Power-Off Monitoring for Relaxed Memory Block Retirement
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Solution Overview
Problem
Conventional memory sub-system controllers fail to distinguish between blocks that have deteriorated due to physical media failure and those that have suffered charge loss from data retention stress during power-off periods, leading to unnecessary retirement of potentially reusable blocks, which reduces drive capacity and lifespan.
Innovation Solution
Implementing a power-off monitor that determines total power-off time and compares it to a configurable threshold, allowing the memory sub-system to enter a relaxed block retirement mode, where blocks meeting certain retirement criteria are not retired if the power-off time exceeds the threshold, enabling reformatting and reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional block retirement criteria are applied without power-off time consideration, then data retention reliability is improved, but drive capacity and lifespan deteriorate due to unnecessary retirement of good blocks
Solution Approach 1:
The patent changes the retirement decision parameter by introducing power-off time as a conditional factor. When power-off time exceeds a threshold, the system transitions from strict retirement criteria to relaxed criteria, allowing blocks that would normally be retired due to charge loss to be preserved and reused, thus maintaining drive capacity while accepting controlled data retention risk
Solution Approach 2:
The block retirement policy is made dynamic rather than static. The system adapts the retirement criteria based on the power-off time condition, switching between normal and relaxed modes. This dynamic adjustment allows the system to optimize between reliability and capacity based on actual operating conditions
2Reliability
If conventional block retirement criteria are applied without power-off time consideration, then data retention reliability is improved, but memory sub-system lifespan deteriorates
Solution Approach 1:
By introducing power-off time as a conditional parameter, the system modifies the retirement decision logic. Blocks experiencing charge loss due to long power-off periods are preserved when the power-off time exceeds the threshold, preventing premature retirement and extending the usable lifespan of the memory sub-system
Solution Approach 2:
The retirement policy dynamically adjusts based on power-off time conditions. During normal operation, strict criteria ensure reliability, but after prolonged power-off periods, relaxed criteria prevent unnecessary block retirement, thereby extending overall system lifespan
3Reliability
If blocks are retired based on charge loss from power-off periods, then data retention reliability is improved, but system resources deteriorate due to loss of usable blocks
Solution Approach 1:
The system changes the retirement parameter by incorporating power-off time threshold comparison. When the power-off time exceeds the threshold, the retirement decision is overridden, preserving blocks that would otherwise be retired due to charge loss, thus reducing loss of usable blocks while maintaining acceptable reliability
Solution Approach 2:
The retirement mechanism dynamically responds to power-off time conditions. Instead of uniformly retiring blocks after charge loss, the system selectively preserves blocks when power-off time exceeds the threshold, optimizing the balance between reliability and resource utilization
Data Source
AI summary
A processing device in a memory sub-system determines a total power-off time of a memory sub-system and identifies a configurable power-off time threshold for the memory sub-system. The processing device determines whether the total power-off time satisfies a threshold criterion based on the configurable power-off time threshold, responsive to determining that the total power-off time satisfies the threshold criterion, causes the memory sub-system to enter a relaxed block retirement mode of operation.