HarmonyCache: Scalable In-Network Cache With Read-Write Separation

doi:10.1109/TPDS.2026.3664186

HarmonyCache: Scalable In-Network Cache With Read-Write Separation

2026-02-12

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DOI：10.1109/TPDS.2026.3664186

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"In key-value storage systems, a small number of hot items account for most traffic. Skewed workloads lead to load imbalance among servers, and those holding hotspots become system bottlenecks, degrading overall performance. Recent studies show that load imbalance can be eliminated by deploying a small, fast cache node in front of back-end servers, i.e., in-network cache. Programmable switches enable placing such caches on switches where traffic must pass. Although existing in-network cache schemes effectively balance loads in large-scale storage systems, they perform poorly under write-intensive workloads and lose scalability with growing clients due to imbalanced cache nodes. This paper introduces HarmonyCache, a scalable, high-performance in-network cache system that supports write-back. HarmonyCache employs cache replication and read-write separation: only one cache node handles write requests, while others serve reads only. To achieve scalability and minimize coherence overhead, HarmonyCache proposes an adaptive cache replication scheme to determine where and how many replicas to deploy. In addition, we design heterogeneous in-network caches using different switch resources and propose a hybrid caching scheme. Prototype and extensive experiments show that HarmonyCache significantly improves throughput under various access patterns (read/write-intensive), achieving up to 7.6× throughput gain over state-of-the-art solutions under skewed write-intensive workloads.

Keywords:

In-network cache

programmable switch

P4

key-value store

HarmonyCache: Scalable In-Network Cache With Read-Write Separation

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