Storage system and data guarantee method

• US 20100057978A1
• Filed: 10/20/2008
• Published: 03/04/2010
• Est. Priority Date: 08/26/2008
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shiino, Naoto, Takamura, Yukiyoshi
• Granted Patent: US 8,180,952 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 2212/7211 Wear leveling

Abstract

A system according to the invention reads/writes data by using a memory device performing a wear leveling. A host 4 reads/writes data from/in a flash memory device 2. A first protection code BC is added to the end of a logical block for every logical block of 512 bytes. A second protection code FC is added to the head of the logical blocks. The first protection code BC and the second protection code FC are configured to include data for specifying the logical address. When data is read from the flash memory device 2, the logical address obtained from the first protection code BC is compared to the logical address obtained from the second protection code. When both logical addresses are identical, it is determined that correct data is read.

Claims

1. A storage system comprising:

a storage device for storing received data, the storage device performing a wear leveling process for taking an average of the number of used times in unit of pages;

a storage controller for controlling the storage device;

an address data setting control unit which associates an address for specifying a logical address of the data to both before and after the data with respect to at least data stored over a plurality of pages in the storage device among data stored in the storage device; and

a determination unit which determines whether or not the data stored over the plurality of pages is correct based on the address data associated to the both before and after the data when the data stored over the plurality of pages is read.

2. The storage system according to claim 1,

wherein a size of a first logical block used for managing data in the storage device is different from a size of a second logical block used for managing data in the storage controller, and

the address data setting control unit includes a first setting unit for converting the first logical block into the second logical block by setting first address data for specifying a logical address of the first logical block to one side of both before and after the first logical block with respect to the data stored in the first logical block.

3. The storage system according to claim 2,

wherein the pages are set to n (n>

2) times the size of the first logical block,

the address data setting control unit further includes a second setting unit which sets second address data for specifying a logical address of the first logical block to the other of both before and after the first logical block with respect to the data stored in the first logical block, and

the determination unit determines that the second logical block data stored over the plurality of pages is read correctly when the first address data is identical to the second address data, and determines that the second logical block data stored over the plurality of pages is read incorrectly when the first address data and the second address data are not identical.

4. The storage system according to claim 2,

wherein the pages are set to identical to the size of the first logical block,

the address data setting control unit further includes a second setting unit which copies first address data included in a page preceding to a predetermined page, which does not include the first address data among the pages, to the head of the predetermined page as second address data with respect to the predetermined page, and

the determination unit determines that the second logical block data stored over the plurality of pages is read correctly when the first address data and the second address data are identical, and determines that the second logical block data stored over the plurality of pages is read incorrectly when the first address data and the second address data are not identical.

5. The storage system according to claim 2,

wherein the pages are set to n (n>

2) times the size of the first logical block, and

the determination unit determines whether or not the second logical block data stored over the plurality of pages is read correctly by comparing the first address data included in the second logical block data and other first address data included in the second logical block data preceding to the second logical block data when the second logical block data stored over the plurality of pages is read.

6. The storage system according to claim 5, wherein the determination unit determines that the second logical block data is read correctly when a first address data vale included in the second logical block data stored over the plurality of pages is contiguous to the other first address data value.

7. The storage system according to claim 2, wherein the first setting unit sets checking data for checking the first logical block data in addition to the data to the first address data.

8. The storage system according to claim 1, wherein the storage device includes a flash memory device.

9. The storage system according to claim 1, wherein the address data setting control unit is provided in the storage controller.

10. The storage system according to claim 1, wherein the address data setting control unit is dispersedly provided at both of the storage controller and the storage device.

11. The storage system according to claim 4, wherein the second setting unit and the determination unit are provided in the storage device.

12. The storage system according to claim 5, wherein the determination unit is provided in the storage device.

13. The storage system according to claim 1,

wherein the storage device is provided with a controller and a memory chip controlled by the controller, and

the controller manages a correspondence relationship between a logical address of data received from a host computer and a page address and pointer of the memory chip.

14. The storage system according to claim 1,

wherein the storage device includes a flash memory device,

a size of a first logical block used for managing data in the storage device is different from a size of a second logical block used for managing data in the storage controller,

the address data setting control unit includes:

(1) a first setting unit which converts the first logical block into the second logical block by setting first address data for specifying a logical address of the first logical block and checking data for checking the first logical block data to one of both before and after the first logical block with respect to the data stored in the first logical block; and

(2) a second setting unit which sets second address data for specifying a logical address of the first logical block to the other of both before and after the first logical block with respect to the data stored in the each first logical block, and

the second setting unit, (2A) sets a logical address of the first logical block to the other side of the first logical block as the second address data, (2B) copies first address data having a page preceding to a predetermined page, which does not include the first address data among the pages, to the head of the predetermined page as second address data with respect to the predetermined page, or (2C) uses address data obtained by adding a predetermined value to the first address data set in another second logical block preceding to the second logical block stored over the plurality of pages, as the second address data.

16. The storage system according to claim 6, wherein the determination unit is provided in the storage device.

15. A data guarantee method of guaranteeing data read from a storage device to be correct data,

wherein a wear leveling is performed in the storage device in order to take an average of the number of used times in unit of pages, and

a size of a first logical block used for managing data in the storage device is different from a size of a second logical block used for managing data in the storage device,

the data guarantee method comprising the steps of:

converting the first logical block into the second logical block with respect to each of data stored in the first logical blocks by setting the first address data for specifying a logical address of the first logical block to the rear side of the first logical block when the storage device is requested for writing therein; and

determining whether or not the second logical block data stored over the plurality of pages is read correctly by comparing the first address data included in the second logical block data and another first address data included in a second logical block data preceding to the second logical block data when the second logical block data stored over the plurality of pages is read.