[Samba] add Samba 4 to existing classic NT4 domain (and upgrade to AD)

[Bram Matthys]

Hi,

We currently have this setup (inherited from my predecessor):
Samba 3.2.x domain with custom (mysql) passdb backend. This means the 
passdb *.tdb files are not being updated and all is retrieved & stored 
in MySQL.

I would like to migrate this to a 'regular' Samba 4.x setup with AD

Since the *.tdb files are not updated, I cannot copy the *.tdb files 
and go the classicupgrade route (from the wiki)
And it seems all other 'joining a domain' howto's in the wiki describe 
joining an AD domain, not an (old/classic) NT4 domain.

Ignoring the custom backend story, I guess my question is: can I join a 
Samba 4 to an existing (classic) NT4 domain and upgrade it to use AD?

One solution would be to first join the domain with a samba 3.6.x 
server, and then later migrate that one to 4.x

Is that the only solution or is there a direct way?

Regards,

Bram Matthys.