Byzantine Disk Paxos: Optimal Resilience with Byzantine Shared Memory

Ittai Abraham Gregory Chokler Idit Keidar Dahlia Malkhi
	Abstract We present Byzantine Disk Paxos, an asynchronous shared-memory consensus protocol that uses a collection of n > 3t disks, t of which may fail by becoming non-responsive or arbitrarily corrupted. We give two constructions of this protocol; that is, we construct two different building blocks, each of which can be used, along with a leader oracle, to solve consensus. One building block is a shared wait-free safe register. The second building block is a regular register that satisfies a weaker termination (liveness) condition than wait freedom: its write operations are wait-free, whereas it's read operations are guaranteed to return only in executions with a finite number of writes. We call this termination condition finite writes (FW), and show that consensus is solvable with FW-terminating registers and a leader oracle. We construct each of these reliable registers from n > 3t base registers, t of which can be non-responsive or Byzantine. All the previous wait-free constructions in this model used at least 4t+1 fault-prone registers, and we are not familiar with any prior FW-terminating constructions in this model.
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