[ClusterLabs] how start resources on the last running node

[Ken Gaillot]

On 04/04/2017 10:01 AM, Ján Poctavek wrote:
> Hi,
> 
> I came here to ask for some inspiration about my cluster setup.
> 
> I have 3-node pcs+corosync+pacemaker cluster. When majority of nodes
> exist in the cluster, everything is working fine. But what recovery
> options do I have when I lose 2 of 3 nodes? If I know for sure that the
> missing nodes are turned off, is there any command to force start of the
> resources? The idea is to make the resources available (by
> administrative command) even without majority of nodes and when the
> other nodes become reachable again, they will normally join to the
> cluster without any manual intervention.
> 
> All nodes are set with wait_for_all, stonith-enabled=false and
> no-quorum-policy=stop.
> 
> Thank you.
> 
> Jan

In general, no. The cluster must have quorum to serve resources.

However, corosync is versatile in how it can define quorum. See the
votequorum(5) man page regarding last_man_standing, auto_tie_breaker,
and allow_downscale. Also, the newest version of corosync supports
qdevice, which is a special quorum arbitrator.