how to check the namenode and datanoden logs in ambari? as the services are not getting started..

[#1]

how to check the namenode and datanoden logs ? as the services are not getting started..

[#2]

@divya_thaore 

Th default location is /var/log/hadoop/hdfs and here you wiill get

• hadoop-hdfs-datanode-<FQDN>.log
• hadoop-hdfs-datanode-<FQDN>.out
• hadoop-hdfs-secondarynamenode-<FQDN>.log
• hadoop-hdfs-secondarynamenode-<FQDN>.out

And it's important too to check the  host server messages

• /var/log/messages

Those files should contain the clue  all the .out are informative  look at the .log most probably the last few entries 

[#3]

I am not able to get how to reach to that location. Shall I go through the
command prompt ?

[#4]

@divya_thaore 

Yes please you need to use the Linux CLI to navigate  to those directories

[#5]

@divya_thaore 

1. If you are starting service via Ambari / Cloudera Manager UI then check the operation logs which are displayed in UI while you start the service

Please check for any errors in the logs clicking the service operational logs.

2. If you do not see any operational logs or any operation triggerred while you start/restart service then kindly restart agent service once [ambari agent/cloudera-scm-agent]

3. Else please check logs from cli as suggested by @Shelton 

If you still need help please revert.