Host-Resident L2P Map Cache Management via Priority-Based Retention
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Solution Overview
Problem
Current semiconductor memory devices, particularly flash memory devices, face challenges in managing meta data efficiently, leading to suboptimal performance and storage capacity utilization due to the lack of effective methods for prioritizing and updating cache data in non-volatile memory systems.
Innovation Solution
A memory system that incorporates a turbo write buffer and a storage controller to manage meta data, using a UFS interface, which maps physical and logical addresses and prioritizes cache data based on the identifier of the turbo write buffer or user storage area, enabling efficient data management and access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If map cache data are managed without priority differentiation, then the management process is simple, but write performance and storage efficiency deteriorate
Solution Approach 1:
The patent applies local quality by differentiating cache management strategies based on the type of data. Map cache data corresponding to the turbo write buffer area is assigned high priority with longer retention, while map cache data for the user storage area is assigned low priority with shorter retention. This localized differentiation optimizes write performance for critical data without unnecessarily complicating the management of all cache data uniformly.
Solution Approach 2:
The patent segments map cache data into two distinct categories based on their correspondence to different storage areas (turbo write buffer area vs. user storage area). This segmentation enables independent priority management and retention policies for each segment, resolving the contradiction by allowing simple yet effective differentiated management rather than uniform complex management.
2Reliability
If all map cache data are retained equally, then data retention is comprehensive, but storage capacity utilization deteriorates
Solution Approach 1:
The patent implements dynamic retention policies where the retention duration of map cache data is not fixed but varies based on its priority classification. High-priority data (corresponding to turbo write buffer) is retained longer to ensure reliability, while low-priority data (corresponding to user storage) is retained shorter to free up cache space. This dynamic approach resolves the contradiction between comprehensive retention and capacity utilization.
Solution Approach 2:
The patent changes the retention time parameter of map cache data based on its type. By adjusting this key parameter differentially - extending retention for high-priority data and shortening it for low-priority data - the system maintains data reliability where needed while optimizing overall storage capacity utilization in the cache memory.
3Measurement precision
If map cache data are updated frequently without priority-based selection, then data freshness is maintained, but processing overhead increases
Solution Approach 1:
The patent applies local quality by updating cache data selectively based on its priority classification. High-priority map cache data (corresponding to turbo write buffer) is updated frequently to maintain data freshness, while low-priority data (corresponding to user storage) is updated less frequently. This localized update strategy maintains freshness where critical without incurring uniform processing overhead across all cache data.
Solution Approach 2:
The patent applies partial action by performing frequent update operations only on the necessary subset of high-priority cache data rather than uniformly updating all cache data. This partial updating approach maintains data freshness for critical operations while reducing overall processing time and overhead by excluding low-priority data from frequent update cycles.
Data Source
AI summary
A memory system includes a storage device including a nonvolatile memory device and a storage controller configured to control the nonvolatile memory device, and a host that accesses the storage device. The storage device transfers map data, in which a physical address of the nonvolatile memory device and a logical address provided from the host are mapped, to the host depending on a request of the host. The host stores and manages the transferred map data as map cache data. The map cache data are managed depending on a priority that is determined based on a corresponding area of the nonvolatile memory device.