In a NiFi Cluster If a node goes down, it is known that the flow can be directed to another node, but what about the data that is queued in the failed node? Will have to wait until the node comes back up or it is taken care by another node? Please explain how it handles this scenario.
NiFi does not replicate data. If you lose a node, then flow can be directed to a available node , flowfile queued for the failed node will either wait until the node comes up or the flowfile is manually is sent to another working node. There is feature proposal for this https://cwiki.apache.org/confluence/display/NIFI/Data+Replication