[DRBD-user] Proxmox VE 4.x DRBD 9 plugin - how is it supposed to work?

Roland Kammerer roland.kammerer at linbit.com
Wed Mar 1 09:27:23 CET 2017

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

On Tue, Feb 28, 2017 at 08:44:46AM -0800, Sean M. Pappalardo wrote:
> On 02/28/2017 12:44 AM, Roland Kammerer wrote:
> >> The doc also implies that it will handle live-migration as
> >> well, even though dual-primary is not yet supported. Is this true?
> > 
> > Yes it uses dual-primary, only during the migration. From what we saw it
> > works reasonably well in these scenarios.
> Oh one other question: At what level does this happen? Per VG or per LV?
> Put another way, does drbdmanage create a separate resource per LV? Or
> does that depend on the storage plugin chosen? (I understand each VM
> disk image gets its own LV.)


I remembered that part wrong and described how it should be, not how it
actually is :-/. From what I see in the plugin, "allow-tow-primaries" is
set in alloc_image() and never reset. Honestly, I don't know if Proxmox
even provides hooks for live migration where this could be turned on and
back off again.

With the LVM/LVM-thin plugins drbdmanage creates an LV for every DRBD
volume (in general a resource can have multiple volumes). AFAIK in
Proxmox environments it is one volume per resource. So you end up with
one LV per resource. The "allow-two-primaries" is set on resource level.
But as I know now, it is enabled for every resource created via the

Regards, rck

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