Our underlying hardware (AWS) is nothing like this reliable. We see regular (several times a year) failure of racks of machines or whole DCs.

Across the whole fleet (all services), we lose 1-10 servers per day as a baseline. Major events are then on top of that and can impact thousand of hosts at once.

What service is this?? This must be huge.

> Even the largest Slack instance probably has under 100,000 users and less than 1000 peak messages per second.

This is not true, by an order of magnitude.