Efficient flash memory device driver

• US 7,526,598 B2
• Filed: 03/03/2003
• Issued: 04/28/2009
• Est. Priority Date: 03/03/2003
• Status: Active Grant

• Current Assignee: Western Digital Israel Limited (Western Digital Corporation)
• Original Assignee: SanDisk IL Ltd. (Western Digital Corporation)
• Inventors: Stern, Ori, Lasser, Menahem
• Primary Examiner(s): Elmore; Stephen C
• Assistant Examiner(s): Rojas; Midys
• Application Number:
  US10/376,504
• Publication Number:
  US 20040177054A1
• Time in Patent Office: 2,248 Days
• Field of Search: 711/100
• US Class Current: 711/100
• CPC Class Codes: G06F 11/1482 by means of middleware or OS functionality
• CPC Class Codes: G06F 11/1497 Details of time redundant execution on a single processing unit
• CPC Class Codes: G06F 3/0614 Improving the reliability of storage systems
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/068 Hybrid storage device

Abstract

A driver for a data storage device includes an access command and a verification command. The access command initiates an access (write, erase or read) of the data storage device while allowing a calling application to continue running without having to wait for the completion of the access. The verification command queries a preceding access. If the query indicates failure of the preceding access, the verification command repeats the preceding access until the preceding access succeeds. The verification command is called by the access command before the access command initiates a new access. The verification command also is called by an application following a sequence of related access command calls. A write access command saves the data to be written in a memory separate from the data storage device, in case the verification command needs that data to repeat a failed write.

Claims

1. A method whereby a host accesses a data storage device during execution of an application program, comprising the steps of:

(a) storing, in an executable memory of the host, a software device driver of the data storage device;

(b) initiating a first access of the data storage device, by the host executing code of said software device driver;

(c) while the data storage device satisfies said first access, continuing the execution of the application program, by the host, until a second access of the data storage device is required by the application program; and

(d) querying a success of said first access prior to said second access, by the host executing code of said software device driver.

2. The method of claim 1, further comprising the step of:

(d) initiating said second access, by the host;

and wherein said initiating of said second access is contingent on said querying indicating a success of said first access.

3. The method of claim 2, further comprising the step of:

(e) if said querying indicates a failure of said first access, repeating said first access and said querying, by the host, until said querying indicates a success of said first access.

4. The method of claim 1, wherein said first access is a write of data to the data storage device.

5. The method of claim 4, further comprising the steps of:

(d) prior to completion of said first access, saving said data in a memory, by the host; and

(e) if said querying indicates a failure of said first access, repeating said first access and said querying, by the host, using said saved data, until said querying indicates a success of said first access.

6. The method of claim 1, wherein said first access is a read of data from the data storage device.

7. The method of claim 1, wherein said first access is an erase of data in the data storage device.

8. The method of claim 1, wherein said first access includes a plurality of successive sub-accesses of respective portions of the data storage device, and wherein said querying is effected after a last said sub-access to query only said last sub-access.

9. The method of claim 8, wherein said first access includes:

prior to each said sub-access subsequent to a first said sub-access;

(i) querying a success of said sub-access that immediately precedes said each sub-access; and

(ii) if said querying indicates a failure of said immediately preceding sub-access, repeating said immediately preceding sub-access until said querying indicates a success of said immediately preceding sub-access.

10. The method of claim 8, wherein said portions are pages of the data storage device, and wherein said sub-accesses are writes of data to respective said pages.

11. The method of claim 10, further comprising the steps of:

(d) prior to completion of said first access, saving, in a memory, only said data that is to be written in said last sub-access, by the host; and

(e) if said querying indicates a failure of said first access, repeating said last sub-access and said querying, by the host, using said saved data, until said querying indicates a success of said last sub-access.

12. The method of claim 8, wherein said portions are pages of the data storage device, and wherein said sub-accesses are reads of data from respective said pages.

13. The method of claim 8, wherein said portions are blocks of the data storage device, and wherein said sub-accesses are erases of respective said blocks.

14. A computer readable storage medium having computer readable code embodied on the computer readable storage medium, the computer readable code comprising:

(a) first code, for a software device drivers, of a data storage device, that is executed by a host of said data storage device, for querying a success of a preceding access to said data storage device;

(b) second code, for said software device driver, for;

if said querying indicates a failure of said preceding access, repeating said preceding access until said querying indicates a success of said preceding access; and

(c) third code, for said software device driver, for initiating a new access to said data storage device if said querying indicates a success of said preceding access;

said first, second and third code being callable by an application program, that is executed by said host and that accesses said data storage device, in a single call to said device driver.

15. The computer readable storage medium of claim 14, wherein said third code initiates said new access only if said querying indicates a success of said preceding access.

16. The computer readable storage medium of claim 14, wherein said new access is a write of new data to said data storage device.

17. The computer readable storage medium of claim 16, wherein the computer readable code further comprises:

(d) fourth code, for said device driver, for saving said new data in a memory separate from said data storage device;

said first, second, third and fourth code being callable by an application program in a single call to said device driver.

18. The computer readable storage medium of claim 17, wherein said preceding access is a write of preceding data to said data storage device, and wherein said second code, in repeating said preceding access, writes, to said data storage device, said preceding data that were saved in said memory by said fourth code during said preceding access.

