Memory system storing transformed units of data in fixed sized storage blocks

• US 7,814,262 B2
• Filed: 10/13/2005
• Issued: 10/12/2010
• Est. Priority Date: 10/13/2005
• 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): Peugh; Brian R
• Assistant Examiner(s): CYGIEL, GARY W
• Application Number:
  US11/250,794
• Publication Number:
  US 20070088904A1
• Time in Patent Office: 1,825 Days
• Field of Search: None
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/401 Compressed data
• CPC Class Codes: G06F 3/061 Improving I/O performance
• 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]

Abstract

A change in the amount of data to be stored that results from various encoding, compression, encryption or other data transformation algorithms, is handled by individually identifying distinct units of the transformed data and storing such units in physical succession within storage blocks of a memory system such as flash memory. The data being stored may come from a host system external to the memory system or from an application running on a processor within the memory system.

Claims

1. A non-volatile memory system, comprising:

a flash memory divided into individual blocks of data storage elements, the individual blocks containing a minimum number of storage elements that are erased together prior to writing data therein, wherein each of said individual blocks stores up to a given amount of data, and

a controller connected with the flash memory and including a microprocessor operated by firmware, wherein the controller operates to divide data received by the flash memory into equal sized individual units of data, said units of data having contiguous logical addresses within a continuous logical address range, and wherein the controller operates to transform said individual units of data into corresponding groups of data in a manner that changes the amount of data in at least some of the units so that the groups of data corresponding to said at least some units contain amounts of data different than that in said at least some units, and to store the groups of data in the blocks of storage elements, each of said units containing an amount of data equal to or less than said given amount of data, and wherein the controller identifies storage locations by physical addresses of data groups having physical boundaries coincident with logical boundaries of the groups, some of the groups being stored entirely within individual blocks of storage elements and others of the groups being stored as separate sub-groups in two different blocks of storage elements with boundaries thereof within blocks of storage elements, the groups and sub-groups being stored contiguously within the individual blocks of storage elements and the sub-groups containing an amount of data less than said given amount, wherein the controller further maintains a central table with entries for the individual groups and sub-groups of data that include the physical addresses thereof.

2. The memory system of claim 1, wherein the controller further operates to maintain the central table with physical addresses of the sub-groups separate and distinct from the physical addresses of the groups of data.

3. The memory system of claim 1, wherein the controller further operates to transform the received data by at least one of encoding, compressing or encrypting the data.

4. The memory system of claim 3, wherein the controller further operates to transform the received data in a manner that reduces the amount of data that existed prior to the transformation.

5. The memory system of claim 3, wherein the controller further operates to transform the received data in a manner that increases the amount of data that existed prior to the transformation.

6. The memory system of claim 1, wherein the controller further operates to transform data received within distinct units of logical addresses that contain equal amounts of data.

7. The memory system of claim 1, wherein the data received by the controller that are transformed originate outside of the memory system.

8. The memory system of claim 1, wherein the data received by the controller that are transformed originate with an application being executed by the controller.

9. The memory system of claim 1, wherein the storage elements include electrically conductive floating gates.

10. The memory system of claim 1, wherein the controller additionally includes a circuit dedicated to perform at least a portion of the transformation of the received data.

11. The memory system of claim 1, wherein the controller further operates to store more than one bit of data in individual ones of the storage elements.

12. The memory system of claim 1, wherein the controller additionally operates to divide a logical address range of the data received by the memory system into a plurality of distinct units of continuous logical addresses, the distinct units individually capable of storing an amount of data equal to or less than said given amount of data.

13. The memory system of claim 1, wherein the controller divides received data into said distinct units, said distinct units being of equal size, each of said distinct units individually containing an amount of data equal to or less than a storage capacity of the individual blocks of storage elements, the data within each of said distinct units having contiguous logical addresses within a logical address range.

14. The memory system of claim 1, wherein one of said blocks of storage elements stores a first data group, such one block having storage capacity available for data in addition to the first data group, the controller storing a sub-group of a second data group distinct from the first data group in such block.