Way to change primary interface - edit /etc/hosts to change ip address returned when cman does lookup of system hostname.
e.g.
127.0.0.1 localhost.localdomain localhost 192.168.40.6 Hildasay.physics.gla.ac.uk Hildasay pvelocalhost # The following lines are desirable for IPv6 capable hosts ::1 ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters ff02::3 ip6-allhosts
With this config cman will return 192.168.40.6 as the address totem should bind to for it's multicast stuff.
There may be certificate problems doing this. Probably best in future to install proxmox with the initial interface on the SAN (or other appropriate private network).