System and method for synchronizing mirrored and striped disk writes

• US 20020078315A1
• Filed: 12/18/2000
• Published: 06/20/2002
• Est. Priority Date: 12/18/2000
• Status: Active Grant

• Current Assignee: Oracle America, Inc. (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Robinson, David, Howard, John H.
• Granted Patent: US 6,745,285 B2
• Time in Patent Office: Days
• US Class Current: 711/162
• CPC Class Codes: G06F 11/2064 while ensuring consistency
• CPC Class Codes: G06F 11/2071 using a plurality of controllers

Abstract

A system and method for synchronizing mirrored and striped disk writes. A data storage system may include a client computer system coupled to a first data storage device and a second data storage device and configured to transmit a first data write request. The first storage device may be configured to transmit a sequence number to the client computer system in response to receiving the first data write request. The client computer system may be further configured to transmit a second data write request including the sequence number to the second storage device. The second data storage device may include a counter and is configured to compare a current counter value to the sequence number. If the counter value is equal to the sequence number, the second storage device stores the data bytes corresponding to the second data write request and increments its counter.

Claims

1. A data storage system comprising:

a client computer system configured to transmit a first data write request and a second data write request;

a first storage device coupled to said client computer system, wherein said first storage device is configured to transmit a sequence number in response to receiving said first data write request;

a second storage device coupled to said client computer system, wherein said second storage device is configured to receive said second data write request;

wherein said client computer system is configured to transmit said second data write request including said sequence number.

2. The data storage system as recited in claim 1, wherein said second storage device includes a counter and is configured to compare a current counter value to said sequence number.

3. The data storage system as recited in claim 2, wherein said second storage device is further configured to store data bytes corresponding to said second data write request in response to detecting a first predetermined relationship between said current counter value and said sequence number.

4. The data storage system as recited in claim 3, wherein said second storage device is further configured to increment said counter in response to storing said data bytes corresponding to said second data write request.

15. The data storage system as recited in claim 2, wherein said first storage device is further configured to transmit said sequence number to said client computer system in response to receiving a first read data request from said client computer system.

18. The data storage system as recited in claim 1, wherein said second data write request is a request to write a mirrored copy of data written in said first data write request.

19. The data storage system as recited in claim 1, wherein each of said first data write request and said second data write request are requests to write a portion of a stripe of data.

5. The data storage system as recited in 4, wherein said first predetermined relationship is characterized by said current counter value being equal to said sequence number.

6. The data storage system as recited in claim 5, wherein said second storage device is further configured to discard said data bytes corresponding to said second data write request in response to detecting a second predetermined relationship between said current counter value and said sequence number.

7. The data storage system as recited in claim 6, wherein said second predetermined relationship is characterized by said current counter value being larger than said sequence number.

8. The data storage system as recited in claim 7, wherein said second storage device is further configured to store data bytes corresponding to a premature second data write request and to store a premature sequence number and a byte range of said data bytes corresponding to said premature second data write request in a record in response to detecting a third predetermined relationship between said current counter value and said sequence number.

9. The data storage system as recited in claim 8, wherein said third predetermined relationship is characterized by said current counter value being less than said sequence number.

10. The data storage system as recited in claim 9, wherein said second storage device is further configured to discard data bytes corresponding to a third data write request which overlap said data bytes corresponding to said premature second data write request in response to detecting a fourth predetermined relationship between said current counter value and a sequence number associated with said third data write request and in response to detecting a fifth predetermined relationship between a sequence number associated with said third data write request and said premature sequence number associated with said premature second data write request.

11. The data storage system as recited in claim 10, wherein said fourth predetermined relationship is characterized by said current counter value being smaller than said sequence number associated with a third data write request.

12. The data storage system as recited in claim 10, wherein said fifth predetermined relationship is characterized by said sequence number associated with said third data write request being smaller than said premature sequence number.

13. The data storage system as recited in claim 12, wherein said second storage device is further configured to increment said counter in response to receiving said second data write request and detecting said first predetermined relationship between said current counter value and said sequence number, wherein said second data write request contains zero data bytes.

14. The data storage system as recited in claim 13, wherein said second storage device is further configured to transmit said current counter value to said client computer system in response to storing said data bytes corresponding to said second data write request.

16. The data storage system as recited in claim 15, wherein client computer system is further configured to retransmit a second read data request in response to detecting a first predetermined relationship between said current counter value received from said second storage device and said sequence number received from said first storage device.

17. The data storage system as recited in claim 16, wherein said first predetermined relationship is characterized by said current counter value received from said second storage device being smaller than said sequence number received from said first storage device.

