Atomic Broadcast in a Real-Time Environment

This paper presents a model for real-time distributed systems that is intermediate in complexity between the simple, perfectly synchronous model in which there are rounds of communication exchange among processors in a completely connected network and an asynchronous model in which there is no reasonable upper bound on the time required for transmission and processing of messages. In this model algorithms are described for atomic broadcast that can be used to update synchronous replicated storage, a distributed storage that displays the same contents at every correct processor as of any clock time. The algorithms are all based on a simple communication paradigm and differ only in the additional checking required to tolerate different classes of failures.