Use One Big Server (2022)

Don't forget the cost of managing your one big server and the risk of having such single point of failure.

My experience after 20 years in the hosting industry is that customers in general have more downtime due to self-inflicted over-engineered replication, or split brain errors than actual hardware failures. One server is the simplest and most reliable setup, and if you have backup and automated provisioning you can just re-deploy your entire environment in less than the time it takes to debug a complex multi-server setup.

I'm not saying everybody should do this. There are of-course a lot of services that can't afford even a minute of downtime. But there is also a lot of companies that would benefit from a simpler setup.

Not to mention the other leading cause of outages: UPS's.

Sigh.

UPSes always seem to have strange failure modes. I've had a couple fail after a power failure. The batteries died and they wouldn't come back up automatically when the power came back. They didn't warn me about the dead battery until after...

That’s why they have self-tests. Learned that one the hard way myself.