HardPaxos: Replication Hardened against Hardware Errors

State Machine Replication (SMR) is a common technique to make services fault-tolerant. Practical SMR systems tolerate process crashes, but no hardware errors such as bit flips. Still, hardware errors can cause major service outages, and their rate is expected to increase in the future. Current approaches either incur a high overhead by hardening large parts of the system in software, or increase the cost of ownership by introducing additional hardware components. This work presents HardPaxos, an atomic broadcast algorithm for SMR that enables services to tolerate hardware errors, while incurring little performance and state overhead. HardPaxos requires no additional hardware and has only a small part of its functionality hardened using a combination of AN-encoding and duplicated execution. Our evaluation shows a throughput overhead of at most 5% for typical payload sizes. Moreover, fault injection experiments show that our hardening decreases the number of undetected errors from 15% to 0.02%.