Storage Controller Voltage Selection for 3D NAND Read Errors
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Solution Overview
Problem
Conventional data reading methods for rewritable non-volatile memory modules, such as 3D NAND flash memory, are inefficient due to high read error rates and require multiple attempts to find an optimized reading voltage set, leading to reduced data-accessing speed and efficiency.
Innovation Solution
A data reading method that identifies a target physical unit in a rewritable non-volatile memory module by using a storage controller to select an optimized reading voltage set based on the program erase cycle value, last write timestamp, and last read timestamp, allowing for direct data retrieval with improved accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive approach is used to adjust the reading voltage set after read failure occurs, then the reading voltage set can be optimized, but the data-reading efficiency is seriously affected and data-accessing speed is reduced
Solution Approach 1:
The patent applies preliminary action by proactively searching for and determining the optimized reading voltage set before actual data reading operations. The storage controller identifies physical unit information including program erase cycle values and timestamp data, then determines the optimal reading voltage set in advance based on this information, so that when reading operations are needed, the optimized voltage is already ready and can be applied immediately without causing read failures or requiring multiple retry attempts.
2Reliability
If multiple reading attempts are made to find the optimized reading voltage set, then the reading voltage can be optimized, but the reading operation is carried out for a number of times which reduces data-accessing speed
Solution Approach 1:
The patent determines the optimized reading voltage set in advance by analyzing physical unit information such as program erase cycle values and timestamp data, so that the optimal voltage is identified before actual data reading operations. This preliminary determination eliminates the need for multiple retry reading attempts, allowing the storage system to directly use the pre-determined optimized voltage set for subsequent reading operations, thereby maintaining both high reliability and fast data accessing speed.
3Reliability
If the rewritable non-volatile memory module is a 3D NAND flash memory module and reads data after a time period, then the read error rate is high causing read errors, but actively searching for optimized reading voltage set before reading can reduce the read error rate
Solution Approach 1:
The patent applies preliminary action by using the storage controller to proactively search for and determine the optimized reading voltage set before actual data reading operations on 3D NAND flash memory. The controller analyzes physical unit information including program erase cycle values and timestamp data to identify the optimal reading voltage in advance. This preliminary determination ensures that when data is read after storage periods, the correct optimized voltage is already available, preventing read errors that would otherwise occur due to voltage drift or degradation over time.
4Productivity
If a predetermined reading voltage set is used without active optimization, then the reading operation is simple and fast, but the read error rate increases and read data cannot be corrected
Solution Approach 1:
The patent applies self-service by enabling the storage controller to automatically and actively search for the optimized reading voltage set based on physical unit information such as program erase cycle values and timestamp data. The system serves itself by autonomously determining the optimal reading voltage without requiring external intervention or manual adjustment. This self-service mechanism ensures that the storage system continuously adapts to changing conditions and maintains high reading reliability while preserving fast reading operation speeds.
Data Source
AI summary
A data reading method for a rewritable non-volatile memory module is provided. The method includes receiving a reading command from a host system; identifying a target physical unit of the rewritable non-volatile memory module according to the reading command, and identifying a program erase cycle value, a first timestamp, a second timestamp of the target physical unit, wherein the first timestamp records a time at which the target physical unit is programmed last, and the second timestamp records a time at which the target physical unit is read last; and selecting a target reading voltage set among a plurality of reading voltage set according to the program erase cycle value, the first timestamp, the second timestamp, so as to read a target data from the target physical unit.