Memory Die Data Migration via Overprovisioning After Failure
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Solution Overview
Problem
Existing storage devices face challenges in accessing user data stored in memory dies that are in an unusable state and experience performance variance between memory die groups due to failures.
Innovation Solution
The storage device groups memory dies into multiple die groups and utilizes a controller to migrate user data from unusable memory dies to overprovisioning blocks within the same or different die groups, using flash translation layers to manage data migration and balance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a memory die is set to unusable state when failure occurs, then data security is protected, but user data accessibility is lost
Solution Approach 1:
The patent introduces overprovisioning blocks as intermediary storage regions that receive migrated data from failed memory dies. These blocks act as a mediator between the failed die and the system, allowing data to be accessed through a different physical location while maintaining the original logical address mapping via FTL updates.
Solution Approach 2:
The patent creates a copy of user data from the failed memory die to overprovisioning blocks through a migration process. The FTL maintains mapping information that redirects access from the original failed location to the copied data in the overprovisioning blocks, enabling continued data accessibility.
2Speed
If data is migrated to overprovisioning blocks in the same die group, then access speed is maintained, but performance variance between die groups increases
Solution Approach 1:
The patent applies local quality by allowing different migration strategies for different scenarios: data can be migrated to overprovisioning blocks within the same die group for speed-critical applications, or to different die groups for load balancing. The FTL manages which strategy to apply based on performance requirements and current system state.
Solution Approach 2:
The patent implements dynamic performance balancing where the system can adaptively choose migration targets based on current die group performance characteristics. The FTL monitors and adjusts data placement to maintain balanced performance across die groups while preserving fast access paths where possible.
3Stability of the object's composition
If multiple FTL instances are used to control different die groups, then performance balance is improved, but device complexity increases
Solution Approach 1:
The patent segments the FTL control function into multiple independent FTL instances, with each instance managing a specific die group. This segmentation allows parallel operation and independent optimization of each die group's performance while simplifying the control logic within each instance compared to a monolithic FTL managing all dies.
Data Source
AI summary
A storage device may group a plurality of memory dies into M memory die groups, and migrate, when a first memory die in a first memory die group among the M memory die groups is determined to be in an unusable state, user data stored in user data blocks of the first memory die to a first overprovisioning block group. The first overprovisioning block group may include overprovisioning blocks of memory dies other than the first memory die among the memory dies in the first memory die group.