Clairvoyant State Machine Replication

Abstract: We propose a new protocol for the generalized consensus problem in asynchronous systems subject to Byzantine server failures. The protocol solves the consensus problem in a setting in which information about conflict between transactions is available (such information can be in the form of transaction read and write sets). Unlike most prior proposals (for generalized or classical consensus), which use a leader to order transactions, this protocol is leaderless, and relies on non-skipping timestamps for transaction ordering. Being leaderless, the protocol does not need to pause for leader elections. The use of non-skipping timestamps permits servers to commit transactions as soon as they know that no conflicting transaction can be ordered earlier. For n servers of which f may be faulty, this protocol requires n > 4f.