Memory System Mapping with Segmented Physical Address Storage
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Solution Overview
Problem
The increasing capacity of memory systems leads to a rise in the amount of mapping information, which increases manufacturing costs when stored in non-volatile memory.
Innovation Solution
A memory system is designed with a non-volatile memory device storing first mapping information and a volatile memory device storing second mapping information, where the memory controller determines a target logical address and obtains a target physical address using both types of mapping information, reducing the amount of data stored in volatile memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mapping information is stored in non-volatile memory to maintain data retention, then reliability is improved, but manufacturing cost increases due to larger storage capacity requirements
Solution Approach 1:
The physical address is segmented into two parts: a first physical address portion stored in non-volatile memory and a second physical address portion stored in volatile memory. This segmentation allows the system to maintain reliability for the critical mapping information while reducing the storage burden on expensive non-volatile memory, thereby lowering manufacturing costs.
2Ease of manufacture
If mapping information is stored in volatile memory to reduce manufacturing cost, then ease of manufacture is improved, but data retention capability deteriorates
Solution Approach 1:
By dividing the mapping information into two segments stored in different memory types, the system achieves cost-effectiveness using volatile memory while preserving data retention capability through non-volatile memory storage of the critical first physical address portion.
Solution Approach 2:
The first physical address portion stored in non-volatile memory acts as an intermediary that enables the volatile memory to store the second physical address portion. This intermediary approach allows volatile memory to be used effectively while maintaining the ability to retrieve complete mapping information when needed.
3Speed
If complete physical address mapping is stored in volatile memory to improve access speed, then speed is improved, but the amount of memory required increases manufacturing cost
Solution Approach 1:
The mapping information is segmented such that the first physical address portion (which changes less frequently) is stored in non-volatile memory, while the second physical address portion (which requires faster access) is stored in volatile memory. This segmentation optimizes both speed and cost by placing each segment in the most appropriate memory type.
Data Source
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AI summary
In some embodiments, the memory system for communicating with a host includes a non-volatile memory device storing first mapping information, a volatile memory device storing second mapping information, and a memory controller. The first mapping information indicates a relationship between a logical address and a portion of a first physical address. The first physical address indicates a location where user data is stored. The second mapping information indicates a second relationship between the logical address and a second physical address that corresponds to a remaining portion of the first physical address. The memory controller is configured to obtain a target logical address that has been received from the host, and determine, based on the second mapping information, a target second physical address mapped to the target logical address. The non-volatile memory device is configured to obtain a target first physical address by using the first mapping information.