Data Storage Device and Operating Method

• US 20160132253A1
• Filed: 11/10/2014
• Published: 05/12/2016
• Est. Priority Date: 11/10/2014
• Status: Active Grant

• Current Assignee: Silicon Motion Incorporated California (Silicon Motion)
• Original Assignee: Silicon Motion Incorporated California (Silicon Motion)
• Inventors: Chiu, Shen-Ting
• Granted Patent: US 9,606,733 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1024 Latency reduction
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0652 Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

A data storage device includes a FLASH memory and a controller. The FLASH memory includes a plurality of blocks wherein each of the blocks includes a plurality of pages. The controller is coupled to the FLASH memory and utilized to execute a garbage-collection process on the FLASH memory according to a number of spare blocks in the FLASH memory and a number of inefficient blocks where most of the pages are spare in the FLASH memory. The garbage-collection process is utilized for merging at least two inefficient blocks to release at least one spare block from the inefficient blocks.

Claims

1. A data storage device, comprising:

a FLASH memory, comprising a plurality of blocks wherein each of the blocks comprises a plurality of pages; and

a controller, coupled to the FLASH memory and utilized to execute a garbage-collection process on the FLASH memory according to a number of spare blocks in the FLASH memory and a number of inefficient blocks where most of the pages are spare in the FLASH memory, wherein the garbage-collection process is utilized for merging at least two inefficient blocks to release at least one spare block from the inefficient blocks.

2. The data storage device as claimed in claim 1, wherein the controller determines that:

the FLASH memory is in a first state when the number of inefficient blocks is less than a first threshold value;

the FLASH memory is in a second state when the number of spare blocks in the FLASH memory is more than or equal to a second threshold value;

the FLASH memory is in a third state or a fourth state when the number of spare blocks in the FLASH memory is more than or equal to a third threshold value but less than the second threshold value;

the FLASH memory is in a fifth state when the number of spare blocks in the FLASH memory is more than or equal to a fourth threshold value but less than the third threshold value; and

the FLASH memory is in a sixth state when the number of spare blocks in the FLASH memory is less than the fourth threshold value, wherein the second threshold value is greater than the third threshold value and the third threshold value is greater than the fourth threshold value.

3. The data storage device as claimed in claim 2, wherein the controller executes more garbage-collection processes when the FLASH memory is in the fourth state than when the FLASH memory is in the third state.

4. The data storage device as claimed in claim 2, wherein the controller further executes the garbage-collection process on the FLASH memory according to an operation mode of the data storage device.

5. The data storage device as claimed in claim 4, wherein the operation mode of the data storage device comprises a read-reclaim operation or a wear-leveling operation, and a priority of executing the garbage-collection process with the wear-leveling operation is higher than that with the read-reclaim operation.

6. The data storage device as claimed in claim 5, wherein the controller assigns the blocks to be reclaimed as the blocks to be merged when the operation mode is the read-reclaim operation, and the read-reclaim operation is executed when the FLASH memory is in the first state, the second state, the third state, the fourth state or the fifth state.

7. The data storage device as claimed in claim 5, wherein the controller assigns the blocks with lower erase counts as the blocks to be merged when the operation mode is the wear-leveling operation, and the wear-leveling operation is executed when the FLASH memory is in the first state, the second state, the third state, the fourth state or the fifth state.

8. The data storage device as claimed in claim 2, wherein the controller is coupled to a host, and the controller further executes the garbage-collection process on the FLASH memory according to a command transmitted by the host.

9. The data storage device as claimed in claim 8, wherein the command transmitted by the host comprises a refresh command or a sanitization command.

10. The data storage device as claimed in claim 9, wherein the garbage-collection process is executed according to the refresh command when the FLASH memory is in the first state, the second state, the third state or the fourth state, and the garbage-collection process is executed according to the sanitization command when the FLASH memory is in the first state or the second state.

11. The data storage device as claimed in claim 2, wherein the frequency of executing the garbage-collection process when the FLASH memory is in the sixth state is higher than that when the FLASH memory is in the first state, the second state, the third state, the fourth state or the fifth state.

12. An operating method for a FLASH memory, comprising:

determining a number of spare blocks in the FLASH memory and a number of inefficient blocks where most of the pages are spare in the FLASH memory; and

executing a garbage-collection process on the FLASH memory according to the number of spare blocks in the FLASH memory and the number of inefficient blocks, wherein the garbage-collection process is utilized for merging at least two inefficient blocks to release at least one spare block from the inefficient blocks.

13. The operating method as claimed in claim 12, further comprising:

determining that the FLASH memory is in a first state when the number of inefficient blocks is less than a first threshold value;

determining that the FLASH memory is in a second state when the number of spare blocks in the FLASH memory is more than or equal to a second threshold value;

determining that the FLASH memory is in a third state or a fourth state when the number of spare blocks in the FLASH memory is more than or equal to a third threshold value but less than the second threshold value;

determining that the FLASH memory is in a fifth state when the number of spare blocks in the FLASH memory is more than or equal to a fourth threshold value but less than the third threshold value; and

determining that the FLASH memory is in a sixth state when the number of spare blocks in the FLASH memory is less than the fourth threshold value, wherein the second threshold value is greater than the third threshold value and the third threshold value is greater than the fourth threshold value.

14. The operating method as claimed in claim 13, wherein the garbage-collection process is executed more when the FLASH memory is in the fourth state than when the FLASH memory is in the third state.

15. The operating method as claimed in claim 13, wherein the garbage-collection process is further executed on the FLASH memory according to an operation mode of the data storage device.

16. The operating method as claimed in claim 15, wherein the operation mode of the data storage device comprises a read-reclaim operation or a wear-leveling operation, and a priority of executing the garbage-collection process with the wear-leveling operation is higher than that with the read-reclaim operation.

17. The operating method as claimed in claim 16, wherein the blocks to be reclaimed are assigned as the blocks to be merged when the operation mode is the read-reclaim operation, and the read-reclaim operation is executed when the FLASH memory is in the first state, the second state, the third state, the fourth state or the fifth state.

18. The operating method as claimed in claim 16, wherein the blocks with lower erase counts are assigned as the blocks to be merged when the operation mode is the wear-leveling operation, and the wear-leveling operation is executed when the FLASH memory is in the first state, the second state, the third state, the fourth state or the fifth state.

19. The operating method as claimed in claim 13, wherein the garbage-collection process is further executed on the FLASH memory according to a command transmitted by a host.

20. The operating method as claimed in claim 19, wherein the command transmitted by the host comprises a refresh command or a sanitization command.

21. The data storage device as claimed in claim 20, wherein the garbage-collection process is executed according to the refresh command when the FLASH memory is in the first state, the second state, the third state or the fourth state, and the garbage-collection process is executed according to the sanitization command when the FLASH memory is in the first state or the second state.

22. The operating method as claimed in claim 13, wherein the frequency of executing the garbage-collection process when the FLASH memory is in the sixth state is higher than that when the FLASH memory is in the first state, the second state, the third state, the fourth state or the fifth state.