Version based non-volatile memory translation layer

• US 7,752,381 B2
• Filed: 05/24/2005
• Issued: 07/06/2010
• Est. Priority Date: 05/24/2005
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Wong, Wanmo
• Primary Examiner(s): Bragdon; Reginald G
• Assistant Examiner(s): VO, THANH DUC
• Application Number:
  US11/136,152
• Publication Number:
  US 20060271725A1
• Time in Patent Office: 1,869 Days
• Field of Search: None
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/7209 Validity control, e.g. using flags, time stamps or sequence numbers

Abstract

A non-volatile memory and erase block/data block/sector/cluster update and address translation scheme utilizing a version number is detailed that enhances data updating and helps reduce program disturb of the memory cells of the non-volatile memory device. The various embodiments utilize a version number associated with each erase block, data block, sector, and/or cluster. This allows for determination of currently valid data block, sector and/or cluster associated with the logical ID of the data grouping by locating the most recent version associated with the logical ID. With this approach, old data need not be invalidated by programming a valid/invalid flag, avoiding the risk of program disturb in the surrounding data rows.

Claims

1. A method of operating a non-volatile memory comprising:

storing a version number associated with a logical sector stored in the non-volatile memory; and

storing one or more frequently updated logical sectors separately from non-frequently updated logical sectors including storing one or more frequently updated logical sectors in one or more frequently updated random sector clusters, wherein each one or more frequently updated random sector clusters contains a version number data field and a plurality of physical sectors for storage of a single logical sector, such that each update of the stored logical sector is written to a new unused physical sector of the cluster.

2. The method of claim 1, wherein the non-volatile memory is one of a non-volatile memory device, a non-volatile memory array, and a non-volatile memory subsystem.

3. The method of claim 1, further comprising:

translating a logical address of the logical sector to a physical sector address by using the stored version number and the logical address to retrieve the physical sector containing the most recent version number which is associated with the logical address of the accessed logical sector.

4. The method of claim 3, further comprising:

forming an address translation table by locating the physical address having the most recent version number associated with each logical address stored in the memory for use in address translation.

5. The method of claim 4, wherein forming an address translation table by locating the physical address having the most recent version number associated with each logical address stored in the memory further comprises scanning the memory upon power-up to locate the physical address having the most recent version number associated with each logical address stored in the memory.

6. The method of claim 1, further comprising:

updating logical sectors of data in the non-volatile memory by retrieving the most recent version number associated with the logical address of a logical sector being updated, incrementing or decrementing the version number, programming the updated data in a selected available physical sector of the non-volatile memory, and programming the updated version number in the version number data field of the selected physical sector.

7. The method of claim 6, further comprising:

programming the logical sector of data in the selected available physical block of the non-volatile memory with an initial version number stored in the version number data field when the logical address is not yet stored in the non-volatile memory device.

8. The method of claim 1, further comprising:

storing logical sectors in clusters of sequentially addressed logical sectors in the non-volatile memory.

9. The method of claim 1, wherein storing one or more frequently updated logical sectors separately from non-frequently updated logical sectors further comprises storing one or more frequently updated logical sectors in one or more frequently updated random sector areas, where each one or more frequently updated logical sectors stored in the one or more frequently updated random sector areas contains a version number data field associated with the frequently updated logical sector, such that each new update of the stored logical sector is written to a new unused physical sector of the one or more frequently updated random sector areas with an incremented version number.

10. The method of claim 1, wherein storing one or more frequently updated logical sectors separately from non-frequently updated logical sectors further comprises promoting logical sectors that are frequently updated to be stored in a frequently updated random sector cluster.

11. The method of claim 1, wherein storing one or more frequently updated logical sectors separately from non-frequently updated logical sectors further comprises demoting logical sectors that are not frequently updated from being stored in a frequently updated random sector cluster to being stored in a conventional physical sector.

12. A method of operating a non-volatile memory comprising:

translating a logical address of the logical sector to a physical sector address by using a stored version number and the logical address to retrieve the physical sector containing the most recent version number which is associated with the logical address of the accessed logical sector; and

accessing one or more frequently updated logical sectors separately from non-frequently updated logical sectors including accessing one or more frequently updated logical sectors in one or more frequently updated random sector clusters, where each of the one or more frequently updated random sector clusters contains a plurality of physical sectors for storage of a single logical sector, such that each update of the stored logical sector is written to a new, unused physical sector of the cluster.

13. The method of claim 12, wherein translating a logical address of the logical sector to a physical sector address by using a stored version number and the logical address to retrieve the physical sector containing the most recent version number which is associated with the logical address of the accessed logical sector further comprises translating a logical address of the logical sector to a physical sector address by using an address translation lookup table to retrieve the physical address of the physical sector that contains the most recent version number associated with the logical address.

14. The method of claim 13, further comprising:

forming the address translation table by scanning the non-volatile memory for the physical address having the most recent version number associated with each logical address stored in the memory.

15. The method of claim 14, further comprising:

updating logical sectors of data in the non-volatile memory by retrieving the most recent version number associated with the logical address of a logical sector being updated, advancing the version number to the next version number in the sequence, programming the updated data in a selected available physical sector of the non-volatile memory, and programming the updated version number in the version number data field of the selected physical sector.

16. The method of claim 15, further comprising:

programming the logical sector of data in the selected available physical block of the non-volatile memory with an initial version number stored in the version number data field when the logical address is not yet stored in the non-volatile memory device.

17. The method of claim 14, further comprising:

accessing logical sectors in the non-volatile memory by reference to a logical cluster address, wherein each cluster contains a plurality of sequentially addressed logical sectors.

