Dynamic Storage Media Remapping via Forward and Reverse Translation
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Solution Overview
Problem
In non-volatile memory systems, the reduction in physical isolation between storage elements leads to defects such as high read and write error rates due to disturb coupling, where thermal effects propagate and affect surrounding storage elements, necessitating active management of coupling effects to maintain data reliability.
Innovation Solution
The implementation of a remapping technique that identifies and remaps defective storage elements to spare locations while minimizing the introduction of new disturb relationships, using a subslice element status map and substitution data structure to perform forward and reverse translations, allowing for dynamic management of error rates and maintain data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If storage elements are forced closer together to achieve smaller products, then product size is reduced, but physical isolation between storage elements decreases leading to increased disturb coupling and error rates
Solution Approach 1:
The memory space is segmented into multiple regions with different remapping policies. The system divides the address space into zones that can be independently managed, allowing defective regions to be isolated and remapped without affecting the entire memory space. This segmentation enables selective remapping of only the problematic storage elements while preserving the rest of the memory system.
Solution Approach 2:
The patent introduces an intermediary remapping layer between the physical storage elements and the logical address space. This intermediary mechanism translates logical addresses to physical addresses dynamically, allowing defective physical locations to be mapped to alternative healthy locations. The remapping table acts as a mediator that decouples the logical memory interface from the physical defects, maintaining data reliability despite reduced physical isolation.
2Reliability
If remapping is performed to relocate defective storage elements, then error rates are reduced, but the complexity of identifying neighbors and remediation cost increases
Solution Approach 1:
The patent applies local quality by implementing remapping policies that are specific to different regions of the memory space. Instead of uniform remapping, the system identifies local defect patterns and applies targeted remapping strategies to affected regions only. This allows the system to maintain simple neighbor identification for the majority of memory space while providing enhanced remapping capabilities only where needed, thus reducing overall complexity.
Solution Approach 2:
The system performs preliminary characterization of the memory space to identify defective regions and pre-compute remapping tables before normal operation begins. By performing the complex neighbor identification and remapping strategy development in advance, the system avoids the need for complex real-time calculations during normal memory operations. The remapping infrastructure is prepared beforehand, allowing simple address translation during actual memory access.
3Object-affected harmful factors
If thermal isolation is increased through substrate choices or physical segregation, then disturb coupling is reduced, but manufacturing cost and complexity increase
Solution Approach 1:
The patent replaces physical/thermal isolation mechanisms with a logical/software-based remapping system. Instead of modifying the physical substrate or increasing physical segregation between storage elements (which would increase manufacturing cost and complexity), the system uses address translation and remapping algorithms to mitigate the effects of thermal disturb coupling. This substitution of mechanical/physical solutions with information-processing solutions maintains manufacturing simplicity while achieving the desired reduction in disturb coupling effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces error rates by remapping defective elements to spare locations, maintaining data reliability and minimizing the introduction of new disturb relationships, thus enhancing the performance and longevity of non-volatile memory systems.
Implementation Method 1
For media that use a thermal process to encode the state of the storage element, such as phase change media, thermal effects propagate to surrounding storage elements.
Data Source
AI summary
Remapping portions of a memory system having a plurality of non-volatile memory dice. A processing device performs a first error analysis of subslice elements to identify a first group of a predetermined number of subslice elements having highest error rates. The processing device determines which of the subslice elements are user subslice elements and remaps user subslice elements of the first group to spare subslice elements to remove subslice elements having the highest rates from a user space of the memory system. The processing device performs a second error analysis to identify a second group of subslice elements having the highest error rates and identifies user subslice elements of the first group that is/are not in the second group. For an identified user subslice element or elements of the first group not in the second group, the processing device reverses the remapping to reinstate removed subslice element(s) back into the user space.