20. A method of operating a data storage system including a client computer system, a first storage device coupled to said client computer system and a second storage device coupled to said client computer system, said method comprising:

receiving a first data write request;

transmitting a sequence number in response to receiving said first data write request;

receiving a second data write request including said sequence number.

21. The method as recited in claim 20 further comprising comparing a current counter value to said sequence number.

22. The method as recited in claim 21 further comprising storing data bytes corresponding to said second data write request in response to detecting a first predetermined relationship between said current counter value and said sequence number.

23. The method as recited in claim 22 further comprising incrementing said counter in response to storing said data bytes corresponding to said second data write request.

24. The method as recited in claim 23, wherein, said first predetermined relationship is characterized by said current counter value being equal to said sequence number.

25. The method as recited in claim 24 further comprising discarding said data bytes corresponding to said second data write request in response to detecting a second predetermined relationship between said current counter value and said sequence number.

26. The method as recited in claim 25, wherein said second predetermined relationship is characterized by said current counter value being larger than said sequence number.

27. The method as recited in claim 26 further comprising storing data bytes corresponding to a premature second data write request and storing a premature sequence number and a byte range of said data bytes corresponding to said premature second data write request in a record in response to detecting a third predetermined relationship between said current counter value and said sequence number.

28. The method as recited in claim 27, wherein said third predetermined relationship is characterized by said current counter value being less than said sequence number.

29. The method as recited in claim 28 further comprising discarding data bytes corresponding to a third data write request which overlap said data bytes corresponding to said premature second data write request in response to detecting a fourth predetermined relationship between said current counter value and a sequence number associated with said third data write request and in response to detecting a fifth predetermined relationship between a sequence number associated with said third data write request and said premature sequence number associated with said premature second data write request.

30. The method as recited in claim 29, wherein said fourth predetermined relationship is characterized by said current counter value being smaller than said sequence number associated with said third data write request.

31. The method as recited in claim 29, wherein said fifth predetermined relationship is characterized by said sequence number associated with said third data write request being smaller than said premature sequence number associated with said premature second data write request.

32. The method as recited in claim 31, further comprising incrementing said counter in response to receiving said second data write request and detecting said first predetermined relationship between said current counter value and said sequence number, wherein said second data write request contains zero data bytes.

33. The method as recited in claim 32 further comprising transmitting said current counter value in response to storing said data bytes corresponding to said second data write request.

34. The method as recited in claim 21 further comprising transmitting said sequence number in response to receiving a first read data request.

35. The method as recited in claim 34 further comprising transmitting said current counter value in response to receiving a second read data request

36. The method as recited in claim 35 further comprising retransmitting said second read data request in response to detecting a first predetermined relationship between said current counter value received and said sequence number received.

37. The method as recited in claim 36, wherein said first predetermined relationship is characterized by said current counter value being smaller than said sequence number.

38. The method as recited in claim 20, wherein said second data write request is a request to write a mirrored copy of data written in said first data write request.

39. The method as recited in claim 20, wherein each of said first data write request and said second data write request are requests to write a portion of a stripe of data.

40. A data storage system comprising:

a client computer system configured to transmit a first data read request and a second data read request;

a first storage device coupled to said client computer system, wherein said first storage device is configured to transmit a sequence number in response to receiving said first data read request;

a second storage device coupled to said client computer system, wherein said second storage device is configured to transmit a current counter value in response to receiving said second read data request.

41. The data storage system as recited in claim 40, wherein said second storage device includes a counter and is configured to generate said current counter value.

42. The data storage system as recited in claim 41, wherein said client computer system is further configured to retransmit said second read data request in response to detecting a first predetermined relationship between said current counter value received and said sequence number received.

43. The data storage system as recited in claim 42, wherein said first predetermined relationship is characterized by said current counter value received being smaller than said sequence number received.

44. A storage device comprising:

an interface;

a sequence number generator coupled to said interface and configured to generate a first sequence number in response to receiving a first data write request from said interface, wherein said sequence number generator is configured to transmit said first sequence number to said interface;

wherein said storage device is configured to transmit a current counter value to said interface in response to receiving a second data write request including a second sequence number.

45. The storage device as recited in claim 44, wherein said storage device further comprises a counter and is configured to compare said current counter value to second sequence number.

46. The storage device as recited in claim 45, wherein said storage device is further configured to store data bytes corresponding to said second data write request in response to detecting a first predetermined relationship between said current counter value and said sequence number.

47. The storage device as recited in claim 46, wherein said first predetermined relationship is characterized by said current counter value being equal to said second sequence number.

