[Samba] Failover DC did not work when Main DC failed

Rowland penny rpenny at samba.org
Wed Jan 29 16:43:11 UTC 2020

On 29/01/2020 15:55, Paul Littlefield via samba wrote:
> We have a main DC (dc3) and failover DC (dc4) running in a Proxmox 
> virtual environment.
> Both DCs are replicating happily and have been running for over a year 
> with no problems.
> This morning, our main DC (running as a VM) was backed up and then 
> restarted but Ubuntu did not start the 'samba-ad-dc' service on boot.
> The failover DC was up and running at the time, but staff could not 
> log in on their workstations and the QNAP file server (which is domain 
> joined) was also not happy.
> The fix was to reboot and everything was well again.
> Lesson learned... check port 135 as well as port 22 on Nagios, and 
> check that the failover DC works!
> My question... why didn't the failover DC do its job?
> Thanks,
> Paul
OK, where did you get the 'failover' DC from ?

As far as I am aware, all DC's are equal except for the FSMO roles and 
these can be on any DC. So terms like 'pdc', 'backup' and 'failover' are 
meaningless, they are all just a 'DC'.

It sounds like your clients are set up to just use the DC that went down 
as their nameserver etc.


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