Flash Memory Copy-Back ECC Without Clean-Sector Flag Bits
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Solution Overview
Problem
Existing semiconductor memory devices face challenges in maintaining data integrity during copy-back operations in SSDs and flash memory devices, particularly due to variations in sector states within a page, which can lead to errors in error correction coding (ECC) processes without the use of flag bits.
Innovation Solution
A storage device and method that perform ECC operations on vectors corresponding to clean sectors and used sectors without relying on flag bits, using an ECC unit and an inverter to detect and handle 'all ones' vectors, allowing for error correction coding on clean sectors by inverting logical values and preventing coding on sectors with all logical '1's.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ECC operation is performed on all vectors in read data during copy-back operation, then data integrity is improved, but operational complexity increases due to handling various sector states
Solution Approach 1:
The patent segments the read data into multiple vectors, where each vector corresponds to a specific sector. The ECC operation is performed independently on each vector based on its sector state. This segmentation allows the system to handle different sector states (clean or used) individually, improving data integrity for used sectors while avoiding unnecessary operations on clean sectors, thus reducing overall operational complexity.
2Productivity
If flag bits are used to identify clean sectors, then ECC operation efficiency is improved, but device structure complexity increases
Solution Approach 1:
The patent employs a self-service mechanism where the ECC unit autonomously determines whether a vector corresponds to a clean sector by examining the data characteristics directly, without requiring external flag bits. The ECC unit performs ECC operations only on vectors that do not represent clean sectors, automatically adapting to the sector state based on the data itself. This eliminates the need for additional flag bit structures while maintaining high ECC operation efficiency.
Data Source
AI summary
A storage device includes a non-volatile memory device outputting read data from a source area and a memory controller configured to execute an ECC operation on a plurality of vectors in the read data and to write the error-corrected read data into target area of the non-volatile memory device. The memory controller declares that a vector corresponding to a clean area is decoding pass without using a flag bit among the plurality of vectors during the error correction operation.