Data segregation in a storage device

• US 9,183,134 B2
• Filed: 04/22/2010
• Issued: 11/10/2015
• Est. Priority Date: 04/22/2010
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Haines, Jonathan W., Feldman, Timothy R., Vinson, Wayne H., Goss, Ryan J., Gomez, Kevin, Gaertner, Mark Allen
• Primary Examiner(s): Rigol, Yaima
• Application Number:
  US12/765,761
• Publication Number:
  US 20110264843A1
• Time in Patent Office: 2,028 Days
• Field of Search: None
• 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 2212/7211 Wear leveling
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0629 Configuration or reconfiguration of storage systems
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

An example method includes providing at least two data storage areas in a memory, providing a first amount of over-provisioning for a first of the at least two data storage areas and a second amount of over-provisioning for a second of the at least two data storage areas, categorizing data based on a characteristic of the data, and storing the data in one of the at least two data storage areas based on the categorization.

Claims

1. A method comprising:

providing at least two data storage areas in a memory;

providing a first amount of over-provisioning for a first of the at least two data storage areas and a second amount of over-provisioning for a second of the at least two data storage areas;

categorizing data being written by a host as having a first designation;

categorizing valid data being collected via a garbage collection operation as having a second designation;

assigning a sequence number to the data being written by the host;

updating the sequence number based on the categorization;

storing the data in either the first or the second of the at least two data storage areas based on the categorization and the sequence number; and

selecting, for garbage collection, erasure blocks containing cold data but having a higher valid data density before selecting erasure blocks containing hot data but having a lower valid data density.

2. The method of claim 1, further comprising

categorizing the data based on a frequency of write access of the data.

3. The method of claim 2, wherein the first amount of over-provisioning is greater than the second amount of over-provisioning, and wherein storing the data in one of the at least two data storage areas based on the categorization comprises:

storing data categorized as having a higher frequency of write access in the first of the at least two data storage areas.

4. The method of claim 2, further comprising:

storing the categorization of the data in at least one of the memory and a controller.

5. The method of claim 2, wherein the data is at least one of data written by a host and data that is copied from at least a first garbage collection unit to at least a second garbage collection unit.

6. The method of claim 5, wherein each of the first garbage collection unit and the second garbage collection unit comprise at least one erasure block.

7. The method of claim 5, wherein storing the data in one of the data storage areas based on the categorization comprises storing the data copied from at least the first erasure block to at least the second erasure block and storing the data written by the host at a location adjacent to the copied data, and wherein the method further comprises:

storing the location in at least one of a non-volatile memory and a memory in a controller.

8. The method of claim 5, further comprising:

storing, in at least one of the memory and a memory in a controller, the categorization of the data that is copied from at least the first erasure block to at least the second erasure block at a time when the data is copied to at least the second erasure block.

9. The method of claim 1, further comprising:

comparing a current sequence number assigned to the data being written by the host to a sequence number previously assigned to the valid data being collected via the garbage collection operation;

determining a difference value between the current sequence number and the sequence number previously assigned to the valid data being collected via the garbage collection operation; and

categorizing the valid data being collected via the garbage collection operation as having the second designation when the determined difference value exceeds a threshold value.

10. The method of claim 1, wherein categorizing data being written by a host as having a first designation comprises:

comparing a current sequence number assigned to the data being written by the host to a sequence number previously assigned to previously written host data;

determining a difference value between the current sequence number and the sequence number previously assigned to the previously written host data; and

categorizing the data being written by the host as having a first designation based on the difference value.

11. The method of claim 1, wherein the memory is non-volatile memory.

12. The method of claim 1, wherein selecting, for garbage collection, erasure blocks having a higher valid data density before selecting erasure blocks having a lower valid data density comprises maintaining or increasing the first amount of over-provisioning.

13. The method of claim 1, wherein selecting, for garbage collection, erasure blocks having a higher valid data density before selecting erasure blocks having a lower valid data density comprises selecting in response to the categorization of the data.

14. The method of claim 1, wherein the erasure blocks with the higher valid data density have a lower write frequency than the erasure blocks with the lower valid data density.

15. The method of claim 1, wherein the first designation includes data that is categorized as having a higher frequency of write access and the second designation includes data that is categorized as having a lower frequency of write access.

16. A system comprising;

a memory; and

at least one controller configured to;

provide at least two data storage areas in the memory;

provide a first amount of over-provisioning for a first of the at least two data storage areas and a second amount of over-provisioning for a second of the at least two data storage areas;

categorize data being written by a host as having a first designation;

categorize valid data being collected via a garbage collection operation as having a second designation;

assign a sequence number to the data being written by the host;

updating the sequence number based on the categorization;

store the data in either the first or the second of the at least two data storage areas based on the categorization and the sequence number; and

select, for garbage collection, erasure blocks containing cold data but having a higher valid data density before selecting erasure blocks containing hot data but having a lower valid data density.

17. The system of claim 16, wherein the at least one controller is configured to:

categorize the data based on a frequency of write access of the data.

18. The system of claim 17, wherein the at least one controller is further configured to:

compare a current sequence number assigned to the data being written by the host to a sequence number previously assigned to the valid data being collected via the garbage collection operation;

determine a difference value between the current sequence number and the sequence number previously assigned to the valid data being collected via the garbage collection operation; and

categorize the valid data being collected via the garbage collection operation as having the second designation when the determined difference value exceeds a threshold value.

