DHCP question

I am trying to design a system with full redundancy. I know I can use FreeRadius proxy and/or multiple front ends with a MySQL master-master for the data. For IP redundancy I can install heartbeat so all of that is fine. My biggest unknown is DHCP. How does the new FreeRadius DHCP server store lease information? Will the design I am creating allow for DHCP failover from one machine to the next. One design caveat, the DHCP request will be Relay with Option 82 (hence the need for heartbeat). Any issues with Option 82 requests? David