Direct logical block addressing flash memory mass storage architecture

• US 7,523,249 B1
• Filed: 06/24/2005
• Issued: 04/21/2009
• Est. Priority Date: 07/31/1995
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Lexar Media Incorporated (Micron Technology, Inc.)
• Inventors: Estakhri, Petro, Assar, Mahmud
• Primary Examiner(s): Verbrugge; Kevin
• Assistant Examiner(s): CARDWELL, ERIC
• Application Number:
  US11/165,864
• Time in Patent Office: 1,397 Days
• Field of Search: None
• US Class Current: 711/103
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: G06F 12/023 Free address space management
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/08 Address circuits; Decoders; Word-line control circuits
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators
• CPC Class Codes: G11C 29/765 in solid state disks
• CPC Class Codes: G11C 29/82 for EEPROMs

Abstract

A nonvolatile semiconductor mass storage system and architecture can be substituted for a rotating hard disk. The system and architecture avoid an erase cycle each time information stored in the mass storage is changed. Erase cycles are avoided by programming an altered data file into an empty mass storage block rather than over itself as a hard disk would. Periodically, the mass storage will need to be cleaned up. These advantages are achieved through the use of several flags, and a map to correlate a logical block address of a block to a physical address of that block. In particular, flags are provided for defective blocks, used blocks, and old versions of a block. An array of volatile memory is addressable according to the logical address and stores the physical address.

Claims

1. A storage device having nonvolatile memory coupled to a host, said nonvolatile memory for storing information, the host for generating a plurality of logical block addresses for use in storing or reading information in and from the nonvolatile memory, the storage device comprising:

a volatile memory device having a plurality of volatile memory locations each of which is uniquely addressable by one of the logical block addresses, and wherein each of the volatile memory locations is configured to store a physical block address without requiring the storage of a corresponding logical block address;

one or more nonvolatile memory devices, coupled to the volatile memory, each of said one or more nonvolatile memory devices being organized into a plurality of nonvolatile data blocks, wherein each block is selectively programmable and erasable and further wherein each block is uniquely addressable by one of the physical block addresses; and

means for receiving a block of data to be stored in the one or more nonvolatile memory devices, for receiving a target logical block address, for identifying a free particular block within the nonvolatile blocks having no data stored therein, and for storing the physical block address of the particular block in the volatile memory location that corresponds to the target logical block address;

wherein the storage device is adapted to copy information stored in the one or more nonvolatile memory devices which correlate to the physical block addresses of the plurality of nonvolatile data blocks to the volatile memory locations during power-up.

2. The storage device of claim 1, wherein the information copied during power-up comprises information flags and logical block addresses which correlate to the physical block addresses of the nonvolatile data blocks.

3. The storage device of claim 2, wherein the storage device is further adapted to copy the information flags to the volatile memory locations before copying the logical block addresses to the volatile memory locations.

4. The storage device of claim 2, wherein the information flags comprise a flag for indicating whether or not the data block contains data that has been superseded, a flag for indicating whether or not a data block contains valid data, and a flag for indicating whether or not the block is defective.

5. The storage device of claim 1, wherein the means for receiving a block of data to be stored in the one or more nonvolatile memory devices, for receiving a target logical block address, for identifying a free particular block within the nonvolatile blocks having no data stored therein, and for storing the physical block address of the particular block in the volatile memory location that corresponds to the target logical block address is further adapted for storing the block of data in the particular block and for setting an information flag indicating that the particular block is no longer free.

6. The storage device of claim 1, wherein the information stored in the one or more nonvolatile memory devices and correlating to the physical block addresses of the plurality of nonvolatile data blocks is updated during use of the storage device.

7. The storage device of claim 1, wherein the storage device is further adapted to copy the information stored in the one or more nonvolatile memory devices which correlate to the physical block addresses of the plurality of nonvolatile data blocks to the volatile memory locations during a system reset.

8. The storage device of claim 1, further comprising means for addressing one of the plurality of volatile memory locations using a desired logical block addresses, means for retrieving a physical block address stored in the volatile memory location that corresponds to the desired logical block address and means for reading a data block within the nonvolatile memory devices identified by the retrieved physical block address.

9. The storage device of claim 1, further comprising means for coupling the data block read from the nonvolatile memory device to the host.

10. The storage device of claim 1, wherein the target logical block address is stored in the corresponding block of the one or more nonvolatile memory devices.

11. The storage device of claim 1, wherein the volatile memory device comprises a random access memory (RAM) type of memory.

