SwitchDelta: Asynchronous Metadata Updating for Distributed Storage with In-Network Data Visibility

TL;DR

SwitchDelta introduces an innovative approach to accelerate distributed storage writes by offloading metadata updates to programmable switches, reducing latency and increasing throughput while maintaining strong consistency.

Contribution

It presents a novel in-network metadata update protocol and a best-effort data plane design to move metadata updates out of the critical path in distributed storage systems.

Findings

Reduces write latency by up to 52.4%.

Increases throughput by up to 126.9%.

Applicable across various storage architectures.

Abstract

Distributed storage systems typically maintain strong consistency between data nodes and metadata nodes by adopting ordered writes: 1) first installing data; 2) then updating metadata to make data visible.We propose SwitchDelta to accelerate ordered writes by moving metadata updates out of the critical path. It buffers in-flight metadata updates in programmable switches to enable data visibility in the network and retain strong consistency. SwitchDelta uses a best-effort data plane design to overcome the resource limitation of switches and designs a novel metadata update protocol to exploit the benefits of in-network data visibility. We evaluate SwitchDelta in three distributed in-memory storage systems: log-structured key-value stores, file systems, and secondary indexes. The evaluation shows that SwitchDelta reduces the latency of write operations by up to 52.4% and boosts the throughput by up to 126.9% under write-heavy workloads.