Storage Capacity Recovery Source Selection in Non-Volatile Memory
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Solution Overview
Problem
Traversing logical-to-physical mapping structures in non-volatile memory devices is time-consuming, especially when these structures are stored in multiple locations or in non-volatile memory, which slows down the operation of the device and hampers storage capacity recovery operations.
Innovation Solution
A system and method for selecting a source block for storage capacity recovery, where a controller maps logical addresses to physical addresses using a logical-to-physical mapping structure stored partially in volatile and partially in non-volatile memory, utilizing a hit count module to estimate the number of mappings likely stored in volatile memory and ranking blocks for garbage collection based on this hit count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the logical-to-physical mapping structure is stored in non-volatile memory, then data integrity is ensured, but the traversal time increases and device operation slows down
Solution Approach 1:
The mapping structure is segmented into two storage locations: volatile memory and non-volatile memory. Frequently accessed mapping entries are stored in volatile memory for fast traversal, while less frequently accessed entries are stored in non-volatile memory to ensure data integrity. This segmentation allows the system to balance between speed and reliability by accessing the appropriate storage medium based on access patterns.
2Ease of operation
If the mapping structure is stored in multiple locations, then data accessibility is improved, but the complexity of managing the mapping structure increases
Solution Approach 1:
The system performs preliminary actions by pre-loading frequently accessed mapping entries into volatile memory before they are needed. The controller monitors access patterns and proactively transfers mapping entries between storage locations, so that when a mapping operation is needed, the data is already in the optimal location, reducing actual operation complexity.
Solution Approach 2:
The system implements feedback mechanisms to track which mapping entries are frequently accessed and adjust the distribution of mapping data between volatile and non-volatile memory accordingly. This feedback-driven approach automatically optimizes the mapping structure management without requiring complex manual intervention.
3Productivity
If garbage collection is performed on blocks with low hit counts, then storage capacity recovery is achieved, but write amplification increases and performance decreases
Solution Approach 1:
The system performs preliminary actions by pre-identifying blocks with low hit counts (indicating few valid mappings) using the hit count module. By proactively selecting candidate blocks for garbage collection based on hit count thresholds, the system prepares a list of optimal blocks before actual garbage collection operations, ensuring that recovery operations target the most suitable blocks and minimize unnecessary data movement.
Data Source
AI summary
A non-volatile memory device includes a volatile memory, a non-volatile memory, and a controller. The controller is configured to map logical addresses for stored data to physical addresses of the stored data in the non-volatile memory using a logical-to-physical mapping structure stored partially in the volatile memory and at least partially in the non-volatile memory. The controller is configured to perform a storage capacity recovery operation for a region of the non-volatile memory that is selected based at least partially on a number of mappings for the region likely to be stored in the volatile memory for the storage capacity recovery operation.