Memory Controller Preventing Copy-Involving Write in NAND Flash
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Solution Overview
Problem
The existing memory systems using NAND flash memory face inefficiencies in file write operations due to the need for 'copy-involving write' processes, which increase overhead and decrease speed, especially as memory capacity increases, when using FAT file systems for managing data.
Innovation Solution
Implementing a memory system with a nonvolatile memory formatted by an additional-write type file system and a memory controller that transmits a write protect error when instructed to write data at or below the address of previously written data, allowing only additional-write operations to prevent data overwrite and maintain high-speed writes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If FAT file system is used to manage NAND flash memory, then data can be managed in clusters with random write capability, but copy-involving write operations increase overhead and decrease write speed
Solution Approach 1:
The patent inverts the conventional FAT file system approach by implementing an additional-write only file system where data can only be written to new clusters rather than overwritten. This reversal of the write paradigm eliminates the need for copy-involving write operations while maintaining cluster-based data management, thereby resolving the contradiction between random write capability and write speed
2Measurement precision
If FAT file system updates management data each time file data is updated, then data allocation can be tracked accurately, but frequent updates cause repeated copy-involving write operations
Solution Approach 1:
The patent extracts the management data update function from the data write operation. By using an additional-write only file system, the system separates file data writes (which no longer trigger management data updates) from management operations, eliminating the causal link between file updates and repeated copy-involving write operations while maintaining allocation tracking
3Quantity of substance
If memory capacity of NAND flash memory increases, then storage capability improves, but block size increases causing longer copy-involving write process time
Solution Approach 1:
The patent applies the inversion principle to the write operation paradigm, transforming it from overwrite-type to additional-write only. This fundamental reversal eliminates copy-involving write operations entirely, so the increasing block size associated with larger memory capacity no longer causes increased copy process time, as copying is no longer required
Data Source
AI summary
A memory system includes a nonvolatile memory including a memory space of logical addresses which is formatted from outside by an additional-write type file system, and a memory controller controlling the nonvolatile memory, the memory controller transmitting n error to the outside of the system if the memory controller is instructed to write data in a logical address which is equal to or smaller than a logical address of previously written data in an address area of the memory space. The memory controller controls the logical address and a physical address of the nonvolatile memory, and in conjunction with the additional-write type file system makes it possible to avoid “copy-involving write” each time file data in the nonvolatile memory is updated, thereby to promote high-speed operation by prevention of decrease in file update speed.