SSD Parity Mode Switching for QLC Data Retention
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Solution Overview
Problem
Portable SSDs with Quad-Level Cell (QLC) technology face high read errors and reduced data retention reliability due to inactivity, as firmware policies like Patrol Read and Random Interval Neighbor Check become less effective when powered off for extended periods, and data retention is compromised.
Innovation Solution
A method and device that dynamically adjust Write Amplification Factor (WAF) and fill factor thresholds based on current parity mode values to optimize data storage, increasing parity size and reducing errors by dynamically selecting higher parity modes when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If QLC technology is used to increase storage capacity, then storage density is improved, but data retention reliability deteriorates
Solution Approach 1:
The patent dynamically changes the code rate parameter based on storage fill factor and write amplification factor. When fill factor exceeds a threshold or WAF indicates high write activity, the system transitions from lower code rate (higher capacity) to higher code rate (lower capacity but higher reliability), thereby maintaining data retention reliability while utilizing QLC technology's high storage capacity
2Use of energy by moving object
If the storage device is powered off for extended periods to save energy, then energy consumption is reduced, but error correction effectiveness deteriorates
Solution Approach 1:
The patent applies preliminary action by proactively increasing the code rate (adding more parity bits) before data degradation occurs during extended idle periods. By detecting high write amplification factors or high fill factors that precede potential data retention issues, the system preemptively enhances error correction capability, ensuring data integrity even when the device remains powered off for long periods without patrol read operations
3Reliability
If higher parity mode is used to reduce read errors, then data retention reliability is improved, but storage efficiency deteriorates
Solution Approach 1:
The patent implements dynamics by making the code rate adjustable and adaptive rather than fixed. The system continuously monitors fill factor and write amplification factor, and dynamically adjusts the code rate accordingly. This allows the storage device to optimize between reliability and efficiency in real-time, using higher parity modes only when necessary based on actual data conditions and write patterns
Data Source
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AI summary
The present disclosure provides storage device and method for writing data in the storage device. The method for writing data in a storage device includes determining, by the storage device, a Write Amplification Factor (WAF) value and a fill factor value associated with the storage device in response to a write request, fetching, by the storage device, a current parity mode value of the storage device, determining, by the storage device, a WAF threshold and a fill factor threshold associated with the current parity mode value, determining, by the storage device, whether to change the current parity mode value to a higher parity mode value of a plurality of parity mode values based on the WAF threshold, the WAF value, the fill factor threshold, and the fill factor value, and writing, by the storage device, data in a storage area of the storage device based on results of the determining.