I don't disagree that there are opportunities to introduce topology. I do disagree that there are opportunities to benefit from distributed consensus. If a server in ORD is down, it doesn't matter what some server in SJC says it's hosting; all the ORD instances of all the apps on that server are down. If that same ORD server is up, it doesn't matter what any server says it's running; it's authoritative for what it's running.

Of course, OSPF has topology and aggregation, too.

At any rate: I didn't design the system we're talking about.

> I do disagree that there are opportunities to benefit from distributed consensus

there's some benefits to static stability and grey failure, but sure, whatever. the important bit is to have clear paths of aggregation and dissemination in your system.

that being said

> it doesn't matter what some server in SJC says it's hosting

it kind of does matter doesn't it? assuming that server in SJC is your forwarding proxy that does your global loadbalancing, what that server is aware of is highly relevant to what global actions you can take safely.

My point is just that there isn't a consensus algorithm that needs to get run to know which of the two proposals to accept.

It doesn't need a raft consensus algorithm, but corrosion does converge to a consensus, doesn't it? In the OSPF example, that does needs to converge to a state that is consistent and replicated on all the routers, otherwise loops and drops will occur. I'm curious if any convergence benchmark has been done that compares raft to corrosion.