Just curious, how familiar are you with Paxos? I'm asking because failure detection is pretty much isomorphic with distributed consensus and generally considered hard. Ie. how do you differentiate between down and slow?
You're correct that failure detection and consensus are very deeply related, in that a strong failure detector is 'sufficient' for consensus.
But my point is about client failure detection, not failure detection between servers (which must have some kind of timeout system; that's ok - you just sacrifice liveness in a few pathological cases rather than sacrificing correctness). If I am to implement leader election with Doozer, does Doozer provide any tools to help us with deciding when to elect a new leader? There's no reason it should, but ZooKeeper, for example, does have that in its arsenal.
Doozer doesn't, AFAIK, expose consensus as a primitive; that's not its model. So the fact that it uses Paxos, or ZAB, or 2PC or whatever doesn't make a difference to its clients.
