Memory Controller Page-Specific Operation Method Selection
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Solution Overview
Problem
Memory systems with non-volatile semiconductor storage devices face variations in operating performance due to differences in write operation speeds across pages, making it challenging to achieve consistent performance indices like storage capacity and transfer speed.
Innovation Solution
A memory system that includes a non-volatile memory and a memory controller, which selects between different operation methods (such as SLC, MLC, TLC, or QLC) for each page based on pre-measured write operation speeds, using a management table to assign specific operation methods to pages with varying speeds to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single operation method is used for all pages, then device complexity is reduced, but variations in write operation speed across pages increase
Solution Approach 1:
The memory system segments pages into different groups based on their write operation speeds. A management table divides pages into first pages (slower speed) and second pages (faster speed), allowing different operation methods to be applied to each segment. This segmentation resolves the contradiction by enabling speed optimization without requiring a completely unified complex management system.
Solution Approach 2:
Different operation methods are assigned to different pages based on their individual characteristics. Pages with slower write speeds use the first operation method, while pages with faster write speeds use the second operation method. This local quality approach allows each page to be optimized according to its specific performance characteristics, resolving the contradiction between simplicity and consistency.
2Stability of the object's composition
If different operation methods are selected for each page based on speed, then write operation speed variations are reduced, but device complexity increases
Solution Approach 1:
The system performs preliminary measurement of write operation speeds for each page before normal operation. These measurements are stored in a management table that pre-classifies pages into different speed groups. This preliminary action eliminates the need for complex real-time decision-making during write operations, resolving the contradiction by preparing the optimization structure in advance.
Solution Approach 2:
The memory system automatically measures and classifies its own pages into different operation method groups without external intervention. The management table is self-generated and maintained by the memory controller, allowing the system to self-optimize its performance characteristics. This self-service approach reduces the complexity burden on external control systems.
3Productivity
If faster operation methods are used for all pages, then productivity increases, but reliability decreases due to errors in slower pages
Solution Approach 1:
The system applies different operation methods to different pages based on their individual reliability characteristics. Pages that can reliably support faster operation methods use those methods, while pages with reliability concerns use more conservative methods. This local quality differentiation allows the system to maximize overall productivity without compromising the reliability of individual pages.
Data Source
AI summary
A memory system includes a non-volatile memory and a memory controller. The non-volatile memory includes a memory cell array having pages. The memory system is configured to execute a first operation method and a second operation method. The memory system includes a control information storage unit in which a first value is set for pages having a write operation speed that is slower than a first speed, and a second value is set for pages having a write operation speed that is equal to or higher than the first speed. The memory system is configured to, at the time of write operation, select the first operation method for a target page having the first value and perform the write operation using the first operation method, and select the second operation method for a target page having the second value and perform the write operation using the second operation method.