If you need a reliable relational database that’s compatible with MySQL, look no further than Amazon Aurora. This database engine combines the best of two worlds: the speed and availability of a high-end DB engine and the flexibility and cost-efficiency of an open source one.
AWS has made Aurora even more useful with additional failover control. Aurora starts you off with up to 15 read replicas that you can use for failover targets. Each of these can now be assigned with a priority tier ranging from 0-15.
This feature lets you prioritize a replica during a failover—the lowest number gets a higher priority. In case two have the same number, the one with the same size as the previous primary instance gets priority.