Fault-tolerant logarithmic mutual exclusion with lazy update propagation

The problem of managing replicated copies of data in a distributed system has received a lot of attention. Both token-passing and quorum consensus methods for managing replicated data have their drawbacks. Token-based solutions, although being able to manage the concurrence with very low overheads, suffer in both reliability and concurrence due to the fact that there only exists a single token. However, although quorum-based protocols can provide higher levels of reliability by committing updates to a set of nodes, as well as being able to provide for concurrence in the form of reads, they do this at costs at orders of magnitude greater than that of token-passing algorithms. In this paper, we present a protocol that can be seen as "multitoken" or "dynamic quorum," which uses aspects of both token-passing and quorum-based protocols to provide not only the reliability and concurrence provided by quorum-based protocols, but at the cost of a token-based protocol