[Samba] What happens if I turn the DC off?

[Rowland Penny]

On Wed, 18 Jul 2018 10:26:31 +0200
"Stefan G. Weichinger via samba" <samba at lists.samba.org> wrote:

> 
> I assume I know it ... but I think this is worth being discussed and 
> clarified.
> 
> At a customer we have 1 samba DC and 1 samba DM = fileserver.
> 
> The DC is supported by a small UPS and the battery in that UPS is 
> getting old and tells me to replace it.
> 
> While it might be possible to swap the battery "online" I prefer to
> shut the supplied server(s) down and do it offline.
> 
> That means turning the DC off.
> 
> And now the question(s): will the PCs notice that? Is it possible to
> use network shares etc while the DC is offline for about 10 minutes?
> Or will the PCs hit problems right away?

Have you ever heard of laptops ? you know those things that wander away
from the domain ;-)

> 
> I understand that logins might fail, sure, but maybe the
> authenticated connections to the DM could be maintained by the DM
> itself for a short period of time?

No, Windows clients should be okay, provided they have logged in at
least once recently, Unix domain members will require 'winbind offline
logon = yes' in smb.conf

> 
> Sorry if I ask obvious things here or show my misunderstanding ...
> but I never tried that and wonder what happens.
> 
> Sure, a 2nd DC would be much better, I know.

Oh definitely, but you can only work with the resources you have and
before anybody mentions VM's, these are only any good if they are on
different machines. If they are on the same machine and the machine
falls over, then you lose both of them.

Rowland