Methods for memory allocation in non-volatile memories with a directly mapped file storage system

• US 20070156998A1
• Filed: 12/21/2005
• Published: 07/05/2007
• Est. Priority Date: 12/21/2005
• Status: Abandoned Application

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Inventors: Gorobets, Sergey
• Application Number:
  US11/316,136
• Publication Number:
  US 20070156998A1
• 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 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7202 Allocation control and policies
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 8/60 Software deployment

Abstract

In a memory system with a file storage system, a scheme for allocating memory locations for a write operation is to write the files substantially contiguously in a memory block one after another rather than to start a new file in a new block. In this way, they are more efficiently packed into the blocks by being written contiguously one after another. In a preferred embodiment, an incrementing write pointer points to the write location in memory for the next data for a file, which is independent of the offset address of the data within the file. When a current write block becomes filled with file data, an erased block is allocated, and the write pointer is moved to this block. Similarly a relocation pointer is used for data relocation during garbage collection or data compaction operations.

Claims

1. A method of allocating memory for writing of data files in a memory organized into erasable blocks, comprising:

identifying individual file data, each belonging to a data file, by a unique file identifier and an offset of data within the data file; and

in a series of write operations over a majority of blocks to be written, writing file data substantially following the location of a last written file data even when the file data being written and the last written one belong to different data files.

2. The method as in claim 1, wherein

individual blocks are organized into multiple pages;

and

file data from each write operation are written to within less than one page following file data written in the last write operation.

3. The method as in claim 1, wherein said file data constitutes a portion of a data file.

4. The method as in claim 1, wherein said file data constitutes the entire portion of a data file.

5. The method as in claim 1, further comprising:

providing a directory to keep track of the locations of the individual file data written to the memory.

6. The method as in claim 1, further comprising:

providing an incrementing write pointer to indicate the writing location.

7. The method as in claim 1, further comprising:

providing an incrementing relocation pointer to indicate the writing location during a relocation operation to copy file data from one block to another block.

8. The method as in claim 6, further comprising:

allocating another block when said writing fills up the block, and

advancing said write pointer to said another block.

9. The method as in any one of claims 1-8, wherein the memory includes memory cells that each store one bit of data.

10. The method as in any one of claims 1-8, wherein the memory includes memory cells that each store more than one bit of data.

11. The method as in claim 6, further comprising:

providing an incrementing relocation pointer to indicate the writing location during a relocation operation to copy file data from one block to another block.

12. The method as in claim 6, further comprising:

advancing said write pointer to another block during a relocation operation to copy file data to said another block.

13. The method as in any one of claims 11-12, wherein the relocation operation occurs at predefined events including when a file or a portion thereof is deleted.

14. The method as in claim 13, wherein the memory includes memory cells that each store one bit of data.

15. The method as in claim 13, wherein the memory includes memory cells that each store more than one bit of data.

16. The method as in any one of claims 11-12, wherein the relocation operation occurs at predefined events including when a file or portion thereof is updated.

17. The method as in claim 16, wherein the memory includes memory cells that each store one bit of data.

18. The method as in claim 16, wherein the memory includes memory cells that each store more than one bit of data.

19. The method as in any one of claims 11-12, wherein the relocation operation occurs at predefined events including when the number of mixed blocks exceeds a predetermined number, the mixed block being one containing file data belonging to a data file and that of another data file.

20. The method as in claim 19, wherein the memory includes memory cells that each store one bit of data.

21. The method as in claim 19, wherein the memory includes memory cells that each store more than one bit of data.

22. The method as in claim 19, wherein the predetermined number of mixed blocks is two.

23. The method as in any one of claims 11-12, wherein the relocation operation occurs at predefined events including when the number of blocks containing obsolete data exceeds a predetermined number.

24. The method as in claim 23, wherein the memory includes memory cells that each store one bit of data.

25. The method as in claim 23, wherein the memory includes memory cells that each store more than one bit of data.