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

Philipp Marek philipp.marek at linbit.com
Wed Feb 3 10:42:04 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.

> > >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 This changes the state of the volume on cluster B to "OutDated" and I am 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 happens on cluster A, the "OutDated" might be okay (because the "original" 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 
> hash.)
To expand on that a little bit - on a "graceful" disconnect DRBD will mark 
itself "OutDated" (on the Secondary).

You can either 
  * make DRBD Secondary on both sides (=> a "real" switchover)
  * or run a forced disconnect - that'll look more like a "connection 
    disrupted", and should leave DRBD as "UpToDate", and so a simple
    open() should be sufficient to make it Primary again.

Hope that helps!

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