core-site and hdfs-site contain information regarding IP addresses to use to connect your cluster. Depending of what is in your configuration files, your NiFi instance may not be able to reach HDFS. ... View more

Could you please provide logs in <NIFI dir>/logs/nifi-app.log? ... View more

Be careful: swap is not for flow files, it is for flow files attributes (it is not flow files content). Flow files content is written in the content repository, have a look here: https://nifi.apache.org/docs/nifi-docs/html/overview.html#nifi-architecture. Regarding swap, it depends of the implementation, but the default is to swap in the Flow File repository. ... View more

When you have a connection between two processors, you can right-click on it to configure it. Then, in settings tab, you can configure back pressure: https://nifi.apache.org/docs/nifi-docs/html/user-guide.html#settings ... View more

Swap is just about information stored in JVM memory. Flow files will be stored in the queue as long as you have available space on disks. However you may want to have a look at back pressure features: You can apply backpressure on a specific connection, it will cause the processor that is the source of the connection to stop being scheduled to run until the queue clears out. However data will still queue up in that processor's incoming connections. So to force backpressure to propagate all the way back to the source, you would need to configure each of the connections in the flow to have backpressure applied. ... View more

Hi @viswanatha reddy, If I am not mistaken, this property means that attributes linked to the related flow files will be swapped to disk instead of keeping the information in memory. In this case, it happens when there are more than queued 20000 flow files. Hope this helps. ... View more