12. The storage device of claim 1, wherein the one or more nonvolatile memory devices comprise flash memory devices.

13. The storage device of claim 1, wherein the volatile memory device is located externally to the means for identifying a free particular block within the nonvolatile blocks having no data stored therein.

14. The storage device of claim 1, wherein the volatile memory device is resident within the means for identifying a free particular block within the nonvolatile blocks having no data stored therein.

15. A storage device having nonvolatile memory coupled to a host, said nonvolatile memory for storing information, the host for generating a plurality of logical block addresses for use in storing or reading information in and from the nonvolatile memory, the storage device comprising:

a volatile memory device having a plurality of volatile memory locations each of which is uniquely addressable by one of the logical block addresses, and wherein each of the volatile memory locations is configured to store a physical block address without requiring the storage of a corresponding logical block address;

one or more nonvolatile memory devices, coupled to the volatile memory, each of said one or more nonvolatile memory devices being organized into a plurality of nonvolatile data blocks, wherein each block is selectively programmable and erasable and further wherein each block is uniquely addressable by one of the physical block addresses; and

means for receiving a block of data to be stored in the one or more nonvolatile memory devices, for receiving a target logical block address, for identifying a free particular block within the nonvolatile blocks having no data stored therein, for storing the physical block address of the particular block in the volatile memory location that corresponds to the target logical block address, for storing the block of data in the particular block and for setting an information flag indicating that the particular block is no longer free;

wherein the storage device is adapted to copy information flags and logical block addresses stored in the one or more nonvolatile memory devices which correlate to the physical block addresses of the plurality of nonvolatile data blocks to the volatile memory locations during power-up.

16. The storage device of claim 15, wherein the storage device is further adapted to copy the information flags to the volatile memory locations before copying the logical block addresses to the volatile memory locations.

17. The storage device of claim 15, wherein the information flags comprise a flag for indicating whether or not the data block contains data that has been superseded, a flag for indicating whether or not a data block contains valid data, and a flag for indicating whether or not the block is defective.

18. The storage device of claim 15, wherein the storage device is further adapted to copy the information flags and logical block addresses stored in the one or more nonvolatile memory devices which correlate to the physical block addresses of the plurality of nonvolatile data blocks to the volatile memory locations during a system reset.

19. The storage device of claim 15, further comprising means for addressing one of the plurality of volatile memory locations using a desired logical block addresses, means for retrieving a physical block address stored in the volatile memory location that corresponds to the desired logical block address and means for reading a data block within the nonvolatile memory devices identified by the retrieved physical block address.

20. A storage device having nonvolatile memory coupled to a host, said nonvolatile memory for storing information, the host for generating a plurality of logical block addresses for use in storing or reading information in and from the nonvolatile memory, the storage device comprising:

a volatile memory device having a plurality of volatile memory locations each of which is uniquely addressable by one of the logical block addresses, and wherein each of the volatile memory locations is configured to store a physical block address without requiring the storage of a corresponding logical block address;

one or more nonvolatile memory devices, coupled to the volatile memory, each of said one or more nonvolatile memory devices being organized into a plurality of nonvolatile data blocks, wherein each block is selectively programmable and erasable and further wherein each block is uniquely addressable by one of the physical block addresses; and

means for receiving a block of data to be stored in the one or more nonvolatile memory devices, for receiving a target logical block address, for identifying a free particular block within the nonvolatile blocks having no data stored therein, for storing the physical block address of the particular block in the volatile memory location that corresponds to the target logical block address, for storing the block of data in the particular block and for setting an information flag indicating that the particular block is no longer free;

wherein the storage device is adapted to copy information flags and logical block addresses stored in the one or more nonvolatile memory devices which correlate to the physical block addresses of the plurality of nonvolatile data blocks to the volatile memory locations during power-up;

wherein the storage device is further adapted to copy the information flags to the volatile memory locations before copying the logical block addresses to the volatile memory locations; and

wherein the information flags comprise a flag for indicating whether or not the data block contains data that has been superseded, a flag for indicating whether or not a data block contains valid data, and a flag for indicating whether or not the block is defective.

21. The storage device of claim 20, wherein the storage device is further adapted to copy the information flags and logical block addresses stored in the one or more nonvolatile memory devices which correlate to the physical block addresses of the plurality of nonvolatile data blocks to the volatile memory locations during a system reset.

22. The storage device of claim 20, further comprising means for addressing one of the plurality of volatile memory locations using a desired logical block addresses, means for retrieving a physical block address stored in the volatile memory location that corresponds to the desired logical block address and means for reading a data block within the nonvolatile memory devices identified by the retrieved physical block address.