Both servers have their own fixed ip-address and both have a virtual
ip-address.
pacemaker makes sure that when one server is down, its virtual ip is
moved to the other node.
So this is more a active-active setup.
Enabled ip_nonlocal_bind, set listening to both virtual ip-addresses
and forcing the socket based on the incoming ip-address.
I don't know if this is a good solution, didn't find much usefull
info on the web,
but it works.