SSD Data Map Fragment Tables for Faster Validity Management
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Solution Overview
Problem
Existing memory systems face challenges in efficiently managing the validity of data in non-volatile memory and optimizing the processing costs associated with data maps, particularly in solid state drives (SSDs) using NAND type flash memory.
Innovation Solution
A memory system with a hierarchical structure for the LUT and VDM, incorporating a plurality of fragment tables across multiple hierarchies, which includes a controller managing data validity and access using a data map with efficient cache memory utilization and garbage collection processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional data map structure is used to manage data validity in non-volatile memory, then the system can track data validity, but the processing costs and overhead increase when managing large memory regions
Solution Approach 1:
The patent divides the data map into multiple fragment tables, where each fragment table manages a specific range of physical block addresses (PBAs). This segmentation allows the system to handle large memory regions by processing only relevant fragments rather than the entire data map, reducing processing overhead and complexity while maintaining reliable data validity tracking.
2Reliability
If the data map is updated frequently to track data validity, then data validity management is accurate, but the processing time and overhead increase
Solution Approach 1:
The patent performs preliminary actions by pre-organizing the data map into fragment tables with defined PBA ranges before data writing operations. When data validity needs to be tracked, the system can directly access the relevant fragment table without scanning the entire data map, thus maintaining accurate data validity management while reducing processing time.
3Speed
If a hierarchical structure with multiple fragment tables is implemented, then the access speed and management efficiency improve, but the device structure becomes more complex
Solution Approach 1:
The patent introduces a hierarchical dimension to the data map structure by organizing fragment tables across multiple levels (first hierarchy, second hierarchy, etc.). Each hierarchy manages different ranges of PBAs, allowing the system to access data validity information at the appropriate level of granularity. This dimensional organization improves access speed by enabling targeted queries while managing complexity through structured hierarchy.
4Reliability
If the entire data map is processed during garbage collection, then data validity is thoroughly managed, but the processing overhead and time consumption increase
Solution Approach 1:
The patent extracts and processes only the relevant fragment tables during garbage collection operations based on the specific PBA ranges that need validation. Instead of processing the entire data map, the system identifies and processes only the fragmented tables containing the relevant data, thereby maintaining thorough data validity management while significantly improving processing efficiency during garbage collection.
Data Source
AI summary
According to one embodiment, a memory system includes a non-volatile memory and a controller. The controller manages validity of data in the non-volatile memory using a data map. The data map includes first fragment tables. Each of the first fragment tables stores first and second information. The first information indicates the validity of each data having a predetermined size written in a range of physical address in the non-volatile memory allocated to the first fragment table. The second information indicates the validity of a plurality of data having a predetermined size in each of entries. The controller selects a write destination block based on a size of write data to be written to the non-volatile memory by a write command from a host.