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.
ssh to Namenode and edit the
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> <value>300000</value> </property>
Copy
hdfs-site.xmlacross all nodes in the cluster.Restart HDFS daemons across nodes for the property to take effect:
$ stop-dfs.sh...