Flash Memory Controller Data Retention Monitoring
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Solution Overview
Problem
3D flash memory designs suffer from data retention issues, where data quality deteriorates significantly after being written, leading to incorrect reading and potential data loss, necessitating a novel management method to address these problems.
Innovation Solution
A flash memory controller with a time-management circuit that monitors data retention by reading the last page of each block to obtain time information and arranges blocks with exceeded thresholds for garbage collection, effectively managing data retention by moving valid data to other blocks and erasing the remaining contents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If 3D flash memory design is used to increase capacity, then storage capacity is improved, but data retention deteriorates
Solution Approach 1:
The system performs preliminary actions by monitoring data retention status before actual data loss occurs. The controller reads time information from the last page of each block, compares it with current time, and proactively identifies blocks that will encounter data retention problems, allowing preventive garbage collection to be performed before data quality deteriorates significantly.
Solution Approach 2:
The system implements feedback mechanisms by continuously monitoring the data retention status of blocks through time information stored in the last page. The controller compares the stored time information with current time to determine retention status, and uses this feedback to dynamically adjust garbage collection operations, ensuring data integrity while managing storage resources efficiently.
2Reliability
If traditional monitoring methods are used, then data retention is monitored, but detection speed is slow
Solution Approach 1:
The system extracts only the critical time information from the last page of each block, rather than performing comprehensive block analysis. By focusing specifically on reading and comparing time stamps, the system achieves fast detection of data retention status without the overhead of full block verification, significantly improving detection speed while maintaining monitoring reliability.
3Measurement precision
If comprehensive block monitoring is performed, then data retention accuracy is improved, but system complexity increases
Solution Approach 1:
The system applies local quality by focusing monitoring efforts specifically on the last page of each block, where time information is stored. Rather than uniformly monitoring all pages or performing comprehensive block analysis, the system targets the specific location containing retention status information, achieving accurate monitoring with minimal complexity.
Data Source
AI summary
A flash memory controller includes a read only memory (ROM) and a microprocessor. The ROM is arranged to store a program code. The microprocessor is arranged to execute the program code to control access of a flash memory module. When executing the program code, the microprocessor is arranged to perform operations of: monitoring data retention state of one or more blocks in the flash memory module by reading a last page of the one or more blocks to obtain time information regarding the one or more blocks, which is generated by the flash memory controller; and arranging a specific block to a garbage collection process if time information obtained from the last page of the specific block exceeds a threshold.