[DRBD-user] Forcing a device to be primary on a backup site

Philipp Marek philipp.marek at linbit.com
Wed Feb 3 07:10:53 CET 2016

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

> >> I now imagine that VM1 on cluster A becomes unreachable, so I want to 
> >> bring up VM1 on cluster B, and attach to it the replicated volume.
> >> I have to make the volume primary on cluster B.
> >> As long as the volume is primary on cluster A, I cannot make it primary 
> on 
> >> cluster B.
> >> 
> >> I want to force the transition of the volume on cluster B from 
> secondary 
> >> to primary, without having to perform operations on cluster A.
> >> 
> >> What is the proper sequence of operations / commands to accomplish 
> this?
> >As in your expected experiment, you will need to cut the communication path 
> >between the two sites.
> >The easiest way to do so is to run "drbdadm disconnect <resource>" on one 
> >of the sites; given your requirements, on cluster B.
> This changes the state of the volume on cluster B to "OutDated" and I am 
> unable
> to change the volume to primary. I seem to still be missing something.
No, that should be the correct way.

(I'm not sure about your exact sequence of events - depending on what 
happens on cluster A, the "OutDated" might be okay (because the "original" 
Primary sees that there are outstanding writes), or it might be a DRBD 
9 bug.
(Would you please tell me what /proc/drbd says? I'll need the exact git 

> I tried to do --force to make the volume primary, but then I was unable to
> import it to (OpenStack) cinder and attach it to an instance, since the id 
> was
> not recognized.
Hmmm, that's not related to DRBD.

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