Storage Device History Read Table Voltage Adjustment
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Solution Overview
Problem
Storage devices face challenges in reliably reading data from memory blocks due to variations in read voltage levels, leading to read failures and errors, which are not effectively addressed by existing technologies.
Innovation Solution
A storage device with a history read table that includes root bit information, read voltage information, and error bit information for each memory block, allowing for read retry operations with adjusted voltages and updating the table based on successful read retry operations to improve data retrieval accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read voltage level is adjusted to improve data reading reliability, then read failure rate decreases, but system complexity increases due to voltage adjustment mechanisms and history read table management
Solution Approach 1:
The system performs preliminary actions by maintaining a history read table that stores root bit information, read voltage information, and error bit information for each memory block before read operations occur. When a read failure happens, the system uses the pre-stored voltage information to quickly adjust the read voltage without complex real-time analysis, thereby improving reliability while keeping the complexity manageable through advance preparation.
Solution Approach 2:
The system implements feedback by comparing root bit information from failed read operations with the history read table, and by monitoring error bit counts. Based on this feedback, the system determines whether to update the history read table and adjust read voltage levels for retry operations. This closed-loop feedback mechanism ensures reliable data reading while maintaining controlled system complexity through systematic decision-making.
2Measurement precision
If read retry operation is performed with changed voltage, then data retrieval accuracy improves, but operation time increases
Solution Approach 1:
The system performs preliminary actions by pre-calculating and storing optimal read voltage levels in the history read table based on root bit information and error patterns. When a read retry is needed, the system directly applies the pre-determined voltage adjustment from the table rather than performing complex real-time voltage optimization, thereby improving data retrieval accuracy while minimizing the time penalty of the retry operation.
Solution Approach 2:
The system changes parameters by adjusting the read voltage level based on stored voltage information and error bit counts from previous operations. The memory controller modifies the read voltage parameter systematically according to the history read table data, enabling accurate data retrieval on retry while keeping the parameter adjustment process efficient and time-bound through predefined voltage levels.
3Reliability
If history read table is updated frequently to maintain accurate voltage information, then read operation reliability improves, but memory access overhead increases
Solution Approach 1:
The system uses feedback control by comparing root bit information from current read operations with the stored root bit information in the history read table. Updates to the history read table are performed selectively based on this comparison and error bit count thresholds, rather than on every read operation. This feedback-based selective updating maintains high read operation reliability while minimizing unnecessary memory access overhead by updating only when actual changes in memory block characteristics are detected.
Data Source
AI summary
A storage device includes a memory device and a memory controller. The memory device stores a history read table including root bit information, read voltage information, and error bit information on each of a plurality of memory blocks, and performs a read operation of reading data stored in the plurality of memory blocks based on the history read table. When the read operation fails, a memory controller changes a level of a read voltage, and controls the memory device to perform a read retry operation of retrying the read operation by using the changed read voltage. When the read retry operation passes, the memory controller determines whether the history read table is to be updated by comparing the root bit information of the read retry operation with the root bit information of the history read table.