The Paxos Algorithm

Some algorithms could arguably be applied as solutions to the consensus problem.

For instance, the 2-phase commit protocol could be used, where the coordinator would drive the voting process.

However, such a protocol would have very limited fault tolerance, since the failure of a single node (the coordinator) could bring the whole system to a halt.

The obvious next step is to allow multiple nodes to inherit the role of the coordinator in these failure cases. This would then mean that there might be multiple primaries that might produce conflicting results.

This phenomenon is demonstrated in the lesson multi-primary replication and the 3-phase commit lesson.