Flash Memory Address Space Partitioning for Multiple Overwrites
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Solution Overview
Problem
Flash memory devices face limitations in rewriting data due to the costly 'erase' operation, which restricts the number of times data can be rewritten, and often result in unused spare memory, as most changes are unpredictable, leading to inefficient memory management.
Innovation Solution
A method is introduced that partitions the address space into a main and a substitute space, using flags to mark locations as 'empty', 'in-use', or 'rejected', allowing for multiple overwrites without erasing, by generating paths in the substitute space that may share locations to avoid mapping conflicts and optimize memory usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the erase operation is used to update data in flash memory, then the data can be rewritten, but the operation is expensive in terms of time and affects large memory areas
Solution Approach 1:
The patent divides the address space into main space and substitute space, creating separate regions for active data storage and historical data. This segmentation allows the system to update data in the main space by copying to substitute locations rather than erasing entire blocks, thereby reducing update time while maintaining rewrite capability.
Solution Approach 2:
The patent implements a copying mechanism where data is copied from the main space to the substitute space during updates. This copying approach avoids the expensive erase operation by preserving existing data in the main space while creating new versions in the substitute space, thus reducing time loss during data updates.
2Ease of operation
If each physical location is mapped to one logical address only, then the memory management is straightforward, but the number of times data can be rewritten is limited
Solution Approach 1:
The patent introduces dynamic mapping where physical locations can be associated with multiple logical addresses through paths in the substitute space. This dynamic approach allows a single physical location to serve multiple logical addresses over time, increasing rewrite capability while maintaining manageable complexity through systematic path management.
Solution Approach 2:
The patent adds a dimensional aspect by introducing paths that connect main space addresses to substitute space locations. This creates a multi-dimensional address mapping system where data can be rewritten multiple times by transitioning through different paths and spaces, thereby increasing rewrite capability without complicating basic memory operations.
3Adaptability or versatility
If spare locations are provided for each logical address, then data can be rewritten multiple times, but the size of the spare array becomes twice as the original array
Solution Approach 1:
The patent makes the substitute space serve multiple functions: it stores historical data, enables rollback operations, and provides rewrite capability for multiple logical addresses. This multi-functionality reduces the need for separate spare arrays for each logical address, thereby reducing total memory capacity requirements while maintaining strong rewrite capability.
Solution Approach 2:
The patent merges the spare storage function with the historical data storage function in the substitute space. Instead of having separate spare arrays for each logical address, the system combines all rewrite operations into a unified substitute space structure, reducing overall memory capacity requirements while enabling multiple rewrites.
4Adaptability or versatility
If paths in substitute space are generated for each address, then multiple overwrites are enabled, but locations may be shared causing mapping conflicts
Solution Approach 1:
The patent implements feedback mechanisms to track and manage path usage in the substitute space. By monitoring which locations are accessed by which paths, the system can resolve conflicts and optimize future path generation, thereby enabling multiple overwrites while managing mapping complexity through intelligent feedback-driven management.
Data Source
AI summary
According to the present disclosure is provided a device and method for mapping management in a flash memory based on partitioning the memory to a main address space and a substitute space, each partition comprising locations in the memory that are denoted by at least three statues according to which locations are mapped from the main space to the substitute space while responsively modifying the statuses.