MySQL 5.7 Release Notes
To use replication as a backup solution, replicate data from the source to a replica, and then back up the replica. The replica can be paused and shut down without affecting the running operation of the source, so you can produce an effective snapshot of “live” data that would otherwise require the source to be shut down.
How you back up a database depends on its size and whether you are backing up only the data, or the data and the replica state so that you can rebuild the replica in the event of failure. There are therefore two choices:
If you are using replication as a solution to enable you to back up the data on the source, and the size of your database is not too large, the mysqldump tool may be suitable. See Section 16.3.1.1, “Backing Up a Replica Using mysqldump”.
For larger databases, where mysqldump would be impractical or inefficient, you can back up the raw data files instead. Using the raw data files option also means that you can back up the binary and relay logs that enable you to re-create the replica in the event of a replica failure. For more information, see Section 16.3.1.2, “Backing Up Raw Data from a Replica”.
Another backup strategy, which can be used for either source or replica servers, is to put the server in a read-only state. The backup is performed against the read-only server, which then is changed back to its usual read/write operational status. See Section 16.3.1.3, “Backing Up a Source or Replica by Making It Read Only”.