Block Retirement Management for Temporary Memory Errors
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Solution Overview
Problem
Memory sub-systems face issues with premature block retirement due to temporary operational conditions, leading to data loss and unnecessary write-protect states, as existing error handling mechanisms fail to distinguish between temporary and permanent defects.
Innovation Solution
Implementing a block retirement management system that detects data loss, identifies behavioral criteria such as cross-temperature and P/E cycles, and adds blocks to a watch list for monitoring. Blocks are then subjected to stress tests to assess their health, allowing healthy blocks to remain operational while defective ones are retired.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing error handling mechanisms retire blocks upon detecting data loss, then data integrity is protected, but healthy blocks are prematurely retired due to temporary operational conditions
Solution Approach 1:
The system performs preliminary actions by adding blocks to a watch list before final retirement, and conducts stress tests to assess whether data loss is due to temporary or permanent conditions. This preliminary assessment prevents premature retirement of healthy blocks while maintaining data integrity protection.
Solution Approach 2:
The watch list serves as an intermediary mechanism between error detection and final block retirement. Blocks experiencing data loss are placed on the watch list for monitoring and stress testing, allowing the system to distinguish between temporary operational conditions and permanent defects before making retirement decisions.
2Reliability
If blocks are monitored with stress tests and watch lists, then premature retirement is prevented, but system complexity increases
Solution Approach 1:
The block management system is segmented into distinct operational states: healthy blocks, watch list blocks, and retired blocks. This segmentation allows the system to apply different management strategies to different block populations, improving assessment accuracy while organizing complexity into manageable segments.
Solution Approach 2:
The system changes the operational parameters of blocks by transitioning them between different states (healthy → watch list → retired) based on stress test results and error patterns. This parameter-based management enables nuanced differentiation between temporary and permanent block issues without requiring entirely new system architectures.
3Productivity
If blocks are added to watch list for monitoring, then healthy blocks remain operational, but time is required for stress testing and assessment
Solution Approach 1:
Blocks on the watch list continue to operate and serve their useful function during the stress testing and assessment period. The monitoring and stress tests are performed concurrently with normal block operation, ensuring continuous useful action while gathering necessary data for retirement decisions.
Solution Approach 2:
The system employs periodic stress tests and assessments for blocks on the watch list rather than immediate retirement or continuous monitoring. This periodic approach balances the need for thorough assessment with the desire to minimize time loss, conducting tests at intervals that allow blocks to remain operational when possible.
Data Source
AI summary
A processing device in a memory system detects a data loss occurrence in a block of a memory component. The processing device further designates the block as a quarantined block, performs a stress test on the block, and depending on whether the stress test on the block satisfies a testing criterion, either designates the block as usable by the memory component or retires the block of the memory component.