[Openais] Split brain when using EVS library

Lars Marowsky-Bree lmb at suse.de
Sat Sep 13 09:16:45 PDT 2008


On 2008-09-09T11:18:59, David Teigland <teigland at redhat.com> wrote:

> > For some reason our cluster splits up into two rings.
> > Scenario is:
> > node1(n1) n2 n3 n4 n5 n6 are in the ring.
> > 
> > Suddenly the ring splits into two rings:
> > n1 n2 n3 got leave msg from n4 n5 n6
> > n4 n5 n6 got leave msg from n1 n2 n3
> > 
> > After a few milliseconds the two rings joins again:
> > n1 n2 n3 got join msg from n4 n5 n6
> > n4 n5 n6 got join msg from n1 n2 n3
> > 
> > The two ring is joined to one ring again:
> > node1(n1) n2 n3 n4 n5 n6 are in the ring.
> 
> We at RH have struggled a great deal with this exact "feature" for quite a
> long time.  It's the biggest problem by far that we've had using openais.

Any insights as to why this occurs? Random membership fluctuations are
... a problem.

Pacemaker can, AFAIK, deal with the rings healing, but the splits are
worrying, as they might cause recovery action to occur.


Regards,
    Lars

-- 
Teamlead Kernel, SuSE Labs, Research and Development
SUSE LINUX Products GmbH, GF: Markus Rex, HRB 16746 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde



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