<section>

            <title>Uninstallation of a Samba 4 domain controller</title>

			<para>

			  The removal of an Samba 4 DC (Active Directory-compatible domain controller) is a

			  far-reaching configuration step and should be prepared thoroughly.

			</para>

			<para>

			  At least on one DC master or DC backup must be the samba 4 packages installed in case

			  the domain should be Active Directory-compatible.

			</para>

			<para>

			  Before uninstalling the packages the domain controller must be removed from Samba 4.

			  That can be done with the helper script purge_s4_computer.py. It must be run on a DC

			  master or DC backup system.

			  The question 'Really remove master from Samba 4?' must be answered with Yes and

			  the question 'Really remove master from UDM as well?' must be answered with No,

			  e.g:

			</para>

<programlisting language="sh">

root@backup:~# /usr/share/univention-samba4/scripts/purge_s4_computer.py --computername=master

Really remove master from Samba 4? [y/N]: Yes

If you are really sure type YES and hit enter: YES

Ok, continuing as requested.

[...]

Removing CN=MASTER,CN=Computers,$ldap_BASE from SAM database.

Really remove master from UDM as well? [y/N]: No

Ok, stopping as requested.

root@backup:~#

</programlisting>

			<para>

			  The S4 connector must be run on one DC master or DC backup in the domain. If samba4

			  was uninstalled on a DC master or DC backup the S4 connector join

			  (97univention-s4-connector) script should be re-executed on another system. That can

			  be done via the UMC module 'Domain join', see <xref linkend="s4connector-rejoin"/>.

			</para>

			<figure id="s4connector-rejoin">

			  <title>Re-execute S4 connector join</title>

			  <graphic scalefit="1" width="80%" fileref="illustrations/s4connector-re-execute.png"/>

			</figure>

			<para>

			  The FSMO (Flexible Single Master Operations) roles should be checked. In case the

			  roles are used by the removed DC, they should be transfered, for example:

			</para>

<programlisting language="sh">

root@backup:~# samba-tool fsmo show

InfrastructureMasterRole owner: CN=NTDS Settings,CN=MASTER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dom,DC=local

RidAllocationMasterRole owner: CN=NTDS Settings,CN=MASTER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dom,DC=local

PdcEmulationMasterRole owner: CN=NTDS Settings,CN=MASTER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dom,DC=local

DomainNamingMasterRole owner: CN=NTDS Settings,CN=MASTER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dom,DC=local

SchemaMasterRole owner: CN=NTDS Settings,CN=MASTER,CN=Servers,CN=Default-First-Site-Name,CN=Sites,CN=Configuration,DC=dom,DC=local

root@backup:~# samba-tool fsmo seize --role=all --force

Will not attempt transfer, seizing...

FSMO transfer of 'rid' role successful

Will not attempt transfer, seizing...

FSMO transfer of 'pdc' role successful

Will not attempt transfer, seizing...

FSMO transfer of 'naming' role successful

Will not attempt transfer, seizing...

FSMO transfer of 'infrastructure' role successful

Will not attempt transfer, seizing...

FSMO transfer of 'schema' role successful

root@backup:~# 

</programlisting>

        </section>