Server Icinga crash -> out of memory

[moreamazingnick]

@anon66228339

The Galera Cluster documentaion tell us we need a minimum of 3 nodes to
create a cluster. Each node should run on a seperate hardware and if
possible in three different data centers. But if you have only 2 it will
also work, but dont let them run on the same hardware or hypervisor.

Galera MySQL cluster with VIPs and HAProxy for IDO-Mysql and more