MySQL 5.7 Reference Manual
        MySQL 5.7 Release Notes
        
The following sections describe how to set up replicas. Before you proceed, ensure that you have:
- Configured the source with the necessary configuration properties. See Section 2.2.1, “Setting the Replication Source Configuration”. 
- Obtained the source's status information, or a copy of the source's binary log index file made during a shutdown for the data snapshot. See Section 2.2.3, “Obtaining the Replication Source's Binary Log Coordinates”. 
- On the source, released the read lock: - mysql> UNLOCK TABLES;