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State machine replication (SMR) is a core mechanism for building highly available and consistent systems. In this paper, we propose Waverunner, a new approach to accelerate SMR using FPGA-based SmartNICs. Our approach does not implement the entire SMR system in hardware; instead, it is a hybrid software/hardware system. We make the observation that, despite the complexity of SMR, the most common routine—the data replication—is actually simple. The complex parts (leader election, failure recovery, etc.) are rarely used in modern datacenters where failures are only occasional. These complex routines are not performance critical; their software implementations are fast enough and do not need acceleration. Therefore, our system uses FPGA assistance to accelerate data replication, and leaves the rest to the traditional software implementation of SMR. Our Waverunner approach is beneficial in both the common and the rare case situations. In the common case, the system runs at the speed of the network, with a 99th percentile latency of 1.8 µs achieved without batching on minimum-size packets at network line rate (85.5 Gbps in our evaluation). In rare cases, to handle uncommon situations such as leader failure and failure recovery, the system uses traditional software to guarantee correctness, which is much easier to develop and maintain than hardware-based implementations. Overall, our experience confirms Waverunner as an effective and practical solution for hardware accelerated SMR—achieving most of the benefits of hardware acceleration with minimum added complexity and implementation effort.
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Much ADO about failures: a fault-aware model for compositional verification of strongly consistent distributed systems
Despite recent advances, guaranteeing the correctness of large-scale distributed applications without compromising performance remains a challenging problem. Network and node failures are inevitable and, for some applications, careful control over how they are handled is essential. Unfortunately, existing approaches either completely hide these failures behind an atomic state machine replication (SMR) interface, or expose all of the network-level details, sacrificing atomicity. We propose a novel, compositional, atomic distributed object (ADO) model for strongly consistent distributed systems that combines the best of both options. The object-oriented API abstracts over protocol-specific details and decouples high-level correctness reasoning from implementation choices. At the same time, it intentionally exposes an abstract view of certain key distributed failure cases, thus allowing for more fine-grained control over them than SMR-like models. We demonstrate that proving properties even of composite distributed systems can be straightforward with our Coq verification framework, Advert, thanks to the ADO model. We also show that a variety of common protocols including multi-Paxos and Chain Replication refine the ADO semantics, which allows one to freely choose among them for an application's implementation without modifying ADO-level correctness proofs.
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- PAR ID:
- 10602649
- Publisher / Repository:
- Association for Computing Machinery (ACM)
- Date Published:
- Journal Name:
- Proceedings of the ACM on Programming Languages
- Volume:
- 5
- Issue:
- OOPSLA
- ISSN:
- 2475-1421
- Format(s):
- Medium: X Size: p. 1-31
- Size(s):
- p. 1-31
- Sponsoring Org:
- National Science Foundation
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