[Samba] Samba4 Multi-Master replication

[Gémes Géza]

On 2012-06-12 12:16, Morten Kramer wrote:
> Hi guys,
>
>
> I'm trying to get the Samba4 multi-master replication to work.
>
>
>
> I set up the primary domain controller using this howto (under CentOS
> 6.2 x64):
>
>
> http://wiki.samba.org/index.php/Samba4/HOWTO
>
>
>
> I installed bind 9.8.3 and enabled encrypted dns updates.
>
>
>
>
> I set up another VM with the same CentOS version and oriented myself
> on this howto:
>
> http://wiki.samba.org/index.php/Samba4/HOWTO/Join_a_domain_as_a_DC
>
> to join the second DC into the domain. I edited /etc/resolv.conf and
> set the nameserver to the IP of the primary DC (bind dns server).
>
>
> Basic replication seems to work (not doing the rsync for sysvol yet).
> However, when i take the primary DC offline (bind keeps running), I
> can't use any of the .msc domain admin tools anymore.
>
> I always get an error message, telling me that there is no RPC server
> available.
> When i run gpmc.msc i can choose the DC i want to work on and I can
> see the secondary one, but it will come back with the RPC error.
>
> I had Wireshark running on one of the Windows7 clients. It seems like
> it tries to talk to the 2nd DC (DCERPC packets). But i'm not an expert
> in packet analysis, could somebody give me a hint what to look for here?
>
>
>
> User authentication does still work and Kerberos tickets are generated
> by the 2nd DC.
>
>
>
> I can find this in the log:
>
>
> ../source4/dsdb/kcc/kcc_topology.c:1402: failed to find nCName
> attribute of object
> CN=ac7bf69c-9458-4205-acba-6fe172412d1b,CN=Partitions,CN=Configuration,DC=aeriatest2,DC=dc,DC=loc
> ../source4/dsdb/kcc/kcc_topology.c:3158: failed to color vertices:
> NT_STATUS_INTERNAL_DB_CORRUPTION
> ../source4/dsdb/kcc/kcc_topology.c:3415: failed to create connections:
> NT_STATUS_INTERNAL_DB_CORRUPTION
> ...
> Warning: 60 extra bytes in incoming RPC request
> ../source4/rpc_server/drsuapi/dcesrv_drsuapi.c:74: doing DsBind with
> system_session
>
>
>
> Do i need to configure something extra, so the secondary DC will be
> able to act as an RPC server?
>
>
>
>
>
> Thanks,
> freezer
Hi,

With your setup DNS is the single point of failure, because with the
(default) DLZ setup bind9 is able to serve DNS records only when samba4
is running on that box.
My recommendation would be to try to set up DNS on the second DC too.

Regards.

Geza