We propose uBFT, the first State Machine Replication (SMR) system to achieve microsecond-scale latency in data centers, while using only $2f{+}1$ replicas to tolerate $f$ Byzantine failures. The Byzantine Fault Tolerance (BFT) provided by uBFT is essential as pure crashes appear to be a mere illusion with real-life systems reportedly failing in many unexpected ways. uBFT relies on a small non-tailored trusted computing base -- disaggregated memory -- and consumes a practically bounded amount of memory. uBFT is based on a novel abstraction called Consistent Tail Broadcast, which we use to prevent equivocation while bounding memory. We implement uBFT using RDMA-based disaggregated memory and obtain an end-to-end latency of as little as 10us. This is at least 50$\times$ faster than MinBFT , a state of the art $2f{+}1$ BFT SMR based on Intel's SGX. We use uBFT to replicate two KV-stores (Memcached and Redis), as well as a financial order matching engine (Liquibook). These applications have low latency (up to 20us) and become Byzantine tolerant with as little as 10us more. The price for uBFT is a small amount of reliable disaggregated memory (less than 1 MiB), which in our prototype consists of a small number of memory servers connected through RDMA and replicated for fault tolerance.

翻译：我们提出uBFT，这是首个在数据中心实现微秒级延迟的状态机复制（SMR）系统，仅需$2f{+}1$个副本即可容忍$f$个拜占庭故障。uBFT提供的拜占庭容错能力至关重要，因为实际系统常以多种意外方式失效，纯崩溃似乎只是假象。uBFT依赖一个小型非定制可信计算基——分解内存，并消耗实际有界的内存容量。uBFT基于一种称为一致性尾部广播（Consistent Tail Broadcast）的新型抽象，该抽象在限制内存的同时防止欺骗行为。我们使用基于RDMA的分解内存实现uBFT，端到端延迟低至10微秒，比基于Intel SGX的先进$2f{+}1$拜占庭容错SMR系统MinBFT快至少50倍。我们利用uBFT复制了两个键值存储（Memcached和Redis）以及一个金融订单撮合引擎（Liquibook）。这些应用的延迟较低（最高20微秒），并仅需额外增加10微秒即可获得拜占庭容错能力。uBFT的代价是少量可靠的分解内存（小于1 MiB），在我们的原型中通过RDMA连接的少量内存服务器实现，并通过复制来保证容错。