inventors: Todd, Stephen J., Blumenau, Steven, D'Errico, Matthew J.
• Primary Examiner(s): Beausoliel, Robert
• Assistant Examiner(s): Wilson, Yolanda L.
• Application Number:
  US10/122,556
• Time in Patent Office: 1,548 Days
• Field of Search: 714/15, 714/5, 714/6, 714/13
• US Class Current: 714/13
• CPC Class Codes: G06F 11/2066 Optimisation of the communication load
• CPC Class Codes: G06F 11/2094 Redundant storage or storage space G06F11/2056 takes precedence
• CPC Class Codes: G06F 3/0617 in relation to availability
• CPC Class Codes: G06F 3/065 Replication mechanisms
• CPC Class Codes: G06F 3/0689 Disk arrays, e.g. RAID, JBOD

Abstract

One embodiment is directed to a method in a computer system including a host computer and at least one storage system including first and second storage volumes, the host computer including at least one application program executing thereon. The method comprises acts of intercepting and redirecting an access request from the at least one application program to the first storage volume to the second storage volume. Other embodiments are directed to a computer readable medium with instructions for performing the method, a host computer with at least one controller to intercept and redirect the access request. Other aspects are directed to methods in a computer system including a host computer, a first storage system including a first storage volume, and a second storage system including a second storage volume, wherein the second storage volume is a hardware mirror of the first storage volume. One method comprises an act of servicing a read request to the second storage volume while maintaining the second storage volume as an active hardware mirror of the first storage volume. Another method comprises an act of, in response to a failure preventing access from the host computer to the first storage volume, servicing access requests directed to the first storage volume from the second storage volume without reconfiguring the host computer.

Claims

1. In a computer system including a host computer and at least one storage system including a first storage volume and a second storage volume, the host computer including at least one application program executing thereon, a method comprising acts of:

(A) intercepting an access request from the at least one application program to the first storage volume; and

(B) redirecting said access request to the second storage volume, so that the access request can be serviced by the second storage volume;

wherein the acts (A) and (B) are performed within the host computer.

2. The method of claim 1, wherein the host computer includes an input/output (I/O) stack, and wherein the acts (A) and (B) are performed in the I/O stack.

3. The method of claim 1, wherein the second storage volume is a mirror of the first storage volume, and wherein the act (B) includes an act of redirecting said access request to the mirror of the first storage volume.

4. The method of claim 1, wherein the acts (A) and (B) are performed in a manner that is transparent to the at least one application program.

5. The method of claim 1, wherein the at least one application program includes a database management system application program.

6. The method of claim 1, wherein the access request is a read request.

7. The method of claim 1, wherein the computer system includes multiple host computers and multiple instances of the at least one application program executing simultaneously on the multiple host computers and sharing access to the first volume;

and

wherein the act (A) includes an act of intercepting an access request from a first instance of the at least one application program to the first storage volume.

8. The method of claim 7, further including an act of, in parallel with the acts (A) and (B), passing requests from a second instance of the at least one application program to the first volume.

9. The method of claim 8, wherein the at least one storage system includes a first storage system that stores the first storage volume and a second storage system that stores the second storage volume, wherein the second storage volume is a hardware mirror of the first storage volume, and wherein the act (B) includes an act of redirecting said access request to the hardware mirror of the first storage volume.

10. The method of claim 7, wherein the at least one storage system includes a first storage system that stores the first storage volume and a second storage system that stores the second storage volume, wherein the second storage volume is a hardware mirror of the first storage volume, and wherein the act (B) includes an act of redirecting said access request to the hardware mirror of the first storage volume.

11. The method of claim 1, wherein the computer system includes multiple host computers and multiple instances of the at least one application program executing simultaneously on the multiple host computers and sharing access to the first volume, the at least one application program including a database management system application program;

and

wherein the act (A) includes an act of intercepting an access request from a first instance of the database management system application program.

12. The method of claim 11, wherein the at least one storage system includes a first storage system that stores the first storage volume and a second storage system that stores the second storage volume, wherein the second storage volume is a hardware mirror of the first storage volume, and wherein the act (B) includes an act of redirecting said access request to the hardware mirror of the first storage volume.

13. The method of claim 1, wherein the at least one application program lacks access privileges to read from the second storage volume.

14. The method of claim 1, wherein the host computer includes an input/output (I/O) stack including a driver, and wherein the acts (A) and (B) are performed by the driver in response to a command received from a user to intercept and redirect access requests to the first storage volume.

15. The method of claim 1, wherein the second storage volume is a hardware mirror of the first storage volume, and wherein the act (B) includes an act of redirecting said access request to the hardware mirror of the first storage volume.

16. The method of claim 1, wherein the first and second storage volumes are included on a same storage system.

17. The method of claim 1, wherein the at least one storage system includes a first storage system that stores the first storage volume and a second storage system that stores the second storage volume.

18. The method of claim 17, wherein the second storage volume is a hardware mirror of the first storage volume, and wherein the act (B) includes an act of redirecting said access request to the hardware mirror of the first storage volume.

19. A computer readable medium encoded with instructions for execution on a computer system including a host computer and at least one storage system including a first storage volume and a second storage volume, the host computer including at least one application program executing thereon, the instructions, when executed, perform a method comprising acts of:

(A) intercepting an access request from the at least one application program to the first storage volume; and

(B) redirecting said access request to the second storage volume, so that the access request can be serviced by the second storage volume;

wherein the instructions are coded to be executed on the host computer so that acts (A) and (B) are performed by the host computer.

20. The computer readable medium of claim 19, wherein the host computer includes an input/output (I/O) stack including a driver, and wherein the instructions are coded to be executed by the driver so that the acts (A) and (B) are performed by the driver.

