Data storage device and data maintenance method thereof

• US 9,996,462 B1
• Filed: 07/28/2017
• Issued: 06/12/2018
• Est. Priority Date: 12/14/2016
• Status: Active Grant

• Current Assignee: Silicon Motion, Inc. (Silicon Motion)
• Original Assignee: Silicon Motion, Inc. (Silicon Motion)
• Inventors: Lin, Wen-Sheng
• Primary Examiner(s): Luu, Pho M
• Application Number:
  US15/662,836
• Publication Number:
  US 20180165191A1
• Time in Patent Office: 319 Days
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/0292 using tables or multilevel address translation means G06F12/023 takes precedence; address translation in virtual memory systems G06F12/10
• CPC Class Codes: G06F 2212/1041 Resource optimization
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/105 Circuits or methods for updating contents of nonvolatile memory, especially with 'security' features to ensure reliable replacement, i.e. preventing that old data is lost before new data is reliably written

Abstract

The present invention provides a data storage device that includes a flash memory and a controller. The flash memory has a plurality of blocks, and each of the blocks has a plurality of pages arranged sequentially along a first direction. The controller determines whether an X-th page of a temporary block of the blocks can be successfully read when the data storage device resumes operation after a power-off event, and writes dummy data and a temporary-block table into the (X+1)-th page of the temporary block when the X-th page can be successfully read, wherein the X-th page is the page that was read last from the temporary block before the power-off event occurred, the temporary-block table records the information of all the pages in the temporary block, and X is a positive integer.

Claims

1. A data storage device, comprising:

a flash memory, having a plurality of blocks, wherein each of the blocks has a plurality of pages arranged sequentially along a first direction; and

a controller, determining whether an X-th page of a temporary block of the blocks can be successfully read when the data storage device resumes operation after a power-off event, and writing dummy data and a temporary-block table into the (X+1)-th page of the temporary block when the X-th page can be successfully read, wherein the X-th page is the page that was read last from the temporary block before the power-off event occurred, the temporary-block table records the information of all the pages in the temporary block, and X is a positive integer.

2. The data storage device as claimed in claim 1, wherein each of the pages in the temporary block is arranged to store a system data sector which is shorter than a predetermined length.

3. The data storage device as claimed in claim 1, wherein the (X+1)-th page of the temporary block does not have user data.

4. The data storage device as claimed in claim 1, wherein the controller repeatedly reads the X-th page by using a plurality of read voltages to determine whether the X-th page can be successfully read, wherein when the controller successfully reads the X-th page by using two or more of the read voltages, the controller writes the data which was successfully read from the X-th page into the X-th page.

5. The data storage device as claimed in claim 1, wherein when the X-th page cannot be successfully read, the controller reads the (X−

1)-th page of the temporary block.

6. The data storage device as claimed in claim 5, wherein when the X-th page cannot be successfully read, the controller abandons the temporary block and selects one of the blocks to serve as a new temporary block, and writes the data stored in the 1-st˜

(X−

1)th pages of the temporary block into the new temporary block.

7. The data storage device as claimed in claim 1, wherein each of the pages has a user-data area and a spare area, and the controller obtains the X-th page of the temporary block through a search process, wherein in the search process, the controller reads the spare areas of the pages distanced by a predetermined number of pages along the first direction starting from the 1-st page of the temporary block until the read spare area does not have valid data.

8. The data storage device as claimed in claim 7, wherein after reading the spare area without valid data, the controller further reads the spare areas of the pages one by one along a second direction starting from the page having the spare area without valid data of the temporary block until the read spare area has valid data, wherein the page having the spare area with valid data obtained by reading the pages along the second direction is a first blank page, and the second direction is opposite to the first direction.

9. The data storage device as claimed in claim 8, wherein the controller further reads the user-data area of the first blank page, and determines whether the user-data area of the first blank page has valid data to confirm whether the first blank page is the first page without user data in the first direction of the temporary block, wherein when the user-data area of the first blank page has valid data, the controller further reads the user-data areas of the pages one by one starting from the first blank page of the temporary block along the first direction until the read user-data area does not have valid data, wherein the page having the user-data area without valid data is arranged to replace the first blank page to serve as a new first blank page.

