Wear leveling of multiple memory devices

• US 9,208,070 B2
• Filed: 12/20/2011
• Issued: 12/08/2015
• Est. Priority Date: 12/20/2011
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Inventors: D'Abreu, Manuel Antonio, Skala, Stephen
• Primary Examiner(s): SCHELL, JOSEPH O
• Application Number:
  US13/331,853
• Publication Number:
  US 20130159766A1
• Time in Patent Office: 1,449 Days
• Field of Search: 714/6.2, 714/6.32, 714/710, 714/711
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1036 Life time enhancement
• CPC Class Codes: G06F 2212/7208 Multiple device management, e.g. distributing data over multiple flash devices
• CPC Class Codes: G06F 2212/7211 Wear leveling

Abstract

A method of managing wear leveling in a data storage device includes determining whether a reliability measurement associated with a first portion of a first nonvolatile memory die satisfies a threshold. The first nonvolatile memory die is included in a plurality of memory dies. The method includes, in response to determining that the reliability measurement associated with the first portion of the first nonvolatile memory die satisfies the threshold, transferring first data from the first portion of the first nonvolatile memory die to a second nonvolatile memory die of the plurality of memory dies.

Claims

1. A data storage device comprising:

a plurality of nonvolatile memory dies;

a plurality of tracking circuits, wherein each tracking circuit is associated with one nonvolatile memory die; and

a controller coupled to each of the plurality of nonvolatile memory dies and to each of the plurality of tracking circuits, wherein the controller is distinct from each tracking circuit and is configured to;

maintain a first reliability measurement associated with a first portion of a first nonvolatile memory die of the plurality of nonvolatile memory dies, the first reliability measurement based on a first tracking circuit associated with the first nonvolatile memory die;

determine that the first reliability measurement associated with the first portion of the first nonvolatile memory die exceeds a threshold;

determine that a second reliability measurement based on a second tracking circuit associated with a second nonvolatile memory die is below the threshold; and

transfer data from the first portion of the first nonvolatile memory die to the second nonvolatile memory die.

2. The data storage device of claim 1, wherein the second reliability measurement is associated with a second portion of the second nonvolatile memory die.

3. The data storage device of claim 1, wherein the first reliability measurement is associated with a count of memory accesses to the first portion of the first nonvolatile memory die.

4. The data storage device of claim 3, wherein the first reliability measurement is updated in response to each instance of memory access to the first portion of the first nonvolatile memory die.

5. The data storage device of claim 1, wherein the first reliability measurement is associated with a count of write operations to the first portion of the first nonvolatile memory die.

6. The data storage device of claim 5, wherein the first reliability measurement is updated in response to each instance of write operation to the first portion of the first nonvolatile memory die.

7. The data storage device of claim 1, wherein the first reliability measurement is associated with an elapsed time since a write time of the data to the first portion of the first nonvolatile memory die.

8. An apparatus comprising:

first peripheral circuitry including first tracking circuitry, the first peripheral circuitry configured to communicate with a first nonvolatile memory die of a plurality of distinct nonvolatile memory dies; and

a controller distinct from the first peripheral circuitry and configured to, in response to determining that a first reliability measurement associated with a first portion of the first nonvolatile memory die exceeds a threshold based on the first tracking circuitry, transfer data from the first portion of the first nonvolatile memory die via the first peripheral circuitry to a second nonvolatile memory die of the plurality of distinct nonvolatile memory dies, wherein a second reliability measurement based on second tracking circuitry that is included in second peripheral circuitry associated with the second nonvolatile memory die is below the threshold.

9. The apparatus of claim 8, further comprising a first peripheral die and a second peripheral die distinct from the first peripheral die, wherein the first peripheral die includes the first peripheral circuitry, wherein the second peripheral die includes the second peripheral circuitry, wherein the controller is configured to transfer the data to the second nonvolatile memory die of the plurality of distinct nonvolatile memory dies via the second peripheral circuitry, and wherein the second peripheral circuitry comprises the second tracking circuitry.

10. The apparatus of claim 8, wherein the controller is configured to maintain the first reliability measurement associated with the first portion of the first nonvolatile memory die based on the first tracking circuitry.

11. The apparatus of claim 8, wherein the controller is coupled to each nonvolatile memory die of the plurality of distinct nonvolatile memory dies via corresponding peripheral circuitry.

12. The apparatus of claim 8, wherein the controller is configured to maintain a corresponding reliability measurement associated with each of a corresponding plurality of portions of each nonvolatile memory die of the plurality of distinct nonvolatile memory dies based on tracking circuitry associated with each of the plurality of distinct nonvolatile memory dies.

13. The apparatus of claim 8, wherein the controller is further configured to:

maintain multiple reliability measurements, each reliability measurement associated with a corresponding portion of the first nonvolatile memory die based on tracking circuitry associated with the first nonvolatile memory die;

identify one or more portions of the first nonvolatile memory die associated with a reliability measurement that satisfies a corresponding threshold; and

transfer data from each identified portion to a corresponding distinct portion of one or more other memory dies of the plurality of distinct nonvolatile memory dies.

