Memory Die Data Migration Using Overprovisioning Blocks
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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 employs 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 overprovisioning block usage across groups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a memory die is set to unusable state when failure occurs, then data integrity is protected, but user data accessibility is lost
Solution Approach 1:
The patent introduces overprovisioning blocks as intermediary storage resources that can receive migrated data from failed memory dies. These blocks act as a mediator between the failed storage capacity and the controller, enabling data recovery without directly accessing the unusable memory die
Solution Approach 2:
The patent implements data migration by creating copies of user data from failed memory dies to overprovisioning blocks. This copying mechanism allows the original data to be preserved in the unusable die while a functional copy is created in the overprovisioning area, enabling accessibility without compromising the original storage structure
2Reliability
If memory dies are grouped into multiple die groups, then performance variance is reduced, but device complexity increases
Solution Approach 1:
The patent divides the memory device into multiple die groups, where each group contains multiple memory dies. This segmentation allows independent management and migration operations on each group, reducing the impact of failures in one group on others while maintaining overall system performance consistency
Solution Approach 2:
The controller is designed with universal functionality to manage multiple die groups and perform migration operations across different groups. This multi-functional capability allows the same controller logic to handle various migration scenarios, reducing the need for separate management mechanisms for each group
3Ease of operation
If user data is migrated to overprovisioning blocks, then data accessibility is maintained, but storage capacity for new data is reduced
Solution Approach 1:
The patent dynamically changes the functional parameter of overprovisioning blocks from being exclusively spare capacity to being active storage for migrated data. This parameter change allows flexible allocation where overprovisioning blocks serve dual purposes: maintaining data accessibility while preserving the ability to reallocate them for new data storage when needed
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.