Faster write operations to nonvolatile memory using FSInfo sector manipulation

• US 8,171,203 B2
• Filed: 12/19/2003
• Issued: 05/01/2012
• Est. Priority Date: 07/31/1995
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Estakhri, Petro, Nemazie, Sam
• Primary Examiner(s): Savla, Arpan P.
• Application Number:
  US10/741,129
• Publication Number:
  US 20050055497A1
• Time in Patent Office: 3,056 Days
• Field of Search: 711/103, 711/165, 711/170, 711/203, 365/185.33
• 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 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 3/0613 in relation to throughput
• 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
• CPC Class Codes: G11C 8/12 Group selection circuits, e.g. for memory block selection, chip selection, array selection

Abstract

An embodiment of the present invention includes a digital equipment system having a host for sending write commands to write files having sector information and having a controller device responsive to the commands for writing and updating FSInfo sector information. The controller controls a nonvolatile memory system organized into blocks, each block including a plurality of sector locations for storing sector information, a particular free block, designated for storing FSInfo sector information. Upon updating of the FSInfo sector, the updated FSInfo sector information is written to a next free sector of the dedicated block thereby avoiding moving the sectors of the particular block to another block, hence, improving system performance.

Claims

1. A method of operating a nonvolatile memory unit having nonvolatile memory storage locations organized into blocks of nonvolatile memory cells, each block having one or more physical sectors of nonvolatile storage locations that are represented by one or more logical sectors, the method comprising:

designating one or more blocks of nonvolatile memory cells for storing only information corresponding to user system data that is frequently accessed;

counting a number of times a physical sector is accessed by a write command and storing the number of access times in an overhead information portion of a logical sector representative of the physical sector;

designating a logical sector corresponding to user system data as containing user system data that is frequently accessed if the stored number of access times for that designated logical sector indicates that the designated logical sector is being accessed more frequently than other sectors;

writing updated information of the designated logical sector corresponding to user system data that is frequently accessed only to a free physical sector of one of the designated blocks of nonvolatile memory cells until the one of the designated blocks is filled; and

writing updated information of a logical sector corresponding to user system data that is not designated as frequently accessed only to a free physical sector of a block of nonvolatile memory cells other than the blocks designated for storing only information corresponding to user system data that is frequently accessed.

2. The method of claim 1, further comprising:

upon filling all of the physical sectors of a designated block, designating a next block only for storing information corresponding user system data that is frequently accessed.

3. The method of claim 2, further comprising:

deeming the filled designated block as old; and

erasing the old designated block after writing information to the next designated block.

4. The method of claim 1, wherein designating one or more blocks for storing information corresponding to user system data that is frequently accessed comprises designating one or more blocks for storing information corresponding to user system data that is frequently accessed and for storing information corresponding to file system data.

5. The method of claim 4, further comprising:

writing information corresponding to file system data to a free physical sector of one of the designated blocks.

6. The method of claim 5, wherein writing information corresponding to file system data or user system data that is frequently accessed only to one of the designated blocks comprises writing such information to a single designated block until that designated block is filled, and writing such information to a next designated block upon filling a prior designated block.

7. The method of claim 5, wherein writing information corresponding to file system data or user system data that is frequently accessed only to one of the designated blocks comprises writing information corresponding to file system data to a first one of the designated blocks and writing information corresponding to user system data that is frequently accessed to a second one of the designated blocks.

8. The method of claim 1, wherein designating a logical sector corresponding to user system data as containing user system data that is frequently accessed if a number of access times for that logical sector exceeds a threshold value comprises designating a logical sector corresponding to user system data as containing user system data that is frequently accessed if a number of access times for that logical sector relative to a number of access times for other logical sectors exceeds a threshold value.

9. The method of claim 1, wherein counting a number of times a logical sector is accessed comprises counting within a controller that is configured to direct the writing of the information to the blocks.

10. The method of claim 1, wherein writing information of a logical sector to a free physical sector of a block comprises also writing to the free physical sector a value of the number of access times for that logical sector.

11. A method for operating a nonvolatile memory unit, the method comprising:

designating a memory block of the nonvolatile memory unit for storing only information corresponding to frequently accessed system data;

counting a number of access times a sector of the nonvolatile memory unit is accessed by a write command and storing the number of access times in an overhead information portion of the sector;

designating a first sector of the designated memory block as containing the frequently accessed system data if the stored number of access times for the first sector indicates that the first sector is being accessed more frequently than other sectors of the nonvolatile memory unit;

writing updated information of the first sector corresponding to the frequently accessed system data to only a free sector of the designated memory block until the designated memory block is filled; and

writing updated information of other sectors of the nonvolatile memory unit corresponding to user system data that is not designated as frequently accessed to only a free sector of a memory block of the nonvolatile memory unit other than the designated memory block.

12. The method of claim 11 wherein designating a first sector of the designated memory block as containing frequently accessed system data further comprises designating a first sector by determining if the stored number of access times exceeds a threshold value stored in a controller that is coupled to the blocks of nonvolatile memory cells.

13. The method of claim 12 wherein determining the designated sector corresponding to system data as containing the frequently accessed system data if the stored access count for the first designated sector indicates that the first designated sector is being accessed more frequently than other sectors of the memory unit is performed by the controller determining a number of times a sector is accessed relative to other sectors of the memory unit.