[ClusterLabs] Two node cluster without fencing and no split brain?

[Strahil Nikolov]

Hi,
consider using a 3rd system as a Q disk. 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<lists at 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).

-- 
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
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