NAND Flash Block Re-alignment to Minimize Read-Disturb Errors
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Solution Overview
Problem
NAND flash memory systems experience read disturb errors due to frequent read operations, leading to data corruption and increased write amplification, which reduces drive endurance and performance.
Innovation Solution
A method and system that identifies frequently accessed blocks and their neighboring blocks, re-aligning them to minimize read disturbance by moving the entire page to a new location when the disturbance threshold is exceeded, using a Flash Translation Layer with a READ access manager and location aligner to optimize block placement and reduce read-disturb errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If read operations are performed frequently on certain blocks, then data access speed is improved, but read-disturb errors increase in neighboring blocks
Solution Approach 1:
The patent segments the flash memory into multiple blocks and implements independent read-disturb monitoring for each block. By dividing the memory space and applying targeted refresh operations only to affected blocks rather than entire pages, the system maintains high read access speed while minimizing read-disturb errors in neighboring blocks through localized management.
2Reliability
If read-disturb errors are handled by re-writing blocks to new locations, then data integrity is improved, but write amplification increases
Solution Approach 1:
The patent applies local quality by implementing block-level rather than page-level refresh operations. When read-disturb errors are detected in specific blocks, only those affected blocks are re-written to new locations,而不是 refreshing entire pages. This localized approach maintains data integrity for disturbed blocks while significantly reducing unnecessary write operations and write amplification.
Solution Approach 2:
The system performs partial refresh actions only when and where needed. By monitoring read-disturb errors at the block level and applying refresh operations selectively to only those blocks that have exceeded disturbance thresholds, the patent avoids excessive full-page refreshes, thereby maintaining data integrity while minimizing write amplification.
3Reliability
If block refresh operations are performed frequently, then read-disturb errors are reduced, but I/O latency increases
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors read-disturb error rates at the block level. Refresh operations are triggered only when specific blocks exceed predetermined disturbance thresholds, rather than performing periodic full-page refreshes. This feedback-driven selective refreshing reduces read-disturb errors effectively while minimizing unnecessary refresh operations that would increase I/O latency.
Data Source
AI summary
An approach for reducing disturbed errors in a flash memory device is disclosed. The approach includes collecting information associated with one or more; determining one or more frequently accessed data blocks from the one or more blocks based on the collected information; determining one or more neighboring blocks from the one or more blocks based on the collected information; determining if the one or more neighboring blocks exceeds a disturbance threshold; and in responsive to the one or more neighboring blocks has exceeded the disturbance threshold, re-align the one or more blocks.