Operating method of data storage device
Provided is an operating method of a data storage device including a plurality of nonvolatile memory devices. The operating method includes the steps of: dividing storage areas of the nonvolatile memory devices into a first memory area and a second memory area; determining wear levels of each of the first memory area and the second memory area; and varying a ratio of the first memory area and the second memory area according to the determined wear levels.
1. An operating method of a data storage device including a plurality of nonvolatile memory devices, the operating method comprising the steps of:
dividing storage areas of the nonvolatile memory devices into a first memory area and a second memory area;
determining wear levels of each of the first memory area and the second memory area; and
varying a ratio of the first memory area and the second memory area according to the determined wear levels.
2. The operating method according to claim 1 , wherein the step of varying the ratio of the first memory area and the second memory area comprises the step of increasing the first memory area when it is determined that the wear level of the first memory area approaches a limit wear level of the first memory area.
3. The operating method according to claim 1 , wherein the step of varying the ratio of the first memory area and the second memory area comprises the step of increasing the second memory area when it is determined that the wear level of the second memory area approaches a limit wear level of the second memory area.
4. The operating method according to claim 1 , wherein the step of dividing the storage areas comprises the step of dividing the storage area of each of the nonvolatile memory devices into the first memory area and the second memory area.
5. The operating method according to claim 4 , wherein the first memory area and the second memory area are controlled through different program methods.
6. The operating method according to claim 1 , wherein the number of bits stored in each of memory cells belonging to the first memory area is less than the number of bits stored in each of memory cells belonging to the second memory area, or the memory cell of the first memory area has a higher program speed or a higher limit wear level than the memory cell of the second memory area.
7. The operating method according to claim 1 , wherein the step of determining the wear levels of each of the first memory area and the second memory area comprises the step of comparing a reference value to an optimized lifetime ratio (OLR) which is decided based on the limit wear levels and the average wear levels of each of the first memory area and the second memory area.
8. The operating method according to claim 1 , wherein the first memory area comprises a buffer area for temporarily storing input data, and the second memory area comprises a main area for storing the data temporarily-stored in the first area.
9. An operating method of a data storage device including a nonvolatile memory device, the operating method comprising the steps of:
dividing a storage area of the nonvolatile memory device into a first memory area and a second memory area having a different program method from the first memory area;
deciding an optimized lifetime ratio (ORL) based on a limit wear level and an average wear level of the first memory area, and a limit wear level and an average wear level of the second memory area;
comparing the ORL to a reference value; and
changing a part of the first memory area to the second memory area or changing a part of the second memory area to the first memory area, according to the result of the step of comparing the ORL to the reference value.
10. The operating method according to claim 9 , wherein the step of changing a part of the first memory area to the second memory area or changing a part of the second memory area to the first memory area comprises the step of changing a part of the second memory area to the first memory area, when the OLR is greater than the reference value.
11. The operating method according to claim 10 , wherein the step of changing a part of the first memory area to the second memory area or changing a part of the second memory area to the first memory area comprises the step of selecting an area having a lower wear level than the average wear level of the second memory area from the second memory area.
12. The operating method according to claim 10 , wherein the area changed into the first memory area from the second memory area is accessed in the manner of the first memory area.
13. The operating method according to claim 10 , wherein the step of changing a part of the first memory area to the second memory area or changing a part of the second memory area to the first memory area comprises the steps of:
comparing the wear level of the area changed from the second memory area to the first memory area to the average wear level of the second memory area; and
when the wear level of the area changed to the first memory area is greater than the average wear level of the second memory area, changing the area changed to the first memory area to the second memory area.
14. The operating method according to claim 9 , wherein the step of changing a part of the first memory area to the second memory area or changing a part of the second memory area to the first memory area comprises the step of changing a part of the first memory area to the second memory area when the ORL is less than the reference value.
15. The operating method according to claim 14 , wherein the step of changing a part of the first memory area to the second memory area or changing a part of the second memory area to the first memory area comprises the step of selecting an area having a lower wear level than the average wear level of the second memory area from the first memory area.
16. The operating method according to claim 14 , wherein the area changed into the second memory area from the first memory area is accessed in the manner of the second memory area.
17. The operating method according to claim 14 , wherein the step of changing a part of the first memory area to the second memory area or changing a part of the second memory area to the first memory area comprises the steps of:
comparing the wear level of the area changed from the first memory area to the second memory area to the average wear level of the first memory area; and
when the wear level of the area changed to the second memory area is greater than the average wear level of the first memory area, changing the area changed to the second memory area to the first memory area.
18. The operating method according to claim 9 , wherein the reference value is decided according to limit wear levels, an initial ratio, or degradation characteristics of the first memory area and the second memory area.
19. The operating method according to claim 9 , wherein the number of bits stored in each of memory cells belonging to the first memory area is less than the number of bits stored in each of memory cells belonging to the second memory area, or the memory cell of the first memory area has a higher program speed or a higher limit wear level than the memory cell of the second memory area.
20. The operating method according to claim 19 , wherein the first memory area comprises single level cells, and the second memory area comprises multi-level cells.