Hi, On Wed, Jun 17, 2009 at 02:39:54PM +0200, Ehlers, Kolja wrote: > Thanks for the fast reply. > > If I set the no-quorum-policy to ignore my 2 ciritical > resources, 2 virtual ip addresses are bound to each node. Of > course I dont want this to happen. You say I must use a fencing > technique/device to do what? To stonith the other node(s)? > Exactly how do I protect my virtual ips from being bound by > more than one node if I do not have a configurable power > supply.
The only way is to use stonith. That is going to protect your resources, because in case of split-brain one node won't start resources before it fences (i.e. kills) the other node. Besides, and that has been discussed often, it is highly recommendable to configure stonith. And there is really no excuse for not doing that, unless it is a stretch cluster. > And again all this theory only works if a majority > count subcluster has quorum, right? See above. > So there is nothing one can do in a two node cluster about a > split brain? I dont see how this is an advantage over just > defining one node as the master node to take over all resources > during a split brain and all other node will not run critical > resources anymore. What if your master node is really down? How do you know it is a split brain? Thanks, Dejan > > Thanks > > > -----Urspr?ngliche Nachricht----- > Von: [email protected] > [mailto:[email protected]] Im Auftrag von Dejan Muhamedagic > Gesendet: Mittwoch, 17. Juni 2009 14:01 > An: General Linux-HA mailing list > Betreff: Re: [Linux-HA] General problems understanding split brain (quorum) > > Hi, > > On Wed, Jun 17, 2009 at 12:55:41PM +0200, Ehlers, Kolja wrote: > > Hello everybody, > > > > I am having problems understanding split brain situations. If I > > understand correctly when a split brain situation happens the larger > > cluster fragment have quorum and these cluster members can decide to fence > > off resources or to stonith the cluster members which > are not seen. > > > > I have read that it is not sane to use a 2 node cluster, because in > > split brain situations no one has quorum and the no-quorum-policy > > decides how to deal with this. > > There is no quorum in two-node clusters, so you set the policy to "ignore". > You can use fencing to effectively replace it. > > > But what if I > > have a 3 node cluster and the switch delivering the heartbeat between > > those members dies. Then again I will have three separate clusters > > each consisting of only 1 node and none having quorum. > > Right. Make sure that your switch doesn't die. Or use more than one switch. > > > If I think of a split brain would it not be the best action to merge > > all resources to the DC and the other node(s) will shut down? Is this > > not possible to configure? > > No. > > Thanks, > > Dejan > > > Thanks for your help > > > > Kolja > > > > Gesch?ftsf?hrung: Dr. Michael Fischer, Reinhard Eisebitt Amtsgericht > > K?ln HRB 32356 > > Steuer-Nr.: 217/5717/0536 > > Ust.Id.-Nr.: DE 204051920 > > -- > > This email transmission and any documents, files or previous email > > messages attached to it may contain information that is confidential > > or legally privileged. If you are not the intended recipient or a > > person responsible for delivering this transmission to the intended > > recipient, you are hereby notified that any disclosure, copying, > > printing, distribution or use of this transmission is strictly > > prohibited. If you have received this transmission in error, please > > immediately notify the sender by telephone or return email and delete > > the original transmission and its attachments without reading or saving in > > any manner. > > > > > _______________________________________________ > > Linux-HA mailing list > > [email protected] > > http://lists.linux-ha.org/mailman/listinfo/linux-ha > > See also: http://linux-ha.org/ReportingProblems > _______________________________________________ > Linux-HA mailing list > [email protected] > http://lists.linux-ha.org/mailman/listinfo/linux-ha > See also: http://linux-ha.org/ReportingProblems > > Gesch?ftsf?hrung: Dr. Michael Fischer, Reinhard Eisebitt > Amtsgericht K?ln HRB 32356 > Steuer-Nr.: 217/5717/0536 > Ust.Id.-Nr.: DE 204051920 > -- > This email transmission and any documents, files or previous email > messages attached to it may contain information that is confidential or > legally privileged. If you are not the intended recipient or a person > responsible for delivering this transmission to the intended recipient, > you are hereby notified that any disclosure, copying, printing, > distribution or use of this transmission is strictly prohibited. If you > have received this transmission in error, please immediately notify the > sender by telephone or return email and delete the original transmission > and its attachments without reading or saving in any manner. > > _______________________________________________ > Linux-HA mailing list > [email protected] > http://lists.linux-ha.org/mailman/listinfo/linux-ha > See also: http://linux-ha.org/ReportingProblems _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
