There are 3 MON needed, what happens if any of node go down? Will it impact the Cluster Work?
Temporarily (for minutes, hours, or even days) the cluster will survive just fine with only 2 MONs, giving you the deliberate time that you need to replace the failed MON. The longer the cluster goes with only 2 MONs, the higher the risk that the 2 MONs will get out of sync and will not be able to serve the cluster maps to clients. While the cluster is operating with only 2 MONs, the cluster health will be reported as “HEALTH_WARN”, but the cluster will still operate.