Hi Antonio, I had the same question/problem few months ago. Now, after study the posibilities, we have in our company a DRBD cluster using Pacemaker and Corosync to manage resources. Using this, you will get HA in your database service. With FreeRADIUS service, you could have in two different machines, managing the requests with a load balancer. If one fails, the other one should attend to all requests. You can choose this or Galera Cluster for MySQL. I have read about FreeRADIUS proxy but I'm not sure that will be the best solution in this case. Regards, Antonio.