Server failover like dhcp?

Hi. I just installed two dhcp 4 server with failover and it works great. So great that i want the same for my freeradius server, so i look at the wikis. As for what i can figure out there's only a module config (sql) for failover? Didn't find anything in the FAQs either. Im not using SQL, only files (yes will make it happend when i have the time : )), is the failover only possible in SQL? What i would like to accomplish is this, if server primary explodes the secondary takes over, just like dhcp. Regards p