Changed limits: max_connections: 214
You can always check if a variable is dynamic or not with on http://dev.mysql.com/doc/refman/5.7/en/dynamic-system-variables.html

Or looking at the parameter directly: 
http://dev.mysql.com/doc/refman/5.7/en/server-system-variables.html#sysvar_open_files_limit

If it is dynamic you can:

set global &lt;variable_name&gt; = &lt;value&gt;;



  Just don't forget to change in your my.cnf also otherwise next restart will override it.


If it is not then you have to restart MySQL to make it happen. Oracle is working on getting more and more variable dynamic and you can see the trend going through 5.5 -> 5.6 -> 5.7. Unfortunately though there's always going to be parameters which require restart.