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arXiv · 2603.09605

Nemo: A Low-Write-Amplification Cache for Tiny Objects on Log-Structured Flash Devices

Xufeng Yang·Tingting Tan·Jingxin Hu·Congming Gao·Mingyang Liu·Tianyang Jiang·Jian Chen·Linbo Long·Yina Lv·Jiwu Shu
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Abstract

Modern storage systems predominantly use flash-based SSDs as a cache layer due to their favorable performance and cost efficiency. However, in tiny-object workloads, existing flash cache designs still suffer from high write amplification. Even when deploying advanced log-structured flash devices (e.g., Zoned Namespace SSDs and Flexible Data Placement SSDs) with low device-level write amplification, application-level write amplification still dominates. This work proposes Nemo, which enhances set-associative cache design by increasing hash collision probability to improve set fill rate, thereby reducing application-level write amplification. To satisfy caching requirements, including high memory efficiency and low miss ratio, we introduce a bloom filter-based indexing mechanism that significantly reduces memory overhead, and adopt a hybrid hotness tracking to achieve low miss ratio without losing memory efficiency. Experimental results show that Nemo simultaneously achieves three key objectives for flash cache: low write amplification, high memory efficiency, and low miss ratio.

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Xufeng Yang, Tingting Tan, Jingxin Hu, Congming Gao, Mingyang Liu, Tianyang Jiang, Jian Chen, Linbo Long, Yina Lv, Jiwu Shu. 2026-03-10. Nemo: A Low-Write-Amplification Cache for Tiny Objects on Log-Structured Flash Devices. https://arxiv.org/abs/2603.09605

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