From the VoltDB 3.0 preview notes:
VoltDB v3.0 includes a new transaction coordination architecture that reduces latency and improves transaction throughput.
In VoltDB versions 1.x and 2.x, transactions were globally ordered and ordered according to time. Each node on the cluster communicated with every other node to agree upon transaction ordering. Maintaining a global agreement based on time caused VoltDB to incur additional latency - intra-node communication agreement involving all nodes. This architecture required users to synchronize cluster node clocks using NTP, because any time drift between nodes would introduce artificial, unneeded latency to the system. This overhead, and the strict need to maintain clock synchronization has been eliminated from the VoltDB v3.0 code base.
So how does the new solution work?
Original title and link: VoltDB 3.0 Will Include a New Transaction Coordination Architecture ( ©myNoSQL)