Comment by gibb0n

Seems to be the same collection of services deployed in different AZs with a load balancer? The trick would be how data is replicated across the instances, which I'm guessing is some sort of event publishing or even backup sources of truth? It says that will come in the next article and surely that's the more interesting part than the load balancing...

Also explains to me why new features would take a while to roll out of you are cautiously updating instances/AZs one by one