Dynamic Address Mapping for Nonvolatile Memory Wear Distribution
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Solution Overview
Problem
Existing memory systems face inefficiencies when accessing specific logical addresses, leading to concentrated wear on real addresses in nonvolatile memory, which can result in premature degradation and reduced performance.
Innovation Solution
A memory system with a controller that translates logical addresses to real addresses based on a dynamic mapping, adjusting the mapping based on the degree of wear to distribute access evenly and prevent concentrated wear, using a combination of volatile and nonvolatile RAM to manage and store wear information and address substitutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed correspondence relation between logical address and real address is used, then address translation is simple and fast, but concentrated access on specific logical address causes concentrated wear on specific real address leading to premature degradation
Solution Approach 1:
The patent implements dynamic address translation by changing the correspondence relation between logical addresses and real addresses based on wear degree. The controller dynamically adjusts the mapping table to redirect accesses from worn areas to less worn areas, transforming a static fixed mapping into a dynamic adaptive mapping that evolves with memory wear patterns.
Solution Approach 2:
The patent changes the parameter of address mapping by modifying the correspondence relation between logical and real addresses. When the wear degree of a real address exceeds a threshold, the system changes the mapping parameter to associate the logical address with a different real address, thereby redistributing wear evenly across the memory device.
2Reliability
If dynamic mapping adjustment based on wear degree is implemented, then wear distribution is improved and memory lifespan is extended, but address translation complexity increases
Solution Approach 1:
The patent introduces a mapping table as an intermediary structure between logical addresses and real addresses. This mapping table stores the correspondence relations and enables the controller to perform wear-based redirection without complex real-time calculations, simplifying the translation process while maintaining dynamic adaptability.
Solution Approach 2:
The system implements feedback by monitoring the wear degree of real addresses and using this information to adjust the mapping table. The controller reads wear information, compares it against thresholds, and modifies the correspondence relation accordingly, creating a closed-loop system that automatically adapts to wear patterns.
3Reliability
If wear information is stored in nonvolatile memory, then data persistence is ensured during power shutdowns, but additional memory resources are consumed
Solution Approach 1:
The patent makes the nonvolatile memory serve multiple functions: it stores both the mapping table for address translation and the wear degree information for monitoring. This multi-functionality eliminates the need for separate memory structures, reducing overall memory resource consumption while ensuring data persistence.
Solution Approach 2:
The patent merges the storage of mapping information and wear information into a single nonvolatile memory structure. By combining these functions, the system reduces the total memory footprint required while maintaining the ability to persist critical data across power cycles.
Data Source
AI summary
According to one embodiment, when the first command is received from a host, a controller translates a first address designated by a first command into a second address representing a real address of the nonvolatile memory based on a first mapping and accesses the translated second address of the nonvolatile memory. The controller determines whether or not the first mapping is changed based on a degree of wear of the nonvolatile memory and changes some of all the correspondence relations in a case where the first mapping is changed.