I worked for a major internet company until 2020. HN would be aghast how much "if we failed to provide this service a good chunk of the internet would either go down or sites wouldn't function properly and the stock market probably would dip" stuff runs on redundant pairs of LAMP stacks and other unsophisticated old stuff HN would turn up its nose at.
"Redundant pair of LAMP stacks"
Damn you got two of those? That's advanced magic
Active/Passive and no one has ever done a failover test.
We did a failover test last time a motherboard failed. It went so well it made the news.