STORAGE APPARATUS AND METHOD OF MANAGING DATA STORAGE AREA

• US 20120191903A1
• Filed: 01/30/2012
• Published: 07/26/2012
• Est. Priority Date: 10/30/2008
• Status: Active Grant

• Current Assignee: Akihiko Araki, Sadahiro Sugimoto, Yoshiki Kano, Yusuke Nonaka
• Original Assignee: Akihiko Araki, Sadahiro Sugimoto, Yoshiki Kano, Yusuke Nonaka
• Inventors: ARAKI, Akihiko, Kano, Yoshiki, Sugimoto, Sadahiro, Nonaka, Yusuke
• Granted Patent: US 8,489,806 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 2212/1036 Life time enhancement
• CPC Class Codes: G06F 2212/7202 Allocation control and policies
• CPC Class Codes: G06F 2212/7211 Wear leveling
• CPC Class Codes: G11C 2211/5641 Multilevel memory having cells with different number of storage levels

Abstract

To extend endurance and reduce bit cost, a storage apparatus includes a controller and a first storage device and a second storage device having a smaller erase count upper limit than the first storage device. Area conversion information includes correspondence of a first address of a data storage destination and a second address of a data storage area The controller selects an area corresponding to the first address, determines whether a rewrite frequency of the selected area is equal to or larger than a first threshold and, when the rewrite frequency is equal to or larger than the threshold, selects an area of the first storage device, and, when the rewrite frequency is smaller than the threshold, selects an area of the second storage device and maps the address of the selected area to the first address.

Claims

1. A storage system comprising:

a plurality of flash memory drives including a first flash memory drive including a single level cell flash memory chip, and a second flash memory drive including a multilevel cell flash memory chip; and

a storage controller configured to copy data between the first flash memory drive and second flash memory drive on the basis of an access status of the data.

2. A storage system according to claim 1, wherein the storage controller is configured to manage a virtual address to access to the plurality of flash memory drives.

3. A storage system according to claim 2, wherein the storage controller is configured to update mapping information of the virtual address and a first logical address indicating a first area in the first flash memory drive and a second logical address indicating a second area in the second flash memory drive in response to copying the data.

4. A storage system according to claim 3, wherein the first area includes at least one first block that is an erase unit and the second area includes at least one second block that is an erase unit.

5. A storage system according to claim 3, wherein the access status is a rewrite frequency of the data.

6. A storage system according to claim 4, wherein the storage controller is configured to copy the data in the first area to the second area when the rewrite frequency is higher than a threshold value.

7. A storage system according to claim 1, wherein a RAID group is configured on the basis of the plurality of flash memory drives.

8. A storage system according to claim 1, wherein:

the first flash memory drive includes a first memory controller that is configured to control an access request to a plurality of first blocks in the first flash memory drive, and

the second flash memory drive includes a second memory controller that is configured to control an access request to a plurality of second blocks in the second flash memory drive.

9. A storage system comprising:

a first flash memory drive in which an endurance is limited to a predetermined value;

a second flash memory drive in which an endurance is shorter than the endurance of the first flash memory drive; and

a storage controller configured to copy data in a first area of the first flash memory drive to a second area in the second flash memory drive on the basis of an access status of the data.

12. A storage system according to claim 9, wherein the storage controller is configured to manage a virtual address to access to the first and second flash memory drives.

13. A storage system according to claim 12, wherein the storage controller is configured to update mapping information of the virtual address and a first logical address indicating a first area in the first flash memory drive and a second logical address indicating a second area in the second flash memory drive in response to copying the data.

14. A storage system according to claim 13, wherein:

the first area includes at least one first block that is an erase unit; and

the second area includes at least one second block that is an erase unit.

15. A storage system according to claim 13, wherein the access status is a rewrite frequency of the data.

16. A storage system according to claim 14, wherein the storage controller is configured to copy the data in the first area to the second area when the rewrite frequency is higher than a threshold value.

17. A storage system according to claim 9, wherein a RAID group is configured on the basis of the first and second flash memory drives.

18. A storage system according to claim 9,

wherein the first flash memory drive includes a first memory controller that is configured to control an access request to a plurality of first blocks in the first flash memory drive, and

the second flash memory drive includes a second memory controller that is configured to control an access request to a plurality of second blocks in the second flash memory drive.

10. A storage system comprising:

a first flash memory drive, in which an acceptable erase count is limited to a predetermined value, including a plurality of first blocks and a first memory controller configured to control an access request to the plurality of first blocks;

a second flash memory drive, in which an acceptable erase count is lower than the acceptable erase count of the first flash memory drive, including a plurality of second blocks and a second memory controller configured to control an access request to the plurality of second blocks; and

a storage controller configured to copy data between at least one first block in the first flash memory drive and at least one second block in the second flash memory drive on the basis of the access status of the data.

19. A storage system according to claim 10, wherein the storage controller is configured to manage a virtual address to access to the first and second flash memory drives.

20. A storage system according to claim 19, wherein the storage controller is configured to update mapping information of the virtual address and a first logical address indicating a first area in the first flash memory drive and a second logical address indicating a second area in the second flash memory drive in response to copying the data.

21. A storage system according to claim 20, wherein:

the first area includes at least one first block that is an erase unit; and

the second area includes at least one second block that is an erase unit.

22. A storage system according to claim 20, wherein the access status is a rewrite frequency of the data.

23. A storage system according to claim 21, wherein the storage controller is configured to copy the data in the first area to the second area when the rewrite frequency is higher than a threshold value.

24. A storage system according to claim 10, wherein a RAID group is configured on the basis of the first and second flash memory drives.

25. A storage system according to claim 10, wherein:

the first flash memory drive includes a first memory controller that is configured to control an access request to a plurality of first blocks in the first flash memory drive, and

the second flash memory drive includes a second memory controller that is configured to control an access request to a plurality of second blocks in the second flash memory drive.

11. A storage system comprising:

a first flash memory drive including a single level cell flash memory chip;

a second flash memory drive including a multi-level cell flash memory chip; and

a storage controller coupled to the first flash memory drive and the second flash memory drive.