18. The method of claim 17, wherein accessing logical sectors in the non-volatile memory by reference to a logical cluster address further comprises translating a logical address of the logical sector to a physical sector address by using a cluster address translation lookup table to retrieve the physical address of the physical cluster the logical sector is stored within.

19. The method of claim 12, wherein accessing one or more frequently updated logical sectors separately from non-frequently updated logical sectors further comprises translating a logical sector address to a physical sector address for the one or more frequently updated logical sectors utilizing a frequently updated logical sector address translation lookup table.

20. A method of translating a logical sector address to a physical sector address in a non-volatile memory comprising:

retrieving the physical address of a physical sector that is assigned to the logical address which contains the most recent version number stored in association with the physical sector wherein one or more frequently updated logical sectors of the non-volatile memory are accessed separately from non-frequently updated logical sectors and one or more frequently updated logical sectors are accessed in one or more frequently updated random sector clusters, where each of the one or more frequently updated random sector clusters contains a plurality of physical sectors for storage of a single logical sector, such that each update of the stored logical sector is written to a new, unused physical sector of the cluster.

21. The method of claim 20, wherein retrieving the physical address of a physical sector that is assigned to the logical address which contains the most recent version number stored in association with the physical sector further comprises translating the logical address to a physical sector address by utilizing an address translation table to translate the logical address to the physical address that is assigned to the logical address and is associated with the most recent version number which is related to the logical address of the accessed logical sector.

22. The method of claim 20, wherein retrieving the physical address of a physical sector that is assigned to the logical address which contains the most recent version number stored in association with the physical sector further comprises retrieving the physical address of a physical sector that is assigned to the logical address by reference to a logical cluster address associated with the logical address to retrieve a physical cluster address, where each cluster contains a plurality of sequentially addressed logical sectors and where the retrieved physical cluster contains the most recent version number stored in association with the physical cluster.

23. A non-volatile memory device comprising:

a memory array having a plurality of non-volatile memory cells arranged in a plurality of clusters, wherein each cluster contains a plurality of sectors;

a plurality of version data fields, each version data field associated with a cluster of the plurality of clusters; and

a control circuit, wherein the control circuit is configured to access a sector from the memory array by translating a logical address of the sector to a physical sector address of the memory array in reference to a logical cluster address and a version number stored in the version number data field associated with each of the physical clusters associated with the logical cluster address wherein the control circuit is further configured to access one or more frequently updated logical sectors separately from non-frequently updated logical sectors and access one or more frequently updated logical sectors in one or more frequently updated random sector clusters, where each of the one or more frequently updated random sector clusters contains a plurality of physical sectors for storage of a single logical sector, such that each update of the stored logical sector is written to a new, unused physical sector of the cluster.

24. The non-volatile memory device of claim 23, wherein the non-volatile memory device is one of a NAND Flash memory device and a NOR Flash memory device.

25. The non-volatile memory device of claim 23, wherein the non-volatile memory device further comprises a non-volatile memory subsystem containing a plurality of non-volatile memory devices.

26. The non-volatile memory device of claim 23, wherein the non-volatile memory device is adapted to access logical sectors of data from the clusters of the memory array utilizing version based cluster address translation to retrieve the physical cluster address that contains the most recent version number in the memory array associated with the logical address of the accessed logical sector.

27. The non-volatile memory device of claim 26, wherein the non-volatile memory device is adapted to update logical sectors of data in the memory array by retrieving the physical cluster having the most recent version number associated with the logical address of a logical sector being updated, advancing the version number, programming the updated data in a selected available physical cluster of the memory array, and programming the incremented version number in the version number data field of the selected physical cluster.

28. The non-volatile memory device of claim 27, wherein the non-volatile memory device is adapted to program new logical sector data into an existing cluster when an associated physical sector is unused in the cluster and when an update to a blank sector of the existing cluster would not write data into the memory array above already existing data in a physical row below the associated physical sector in the array.

29. The non-volatile memory device of claim 23, wherein the non-volatile memory device is adapted to store the one or more frequently updated logical sectors in one or more frequently updated random sector clusters, where each one or more frequently updated random sector clusters contains a version number data field and a plurality of physical blocks for storage of a single logical sector, such that each new update of the stored logical sector is written to a new unused physical block of the cluster.

30. The non-volatile memory device of claim 23, wherein the non-volatile memory device is adapted to move an existing cluster to a new unused cluster with an advanced version number when an update to a blank sector of the existing cluster would write data into the memory array above already existing data in a physical row below the blank sector in the array.

31. A method of operating a non-volatile memory comprising:

storing a version number associated with a logical cluster address stored in the non-volatile memory, wherein each cluster contains a plurality of sequentially addressed logical sectors;

accessing logical sectors in a non-volatile memory by reference to the logical cluster address; and

accessing one or more frequently updated logical sectors separately from non-frequently updated logical sectors including accessing one or more frequently updated logical sectors in one or more frequently updated random sector clusters, where each of the one or more frequently updated random sector clusters further contains a version number data field and a plurality of physical blocks for storage of a random logical sector, such that each update of the stored logical sector is written to a new unused physical block of the cluster without having to update the version number data field until all physical blocks of the random sector cluster have been utilized.

32. The method of claim 31, wherein accessing logical sectors in a non-volatile memory by reference to a logical cluster address further comprises translating a logical address of the logical sector to a physical block address by using a cluster address translation lookup table to retrieve the physical address of the physical cluster that the logical sector is associated with which has a most recent version number stored in the version number data field of the physical cluster.