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NAND flash-based storage device and methods of using

  • US 9,298,603 B2
  • Filed: 11/15/2012
  • Issued: 03/29/2016
  • Est. Priority Date: 09/09/2011
  • Status: Active Grant
First Claim
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1. A NAND flash memory-based solid state drive comprising:

  • at least one NAND flash memory component that is organized in blocks, pages and cells and defines a memory space partitioned into at least an overprovisioning pool and a user memory pool for host writes and permanent storage, respectively, a first number of the blocks being dynamically assigned to the overprovisioning pool and at least one bit per cell is stored in the first number of the blocks using only a first mode of operation, and data being consolidated in a second number of the blocks that are dynamically assigned to the user memory pool and two or more bits per cell are stored in the second number of the blocks using only a second mode of operation; and

    means for dynamically cycling the first and second numbers of the blocks between the overprovisioning pool and the user memory pool on demand and based on wear history thereof;

    wherein the first mode of operation entails programming fewer bits of a cell in fewer passes as compared to the second mode of operation, and all data written by a host computer to the at least one NAND flash memory component are written to the overprovisioning pool using the first mode.

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