[DRBD-user] .drbdctrl and resource roles

[Roland Kammerer]

On Fri, Nov 09, 2018 at 11:27:41AM +0100, Julien Escario wrote:
> Le 09/11/2018 à 11:20, Roland Kammerer a écrit :
> > On Thu, Nov 08, 2018 at 09:58:28PM +0200, Daniel Hertanu wrote:
> >> I would like to understand why, on server2, .drbdctrl role is secondary and
> >> res1 role is primary, while on server3 .drbdctrl role is primary and res1
> >> role is secondary.
> > 
> > Why not? A resource is Primary on that host that "uses" it. Auto-promote
> > with DRBD9 and an open(), or set to Primary.
> > 
> >> I can switch res1 primary role between server2 and server3 without problems
> >> but I can't do anything about .drbdctrl. Trying to change the role to
> >> secondary on server3 doesn't return any error but it's just not happening.
> > 
> > a) don't touch the control-volume. Drbdmanage, and only drbdmanage is
> > responsible to switch it Primary on a node. You do not do that manually,
> > DM selects one. You can stop all nodes, manually switch it to Primary on
> > your favorite host and then start all cluster nodes. Then you
> > "preselected" a leader node.
> 
> May I add that's it's already a strange state as AFAIK when no
> management task is executed BOTH .drbdctrl should be in secondary state.

FWIW (nothing, because DM is EoL), that behavior was changed years ago.
Opening/closing the ctlrvol was a bottleneck. That was why we introduced
the whole leader/satellite thing. The leader is the only node that has
it open, always. So that state is perfectly fine.