48. The storage device as recited in claim 47, wherein said storage device is further configured to discard said data bytes corresponding to said second data write request in response to detecting a second predetermined relationship between said current counter value and said sequence number.

49. The storage device as recited in claim 48, wherein said second predetermined relationship is characterized by said current counter value being larger than said sequence number.

50. The storage device as recited in claim 48, wherein said storage device is further configured to store data bytes corresponding to a premature second data write request and to store a premature sequence number and a byte range of said data bytes corresponding to said premature second data write request in a record in response to detecting a third predetermined relationship between said current counter value and said second sequence number.

51. The storage device as recited in claim 50, wherein said third predetermined relationship is characterized by said current counter value being less than said second sequence number.

52. The storage device as recited in claim 51, wherein said storage device is further configured to discard data bytes corresponding to a third data write request which overlap said data bytes corresponding to said premature second data write request in response to detecting a fourth predetermined relationship between said current counter value and a sequence number associated with said third data write request and in response to detecting a fifth predetermined relationship between a sequence number associated with said third data write request and said premature sequence number associated with said premature second data write request.

53. The storage device as recited in claim 52, wherein said fourth predetermined relationship is characterized by said current counter value being smaller than said sequence number associated with a third data write request.

54. The storage device as recited in claim 52, wherein said fifth predetermined relationship is characterized by said sequence number associated with said third data write request being smaller than said premature sequence number.

55. The storage device as recited in claim 54, wherein said storage device is further configured to increment said counter in response to receiving said second data write request and detecting said first predetermined relationship between said current counter value and said second sequence number, wherein said second data write request contains zero data bytes.

57. The apparatus as recited in claim 56, wherein said second storage device includes a counter and is configured to compare a current counter value to said sequence number.

58. The apparatus as recited in claim 57, wherein said second storage device is further configured to store data bytes corresponding to said second data write request in response to detecting a first predetermined relationship between said current counter value and said sequence number.

59. The apparatus as recited in claim 58, wherein said second storage device is further configured to increment said counter in response to storing said data bytes corresponding to said second data write request.

70. The apparatus as recited in claim 56, wherein said second data write request is a request to write a mirrored copy of data written in said first data write request.

71. The apparatus as recited in claim 56, wherein each of said first data write request and said second data write request are requests to write a portion of a stripe of data.

72. The apparatus as recited in claim 56, wherein said first storage device is configured to transmit said sequence number in response to receiving a first read data request.

73. The apparatus as recited in claim 56, wherein said second storage device is configured to transmit said current counter value in response to receiving a second read data request.

56. An apparatus comprising a first storage device and a second storage device, wherein said first storage device is configured to transmit a sequence number in response to receiving a first data write request, wherein said second storage device is configured to transmit a current counter value in response to receiving said second data write request.

60. The apparatus as recited in 59, wherein said first predetermined relationship is characterized by said current counter value being equal to said sequence number.

61. The apparatus as recited in claim 60, wherein said second storage device is further configured to discard said data bytes corresponding to said second data write request in response to detecting a second predetermined relationship between said current counter value and said sequence number.

62. The apparatus as recited in claim 61, wherein said second predetermined relationship is characterized by said current counter value being larger than said sequence number.

63. The apparatus as recited in claim 62, wherein said second storage device is further configured to store data bytes corresponding to a premature second data write request and to store a premature sequence number and a byte range of said data bytes corresponding to said premature second data write request in a record in response to detecting a third predetermined relationship between said current counter value and said sequence number.

64. The apparatus as recited in claim 63, wherein said third predetermined relationship is characterized by said current counter value being less than said sequence number.

65. The apparatus as recited in claim 64, wherein said second storage device is further configured to discard data bytes corresponding to a third data write request which overlap said data bytes corresponding to said premature second data write request in response to detecting a fourth predetermined relationship between said current counter value and a sequence number associated with said third data write request and in response to detecting a fifth predetermined relationship between a sequence number associated with said third data write request and said premature sequence number associated with said premature second data write request.

66. The apparatus as recited in claim 65, wherein said fourth predetermined relationship is characterized by said current counter value being smaller than said sequence number associated with a third data write request.

67. The apparatus as recited in claim 65, wherein said fifth predetermined relationship is characterized by said sequence number associated with said third data write request being smaller than said premature sequence number.

68. The apparatus as recited in claim 67, wherein said second storage device is further configured to increment said counter in response to receiving said second data write request and detecting said first predetermined relationship between said current counter value and said sequence number, wherein said second data write request contains zero data bytes.

69. The apparatus as recited in claim 68, wherein said second storage device is further configured to transmit said current counter value in response to storing said data bytes corresponding to said second data write request.