https://www.quora.com/How-do-Google-and-Facebook-servers-synchronize-data
https://severalnines.com/blog/how-does-database-load-balancer-work/
https://severalnines.com/resources/whitepapers/mysql-load-balancing-with-haproxy/
https://severalnines.com/blog/clustered-database-node-failure-and-its-impact-high-availability/
https://galeracluster.com/