i'm afraid you will just have to sit down with the code and work that one out for yourself. Check out doxygen linked on
www.openser.org. Dont forget its not just usrloc data-structures, but all the timer's that maintain valid registration bindings as well. Most people implement the HA within their RDMS, and use OpenSER with db_mode=3 to achieve this. Another possibility is t_replicate() function, but this does not scale (and also requires another openser acting as the 'passive' server.