Memory System With Management of Memory Blocks That Directly Store Data Files

• US 20070033329A1
• Filed: 05/08/2006
• 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 7,581,057 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 16/1847 specifically adapted to static storage, e.g. adapted to flash memory or SSD
• 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 3/0605 by facilitating the interaction with a user or administrator
• CPC Class Codes: G06F 3/0608 Saving storage space on storage systems
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• CPC Class Codes: G06F 3/0652 Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators

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. A type of memory block is selected to receive additional data of a file that depends upon the types of blocks into which data of the file have already been written. Blocks containing data are selected for reclaiming any unused capacity therefrom by a process that selects blocks in order starting with those containing the least amount of valid data.

Claims

1. A reprogrammable non-volatile memory system, comprising:

blocks of non-volatile memory cells characterized by being erased prior to rewriting data therein, and

a controller operably connected with the memory cell blocks to cause data of individual files to be written into one or more memory cell blocks selected to maintain a number of blocks partially containing data of any one file below a preset limit.

2. The memory system of claim 1, wherein the controller further operates to assign one of a plurality of designated states to the individual files depending upon the number of memory cell blocks that are partially filled with data of the file.

3. The memory system of claim 1, wherein the controller further operates to assign a state to each file having data stored in the memory cell blocks, and to select a block in which data of a given file are to be stored based on the state of the given file.

4. The memory system of claim 3, wherein the controller further operates to assign a state to each file having data stored in the memory cell blocks that is based upon a number of blocks that are partially filled with data of the file.

5. The memory system of claim 4, wherein the controller further operates to assign a state to each file having data stored in the memory cell blocks that is additionally based upon a number of blocks partially filled with data of the file that also contain erased capacity in which data may be written.

6. The memory system of claim 4, wherein the controller further operates to assign a state to each file having data stored in the memory cell blocks that is additionally based upon a number of blocks partially filled with data of the file that also contain data of one or more other files.

7. A reprogrammable non-volatile memory system, comprising:

an array of non-volatile memory cells organized into blocks of memory cells that are simultaneously erasable, and

a controller operably connected with the memory array to assign a state to each file that is used to select a block in which data of a given file are stored, the states including those dependent upon a number of one or more blocks partially filled with data of the file, whether any such partially filled one or more blocks also contain data of another file and whether any such partially filled one or more blocks contain erased capacity in which additional data may be written.

8. The memory system of claim 7, wherein the controller further operates to select a block in which data of the given file are written that maintains a number of blocks partially containing data of the given file below a preset limit.