Comment # 1 on bug 1055387 from nick wang

(In reply to Bill Weidman from comment #0)
> DRBD 9.0.x doesn't support dual-primary mode.  This is basic functionality
> necessary for live migrations using Xen.  Not having this makes Leap 42.3
> useless for Xen servers.
> 
> Recommend making the latest 8.4.x packages available until 9.0.x supports
> live migration.
> 
> http://docs.linbit.com/docs/users-guide-9.0/#s-dual-primary-mode
> 
> "With current DRBD-9.0 version running in Dual-Primary mode is not
> recommended...
> In DRBD-9.1 it will be possible to have more than two primaries at the same
> time."

I did have some conversation regarding deliver both drbd8.4 and drbd9, but we
decide to include drbd9 only to avoid the possible confusing.

I did try dual-primary in some early version of drbd9, the basic functionality
looks fine. I suggest you try the dual-primary on drbd9 for live migrations in
test environment first and report any issue you meet. 
And please not to use more than two nodes in dual-primary, i think this
scenario is not ready yet.