Depending on how bad & frequent you want outages to be and whether you want the whole thing to go down for scheduled maintenance, it can get quite a bit more co

Depending on how bad & frequent you want outages to be and whether you want the whole thing to go down for scheduled maintenance, it can get quite a bit more complicated. A pair of servers with some level of RAID is probably the minimum to achieve any amount of availability better than a server in someone's closet. Then you need a cold backup, on top of that, no matter how many live servers you have. I've also had much better luck with connectivity, transfer speeds, and latency, for clients in some regions, with AWS than with some other hosts (e.g. Digital Ocean). It seems peering agreement quality really matters. Not sure how the big physical server hosts fare on that front vs. AWS (which is basically the gold standard, as far as I can tell) and it's hard to find such info without trying and seeing what happens. This matters if you're trying to serve a large audience over much of the Earth. The easy single-server solution might well see some clients lost 95% of their transfer speed from your service, or not be able to connect at all, compared with AWS.