SSD Memory System Batch Delete Notification Processing
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Solution Overview
Problem
The existing connection protocol between a host apparatus and a memory system fails to effectively delete data, leading to host-invalid and device-valid data, which causes fragmentation of free areas in solid state drives (SSDs), resulting in performance deterioration and inefficient use of memory resources.
Innovation Solution
A memory system with a delete notification buffer that accumulates delete notifications and processes them collectively, invalidating data in processing units while copying valid data to other areas, thereby preventing fragmentation and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If data is deleted on the OS but not actually deleted in the memory system, then performance of the host apparatus is improved, but free areas in the memory system become exhausted due to host-invalid and device-valid data
Solution Approach 1:
The system performs preliminary classification of delete notifications into processing unit areas before executing invalidation. By organizing delete notifications in advance and grouping them by processing unit area, the system prepares the data structure needed for efficient batch invalidation, preventing free area exhaustion while maintaining host performance
Solution Approach 2:
The system merges multiple delete notifications into a single batch processing operation. By collecting delete notifications and processing them collectively for each processing unit area rather than individually, the system recovers free areas more effectively while reducing the overhead that would otherwise degrade host apparatus performance
2Manufacturing precision
If delete notifications are processed individually, then data management precision is improved, but transfer speed deteriorates due to frequent processing interruptions
Solution Approach 1:
Multiple delete notifications are merged into a single batch processing operation. The system collects delete notifications and processes them together for each processing unit area, which maintains precise data management tracking while reducing the frequency of processing interruptions that would otherwise degrade transfer speed
Solution Approach 2:
The system employs periodic batch processing of delete notifications rather than continuous individual processing. By organizing processing around batch intervals and processing unit area boundaries, the system maintains data management precision while creating regular processing cycles that minimize impact on transfer speed
3Device complexity
If data is invalidated without copying to other processing unit areas, then device complexity is reduced, but wear leveling performance deteriorates
Solution Approach 1:
The memory system is segmented into multiple processing unit areas, and invalidation is performed at the processing unit area level rather than at the individual data level. This segmentation allows the system to invalidate entire processing unit areas efficiently while maintaining wear leveling performance by ensuring uniform erasure patterns across the memory device
Solution Approach 2:
The system merges the invalidation operation with wear leveling considerations by processing entire processing unit areas as units. When valid data is copied out of a processing unit area, the entire area is invalidated together, which simplifies the invalidation process while simultaneously improving wear leveling by creating uniform erasure patterns
Data Source
AI summary
According to one embodiment, a memory system includes: a memory area; a transfer processing unit that stores write data received from a host apparatus in the memory area; a delete notification buffer that accumulates a delete notification; and a delete notification processing unit. The delete notification processing unit collectively reads out a plurality of delete notifications from the delete notification buffer and classifies the read-out delete notifications for each unit area. The delete notification processing unit sequentially executes, for each unit area, processing for collectively invalidating write data related to one or more delete notifications classified in a same unit area and, in executing processing for one unit area in the processing sequentially executed for the each unit area, invalidates all write data stored in the one unit area after copying write data excluding write data to be invalidated stored in the one unit area to another unit area.