Distributed and highly available systems are pretty interesting but something I've noticed is that it's really surprising how much you can get done with a centr

Distributed and highly available systems are pretty interesting but something I've noticed is that it's really surprising how much you can get done with a centralized system (say a single redis instance) and how much easier it is. Some of the cloud VMs can run for years with only transient issues (GCE live migration is neat). High availability is really cool as well, but I recently learned that world of Warcraft has apparently had <97% uptime for years due to weekly maintenance. That leads me to reconsider just how necessary those additional nines are. It seems like a lot of services would be better off optimizing for, say, operational efficiency than uptime. Doing server upgrades and rolling out patches when you have a multi hour maintenance window sounds waaay easier than live updates to your servers. Of course it depends entirely on the service you are running, but I'm still impressed that a service as large as world of Warcraft can work fine with that level of uptime.