Non-Volatile Memory Controller Cross-Channel Access Management
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Solution Overview
Problem
As non-volatile memory sizes increase, the complexity and memory requirements of mapping tables for cross-channel accessing areas become a burden, leading to inefficiencies in data storage and retrieval, particularly in devices with limited RAM.
Innovation Solution
A simplified management system using three tables - a first table to mark substitution needs, a second table to store substitution information, and a third table for substitute storage unit indications - is implemented to efficiently manage cross-channel accessing areas, avoiding the use of damaged storage units and reducing RAM requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mapping table is used to manage cross-channel accessing areas, then damaged storage units can be avoided, but the table size increases as non-volatile memory size increases, becoming a burden on RAM resources
Solution Approach 1:
The patent divides the mapping table into multiple separate tables: a first table storing only cross-channel accessing area information, a second table storing substitution information, and a third table storing substitute storage unit indications. This segmentation reduces the size of each individual table that must be held in RAM while maintaining the complete mapping functionality.
Solution Approach 2:
The patent extracts only the essential cross-channel accessing area information into the first table, separating it from the complete mapping information. This allows the first table to be kept small and stored in RAM, while the larger second and third tables can be stored in the non-volatile memory itself, reducing RAM burden.
2Speed
If a complete mapping table is stored in RAM, then fast access is achieved, but devices with limited RAM cannot accommodate large mapping tables
Solution Approach 1:
By segmenting the mapping information into multiple tables with different purposes, the patent enables the critical first table to be stored in RAM for fast access, while the larger second and third tables are stored in non-volatile memory, making the system compatible with devices having limited RAM.
Solution Approach 2:
The patent performs preliminary processing to identify and mark only the cross-channel accessing areas in the first table during initialization. This allows the controller to quickly determine whether substitution is needed without having to search through the entire mapping table in RAM, improving access speed while minimizing RAM usage.
3Reliability
If substitution information is stored for all storage units, then complete substitution management is achieved, but the table size increases unnecessarily for storage units without substitution needs
Solution Approach 1:
The patent applies local quality by making the first table selective - it only contains entries for cross-channel accessing areas that actually need substitution management. Storage units without substitution needs are not included in the first table, reducing its size and simplifying the overall structure while maintaining complete substitution management where needed.
Solution Approach 2:
Instead of storing complete mapping information for all storage units in the first table, the patent uses partial action by storing only the essential cross-channel accessing area information. The complete substitution management is achieved through the combination of all three tables, with the first table containing only the necessary subset for quick reference.
Data Source
AI summary
Multi-channel accessing of non-volatile memory. A controller uses three kinds of tables to manage cross-channel accessing areas and, accordingly, to access the non-volatile memory through multiple channels. Each cross-channel accessing area includes M storage units, where M is an integer greater than 1. For each cross-channel accessing area, the first table marks whether there is a need for storage unit substitution and points to substitution information. The substitution information is stored in the second table and the third table. For each cross-channel accessing area marked in the first table, the second table stores M bits corresponding to M storage units of the marked cross-channel accessing area for substitution indication, and related substitute storage unit indication is stored in the third table.