METHOD FOR EFFICIENT STORAGE OF METADATA IN FLASH MEMORY

• US 20080270730A1
• Filed: 04/14/2008
• Published: 10/30/2008
• Est. Priority Date: 04/30/2007
• Status: Active Grant

• Current Assignee: Western Digital Israel Limited (Western Digital Corporation)
• Original Assignee: SanDisk IL Ltd. (Western Digital Corporation)
• Inventors: Murin, Mark, LASSER, Menahem
• Granted Patent: US 8,332,574 B2
• Time in Patent Office: Days
• US Class Current: 711/170
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7207 management of metadata or control data

Abstract

User data are stored in a memory that includes one or more blocks of pages by, for one of the blocks, and optionally for all of the blocks, whenever writing any of the user data to that block, writing the block according to a predefined plan for specifying, with respect to each page of that block, a portion of the user data that is to be written to that page. Alternatively or additionally, each page that stores user data has associated therewith a metadatum related to the age of the user data stored therein; and, for one of the blocks, at any time that two or more of the pages of that block store user data, a common value of the metadatum is associated with all such pages.

Claims

1. A method of storing data, comprising:

(a) receiving user data to be stored in a memory that includes at least one block, each block including a plurality of pages; and

(b) for one of the at least one block, whenever writing any of the user data to the one block, writing the one block according to a predefined plan for specifying, with respect to each page of the one block, a portion of the user data that is to be written to the each page of that block.

2. The method of claim 1, wherein the specifying of the user data includes preparing at least one pointer to a corresponding location where a corresponding at least portion of the user data is located prior to being written to the one block.

3. The method of claim 1, wherein the user data are received from a host of the memory, and wherein, if, during the writing of the one block, the host substitutes new user data for the portion of the user data that has been specified to be written to one of the pages of the one block, the method further comprises:

(c) writing the specified portion of the user data to the one page of the one block despite the substitution.

4. The method of claim 1, wherein the user data are received from a host of the memory, and wherein if, during the writing of the one block, the host substitutes new user data for the portion of the user data that has been specified to be written to one of the pages of the one block, the method further comprises:

(c) terminating the writing of the user data to the one block.

5. The method of claim 4, wherein the terminating is effected only if the host substitutes the new user data after the specified portion of the user data has been written to the one page of the one block.

6. The method of claim 1, further comprising:

(c) storing, in a cache, a set, of user data, that is at most as large as a data capacity of the one block, the writing according to the predefined plan including copying the set of user data to the one block.

7. The method of claim 1, wherein the memory includes a plurality of the blocks and wherein, whenever user data are written to any one of the blocks, the user data are written according to a predefined plan for specifying, with respect to each page of the any one block, a portion of the user data to be written to the each page of the any one block.

8. A memory device comprising a memory that includes at least one block, each block including a plurality of pages, wherein, for one of the at least one block, whenever user data are written to the one block, the user data are written to the one block according to a predefined plan for specifying, with respect to each page of the one block, a portion of the user data that is to be written to the each page of the one block.

9. A memory device comprising:

(a) a controller, for storing user data in a memory that includes at least one block, each block including a plurality of pages, by, for one of the at least one block, whenever writing user data to the one block, writing the user data to the one block according to a predefined plan for specifying, with respect to each page of the one block, a portion of the user data that is to be written to the each page of the one block.

10. The memory device of claim 9, further comprising:

(b) the memory.

11. A system comprising:

(a) a nonvolatile memory wherein is stored a driver for a memory device that includes at least one block, each block including a plurality of pages, the driver including code for storing data in the memory device by, for one of the at least one block, whenever writing user data to the one block, writing the user data to the one block according to a predefined plan for specifying, with respect to each page of the one block, a portion of the user data that is to be written to the each page of the one block; and

(b) a processor for executing the code.

12. The system of claim 11, further comprising:

(c) the memory device.

13. A computer-readable storage medium having computer-readable code embedded thereon, the computer-readable code being driver code for a memory device that includes at least one block, each block including a plurality of pages, the computer-readable code comprising program code for storing data in the memory device by, for one of the at least one block, whenever writing user data to the one block, writing the user data to the one block according to a predefined plan for specifying, with respect to each page of the one block, a portion of the user data that is to be written to the each page of the one block.

14. A method of storing data, comprising:

(a) storing the data in a memory that includes at least one block, each block including a plurality of pages, each page in which user data are stored having associated therewith a metadatum related to an age of the user data that are stored in the each page; and

(b) for one of the at least one block, at any time that at least two pages of the one block have user data stored therein, associating, with all the pages of the one block wherein the user data are stored, a value of the metadatum that is common to all the pages of the one block wherein the user data are stored.

15. The method of claim 14, further comprising the step of:

(c) whenever writing any of the user data to the one block, writing the one block according to a predefined plan for specifying, with respect to each page of the one block, a portion of the user data, that is to be written to the each page of that block.

16. The method of claim 14, wherein the associating of the common value of the metadatum with all the at least two pages includes writing the common value of the metadatum in a respective location in the memory.

17. The method of claim 16, wherein the respective location in which the common value of the metadatum is written is in the one block.

18. The method of claim 16, wherein the respective location in which the common value of the metadatum is written is outside the one block.

19. The method of claim 16, further comprising the step of:

(c) replacing the common value with a revised version thereof by writing the revised version in a respective location thereof in the memory.

20. The method of claim 19, wherein the respective location in which the revised version is written is different from the respective location in which the common value is written.

21. The method of claim 19, wherein the respective location in which the revised version is written is the respective location in which the value is written.

22. The method of claim 14, further comprising the step of:

(c) replacing the common value with a revised version thereof.

23. The method of claim 14, wherein the metadatum is related to a reference voltage for reading the user data.

24. The method of claim 14, further comprising the step of:

(c) reading at least a portion of the user data, that are stored in the at least two pages, in accordance with the common value of the metadatum.

25. A memory device comprising:

(a) a controller for storing user data in a memory that includes at least one block, each block including a plurality of pages, and for associating, with each page in which user data are stored, a metadatum related to an age of the user data that are stored in the each page;

wherein, for one of the at least one block, at any time that at least two pages of the one block have user data stored therein, the controller associates, with all the pages of the one block wherein the user data are stored, at most one common value of the metadatum.

26. The memory device of claim 25, further comprising:

(b) the memory.

27. A system comprising:

(a) a nonvolatile memory wherein is stored a driver of a memory device that includes at least one block, each block including a plurality of pages, the driver including code for storing user data in the memory device and for associating, with each page of the memory device in which user data are stored, a metadatum related to an age of the user data that are stored in the each page, wherein, for one of the at least one block, at any time that at least two pages of the one block have user data stored therein, all the pages of the one block wherein the user data are stored have associated therewith at most one common value of the metadatum; and

(b) a processor for executing the code.

28. The system of claim 27, further comprising:

(c) the memory device.

29. A computer-readable storage medium having computer-readable code embedded thereon, the computer-readable code being driver code for a memory device that includes at least one block, each block including a plurality of pages, the computer-readable code comprising program code for storing user data in the memory device and for associating, with each page of the memory device in which user data are stored, a metadatum related to an age of the user data that are stored in the each page, wherein, for one of the at least one block, at any time that at least two pages of the one block have user data stored therein, all the pages of the one block wherein the user data are stored have associated therewith at most one common value of the metadatum.