Nezha: A Key-Value Separated Distributed Store with Optimized Raft Integration

TL;DR

Nezha is a distributed key-value store that optimizes Raft integration by separating key-value storage, reducing I/O overhead, and significantly boosting throughput for big data applications.

Contribution

Nezha introduces a novel key-value separation and optimized persistence strategy to enhance performance in Raft-based distributed stores.

Findings

Achieves 460.2% throughput increase for put operations

Reduces I/O overhead in persistence operations

Improves overall read/write performance significantly

Abstract

Distributed key-value stores are widely adopted to support elastic big data applications, leveraging purpose-built consensus algorithms like Raft to ensure data consistency. However, through systematic analysis, we reveal a critical performance issue in such consistent stores, i.e., overlapping persistence operations between consensus protocols and underlying storage engines result in significant I/O overhead. To address this issue, we present Nezha, a prototype distributed storage system that innovatively integrates key-value separation with Raft to provide scalable throughput in a strong consistency guarantee. Nezha redesigns the persistence strategy at the operation level and incorporates leveled garbage collection, significantly improving read and write performance while preserving Raft's safety properties. Experimental results demonstrate that, on average, Nezha achieves throughput improvements of 460.2%, 12.5%, and 72.6% for put, get, and scan operations, respectively.