@sneha challa We need to check if the "Port Forwarding" for the port 8888 is present or not? Please check: https://community.hortonworks.com/articles/65914/how-to-add-ports-to-the-hdp-25-virtualbox-sandbox.html - We can also check if we have set the networking mode to host-only on the VirtualBox instance. - If the port forwarding is enabled for 8888 port then we should check if by any chance firewall is not causing any issue. - So please try to do SSH to the sandbox as following (on port 2222 only), Default password should be "hadoop" # ssh root@127.0.0.1 -p 2222 - After doing SSH, please check if the firewall is disabled. # service iptables status iptables: Firewall is not running. - Also please check if the port 8888 is opened inside the Sandbox? # netstat -tnlpa | grep 8888 . ... View more

@Sami Ahmad - If we try to understand what is happening behind the error: 2017-06-16 21:27:10,803 - Error downloading DBConnectionVerification.jar from Ambari Server resources. Check network access to Ambari Server. HTTP Error 504: Gateway Timeout - Ambari uses the following JAR "/var/lib/ambari-server/resources/DBConnectionVerification.jar" to perform various DB connectivity tests. - This JAR need to be present in all the Ambari Agent Hosts. So Ambari Agents uses the following URL to download the mentioned JAR from ambari server host and then puts it inside their "/var/lib/ambari-agent/tmp/DBConnectionVerification.jar" location. http://$AMBARI_SERVERHOST:8080/resources/DBConnectionVerification.jar - Now if due to some reason the agents are not able to download this JAR from ambari server host over HTTP then the clients (agents) will fail to perform the DB connection check. - In your case the Agents are not able to download this JAR from ambari server host because of the following error: HTTP Error 504: Gateway Timeout - This indicates that from the agent machines the following URL access is failing (using wget here just for demo, agents will use the python approach to download this jar): wget http://$AMBARI_SERVERHOST:8080/resources/DBConnectionVerification.jar What is the root cause: - Putting this JAR manually from Ambari Server host to Agents machines can make it work temporarily, but it will not fix the permanent issue. We should findout why the Agents are not able to download this jar from ambari server host. Agents should be able to access ambari server resources using HTTP. . ... View more

@Sami Ahmad Ambari Agent can be installed manually as well as via Ambari UI and both options are valid. You mentioned that "apparently ambari install is expecting ambari-agent to be installed already?" >>> Ambari Server installation does not require the agent to be installed already. Can you please share the Ambari Server installation log/output of the console which makes you feel that ambari installation is expecting agent installation? . Are you getting the same IOError and file not found on every ambari agent host? /usr/sbin/ambari-agent: line 97: ambari-sudo.sh: command not found IOError: [Errno 2] No such file or directory: \'/var/lib/ambari-agent/data/version\' If that is happening on any particular Agent host then it might be due to incomplete agent installation. So either you willl need to check the "yum.log" to see if the agent installation was successful or not? (OR) Better to run the following command manually on the agent hosts to recover the installation. # yum reinstall ambari-agent -y . ... View more