Irregular MetaBlock Wear Leveling and UGSD Recovery
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Solution Overview
Problem
The use of irregular MetaBlocks (IRMBs) in Solid-State Memory Devices (SSD) leads to performance issues due to unbalanced wear leveling between host and control pools, causing program-erase count (PEC) deviations and endurance challenges, especially during ungraceful shutdowns.
Innovation Solution
Implementing a controller that dynamically swaps blocks between host and control pools based on PEC thresholds to create irregular MetaBlocks, ensuring efficient wear leveling and recovery from ungraceful shutdowns by rearranging blocks within and across pools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If irregular MetaBlocks (IRMBs) are used in control blocks to ease FBB criteria, then manufacturing yield is improved, but program-erase count (PEC) deviation between host and control pools increases
Solution Approach 1:
The system dynamically creates and manages IRMBs based on real-time PEC differences between host and control pools. The controller monitors PEC thresholds and adaptively swaps blocks between pools, transforming the static IRMB structure into a dynamic wear-leveling mechanism that responds to actual wear conditions.
Solution Approach 2:
The invention changes the structural parameter of MetaBlocks by creating irregular MetaBlocks with varying numbers of blocks (e.g., 3-5 blocks per MetaBlock instead of uniform structure). This parameter variation allows flexible wear distribution while maintaining manufacturing yield benefits.
2Ease of manufacture
If IRMBs are used in control pools, then FBB tolerance is increased, but host block endurance deteriorates due to higher PEC
Solution Approach 1:
The controller implements a feedback mechanism that continuously monitors PEC values in both host and control pools. When PEC deviation exceeds a threshold, the system triggers block swapping operations to rebalance wear, ensuring host block endurance is maintained while preserving FBB tolerance benefits.
Solution Approach 2:
The system recovers worn blocks from the host pool by swapping them with fresher blocks from the control pool containing IRMBs. This allows the host pool to discard high-PEC blocks and recover endurance by utilizing the wear-absorbing capacity of IRMB-containing control blocks.
3Adaptability or versatility
If IRMBs are used in control blocks, then manufacturing flexibility is improved, but wear leveling balance deteriorates
Solution Approach 1:
The system transforms the static IRMB structure into a dynamic wear-leveling solution by implementing real-time monitoring and swapping operations. The controller adaptively manages IRMB distribution between host and control pools based on actual wear conditions, maintaining balance despite manufacturing flexibility variations.
4Stability of the object's composition
If blocks are swapped between host and control pools based on PEC thresholds, then wear leveling is improved, but device complexity increases
Solution Approach 1:
The system implements a self-service wear-leveling mechanism where the controller autonomously monitors PEC thresholds and performs block swapping operations without external intervention. This self-managing approach simplifies overall system complexity by embedding the intelligence directly in the controller rather than requiring external management.
Data Source
AI summary
The present disclosure generally relates to using irregular MetaBlocks (IRMBs) in both host and control pools. The IRMBs are used to ensure efficient wear leveling. Blocks in the control pool are swapped with blocks in the host pool upon exceeding a program-erase count (PEC) threshold. Additionally, the swapping algorithm for IRMBs can be used to ensure an efficient recovery from an ungraceful shutdown (UGSD) event.