The Datanodes periodically update the Namenode about its presence or any changes in the blocks. The default Datanode heartbeat time is three seconds. But this does not mean that if a Datanode does not send a heartbeat for, say, 10 seconds, that the node will be marked dead.
In this recipe, we will look at how a heartbeat is configured and the parameters that play a role in its function.
You have a running cluster, and the user is familiar with Datanode communication with Namenode.
hdfs-site.xmlfile to add the following property to it:
<property> <name>dfs.heartbeat.interval</name> <value>3</value> </property> <property> <name>dfs.namenode.heartbeat.recheck-interval</name> ...