Increasing the resilience of atomic commit, at no additional cost

This paper presents a new atomic commitment protocol that always allows a quorum in the system to make progress. Previously suggested quorum-based protocols (e.g. [12]) allow a quorum to make progress in case of one failure. If failures cascade, however, and the quorum in the system is \lost" (i.e. at a given time no quorum component exists, e.g. because of a total crash), a quorum can later become connected and still remain blocked. The importance of this work is in demonstrating, using a simple algorithm, how protocols that always allow a majority to make progress can be constructed.