Read Scrub Counters With CVD Time Tags for Read Disturb Detection
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Solution Overview
Problem
Current non-volatile data storage devices face challenges in detecting and correcting read disturb errors due to the random selection of memory blocks for read scrub operations, leading to a low probability of identifying and correcting impacted memory blocks.
Innovation Solution
Implementing a read scrub management system that utilizes Cell Voltage threshold Distribution (CVD) time tags with associated read scrub counters, incrementing the counters with each memory block access, and initiating a read scrub operation when the counter exceeds a threshold, thereby targeting groups of memory blocks with similar operating parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If random read scrub operations are implemented, then read disturb errors can be detected and corrected, but the probability of detecting and correcting impacted memory blocks is low
Solution Approach 1:
The patent applies preliminary action by incrementing read scrub counters each time memory blocks are accessed, tracking the number of reads before a scrub operation is needed. This pre-tracking mechanism identifies memory blocks that have been accessed frequently and are therefore more likely to have read disturb errors, allowing the system to prioritize scrub operations on high-risk blocks rather than using random selection.
Solution Approach 2:
The patent changes the parameter selection criterion from random selection to counter-value-based selection. Memory blocks are selected for read scrub operations based on their read scrub counter values, which reflect their access history and susceptibility to read disturb. This parameter change transforms the selection mechanism from stochastic to deterministic based on measured usage patterns.
2Reliability
If multiple time tags with read scrub counters are implemented, then the probability of detecting read disturb errors increases, but the device complexity increases
Solution Approach 1:
The patent segments the memory block management system by introducing time tags that group memory blocks with similar operating parameters and access patterns. Each time tag maintains its own read scrub counter, allowing independent tracking and scrub operation initiation for each segment. This segmentation enables targeted error detection in high-risk segments without requiring comprehensive monitoring of all memory blocks, balancing reliability improvement with manageable complexity.
Data Source
AI summary
A read scrub management system of a data storage device maintains and updates information associated with one or more Cell Voltage threshold Distribution (CVD) time tags. Each time tag is associated with one or more memory blocks and includes information about operating parameters associated with the memory blocks. Each time tag also includes its own read scrub counter. The read scrub management system increments the read scrub counter associated with a particular time tag each time one or more memory blocks associated with the particular time tag are accessed. When the read scrub counter reaches or exceeds a threshold value, the read scrub management system initiates a read scrub operation on the memory block(s) associated with the particular time tag.