Hi! Maybe someone feels motivated to write some article comparing the concepts * split brain * quorum * fencing
There are eight possible states that I tried to illustrate on the attached sketch (S="Split Brain", "Q=Quorum, F=Fencing). ;-) Regards, Ulrich >>> Andrei Borzenkov 21.07.2021, 07:52 >>> On 21.07.2021 07:28, Strahil Nikolov via Users wrote: > Hi, > consider using a 3rd system as a Q disk. What was not clear in "Quorum is a different concept and doesn't remove the need for fencing"? > Also, you can use iscsi from that node as a SBD device, so you will have > proper fencing .If you don't have a hardware watchdog device, you can use > softdog kernel module for that. > Best Regards,Strahil Nikolov > > > On Wed, Jul 21, 2021 at 1:45, Digimer<li...@alteeve.ca> wrote: On 2021-07-20 > 6:04 p.m., john tillman wrote: >> Greetings, >> >> Is it possible to configure a two node cluster (pacemaker 2.0) without >> fencing and avoid split brain? > > No. > >> I was hoping there was a way to use a 3rd node's ip address, like from a >> network switch, as a tie breaker to provide quorum. A simple successful >> ping would do it. > > Quorum is a different concept and doesn't remove the need for fencing. > >> I realize that this 'ping' approach is not the bullet proof solution that >> fencing would provide. However, it may be an improvement over two nodes >> alone. > > It would be, at best, a false sense of security. > >> Is there a configuration like that already? Any other ideas? >> >> Pointers to useful documents/discussions on avoiding split brain with two >> node clusters would be welcome. > > https://www.alteeve.com/w/The_2-Node_Myth > > (note: currently throwing a cert error related to the let's encrypt > issue, should be cleared up soon). > > > _______________________________________________ > Manage your subscription: > https://lists.clusterlabs.org/mailman/listinfo/users > > ClusterLabs home: https://www.clusterlabs.org/ > _______________________________________________ Manage your subscription: https://lists.clusterlabs.org/mailman/listinfo/users ClusterLabs home: https://www.clusterlabs.org/
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