Data operations in flash memories utilizing direct data file storage

• US 7,590,794 B2
• Filed: 08/02/2006
• Issued: 09/15/2009
• 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: Sinclair, Alan W., Wright, Barry
• Primary Examiner(s): Sough; Hyung S
• Assistant Examiner(s): Ahmed; Hamdy S
• Application Number:
  US11/462,007
• Publication Number:
  US 20070033377A1
• Time in Patent Office: 1,140 Days
• Field of Search: 711/103, 711/104
• 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.

Claims

1. A method of operating a re-programmable non-volatile memory system having a plurality of blocks of memory cells that are individually erased prior to data being written therein, wherein said memory system receives data having logical addresses of unique file identifiers and offsets within the individual files and uses said unique file identifiers and offsets for logically addressing the data in said individual files, by means of a directory of the memory system for locating said individual files, when data of a first file are stored in at least first and second blocks with the second block being only partially filled with data of the first file and a remaining portion of the second block being erased, and wherein, in response to data of the first file being relocated from the first block, valid data of the first file is copied from the first block into the erased portion of the second block, whereby said valid data are not copied into a totally erased block, so that more of the data in the first file is stored in the second block after the copying than before the copying.

2. The method of claim 1, wherein data of a second file are also stored in the first block prior to copying data of the first file from the first block.

3. The method of claim 1, wherein data of the first file are stored as a plurality of data groups that individually have both contiguous logical offset addresses and contiguous physical addresses of data within the group.

4. A method of operation of a re-programmable non-volatile memory system having a plurality of blocks of memory cells that are individually erased prior to data being written therein, wherein said memory system receives data as individual files having logical addresses of unique file identifiers and offsets of data within the individual files, said method comprising:

the memory system using a unique file identifier and offset for logically addressing the data of a file, by means of a directory of the memory system for locating said file,

writing data of said file to successive pages of one or more erased blocks, and

in a case where data of the file are written to only a portion of the pages of one of the one or more erased blocks and then closed, a garbage collection operation is performed immediately on the one block in response to receipt of a command after the file is closed only if, in addition, at least some of the data of the file stored in the one block are obsolete.

5. The method of claim 4, wherein writing data of the file includes writing a plurality of data groups that individually have both contiguous logical offset addresses and contiguous physical addresses of data within the group.

6. A method of operating a re-programmable non-volatile memory system having a plurality of blocks of memory cells that are individually erased prior to data being written therein, wherein said memory system receives data having logical addresses of unique file identifiers and offsets within the individual files, said method comprising:

the memory system using a unique file identifier and offset for logically addressing the data of a given file, by means of a directory of the memory system for locating said given file,

storing data of said given file in a first block,

writing newly received data of the given file into a second block, and

performing garbage collection of the given file by copying data of the given file from the first block into the second block, so that more of the data in the given file is stored in the second block after the copying than before the copying.

7. The method of claim 6, additionally comprising maintaining a record of storage locations of the given file within the memory system as a plurality of data groups that individually have both contiguous logical offset addresses and contiguous physical addresses of data within the group.