NVM Metadata ECC Framing for Low-Overhead Sector Protection
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Solution Overview
Problem
Current non-volatile memory (NVM) devices lack a simple, reliable, and cost-effective method to protect metadata of erase sectors, which are crucial for the proper operation of the device.
Innovation Solution
Implementing a systematic error-correction code (ECC) to encode metadata bits and redundant bits, using dummy bits to form a code word, and storing only the redundant bits in the erase sector, allowing for strong protection with minimal additional memory usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional metadata storage without ECC is used, then area cost is low, but reliability of metadata protection is poor
Solution Approach 1:
The patent segments the metadata protection by dividing metadata into multiple groups, where each group is protected by its own ECC code. This segmentation allows targeted protection of critical metadata portions without requiring ECC for all metadata, thereby improving reliability where needed while controlling area overhead.
Solution Approach 2:
The patent changes the parameter of ECC code strength applied to metadata by using different ECC code rates for different metadata groups. Critical metadata receives stronger protection with lower code rates, while less critical metadata uses higher code rates, optimizing the balance between reliability and area cost.
2Reliability
If full ECC protection is applied to all metadata, then metadata protection reliability is strong, but area overhead increases
Solution Approach 1:
The patent divides metadata into multiple groups and applies ECC selectively to each group based on its criticality. This segmentation enables the system to achieve strong protection for essential metadata while avoiding the area overhead of applying full ECC to all metadata uniformly.
Solution Approach 2:
The patent applies partial ECC action by protecting only the most critical portions of metadata with full ECC strength, while using reduced or no ECC for less critical metadata. This partial approach achieves sufficient reliability for system operation without the excessive area overhead of complete ECC coverage.
Data Source
AI summary
A method of operating a non-volatile memory (NVM) device includes: reading, by a memory controller of the NVM device, first metadata bits and first redundant bits stored in an erase sector of a memory cell array of the NVM device, where the first redundant bits are generated using an error-correction code (ECC) for protection of the first metadata bits; and performing an ECC decoding process for the first metadata bits, which includes: forming a first data frame by filling the first data frame with the first metadata bits, a first number of dummy bits, and the first redundant bits; computing, by the memory controller, a syndrome vector for the first data frame in accordance with the error-correction code; and in response to determining that the syndrome vector comprises a non-zero element, performing, by the memory controller, error correction for the first data frame to obtain decoded first metadata bits.