Reprogrammable Non-Volatile Memory Systems With Indexing of Directly Stored Data Files

• US 20070033374A1
• Filed: 07/21/2006
• Published: 02/08/2007
• Est. Priority Date: 08/03/2005
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: SanDisk Corporation (Western Digital Corporation)
• Inventors: Wright, Barry, Sinclair, Alan
• Granted Patent: US 7,669,003 B2
• Time in Patent Office: Days
• US Class Current: 711/203
• 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

Abstract

Host system data files are written directly to a large erase block flash memory system with a unique identification of each file and offsets of data within the file but without the use of any intermediate logical addresses or a virtual address space for the memory. Directory information of where the files are stored in the memory is maintained within the memory system by its controller, rather than by the host. Each data file is uniquely identified in a file directory, which points to entries in a file index table (FIT) of data groups that make up the file and their physical storage locations in the memory.

Claims

1. A memory system of non-volatile memory storage cells grouped into blocks of memory cells that are erased together prior to reprogramming with data, wherein:

data of files with unique file identifiers received from outside the memory system are stored in the memory blocks by their file identifiers, records of the physical block locations of data are maintained for the individual files,

a classification of the individual files is maintained as either (1) likely to be modified in the near future or (2) not likely to be modified in the near future, and

a directory of links to the records of the files are maintained by their unique file identifiers, the links being indirect for records of files classified as (1) and direct for records of files classified as (2).

2. The memory system of claim 1, further wherein a file is maintained in classification (1) while a host system to which the memory system is connected designates the individual file to be opened, and wherein a file is maintained in classification (2) while the host system to which the memory system is connected designates the individual file as closed.

3. The memory system of claim 1, further wherein the indirect link of a file includes an entry in the directory of an address of a first location in the memory that does not change as a second location containing the record of the file changes, the first location containing an address of the second location with any changes thereof, and wherein the direct link of a file includes an entry in the directory of an address of the second location.

4. The memory system of claim 1, further wherein records of files classified as (1) are maintained in individual pages within the memory blocks without records of other files therein, and wherein multiple records of files classified as (2) are maintained in individual pages within the memory blocks.

5. The memory system of claim 1, further wherein a number of records of files classified as (2) are grouped together in a first page of the memory blocks, and a number of links to those numbers of records are grouped together in a second page of the memory blocks forming the directory.

6. The memory system of claim 5, further wherein the number of records of files classified as (2) stored in the first page are limited to files whose links are stored in the second page.

7. A memory system of non-volatile memory storage cells grouped into blocks of memory cells that are erased together prior to reprogramming data into pages of the blocks, wherein:

data of files that individually have a unique file identifier are stored in a first plurality of pages,

records of the physical page locations of where data of the uniquely identified files are maintained in at least a second page, and

pointers to the locations of records in the at least a second page are maintained in at least a third page, wherein the records in the second page are limited to those of the files whose pointers are stored in the third page.

8. The memory system of claim 7, further wherein the first plurality of pages are located in a first group of one or more blocks, said at least a second page is located in a second group of one or more blocks, and said at least a third page is located in a third group of one or more blocks.

9. The memory system of claim 7, wherein the first plurality of pages are located in a first group of one or more blocks, and said at least a second page and said at least a third page are located in common blocks of a second group of one or more blocks.

10. The memory system of claim 7, wherein the first plurality of pages, said at least a second page and said at least a third page are located together in common blocks of a group of one or more blocks.