Technical troubleshooting and more

Hi All, This is a very simple operation intend to be very confusing as I saw in other posts I read. What you will need to add storage to hadoop is a new disk, mounted on a new volume (directory) After you got a new disk, ask you system administrator to mount him on a new desired directory: [root@RHEL7datanode1 ~]# mkdir -p /hadoop/add_disk/ [root@RHEL7datanode1 ~]# chown -R hdfs:hadoop /hadoop [root@RHEL7datanode1 ~]# su - hdfs now you need to change conf file and add this new folder to the hdfs-site.xml vi /usr/hdp/2.3.0.0-2557/hadoop/conf/hdfs-site.xml     <property>       <name>dfs.datanode.data.dir</name>       <value>/data2/hdp,/data1/hdp, /hadoop/add_disk </value>     </property> Restart datanode: [hdfs@RHEL7datanode1 ~]$ /usr/hdp/2.3.0.0-2557/hadoop/sbin/hadoop-daemon.sh stop datanode stopping datanode [hdfs@RHEL7datanode1 ~]$ /usr/hdp/2.3.0.0-2557/hadoop/sbin/hadoop-daemon.sh startp datanode starting datanode, loggin

This time I faced this scenario, One of my client called me and tell me that his application server faces difficulties to create the connection pool against the DB. first I have checked the DB server side and I saw everything is ok I tried to connect from my laptop - again OK from the application server things were getting weird.. once every few tnsping commands or sqlplus command using tnsnames.ora sqlnet.ora the command tooks more than 10 seconds to return to prompt... I did these changes to isolate the problem sqlnet.ora I've changed - SQLNET . AUTHENTICATION_SERVICES = ( NTS ) to: SQLNET . AUTHENTICATION_SERVICES = ( NONE ) and  in the tnsnames.ora - I've used IP instead of the DB hostname. but still - same behavior as above. then I've started to drill down and found these amazing finding: * in the registry key called TNS_ADMIN under LOCAL MACHINE -> SOFTWARE -> ORACLE I found out that the value is pointing to a centralized Oracle client s