Mysqld_multi is a amazing feather, You can very easy to manage multi mysql instances on one system. If you are a tester you would love it
0:00 1.Stop the current running MySQL instance
0:06 2.Modify the /etc/my.cnf file as text blow
0:41 3.Start these MySQL instances using commands below
1:15 4.Check these MySQL instances running status and try logging into them.
3:19 5.You could still Recover the MySQL instance to its previous state if you want