[Pacemaker] Strange behaviour of dual master DRBD

[Michael Schwartzkopff]

Am Donnerstag, 10. September 2009 19:25:53 schrieb Lars Ellenberg:
> On Thu, Sep 10, 2009 at 05:10:39PM +0200, Michael Schwartzkopff wrote:
> > Hi,
> >
> > I configured a dual master DRBD-8.3.2. When the nodes stat there is no
> > problem. Both DRBD become master. But when I set on node to standby and
> > wake it up again, the DRBD on that node stays secondary and does not
> > become master.
> >
> > My config:
> > primitive resDRBD ocf:linbit:drbd params drbd_resource="r0"
> > ms msDRBD resDRBD meta notify="true" master-max="2"
> >
> > No further constraints.
> >
> > When the second node is online again ptest -sL shows:
> > (...)
> > resDRBD:0 promotion score on suse2: 50
> > resDRBD:1 promotion scpre on suse1: -1
> >
> > Since the "-1" prevents the resource from beein promoted, I understand
> > the behaviour of the cluster, but why isn't the resource beeing allowed
> > th become master on that node?
> >
> > Thanks for any enlightenting answers.
>
> Most likely it prevents you from shoting yourself in the foot ;)
>
> look at /proc/drbd and the kernel logs (appart from the ha.log, of
> course) on the drbd nodes to find out more.
> I bet you manoevered yourself into diverging data sets (aka DRBD "split
> brain").
>
> If it turns out to be a drbd.ocf bug,
> let me know.

Hi,

another confusing fact:

The primitive DRBD was created without a monitor operation. When I add a 
monitor operation, better two (Master,Slave) the described problem goes away. 
But in my understanding the complete setup should work as expected WITHOUT the 
monitoring operation.

-- 
Dr. Michael Schwartzkopff
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