Cloudera Hadoop Setup - HDFS Canary Health Check issue

After setting up Hadoop Cluster using Cloudera Manager, one of the common issues some of us face is Canary Health Check issues. This most often happens due to connectivity between the Master and Slave Nodes. In my case HDFS was throwing Canary error saying unable to write/read to /tmp/.cloudera_health_monitoring_canary_timestamp. Then I finally had to open corresponding Port on my DataNodes to resolve this error: Open ports from Firewall list: $ iptables-save | grep 8042 output: Will be blank $ firewall-cmd --zone=public --add-port=8042/tcp --permanent output: success $ firewall-cmd --reload output: success $ iptables-save | grep 8042 output: -A IN_public_allow -p tcp -m tcp --dport 7180 -m conntrack --ctstate NEW -j ACCEPT

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