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St. Louis, MO
I'm involved in many open source development communities (like Drupal and Ansible), I'm the author of Ansible for DevOps and Ansible for Kubernetes, and I've been involved in the development of many large websites and applications.
Authored Comments
@Drew - I actually have a lot of detailed benchmarks available over on the cluster's GitHub project Wiki: https://github.com/geerlingguy/raspberry-pi-dramble/wiki/Dramble-D8-Ben…
The Pi 2 is respectable compared to a low-end PC or low-end cloud server; it is generally 20-30% slower in my testing than a micro AWS instance or a Digital Ocean droplet, but the performance difference depends on a lot of different things, especially what kind of application you run on it.
Regarding clustering in general: there's always a tradeoff to be made when clustering; you can aim for better performance and better availability, but if you want both, that requires many more servers. In this cluster, I have 6, with a load balancer, four webservers, and a database server. If the database fails, then everything is offline.
You can also add a reverse proxy so things are cached and you protect your 'backend' servers more, and you can set up the database in a master-slave configuration so you can fail over if the master goes down.
Once you get into clustering, the rabbit hole is very deep :)