19. The computer readable storage medium of claim 14, wherein said new access is a read from said data storage device.

20. The computer readable storage medium of claim 14, wherein said new access is an erase of at least a portion of said data storage device.

21. The computer readable storage medium of claim 14, wherein the computer readable code further comprises:

(d) multi-portion code, for said device driver, for executing said first, second and third code successively for accessing each of a plurality of portions of said data storage device;

said first, second, third and multi-portion code being callable by an application program in a single call.

22. The computer readable storage medium of claim 21, wherein said accesses are writes of data to respective pages of said data storage device.

23. The computer readable storage medium of claim 22, wherein the computer readable code further comprises:

(e) fourth code, for said device driver, for saving only said data of a last said write in a memory separate from said data storage device;

said first, second, third fourth and multi-portion code being callable by an application program in a single call.

24. The computer readable storage medium of claim 21, wherein said accesses are reads from respective pages of said data storage device.

25. The computer readable storage medium of claim 21, wherein said accesses are erases of respective blocks of said data storage device.

26. The computer readable storage medium of claim 14, wherein said preceding access is a write to said data storage device.

27. The computer readable storage medium of claim 14, wherein said preceding access is a read from said data storage device.

28. The computer readable storage medium of claim 14, wherein said preceding access is an erase of at least a portion of said data storage device.

29. A computer readable storage medium having computer readable code embodied on the computer readable storage medium, the computer readable code comprising:

(a) first code, for a software device drivers of a data storage device, that is executed by a host of said data storage device, for querying a success of a preceding access to said data storage device; and

(b) second code, for said software device driver, for initiating a new access to said data storage device if said querying indicates a success of said preceding access;

said first and second code being callable by an application program, that is executed by said host and that accesses said data storage device, in a single call to said device driver.

30. The computer readable storage medium of claim 29, wherein said second code initiates said new access only if said querying indicates a success of said preceding access.

31. The computer readable storage medium of claim 29, wherein said new access is a write to said data storage device.

32. The computer readable storage medium of claim 29, wherein said new access is a read from said data storage device.

33. The computer readable storage medium of claim 29, wherein said new access is an erase of at least a portion of said data storage device.

34. The computer readable storage medium of claim 29, wherein the computer readable code further comprises:

(d) multi-portion code, for said device driver, for executing said first and second code successively for accessing each of a plurality of portions of said data storage device;

said first, second and multi-portion code being callable by an application program in a single call.

35. The computer readable storage medium of claim 34, wherein said accesses are writes of data to respective pages of said data storage device.

36. The computer readable storage medium of claim 34, wherein said accesses are reads from respective pages of said data storage device.

37. The computer readable storage medium of claim 34, wherein said accesses are erases of respective blocks of said data storage device.

38. The computer readable storage medium of claim 29, wherein said preceding access is a write to said data storage device.

39. The computer readable storage medium of claim 29, wherein said preceding access is a read from said data storage device.

40. The computer readable storage medium of claim 29, wherein said preceding access is an erase of at least a portion of said data storage device.

41. A method of accessing a data storage device, comprising the steps of:

(a) providing an access command in an Application Programming Interface of a software device driver of the data storage device;

(b) storing said software device driver in an executable memory of a host of the data storage device; and

(c) issuing said access command, by an application program that is executed by said host, to initiate an access of the data storage device by said device driver;

wherein, when said host executes said access command for a new access to the data storage device;

(i) said host executes code of said software device driver to query a success of a preceding access to the data storage device; and

(ii) if said querying indicates a failure of said preceding access, said host executes code of said software device driver to repeat said preceding access until said querying indicates a success of said preceding access.

42. The method of claim 41, wherein said access command is a write command.

43. The method of claim 41, wherein said access command is a read command.

44. The method of claim 41, wherein said access command is an erase command.

45. The method of claim 41, wherein said access command for said new access is a write command for writing new data to the data storage device, and wherein, in executing said access command for said new access to the data storage device:

(iii) said device driver also saves said new data in a memory separate from said data storage device.

46. The method of claim 45, wherein said preceding access is a write of preceding data to the data storage device, and wherein, in executing said access command for said new access to the data storage device, said repeating of said preceding access includes writing, to the data storage device, said preceding data as saved in said memory by said device driver during said preceding access.

47. The method of claim 41, wherein said access command is for accessing a single portion of the data storage device.

48. The method of claim 47, wherein said access command is a write command, and wherein said single portion is a page of the data storage device.

49. The method of claim 47, wherein said access command is a read command, and wherein said single portion is a page of the data storage device.

50. The method of claim 47, wherein said access command is an erase command, and wherein said single portion is a block of the data storage device.

51. The method of claim 41, wherein said access command is for accessing, successively, a plurality of portions of the data storage device.

52. The method of claim 41, further comprising the steps of:

(c) providing a verification command in said Application Programming Interface of said device driver; and

(d) subsequent to said issuing of said access command, issuing said verification command to verify a success of said access.

53. The method of claim 52, wherein, in executing said verification command to verify said success of said access:

(i) said device driver queries said success of said access; and

(ii) if said querying indicates a failure of said access, said device driver repeats said access until said querying indicates a success of said access.