14. The apparatus of claim 13, wherein each reliability measurement is associated with a count of memory accesses to the corresponding portion of the first nonvolatile memory die.

15. The apparatus of claim 14, wherein the multiple reliability measurements are maintained by, in response to each instance of memory access to a particular portion of the first nonvolatile memory die, updating the reliability measurement corresponding to the particular portion of the first nonvolatile memory die.

16. The apparatus of claim 13, wherein each reliability measurement is associated with a count of write operations to the corresponding portion of the first nonvolatile memory die.

17. The apparatus of claim 16, wherein the multiple reliability measurements are maintained by, in response to each instance of write operation to a particular portion of the first nonvolatile memory die, updating the reliability measurement corresponding to the particular portion of the first nonvolatile memory die.

18. The apparatus of claim 13, wherein each reliability measurement is associated with an elapsed time since a write time to the corresponding portion of the first nonvolatile memory die.

19. A method of managing wear leveling in a data storage device, the method comprising:

determining, at first tracking circuitry associated with a first nonvolatile memory die, whether a first reliability measurement associated with a first portion of the first nonvolatile memory die exceeds a threshold, wherein the first nonvolatile memory die is one of a plurality of memory dies in the data storage device, and wherein the first tracking circuitry is coupled to a controller via a controller interface and is distinct from the controller;

sending, by the first tracking circuitry, a signal to the controller, the signal indicating that first data at the first portion of the first nonvolatile memory die is to be moved, the signal sent responsive to determining that the first reliability measurement associated with the first portion of the first nonvolatile memory die exceeds the threshold;

determining, by the controller, that a second reliability measurement at second tracking circuitry associated with a second portion of a second nonvolatile memory die is less than the threshold, wherein the second nonvolatile memory die is distinct from the first nonvolatile memory die, and wherein the second tracking circuitry is distinct from the controller and is distinct from the first tracking circuitry and is coupled to the controller via a second controller interface; and

transferring the first data from the first portion of the first nonvolatile memory die to the second portion of the second nonvolatile memory die.

20. The method of claim 19, wherein the first data is transferred from the first portion of the first nonvolatile memory die to the second portion of the second nonvolatile memory die via first peripheral circuitry, the first peripheral circuitry comprising the first tracking circuitry and configured to communicate with the first nonvolatile memory die.

21. The method of claim 20, wherein the first data is transferred to the second nonvolatile memory die via second peripheral circuitry, the second peripheral circuitry comprising the second tracking circuitry and configured to communicate with the second nonvolatile memory die.

22. The method of claim 21, further comprising determining that a reliability measurement associated with a particular portion of a third nonvolatile memory die of the plurality of memory dies satisfies a corresponding threshold and in response to the determination, transferring second data stored in the particular portion of the third nonvolatile memory die to a fourth nonvolatile memory die of the plurality of memory dies.

23. The method of claim 22, wherein the second data is transferred via third peripheral circuitry, the third peripheral circuitry configured to communicate with the third nonvolatile memory die.

24. The method of claim 23, wherein the second data is transferred to the fourth nonvolatile memory die via fourth peripheral circuitry, the fourth peripheral circuitry configured to receive the second data from the third peripheral circuitry and to communicate the second data to the fourth nonvolatile memory die.

25. The method of claim 19, further comprising maintaining a corresponding reliability measurement associated with each portion of a plurality of portions of the first nonvolatile memory die.

26. The method of claim 19, further comprising maintaining a corresponding reliability measurement associated with each portion of a corresponding plurality of portions of each nonvolatile memory die of the plurality of memory dies.

27. The method of claim 19, wherein the controller is included in a controller die and wherein the first tracking circuitry in included in a peripheral die that is distinct from the controller die and that is distinct from the first nonvolatile memory die.

28. The method of claim 19, wherein a reliability measurement table associated with the first portion of the first nonvolatile memory die is usable to determine the first reliability measurement and is maintained by the first tracking circuitry.

29. The method of claim 28, wherein the reliability measurement table includes a plurality of reliability measurements.

30. The method of claim 19, wherein for each portion of a plurality of portions of each nonvolatile memory die, a corresponding reliability measurement is maintained.

31. The method of claim 19, wherein the first reliability measurement associated with the first portion of the first nonvolatile memory die is associated with a count of memory accesses to the first portion of the first nonvolatile memory die.

32. The method of claim 31, wherein the first reliability measurement associated with the first portion of the first nonvolatile memory die is updated in response to each instance of memory access to the first portion of the first nonvolatile memory die.

33. The method of claim 19, wherein the first reliability measurement associated with the first portion of the first nonvolatile memory die is associated with a count of write operations to the first portion of the first nonvolatile memory die.

34. The method of claim 33, wherein the first reliability measurement associated with the first portion of the first nonvolatile memory die is updated in response to each instance of write operation to the first portion of the first nonvolatile memory die.

35. The method of claim 19, wherein the first reliability measurement associated with the first portion of the first nonvolatile memory die is associated with an elapsed time since a write time of the first data to the first portion of the first nonvolatile memory die.