Back in 2014 or so, I saw the FoundationDB team demo the product at a developer conference. They had the database running across a bunch of machines, with a visual showing their health and data distribution. One team member would then be turning machines on and off (or maybe unplugging them from the network) and you could see FDB effortlessly rebalancing the data across the available nodes. It was a very striking, impressive presentation (especially as we were dealing with the challenges of distributed Cassandra at the time).