Non-volatile memory and method with multi-stream update tracking

• US 7,366,826 B2
• Filed: 07/27/2005
• Issued: 04/29/2008
• Est. Priority Date: 12/16/2004
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Corporation (Western Digital Corporation)
• Inventors: Smith, Peter John, Bennett, Alan David, Gorobets, Sergey Anatolievich
• Primary Examiner(s): Nguyen; Hiep T.
• Application Number:
  US11/192,220
• Publication Number:
  US 20060155921A1
• Time in Patent Office: 1,007 Days
• Field of Search: 711/103, 365/185.33
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1032 Reliability improvement, data loss prevention, degraded operation etc
• CPC Class Codes: G06F 2212/7203 Temporary buffering, e.g. using volatile buffer or dedicated buffer blocks

Abstract

Update data to a non-volatile memory may be recorded in at least two interleaving streams such as either into an update block or a scratch pad block depending on a predetermined condition. The scratch pad block is used to buffered update data that are ultimately destined for the update block. Synchronization information about the order recording of updates among the streams is saved with at least one of the streams. This will allow the most recently written version of data that may exist on multiple memory blocks to be identified. In one embodiment, the synchronization information is saved in a first block and is a write pointer that points to the next recording location in a second block. In another embodiment, the synchronization information is a time stamp.

Claims

1. A method of recording data from a host comprising:

(a) providing first and second nonvolatile storages, each for sequentially recording data units;

(b) designating either the first or second storage as storage for priority information, said priority information allowing determination of whether a first data unit in the first storage was recorded before or after a second data unit in the second storage;

(c) receiving the data from the host;

(d) recording the received data to a next available location in either the first storage or the second storage respectively depending on whether or not a predetermined condition is satisfied;

(e) wherein whenever the received data is being recorded to the designated storage, the priority information is also being recorded thereto; and

(f) repeating (c)-(e) until there is no more received data to be recorded.

2. A method as in claim 1, wherein each of the first and second storages is organized into a block of memory units that are erasable together.

3. A method as in claim 1, wherein the first and second storages are part of a flash EEPROM.

4. A method as in claim 1, wherein said priority information is a write pointer providing an address of the location where a next recording will take place in the non-designated storage.

5. A method as in claim 4, wherein:

the data from the host is update data for a group of data units;

the first storage is for storing the update data; and

the second storage is for buffering the update data before being transferred to the first storage, and is the designated storage for the priority information.

6. A method as in claim 5, wherein:

the first storage is one of a plurality of storages for storing update data; and

the second storage is for buffering the update data before being transferred to one of the plurality of the first storages.

7. A method as in claim 5, further comprising:

organizing the data into data units having a predetermined order; and

organizing the first and second nonvolatile storages into pages, each page for programming together multiple data units having predetermined page offsets.

8. A method as in claim 6, wherein each page is once-programmable after an erase.

9. A method as in claim 6, wherein:

the predetermined condition is when one of the received data units has a page-end offset; and

said recording the data to the first storage includes recording to a page of the first storage said page-end data unit and any preceding data units in the page.

10. A method as in claim 6, wherein the write pointer is recorded to a location of a page unoccupied by data in the second storage.

11. A method as in claim 6, wherein said write pointer is recorded to a location of a page having a page-end offset in the second storage.

12. A method as in claim 4, wherein:

the data from the host is update data for a group of data units;

the first storage is for storing the update data, and is designated as storage for the priority information; and

the second storage is for buffering the update data before being transferred to the first storage.

13. A method as in claim 12, wherein:

the first storage is one of a plurality of storages for storing update data; and

the second storage is for buffering the update data before being transferred to one of the plurality of storages.

14. A method as in claim 12, further comprising:

organizing the data into data units having a predetermined order; and

organizing the first and second nonvolatile storages into pages, each page for programming together multiple data units having predetermined page offsets.

15. A method as in claim 13, wherein each page is once-programmable after an erase.

16. A method as in claim 13, wherein:

the predetermined condition is when one of the received data units has a page-end offset; and

said recording the data to the first storage includes recording to a page of the first storage said page-end data unit and any preceding data units in the page.

17. A method as in claim 13, wherein the write pointer is recorded to a location of the page unoccupied by data in the first storage.

18. A method as in claim 13, wherein:

the data units are individually partitioned into a data portion and an overhead portion; and

the write pointer is recorded in an overhead portion of at least one of the data units of the page in the first storage.

19. A method as in any one of claims 1-18, wherein the first and second nonvolatile storages are constituted from memory cells that individually store one bit of data.

