quorum in a two-node cluster with pacemaker

I have two node active-passive cluster. Clusters_from_Scratch > If a cluster splits into two (or more) groups of nodes that can no > longer communicate with each other (aka. partitions), quorum is used > to prevent resources from starting on more nodes than desired, which > would risk data corruption. A cluster has quorum when more than half > of all known nodes are online in the same partition > > By the above definition, a two-node cluster would only have quorum > when both nodes are running. This would make the creation of a > two-node cluster pointless, but corosync has the ability to treat > two-node clusters as if only one node is required for quorum. The pcs > cluster setup command will automatically configure two_node: 1 in > corosync.conf, so a two-node cluster will "just work". Here's my config: So how can the cluster now decide which one has quorum?