Summary
This chapter taught us why and how to create a Neo4j cluster with different kinds of servers. After the concepts, we saw how to build a cluster. We also saw the magic of the bolt+routing protocol.
You learned that we can grow from a cluster of several credit card-sized computers like Raspberry Pis (https://www.raspberrypi.org/) to a cluster made from several clouds (you'll need a strong credit card for that).
We also saw a disaster recovery procedure to which I'll add this tip:
Note
With any software, disaster recovery must always be team work. Otherwise, it is too easy to put the blame on one person because non-tech people need to act as inactivity makes them feel 'not in power' and blaming is so easy, as they believe failure should not have had happened first. No matter Murphy's law. If you are the one who understood what failed and how to solve the issue, and get the blame anyway instead the credit: change of shop. I saw firsthand that a client lost their best sysadmin as he got bored...