Memory Block Scan Criteria for Fast and Latent Read Disturb
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Solution Overview
Problem
Existing memory sub-systems face inefficiencies in managing read disturb, particularly due to the uniform application of scan thresholds that do not account for varying levels of read disturb degradation across memory blocks, leading to excessive resource usage and performance reduction.
Innovation Solution
A memory sub-system that maintains a read counter for each block, incrementing it based on read-to-read delay to accurately reflect the amount of degradation, thereby performing media management scans only when necessary, thus reducing unnecessary operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniform scan thresholds are applied to all memory blocks, then read disturb management is simplified, but excessive scans are performed leading to resource waste and performance reduction
Solution Approach 1:
The patent applies local quality by transitioning from uniform scan thresholds to block-specific dynamic thresholds. Each memory block receives a customized scan threshold based on its individual read disturb characteristics, which are determined by monitoring read counts and calculating degradation levels. This allows the system to perform scans only when necessary for each specific block, reducing unnecessary scans and improving overall system performance while maintaining data integrity.
2Reliability
If frequent scans are performed on all memory blocks, then read disturb degradation is detected earlier, but resource consumption increases and system performance decreases
Solution Approach 1:
The patent implements dynamics by introducing dynamic scan thresholds that adapt to each memory block's actual degradation state. Instead of using fixed or uniform thresholds, the system continuously monitors read counts, calculates read disturb degradation levels, and adjusts scan thresholds accordingly. This dynamic approach ensures scans are performed with appropriate frequency for each block's condition, detecting degradation accurately while minimizing unnecessary resource consumption.
Solution Approach 2:
The patent applies feedback by establishing a closed-loop monitoring system that tracks read counts for each memory block, calculates degradation levels based on read-to-read delays, and uses this information to dynamically adjust scan thresholds. This feedback mechanism ensures that scan operations are triggered only when actual degradation reaches critical levels, optimizing the balance between reliability and resource consumption.
3Productivity
If block-specific dynamic thresholds are used, then scan operations are optimized reducing resource waste, but system complexity and monitoring overhead increase
Solution Approach 1:
The patent applies segmentation by dividing the memory system into individual block-level monitoring units. Each memory block has its own read counter and degradation calculation mechanism, allowing independent threshold management. This segmentation enables the system to handle complexity at the block level rather than requiring complex global management, improving scan operation efficiency while distributing the monitoring overhead across manageable units.
Data Source
AI summary
A system may include a memory device comprising a plurality of memory blocks, and a processing device to, responsive to receiving a request to read a memory block from the memory device, determine a time difference between a current time and a timestamp associated with the memory block, determine whether the time difference satisfies a first threshold increment criterion, responsive to determining that the time difference satisfies the first threshold increment criterion, increment a read counter associated with the memory block by a first increment value associated with the first threshold increment criterion, determine that the read counter associated with the memory block satisfies a threshold scan criterion, and responsive to determining that the read counter satisfies the threshold scan criterion, perform a media scan with respect to the memory block.