Method and system for dual mode access for storage devices

• US 7,627,733 B2
• Filed: 08/03/2005
• Issued: 12/01/2009
• 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.
• Primary Examiner(s): Thai; Tuan V
• Assistant Examiner(s): CHOE, YONG J
• Application Number:
  US11/196,168
• Publication Number:
  US 20070033373A1
• Time in Patent Office: 1,581 Days
• Field of Search: 711/203, 711/103, 711/209, 707/1, 707/104.1, 365/232
• US Class Current: 711/203
• CPC Class Codes: G06F 3/0613 in relation to throughput
• 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: Y10S 707/99931 Database or file accessing
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing

Abstract

A method and system for reading data from a non-volatile mass storage device is provided. The method includes, performing logical configuration for the non-volatile mass storage device, wherein file data is allocated addresses in a virtual logical address space; and data identified by virtual logical addresses is read by a host system. The system includes a file storage segment that reads and writes data on a file-by-file basis, allowing a host system to access data from the non-volatile mass storage device using a file interface format; and a logical interface segment that allows the host system to access data using logical addressing, wherein the host system is unaware of a storage format under which data is stored on a file-by-file basis.

Claims

1. A method for reading data from a non-volatile mass storage device, comprising:

operating a non-volatile mass storage device in a direct data file storage (DFS) mode where a host system sends a file identifier and an offset address to a direct data file interface of the non-volatile mass storage device and wherein the non-volatile mass storage device generates a file directory and a file index table;

when the non-volatile mass storage device detects that it is inserted into a legacy host system, operating the non-volatile mass storage device in a logical configuration mode by performing a logical configuration for the non-volatile mass storage device, wherein the logical configuration is performed by a memory controller of the non-volatile mass storage device and during the logical configuration a logical index is created by the memory controller, where the logical index includes an entry for each file that is identified in the file directory, which is maintained by the memory controller; and

each entry specifies an address for a file identified in the file directory within a virtual logical address space for the non-volatile mass storage device maintained by the memory controller, and a corresponding entry location in the file directory; and

operating the non-volatile mass storage device such that data identified by the virtual logical address is read by the host system.

2. The method of claim 1, wherein during a logical read-only mode, entries relating to a logical sector address from the host system is converted to an entry address in the file directory with a file offset address obtained from the entries in the logical index.

3. The method of claim 2, wherein sector data is read via a direct data file storage manager.

4. The method of claim 1, wherein during the logical configuration, a file allocation table (“

FAT”

) index is created which includes a list for each FAT sector and provides an entry number for each FAT sector number.

5. The method of claim 4, wherein during the logical read only mode, entries relating to a FAT sector are updated based on entries in the FAT index, before being sent to the host system.

6. The method of claim 1, wherein the host system is unaware of a storage format which allows data to be stored on a file-by-file basis by the non-volatile mass storage device.

7. A method for reading data from a non-volatile mass storage device that stores data on a file-by-file basis, comprising:

operating a non-volatile mass storage device in a direct data file storage (DFS) mode where a host system sends a file identifier and an offset address to a direct data file interface of the non-volatile mass storage device and wherein the non-volatile mass storage device generates a file directory and a file index table;

when the non-volatile mass storage device detects that it is inserted into a legacy host system, operating the non-volatile mass storage device in a logical configuration mode by performing a logical configuration for the non-volatile mass storage device, wherein the logical configuration is performed by a memory controller of the non-volatile mass storage device and during the logical configuration, addresses in a virtual logical address space maintained by the memory controller are allocated for files identified in the file directory and

reading the file data from the non-volatile mass storage device via the logical interface by identifying the file data to be read from the non-volatile mass storage device to the non-volatile mass storage device using the addresses in the virtual logical address space.

8. The method of claim 7, wherein during a logical read-only mode, entries relating to a logical sector address from the host system is converted to an entry address in a file directory with a file offset address obtained from entries in a logical index table.

9. The method of claim 8, wherein sector data is read via a direct data file storage manager.

10. The method of claim 7, wherein during a logical configuration, a file allocation table (“

FAT”

) index is created which includes a list for each FAT sector and provides an entry number for each FAT sector number.

11. The method of claim 10, wherein during a logical read-only mode, entries relating to a FAT sector are updated based on entries in the FAT index, before being sent to the host system.

12. The method of claim 7, wherein the host system is unaware of a storage format under which data is stored on a file-by-file basis by the non-volatile storage device.