Delta Queue Flush Handling for Flash Memory Write Amplification
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Solution Overview
Problem
Flash memory devices experience increased write amplification due to frequent writes, leading to inefficient data storage and potential instability of logical-to-physical (L2P) mapping information, which can result in premature flushing and increased search times for delta queue entries.
Innovation Solution
Implementing a data storage device with multiple delta queues, each associated with a range of logical flash management units, where the controller determines when to flush delta queue entries to non-volatile memory based on invalidation frequencies and available space, reducing write amplification and search times by optimizing the flushing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If delta queue flush is performed frequently to ensure L2P information stability, then reliability is improved, but write amplification increases
Solution Approach 1:
The patent implements dynamic flushing by monitoring L2P information stability metrics and adjusting flush timing accordingly. The system transitions from static periodic flushing to adaptive flushing based on actual data stability, reducing unnecessary writes while maintaining reliability.
Solution Approach 2:
The system changes the parameter of flush frequency based on L2P stability assessment. When L2P information is determined to be stable, the flush interval is extended; when instability is detected, flushing is triggered earlier, optimizing the balance between reliability and write amplification.
2Loss of substance
If delta queue size is increased to reduce flush frequency, then write amplification is reduced, but search time for L2P entries increases
Solution Approach 1:
The patent segments the delta queue into multiple smaller queues organized in a tree structure. This segmentation reduces the search space in each queue while maintaining overall capacity, thereby reducing search time without increasing flush frequency or write amplification.
Solution Approach 2:
The system introduces a hierarchical dimension to the delta queue structure, organizing entries in a tree with multiple levels. This dimensional change allows efficient navigation to L2P entries through hierarchical indexing, reducing search time complexity from linear to logarithmic.
3Device complexity
If single delta queue is used to simplify structure, then device complexity is reduced, but search time and write amplification worsen
Solution Approach 1:
The patent divides a single large delta queue into multiple smaller delta queues organized in a tree structure. Each queue handles a specific subset of L2P mappings, reducing search time within each queue while the hierarchical structure manages overall complexity through systematic organization.
Solution Approach 2:
The patent introduces a delta queue manager as an intermediary component that coordinates between multiple delta queues and the flush operation. This mediator handles queue selection, entry distribution, and flush coordination, managing complexity centrally while enabling efficient distributed queue operations.
Data Source
AI summary
Embodiments herein provide a data storage device including a non-volatile memory, a second memory, and a controller coupled to the non-volatile memory and the second memory. The second memory is configured to store a plurality of delta queues. Each of the plurality of delta queues includes delta queue entries. The delta queue entries are grouped into one or more logical-to-physical (L2P) pages. Each of the one or more L2P pages is associated with a plurality of logical flash management units (LFMUs) corresponding to a plurality of physical addresses in the non-volatile memory. The controller is configured to determine that a delta queue flush is required. In response to determining that the delta queue flush is required, the controller selects one of the plurality of delta queues to flush, and flushes the one or more L2P pages stored in the one of the plurality of delta queues to the non-volatile memory.