On 18/04/17 08:50 PM, Dimitri Maziuk wrote: > On 04/18/2017 07:05 PM, Digimer wrote: > >> Certainly, the people creating the software have to assume that a >> split-brain is devastating. Same for people who teach others and people >> who write documentation. > > <sigh.../> split brain is devastating when you're drbd. When you're a > mere floating ip, assume makes an ass of you and me.
If you want to talk about a hypothetical cluster where the only thing hosted is an IP, and nothing else, then yes, a split-brain would mean that you have a random node accessible. This is not a common configuration, to be sure, if you don't care that the active node will waffle back and forth whenever a node says that it has the IP. The majority of clusters are not so simple. In the *vast* majority of real-world clusters, a split-brain is devastating. We've seen for years how people misbelieve that fencing is optional, and we've seen countless people coming along asking why their cluster "that worked fine for years!", is not offline or, worse, destroyed. Given how rare your proposed scenario is, it strikes me that suggesting fencing is optional is a dis-service with potentially devastating consequences for those new to the technology. So, I stand by my statement that all clusters need fencing. -- Digimer Papers and Projects: https://alteeve.com/w/ "I am, somehow, less interested in the weight and convolutions of Einstein’s brain than in the near certainty that people of equal talent have lived and died in cotton fields and sweatshops." - Stephen Jay Gould _______________________________________________ Users mailing list: Users@clusterlabs.org http://lists.clusterlabs.org/mailman/listinfo/users Project Home: http://www.clusterlabs.org Getting started: http://www.clusterlabs.org/doc/Cluster_from_Scratch.pdf Bugs: http://bugs.clusterlabs.org