19. The system of claim 18, wherein the at least one controller is further configured to update the sequence number by decrementing the sequence number when the determined difference value exceeds the threshold value.

20. The system of claim 17, wherein the at least one controller configured to categorize data being written by a host as having a first designation is further configured to:

compare a current sequence number assigned to the data being written by the host to a sequence number previously assigned to previously written host data;

determine a difference value between the current sequence number and the sequence number previously assigned to the previously written host data; and

categorize the data being written by the host as having a first designation based on the difference value.

21. The system of claim 17, wherein the first amount of over-provisioning is greater than the second amount of over-provisioning, and wherein the at least one controller, configured to store the data in one of the at least two data storage areas based on the categorization, is configured to:

store data categorized as having a higher frequency of write access in the first of the at least two data storage areas.

22. The system of claim 17, wherein the at least one controller is further configured to:

store the categorized data in at least one of the memory and the controller.

23. The system of claim 17, wherein the data is at least one of data written by a host and data that is copied from at least a first garbage collection unit to at least a second garbage collection unit.

24. The system of claim 23, wherein each of the first garbage collection unit and the second garbage collection unit comprise at least one erasure block.

25. The system of claim 23, wherein the at least one controller, configured to store the data in one of the data storage areas based on the categorization, is configured to store the data copied from at least a first erasure block to at least a second erasure block and store the data written by the host at a location adjacent to the copied data, and wherein the at least one controller is further configured to:

store the location in at least one of the memory and the controller.

26. The system of claim 23, wherein the at least one controller is further configured to:

store, in at least one of the memory and a memory in the controller, the categorization of the data that is copied from at least the first erasure block to at least the second erasure block at a time when the data is copied to the at least the second erasure block.

27. The system of claim 16, wherein the memory is non-volatile memory.

28. The system of claim 16, wherein the at least one controller is further configured to update the sequence number by incrementing the sequence number in response to a host write.

29. The system of claim 28, wherein the at least one controller is further configured to update the sequence number by decrementing the sequence number in response to a garbage collection operation.

30. A non-transitory computer-readable storage medium comprising instructions encoded on the computer-readable medium that, upon execution, cause a controller within a device to:

provide at least two data storage areas in a memory;

provide a first amount of over-provisioning for a first of the at least two data storage areas and a second amount of over-provisioning for a second of the at least two data storage areas;

categorize data being written by a host as having a first designation;

categorize valid data being collected via a garbage collection operation as having a second designation;

assign a sequence number to the data being written by the host;

update the sequence number based on the categorization;

store the data in either the first or the second of the at least two data storage areas based on the categorization and the sequence number; and

select, for garbage collection, erasure blocks containing cold data but having a higher valid data density before selecting erasure blocks containing hot data but having a lower valid data density.

31. The non-transitory computer-readable storage medium of claim 30, wherein the instructions cause the controller to:

categorize the data based on a frequency of write access of the data.

32. The non-transitory computer-readable storage medium of claim 30, further comprising instructions that, upon execution, cause the controller to:

compare a current sequence number assigned to the data being written by the host to a sequence number previously assigned to valid data being collected via the garbage collection operation;

determine a difference value between the current sequence number and the sequence number previously assigned to the valid data being collected via the garbage collection operation; and

categorize the valid data being collected via the garbage collection operation as having the second designation when the determined difference value exceeds a threshold value.

33. The non-transitory computer-readable storage medium of claim 30, wherein the instructions that cause the controller to categorize data being written by a host as having a first designation further comprise instructions that, upon execution, cause the controller to:

compare a current sequence number assigned to the data being written by the host to a sequence number previously assigned to previously written host data;

determine a difference value between the current sequence number and the sequence number previously assigned to the previously written host data; and

categorize the data being written by the host as having a first designation based on the difference value.

34. The non-transitory computer-readable storage medium of claim 30, wherein the first amount of over-provisioning is greater than the second amount of over-provisioning, and wherein the instructions that cause the controller to store the data in one of the at least two data storage areas based on the categorization comprise instructions that, upon execution, cause the controller to:

store data categorized as having a higher frequency of write access in the first of the at least two data storage areas.

35. The non-transitory computer-readable storage medium of claim 30, further comprising instructions that, upon execution, cause the controller to:

store the categorization of the data in at least one of the memory and the controller.

36. The non-transitory computer-readable storage medium of claim 30, wherein the data is at least one of data written by a host and data that is copied from at least a first garbage collection unit to at least a second garbage collection unit.

37. The non-transitory computer-readable storage medium of claim 36, wherein each of the first garbage collection unit and the second garbage collection unit comprise at least one erasure block.

38. The non-transitory computer-readable storage medium of claim 36, wherein the instructions that cause the controller to store the data in one of the data storage areas based on the categorization comprise instructions that, upon execution, cause the controller to store the data copied from at least the first erasure block to at least the second erasure block and storing the data written by the host at a location adjacent to the copied data, and wherein the computer-readable storage medium further comprises instructions that, upon execution, cause the controller to:

store the location in at least one of the memory and the controller.

39. The non-transitory computer-readable storage medium of claim 36, further comprising instructions that, upon execution, cause the controller to:

store, in at least one of the memory and the controller, the categorization of the data that is copied from at least the first erasure block to at least the second erasure block at a time when the data is copied to the at least the second erasure block.

40. The non-transitory computer-readable storage medium of claim 30, wherein the memory is non-volatile memory.