[Samba] 2 DCs FSMO when one DC die/accident offline

Marc Muehlfeld mmuehlfeld at samba.org
Sun Feb 22 04:48:12 MST 2015

Hello Min Wai,

Am 22.02.2015 um 12:19 schrieb Min Wai Chan:
> Let say I've 2 x vm (DC1 and DC2) both Vm on 2 different host.
> If there is a failure on host1 hardware and I'm unable to bring DC1 back
> online...
> Did I need to do the DC2 seizing FSMO roles? (Or it will be done
> automatically)

If DC is dead, you seize the roles on DC2. And you have to ensure, that
DC1 never comes back online with started Samba! Otherwise both think
they own the roles an it can cause damage in your AD fast.

> When happen in windows DC... was it done automatically or still need a DC2
> FSMO seizing?

It's the same like in Samba. Roles have to be transfered manually.

It can't be done automatically. Imaging the following: You mainboard is
broken on DC1. So nothing really serious, because it can be replaced
without effecting your OS. DC1 is offline for 2 days, until the new
mainboard arrives and you have replaced it. During that time you domain
is still online and everything is working, except the (in most
environments) negligible FSMO jobs

If DC1 comes online again and the role was seized automatically, you
have a split brain situation: DC2 would own the roles, and DC1 still
belive also to own. And both would assign RID pools and everything else
the roles are responsible for.

> I've this question when my DC1 offline and the Member server (CTDB later
> crash Zombies)
> So I wonder DC2 is still on but why...

Sorry. I don't understand that.
If DC1 is offline, why DC2 shouldn't be on? That's what multiple DCs in
an AD are for: Fail-over. :-)


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