Solid State Storage Read Table Management
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Solution Overview
Problem
Conventional solid state storage devices experience slower read speeds due to the fixed sequence of read voltage sets in the read table, which does not adapt to changing conditions such as temperature shifts and data retention over time, leading to increased error bits and longer decoding times.
Innovation Solution
A dynamic read table management method that divides read voltage sets into hot and cold groups, with the control circuit swapping these groups based on accumulative counts during a read table adjusting process, prioritizing read voltage sets with higher successful decoding probabilities to improve read speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a fixed sequence of read voltage sets is used in the read table, then the device structure remains simple, but the read speed decreases due to inability to adapt to changing conditions
Solution Approach 1:
The patent implements a dynamic read table management mechanism that automatically adjusts the sequence of read voltage sets based on accumulative read counts. The system transitions from a static fixed sequence to a dynamic adaptive sequence, where frequently used read voltage sets are prioritized in the sequence, thereby improving read speed without requiring complex external control systems.
Solution Approach 2:
The control circuit performs self-adjustment of the read voltage set sequence by monitoring accumulative read counts and automatically reordering the read table. This self-service mechanism eliminates the need for external intervention or complex control systems, achieving adaptive optimization while maintaining relatively simple device structure.
2Speed
If read voltage sets are reordered based on accumulative counts, then read speed improves, but the control logic becomes more complex
Solution Approach 1:
The system implements a feedback mechanism where the control circuit monitors accumulative read counts for each read voltage set and uses this information to dynamically adjust the read table sequence. This feedback loop enables automatic optimization of read speed based on actual usage patterns, with the control complexity confined to the existing control circuit's ability to track and reorder entries.
Solution Approach 2:
The patent changes the operational parameter of the read table from a fixed sequence to a dynamic sequence based on accumulative counts. By modifying the sequence parameter rather than the fundamental structure, the system improves read speed while keeping the control circuit's functional complexity within acceptable limits.
3Loss of time
If the read table adjusts sequence dynamically, then decoding time is reduced, but the adjustment process consumes additional time
Solution Approach 1:
The read table adjustment is performed periodically based on accumulative read counts rather than continuously. The control circuit monitors the count and triggers reordering only when threshold conditions are met, thereby reducing the frequency of adjustment operations and minimizing the time lost to reordering while still achieving significant reductions in decoding time.
Solution Approach 2:
The system performs preliminary ordering of read voltage sets based on accumulated usage data before actual read operations occur. By preparing the optimized sequence in advance based on historical data, the system minimizes the impact of adjustment time on actual decoding operations, as the reordering is based on patterns learned from previous operations.
Data Source
AI summary
A read table management method for a solid state storage device includes the following steps. If the lowest computation value in a hot group is lower than the highest computation value in a cold group when a read table adjusting process is enabled, a first read voltage set corresponding to the lowest computation value in the hot group and a second read voltage set corresponding to the highest computation value in the cold group are swapped with each other. Consequently, the second read voltage set becomes to belong to the hot group, and the first read voltage set becomes to belong to the cold group.