21. The computer readable medium of claim 19, wherein the second storage volume is a mirror of the first storage volume, and wherein the act (B) includes an act of redirecting said access request to the mirror of the first storage volume.

22. The computer readable medium of claim 19, wherein the acts (A) and (B) are performed in a manner that is transparent to the at least one application program.

23. The computer readable medium of claim 19, wherein the at least one application program includes a database management system application program.

24. The computer readable medium of claim 19, wherein the access request is a read request.

25. The computer readable medium of claim 19, wherein the computer system includes multiple host computers and multiple instances of the at least one application program executing simultaneously on the multiple host computers and sharing access to the first volume;

and

wherein the act (A) includes an act of intercepting an access request from a first instance of the at least one application program to the first storage volume.

26. The computer readable medium of claim 19, wherein the computer system includes multiple host computers and multiple instances of the at least one application program executing simultaneously on the multiple host computers and sharing access to the first volume, the at least one application program including a database management system application program;

and

wherein the act (A) includes an act of intercepting an access request from a first instance of the database management system application program.

27. The computer readable medium of claim 19, wherein the at least one application program lacks access privileges to read from the second storage volume.

28. The computer readable medium of claim 19, wherein the host computer includes an input/output (I/O) stack including a driver, and wherein instructions are coded to be responsive to a command received from a user to intercept and redirect access requests to the first storage volume so that the acts (A) and (B) are performed by the driver in response to the command received from the user.

29. The computer readable medium of claim 19, wherein the second storage volume is a hardware mirror of the first storage volume, and wherein the act (B) includes an act of redirecting said access request to the hardware mirror of the first storage volume.

30. The computer readable medium of claim 19, wherein the first and second storage volumes are stored on a same storage system.

31. The computer readable medium of claim 19, wherein the at least one storage system includes a first storage system that stores the first storage volume and a second storage system that stores the second storage volume.

32. The computer readable medium of claim 31, wherein the second storage volume is a hardware mirror of the first storage volume, and wherein the act (B) includes an act of redirecting said access request to the hardware mirror of the first storage volume.

33. An apparatus for use in a computer system including the apparatus and at least one storage system including a first storage volume and a second storage volume, the apparatus comprising:

a host computer comprising;

at least one processor to execute at least one application program; and

at least one controller that intercepts an access request from the at least one application program to the first storage volume and redirects said access request to the second storage volume, so that the access request can be serviced by the second storage volume.

34. The apparatus of claim 33, wherein the host computer further comprises an input/output (I/O) stack, and wherein the at least one controller is disposed within the I/O stack.

35. The apparatus of claim 33, wherein the at least one controller comprises means for intercepting the access request from the at least one application program to the first storage volume and redirecting said access request to the second storage volume, so that the access request can be serviced by the second storage volume.

36. The apparatus of claim 33, wherein the second storage volume is a mirror of the first storage volume, and wherein the at least one controller redirects said access request to the mirror of the first storage volume.

37. The apparatus of claim 33, wherein the at least one controller intercepts and redirects the access request in a manner that is transparent to the at least one application program.

38. The apparatus of claim 33, wherein the at least one application program includes a database management system application program.

39. The apparatus of claim 33, wherein the access request is a read request.

40. The apparatus of claim 33, in combination with the computer system, wherein the host computer is a first host computer and the at least one application program is a first instance of the at least one application program, wherein the computer system further includes a second host computer executing a second instance of the at least one application program, and wherein the first and second instances of the at least one application program share access to the first volume.

41. The apparatus of claim 40, in combination with the computer system, wherein the at least one application program comprises a database management system application program.

42. The apparatus of claim 33, wherein the at least one application program lacks access privileges to read from the second storage volume.

43. The apparatus of claim 33, wherein the at least one controller is responsive to a command received from a user to intercept and redirect access requests to the first storage volume.

44. The apparatus of claim 33, wherein the host computer further comprises a driver disposed in the I/O stack, and wherein the at least one controller is implemented by the driver.

45. The apparatus of claim 33, wherein the second storage volume is a hardware mirror of the first storage volume, and wherein the at least one controller redirects said access request to the hardware mirror of the first storage volume.

46. The apparatus of claim 33, wherein the first and second storage volumes are included on a same storage system.

47. The apparatus of claim 33, wherein the at least one storage system includes a first storage system that stores the first storage volume and a second storage system that stores the second storage volume.

48. In a computer system including a host computer, a first storage system including a first storage volume, and a second storage system including a second storage volume, the host computer including at least one application program executing thereon, the first and second storage systems being coupled together, the second storage volume being an active hardware mirror of the first storage volume, a method comprising an act of:

(A) servicing a read request, from the at least one application program, to the second storage volume while maintaining the second storage volume as an active hardware mirror of the first storage volume;

wherein the act (A) is performed within the host computer.

49. The method of claim 48, wherein the act (A) is performed in a manner that is transparent to the at least one application program.

50. The method of claim 48, wherein the host computer includes an input/output (I/O) stack, and wherein the act (A) is performed in the I/O stack.

51. The method of claim 48, wherein the at least one application program includes a database management system application program.

52. In a computer system including a host computer, a first storage system including a first storage volume, and a second storage system including a second storage volume, the host computer including at least one application program executing thereon, the first and second storage systems being coupled together, the second storage volume being an active hardware mirror of the first storage volume, a method comprising an act of:

(A) in response to a failure preventing access from the host computer to the first storage volume, servicing access requests directed to the first storage volume from the second storage volume without reconfiguring the host computer;

wherein the act (A) is performed within the host computer.

53. The method of claim 52, wherein the act (A) is performed in a manner that is transparent to the at least one application program.

54. The method of claim 52, wherein the host computer includes an input/output (I/O) stack, and wherein the act (A) is performed in the I/O stack.