[ClusterLabs] Recovering after split-brain

Digimer lists at alteeve.ca
Tue Jun 21 12:47:11 EDT 2016

On 21/06/16 10:57 AM, Dmitri Maziuk wrote:
> On 2016-06-20 17:19, Digimer wrote:
>> Nikhil indicated that they could switch where traffic went up-stream
>> without issue, if I understood properly.
> They have some interesting setup, but that notwithstanding: if split
> brain happens some clients will connect to "old master" and some: to
> "new master", dep. on arp update. If there's a shared resource
> unavailable on one node, clients going there will error out. The other
> ones will not. It will work for some clients.
> Cf. both nodes going into stonith deathmatch and killing each other: the
> service now is not available for all clients. What I don't get is the
> blanket assertion that this "more highly" available that option #1.
> Dimitri

As I've explained many times (here and on IRC);

If you don't need to coordinate services/access, you don't need HA.

If you do need to coordinate services/access, you need fencing.

So if Nikhil really believes s/he doesn't need fencing and that
split-brains are OK, then drop HA. If that is not the case, then s/he
needs to implement fencing in pacemaker. It's pretty much that simple.

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