Backup DC promotion

I would like to test demotion of master DC so that the backup DC is promoted as new master. Is there any doc which explains what to check in such situation? What I mean, is there a way to flip over or should I just take offline the current master DC?

Also 2 related questions:

  • I already installed a couple UCS applications (the self service one and the ucs dashboard) on the master DC. Do I have to install them also on the backup DC manually for them to be available after the ‘promotion’ process is completed?
  • what to do then with the failed (former) master DC host? Best to reinstall it from scratch and have it setup as (new) backup DC?

Thanks in advance


search for “backup2master” and you will find detailed instructions.
Yes, you should install the same apps on the backup so in case of emergency you are ready to go. And you have to decommission the former master completely. You will be able to install a new backup machine, though.


ok, found the docs, thanks for the pointer. It all went well AFAICS, though after promoting, I see this ucr var points to the former master DC hostname (where the self service app was installed):


this even after installing the self service app on the new master DC. Is it normal? Can I just update it to point to the new/current master DC hostname?

Also, a related question: can I now re-install the former master as backup DC without changing its hostname?



yes, simply set the variable to the new server name.

And no, you can not re-use the previous master. You have to decommission it.


sorry, perhaps I was not clear enough: what I had before:

it0auth -> backup
it1auth -> master

then I powered off (they are all VMs ) the master and promoted the backup as new master, so I have now only:

it0auth -> master

Now I want to install from scratch (i.e. from ISO image downloaded from univention) a new backup DC and want to give it the same hostname that was used by the former master DC (it1auth). Would that be ok?

side note, I don’t run samba, so there is no decommission script

# ls /usr/share/univention-samba4/scripts/
ls: cannot access '/usr/share/univention-samba4/scripts/': No such file or directory

just for the record: meanwhile I went ahead and all worked fine, I guess I was being too paranoid …