System and method for storing first and second files in a memory device

• US 6,697,928 B2
• Filed: 09/23/2002
• Issued: 02/24/2004
• Est. Priority Date: 09/15/2000
• Status: Expired due to Term

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Matrix Semiconductor, Inc. (Western Digital Corporation)
• Inventors: Moore, Christopher S., Brown, Daniel T., March, Roger W.
• Primary Examiner(s): PORTKA, GARY J
• Application Number:
  US10/253,163
• Publication Number:
  US 20030023821A1
• Time in Patent Office: 519 Days
• Field of Search: 711/101, 711/102, 711/103, 711/170, 711/171, 711/173, 707/205, 707/206
• US Class Current: 711/171
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G06F 3/08 from or to individual record carriers, e.g. punched card , memory card, integrated circuit [IC] card or smart card
• CPC Class Codes: G11C 17/00 Read-only memories programmable only once; Semi-permanent stores, e.g. manually-replaceable information cards
• CPC Class Codes: Y10S 707/99934 Query formulation, input preparation, or translation
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99956 File allocation

Abstract

The preferred embodiments described herein provide a memory device and methods for use therewith. In one preferred embodiment, a method is presented for using a file system to dynamically respond to variability in an indicated minimum number of memory cells of first and second write-once memory devices. In another preferred embodiment, a method for overwriting data in a memory device is described in which an error code is disregarded after a destructive pattern is written. In yet another preferred embodiment, a method is presented in which, after a block of memory has been allocated for a file to be stored in a memory device, available lines in that block are determined. Another preferred embodiment relates to reserving at least one memory cell in a memory device for file structures or file system structures. A memory device is also provided in which file system structures of at least two file systems are stored in the same memory partition. Additionally, methods for permanently preventing modification of data stored in a memory device and for identifying memory cells storing data are disclosed.

Claims

1. A method for storing first and second files in a memory device, the method comprising:

(a) connecting a memory device to a data storage device, wherein the memory device comprises a memory array that is logically organized into a plurality of blocks, each block comprising a plurality of lines, and wherein the data storage device comprises a file system;

(b) allocating a set of blocks for a first file;

(c) storing the first file in the set of blocks, wherein the first file only partially fills one of the blocks;

(d) determining a set of available lines in the block that is partially filled with the first file; and

(e) storing a second file in the set of available lines of the block that is only partially filled with the first file;

wherein (b) and (d) are performed by the file system in the data storage device and not by a component in the memory device.

2. The method of claim 1, wherein a line comprises a minimum number of memory cells that can be written into the memory array.

3. The method of claim 1 further comprising storing the first and second files in a memory cache prior to storing them in the memory array.

4. The method of claim 1, wherein the set of available lines stores only part of the second file, and wherein the method further comprises:

(f) allocating a second set of blocks for the second file; and

(g) storing the remainder of the second file in the second set of blocks;

wherein (f) is performed by the file system in the data storage device and not by a component in the memory device.

5. The method of claim 1, wherein the memory array comprises a write-once memory array.

6. The method of claim 1, wherein the memory array comprises a three-dimensional write-once memory array.

7. A method for storing first and second files in a memory device, the method comprising:

(a) connecting a memory device to a data storage device, wherein the data storage device comprises a file system;

(b) allocating a block for a first file in a memory cache, the block comprising a plurality of lines;

(c) storing the first file in the block, wherein the first file only partially fills the block;

(d) determining a set of available lines in the block;

(e) storing a second file in the set of available lines of the block;

(f) over-writing at least one of the first and second files with a third file; and

(g) storing the block in the memory device;

wherein (b) and (d) are performed by the file system in the data storage device and not by a component in the memory device.

8. The method of claim 7, wherein the memory array comprises a write-once memory array.

9. The method of claim 7, wherein the memory array comprises a three-dimensional write-once memory array.

10. A system for storing first and second files, the system comprising:

a memory device comprising a memory array logically organized into a plurality of blocks, each block comprising a plurality of lines; and

a data storage device operative to connect to the memory device, wherein the data storage device comprises a file system comprising;

an allocator operative to allocate a set of blocks for a first file; and

a micro-allocator operative to determine a set of available lines in the block if the first file partially fills one of the allocated blocks;

wherein the allocator and micro-allocator are located in the file system in the data storage device and not in a component in the memory device.

11. The system of claim 10, wherein a line comprises a minimum number of memory cells that can be written into the memory array.

12. The system of claim 10, wherein the file system is operative to store the first and second files in a memory cache prior to storing them in the memory array.

13. The system of claim 10, wherein the memory array comprises a write-once memory array.

14. The system of claim 10, wherein the memory array comprises a three-dimensional write-once memory array.