ZZ and the Art of Practical BFT Execution
The high replication cost of Byzantine Fault-Tolerance (BFT) methods has been a major barrier to their widespread adoption in commercial distributed applications. The authors present ZZ, a new approach that reduces the replication cost of BFT services from 2f +1 to practically f +1. The key insight in ZZ is to use f + 1 execution replicas in the normal case and to activate additional replicas only upon failures. In data centers where multiple applications share a physical server, ZZ reduces the aggregate number of execution replicas running in the data center, improving throughput and response times.