We are using external database PostgreSQL for all our service like Hive, Sentry, Hue, etc. on our Hadoop cluster. We need to apply periodic security patches and reboot this Linux server hosting PostgreSQL database.   My question is what should we do with Hadoop cluster during this PostgreSQL server maintenance and reboot. We will ensure that this cluster is not used during this maintenance window.   Should we put Hadoop cluster in maintenance mode or we should completely stop the service on this cluster. ... View more