20. A method as in any one of claims 1-18, wherein said first and second nonvolatile storages are constituted from memory cells that individually store more than one bit of data.

21. A nonvolatile memory comprising:

a memory organized into a plurality of blocks, each block being a plurality of memory units that are erasable together, each memory unit for storing a data unit;

a controller for controlling operations of said blocks;

first and second blocks, each for sequentially recording data units;

priority information for allowing determination of whether a first data unit in the first block was recorded before or after a second data unit in the second block;

a designated block designated from one of said first and second blocks for storing said priority information;

a buffer for receiving the data from the host;

said controller controlling recording of the received data to a next available location in either said first block or said second block respectively depending on whether or not a predetermined condition is satisfied; and

wherein said priority information is being stored in said designated block whenever the received data is being recorded to the designated block.

22. A nonvolatile memory as in claim 21, wherein said nonvolatile memory is flash EEPROM.

23. A nonvolatile memory as in claim 21, wherein said nonvolatile memory is in the form of a removable memory card.

24. A nonvolatile memory as in claim 21, wherein:

said priority information is a write pointer providing an address of the location where a recording will take place in the non-designated block.

25. A nonvolatile memory as in claim 24, wherein:

said data from the host is update data for a group of data units;

said first block is for storing said update data; and

said second block is for buffering said update data before being transferred to the first block, and is designated for storing said priority information.

26. A nonvolatile memory as in claim 25, wherein:

said first block is one of a plurality of blocks for storing update data; and

said second blocks is for buffering the update data before being transferred to one of the plurality of said first blocks.

27. A nonvolatile memory as in claim 25, wherein:

the data is organized into data units having a predetermined order; and

said first and second blocks are organized into pages, each page for programming together multiple data units having predetermined page offsets.

28. A nonvolatile memory as in claim 26, wherein each page is once-programmable after an erase.

29. A nonvolatile memory as in claim 26, wherein:

the predetermined condition is when one of the received data units has a page-end offset; and

said controller controlling recording the data to said first block includes recording to a page of said first block said page-end data unit and any preceding data units in the page.

30. A nonvolatile memory as in claim 26, wherein said write pointer is recorded to a location of a page unoccupied by data in said second block.

31. A nonvolatile memory as in claim 26, wherein said write pointer is recorded to a location of a page having a page-end offset in said second block.

32. A nonvolatile memory as in claim 24, wherein:

said data from the host is update data for a group of data units;

said first block is for storing said update data, and is designated for storing said priority information; and

said second block is for buffering said update data before being transferred to the first block.

33. A nonvolatile memory as in claim 32, wherein:

said first block is one of a plurality of blocks for storing update data; and

said second blocks is for buffering the update data before being transferred to one of the plurality of said first blocks.

34. A nonvolatile memory as in claim 32, wherein:

the data is organized into data units having a predetermined order; and

said first and second blocks are organized into pages, each page for programming together multiple data units having predetermined page offsets.

35. A nonvolatile memory as in claim 32, wherein each page is once-programmable after an erase.

36. A nonvolatile memory as in claim 35, wherein:

the predetermined condition is when one of the received data units has a page-end offset; and

said controller controlling recording the data to said first block includes recording to a page of said first block said page-end data unit and any preceding data units in the page.

37. A nonvolatile memory as in claim 35, wherein said write pointer is recorded to a location of a page unoccupied by data in said first block.

38. A nonvolatile memory as in claim 35, wherein the data units are individually partitioned into a data portion and an overhead portion;

and

said write pointer is recorded to a an overhead portion of at least one of the data units of the page in said first block.

40. A nonvolatile memory as in any one of claims 21-39, wherein the first and second nonvolatile storages are constituted from memory cells that individually store one bit of data.

41. A nonvolatile memory as in any one of claims 21-39, wherein said first and second nonvolatile storages are constituted from memory cells that individually store more than one bit of data.

39. A nonvolatile memory comprising:

a memory organized into a plurality of blocks, each block being a plurality of memory units that are erasable together, each memory unit for storing a logical unit of data;

first and second blocks, each for sequentially recording data from a host;

a write pointer pointing to the next recording location of said first block;

a designated block designated from one of said first and second blocks for storing said write pointer;

a buffer for receiving the data from the host;

means for recording the received data to a next available location in either said first block or said second block respectively depending on whether or not a predetermined condition is satisfied; and

wherein said write pointer is being stored in said designated block whenever the received data is being recorded to the designated block.