First result: IP-switching is not possible. I have an open ticket on how to remotely control the switch port / routing, no answer yet.
Second problem was: ovh uses selfmade kernels without module support. There's no "quick install" because the kernel has to be recompiled for a lot of funktionality apart from module support (which is needed for drbd, nfs and other stuff). Positive: the Webinterface is quite nice, you can even partition your drives via webgui for reinstalls.