What is hadoop_secure_dn_pid under /var/run/hadoop/hdfs directory?

[#1 · Accepted solution]

@Ashwini Patkar

In a kerberized environment the DataNode does not use the RPC framework of Hadoop, DataNode must authenticate itself by using privileged ports which are specified by dfs.datanode.address and dfs.datanode.http.address. There you will see this PID is being used. "/var/run/hadoop/hdfs/hadoop_secure_dn.pid"

Example:

jsvc.exec -Dproc_datanode -outfile /var/log/hadoop/hdfs/jsvc.out -errfile /var/log/hadoop/hdfs/jsvc.err -pidfile /var/run/hadoop/hdfs/hadoop_secure_dn.pid

You can find the "HADOOP_SECURE_DN_PID" parameter info inside the "/usr/hdp/current/hadoop-hdfs-datanode/bin/hdfs.distro" file.

Please see: https://community.hortonworks.com/articles/90673/why-datanodes-have-two-processes-on-a-kerberized-c....

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[#2]

Thanks@Jay SenSharma ...i understood the parameter..but i'm facing one problem with this. I had set the permission rights for both of the pid but when i checked this few days back permissions was changed..i set that back and today again i found it has changed.So can anybody help me with this..what will be the cause to change this parameter's permissions frequently?