10. The data storage device as claimed in claim 9, wherein the controller further reads the user-data areas of the pages of the temporary block one by one starting from the page prior to the first blank page or starting from the page prior to the new first blank page along the second direction, and determines whether the read user-data area of the page has valid data, wherein the page having the user-data area with valid data obtained by reading the pages along the second direction is the X-th page, and the X-th page is the last page with valid data in the first direction.

11. The data storage device as claimed in claim 1, wherein each of the pages has a user-data area and a spare area, wherein the spare areas are arranged to store the information of the corresponding pages, the user-data area of each of the pages of the temporary block is arranged to store a system data sector that is shorter than a predetermined length, and the temporary-block table is stored in the spare area of the (X+1)-th page.

12. A data maintenance method, applied to a data storage device having a flash memory, wherein the flash memory comprises a plurality of blocks, and each of the blocks has a plurality of pages arranged sequentially along a first direction, the data maintenance method comprising:

determining whether an X-th page of a temporary block of the blocks can be successfully read when the data storage device resumes operation after a power-off event; and

writing dummy data and a temporary-block table into the (X+1)-th page of the temporary block when the X-th page can be successfully read, wherein the X-th page is the page that was read last from the temporary block before the power-off event occurred, the temporary-block table records the information of all the pages in the temporary block, and X is a positive integer.

13. The data maintenance method as claimed in claim 12, wherein each of the pages in the temporary block is arranged to store a system data sector which is shorter than a predetermined length.

14. The data maintenance method as claimed in claim 12, wherein the (X+1)-th page of the temporary block does not have user data.

15. The data maintenance method as claimed in claim 12, wherein the step of determining whether the X-th page can be successfully read further comprises:

repeatedly reading the X-th page by using a plurality of read voltages to determine whether the X-th page can be successfully read, wherein when the controller successfully reads the X-th page by using two or more of the read voltages, the data maintenance method further comprises writing the data which was successfully read from the X-th page into the X-th page.

16. The data maintenance method as claimed in claim 12, further comprising:

when the X-th page cannot be successfully read, reading the (X−

1)-th page of the temporary block.

17. The data maintenance method as claimed in claim 16, further comprising:

when the X-th page cannot be successfully read, abandoning the temporary block and selecting one of the blocks to serve as a new temporary block, and writing the data stored in the 1-st˜

(X−

1)-th pages of the temporary block into the new temporary block.

18. The data maintenance method as claimed in claim 12, wherein each of the pages has a user-data area and a spare area, and the data maintenance method further comprises obtaining the X-th page of the temporary block through a search process, wherein the search process comprises:

reading the spare areas of the pages distanced by a predetermined number of pages along the first direction starting from the 1-st page of the temporary block until the read spare area does not have valid data.

19. The data maintenance method as claimed in claim 18, further comprising:

after reading the spare area without valid data, reading the spare areas of the pages one by one along a second direction starting from the page having the spare area without valid data of the temporary block until the read spare area has valid data, wherein the page having the spare area with valid data obtained by reading the pages along the second direction is a first blank page, and the second direction is opposite to the first direction.

20. The data maintenance method as claimed in claim 19, further comprising:

reading the user-data area of the first blank page, and determining whether the user-data area of the first blank page has valid data to confirm whether the first blank page is the first page without user data in the first direction of the temporary block; and

when the user-data area of the first blank page has valid data, reading the user-data areas of the pages one by one starting from the first blank page of the temporary block along the first direction until the read user-data area does not have valid data, wherein the page having the user-data area without valid data is arranged to replace the first blank page to serve as a new first blank page.

21. The data maintenance method as claimed in claim 20, further comprising:

reading the user-data areas of the pages of the temporary block one by one starting from the page prior to the first blank page or starting from the page prior to the new first blank page along the second direction; and

determining whether the read user-data area of the page has valid data, reading the pages along the second direction is the X-th page, and the X-th page is the last page with valid data in the first direction.

22. The data maintenance method as claimed in claim 20, wherein each of the pages has a user-data area and a spare area, wherein the spare areas are arranged to store the information of the corresponding pages, the user-data area of each of the pages of the temporary block is arranged to store a system data sector that is shorter than a predetermined length, and the temporary-block table is stored in the spare area of the (X+1)-th page.