Why use a semi-sync backup master and slaves?

A backup master reduces the impact of a master failure:

-       No data loss

-       Simplified reconfiguration of the replication cluster

-       The overall system is more stable

The master handles connections from different applications, executes write transactions and writes them to disk.

The backup master will synchronize with the master using semi-sync replication.  Since it has the same data as the master, we are minimizing the risk of data loss in case we lose the master.

In case of failure of a database node, the other nodes in the Replication cluster might need to be reconfigured in order for the system to reach a stable state. The backup master facilitates this.