Medon was unstable, it was hanging after about 3 hours. I moved the drives to another C2 and it has been stable since. Don't know what the problem with that board is, will look into it later.
Rigel is now up as an internal DNS running BIND.
Onlo is the external DNS also running BIND.
Onlo and Rigel are also internal NTP servers using Chrony (with config changes to better support NTP clients).
Next is my mailserver on a CubieTruck. The EPEL repo for armv7 still has some rpms that did not build, and one I need for my system. So it might be a while before I report on a full mailserver function for Cubie with Centos. Thing is that my current mailserver is running Redsleeve6 (Centos6 arm clone), and avmavis is beating up those 2 cores. I am seriously considering the CubieTruck plus to get 4 cores.