more than 2TB?

[Holger Schurig]

> See above. I'm maintaining a FAI setup tree for production use and
> won't take the risk to break something.

You can have several, independend FAI setup tree!

Several ways are possible

*) use the -c option to make-fai-nfsroot and a completely different fai 
fai config and nfsroot directory

*) use a different machine for the test-FAI and let your DHCP-Server serve 
a different root-path for those machines that you test with FAI.