It's not a lie if you don't get caught: simplifying reconfiguration in SMR through dirty logs

TL;DR

The paper introduces Gauss, a modular reconfiguration engine for state-machine replication that enables independent upgrades of components with minimal downtime, improving maintainability and system evolution.

Contribution

Gauss separates the consensus protocol's inner and outer logs, allowing independent reconfiguration and upgrades in SMR systems, which was not possible with prior tightly coupled approaches.

Findings

Enables seamless protocol upgrades with minimal downtime

Supports independent reconfiguration of membership and failure thresholds

Demonstrated effective evolution of SMR stack in Rialo blockchain

Abstract

Production state-machine replication (SMR) implementations are complex, multi-layered architectures comprising data dissemination, ordering, execution, and reconfiguration components. Existing research consensus protocols rarely discuss reconfiguration. Those that do tightly couple membership changes to a specific algorithm. This prevents the independent upgrade of individual building blocks and forces expensive downtime when transitioning to new protocol implementations. Instead, modularity is essential for maintainability and system evolution in production deployments. We present Gauss, a reconfiguration engine designed to treat consensus protocols as interchangeable modules. By introducing a distinction between a consensus protocol's inner log and a sanitized outer log exposed to the RSM node, Gauss allows engineers to upgrade membership, failure thresholds, and the consensus protocol itself independently and with minimal global downtime. Our initial evaluation on the Rialo blockchain shows that this separation of concerns enables a seamless evolution of the SMR stack across a sequence of diverse protocol implementations.