Method and system for dual mode access for storage devices

• US 8,209,516 B2
• Filed: 02/26/2010
• Issued: 06/26/2012
• Est. Priority Date: 12/21/2005
• Status: Active Grant

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Sandisk Technologies Incorporated (Western Digital Corporation)
• Inventors: Sinclair, Alan W.
• Primary Examiner(s): CHOE, YONG J
• Application Number:
  US12/714,237
• Publication Number:
  US 20100223308A1
• Time in Patent Office: 851 Days
• Field of Search: 711/102, 711/203, 711/E12.001, 707/831, 707/E17.01
• US Class Current: 711/203
• CPC Class Codes: G06F 3/0607 by facilitating the process of upgrading existing storage systems, e.g. for improving compatibility between host and storage device
• CPC Class Codes: G06F 3/0638 Organizing or formatting or addressing of data
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

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 system for reading data in a non-volatile mass storage device, comprising:

a direct data file storage segment that operates in a direct data file access mode allowing a host system to access data from the non-volatile mass storage device on a file-by-file basis; 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 file-by-file basis, wherein the logical interface includes a directory index, a file allocation table (“

FAT”

) index and a logical index created during a logical configuration mode.

2. The system of claim 1, wherein in the directory index a virtual logical address is assigned to each entry in a file directory.

3. The system of claim 1, wherein the logical index includes an entry for each file that is identified in a file directory and each entry specifies a virtual logical address space and a corresponding entry location in the file directory.

4. The system of claim 1, wherein the FAT index includes a list for each FAT sector and provides an entry number for each FAT sector number.

5. The system of claim 1, wherein during a logical read-only mode, entries relating to a directory sector are read from a file directory and modified by an entry from the directory index.

6. The system 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 a file directory with a file offset address obtained from entries in the logical index.

7. The system of claim 1, 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.

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

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 based protocol; 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, wherein the logical interface segment includes a directory index, a file allocation table (“

FAT”

) index and a logical index created during a logical configuration mode.

9. The system of claim 8, wherein in the directory index, a virtual logical address is assigned to each entry in a file directory.

10. The system of claim 8, wherein the logical index includes an entry for each file that is identified in a file directory and each entry specifies a virtual logical address space and a corresponding entry location in the file directory.

11. The system of claim 8, wherein the FAT index includes a list for each FAT sector and provides an entry number for each FAT sector number.

12. The system of claim 8, wherein entries relating to a directory sector are read from a file directory and modified by an entry from the directory index.

13. The system of claim 8, wherein 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 the logical index.

14. The system of claim 8, wherein entries relating to a FAT sector are updated based on entries in the FAT index, before being sent to the host system.