Data Writing Method and Data Storage Device

• US 20110264847A1
• Filed: 04/18/2011
• Published: 10/27/2011
• Est. Priority Date: 04/21/2010
• Status: Active Grant

• Current Assignee: Silicon Motion Incorporated California (Silicon Motion)
• Original Assignee: Silicon Motion Incorporated California (Silicon Motion)
• Inventors: Hsiao, Wei-Yi
• Granted Patent: US 9,075,707 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7202 Allocation control and policies
• CPC Class Codes: G06F 2212/7211 Wear leveling

Abstract

The invention provides a data writing method for a memory. In one embodiment, the memory comprises a data area and a spare area, the data area comprises a plurality of data blocks storing data, and the spare area comprises a plurality of spare blocks having no data stored therein. First, a write command for writing a write data to a first data block of the memory is received from a host. The spare blocks of the spare area are then sorted according to the erase counts of the spare blocks. A first spare block with the least erase counts is then selected from the spare blocks of the spare area. The write data is then written to the first spare block. Data is then erased from the first data block to convert the first data block to a spare block.

Claims

1. A data writing method for a memory, wherein the memory comprises a data area and a spare area, the data area comprises a plurality of data blocks storing data, and the spare area comprises a plurality of spare blocks having no data stored therein, comprising:

receiving a write command for writing a write data to a first data block of the memory from a host;

sorting the spare blocks of the spare area according to the erase counts of the spare blocks;

selecting a first spare block with the least erase counts from the spare blocks of the spare area;

writing the write data to the first spare block; and

erasing data from the first data block to convert the first data block to a spare block.

2. The data writing method as claimed in claim 1, wherein the data writing method further comprises:

calculating a total number of worn-out blocks in the spare area, wherein the erase counts of the worn-out blocks are greater than a first threshold;

checking whether the total number of the worn-out blocks is greater than a specific number; and

if the total number of the worn-out blocks is greater than the specific number, performing a wear-leveling process to swap the worn-out blocks in the spare area for the data blocks in the data area.

3. The data writing method as claimed in claim 2, wherein the performing of the wear-leveling process comprises:

selecting a second spare block with the largest erase count from the worn-out obtaining a second data block with an erase count less than a second threshold from the data area;

writing data stored in the second data block to the second spare block; and

erasing data from the second data block to convert the second data block to a spare block.

4. The data writing method as claimed in claim 3, wherein the second threshold is equal to half of the first threshold.

5. The data writing method as claimed in claim 2, wherein the specific number is equal to two.

6. The data writing method as claimed in claim 3, wherein obtaining of the second data block comprises:

when the data area does not comprise any data blocks with erase counts less than the second threshold, subtracting a predetermined number from the erase counts of all data blocks of the data area; and

searching the data area for the second data block with an erase count less than the second threshold.

7. The data writing method as claimed in claim 6, wherein the predetermined number is equal to half of the first threshold.

8. A data storage device, comprising:

a memory, comprising a data area and a spare area, wherein the data area comprises a plurality of data blocks storing data, and the spare area comprises a plurality of spare blocks having no data stored therein; and

a controller, receiving a write command for writing a write data to a first data block of the memory from a host, sorting the spare blocks of the spare area according to the erase counts of the spare blocks, selecting a first spare area, writing the write data to the first spare block, and erasing data from the first data block to convert the first data block to a spare block.

9. The data storage device as claimed in claim 8, wherein the controller calculates a total number of worn-out blocks with erase counts greater than a first threshold in the spare area, checks whether the total number of the worn-out blocks is greater than a specific number, and performs a wear-leveling process to swap the worn-out blocks in the spare area for the data blocks in the data area if the total number of the worn-out blocks is greater than the specific number.

10. The data storage device as claimed in claim 9, wherein when the controller performs of the wear-leveling process, the controller selects a second spare block with the largest erase count from the worn-out blocks of the spare area, obtains a second data block with an erase count less than a second threshold from the data area, writes data stored in the second data block to the second spare block, and erases data from the second data block to convert the second data block to a spare block.

11. The data storage device as claimed in claim 10, wherein the second threshold is equal to half of the first threshold.

12. The data storage device as claimed in claim 9, wherein the specific number is equal to two.

13. The data storage device as claimed in claim 10, wherein when the controller searches the data area for the second data block, if the data area does not comprise any data blocks with erase counts less than the second threshold, the controller subtracts a predetermined number from the erase counts of all data blocks of the data area, and then searches the data area for the second data block with an erase count less than the second threshold again.

14. The data storage device as claimed in claim 13, wherein the predetermined number is equal to half of the first threshold.