[corosync] Allow votequorum to degrade to a single node without qdisc?

Fabio M. Di Nitto fdinitto at redhat.com
Thu Nov 7 06:40:33 UTC 2013


On 11/06/2013 09:44 PM, Jason Harley wrote:
> Hello —
> 
> I have a four node Corosync (2.3.0-1ubuntu4) cluster configured and happy.  However, I’d like to be able to allow the cluster to degrade to a single node in an (extreme) failure state — but still require (at least) two nodes to establish the cluster.  Using qdisc is not an option in my environment, so I’m curious if I can achieve this using new features in ‘Needle’ like ‘last_man_standing’ and ‘auto_tie_breaker’.
> 
> This is the ‘quorum’ block from my corosync.conf:
> 
>> quorum {
>>         provider: corosync_votequorum
>>         expected_votes: 4
>>         last_man_standing: 1
>>         last_man_standing_window: 10000
>>         auto_tie_breaker: 1
>> }
> 
> 
> Is this as simple as telling votequorum that I have a two node cluster (‘two_node: 1’) and enabling ‘allow_downscale’?

We should really change the man page to mark allow_downscale as
unsupported. It's only 90% implemented before people will shot
themselves in the foot.

Chrissie can you please take care of it?

Fabio


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