Question-41: What are the two possible state of the Cloudera Hadoop Cluster as per the Cloudera Manager?

Answer: Cloudera Manager Maintains following two stats of the cluster

• Model - This tells the state of the Clusters, Hosts, Services, Roles & Config. Using the model state Cloudera Manager captures what is supposed to run where, and what configurations. Like 20 node cluster models can tell you that all 20 nodes should run DataNode. 
• Runtime: It tells what is currently and where it is running e.g. HDFS rebalancing

Suppose you update any configuration like port for any service etc, you have updated the model state. 

Question-42: Why do you see “outdated configuration” for one of the services?

Answer: When you update the configuration let’s say Hue Web Server port, which update the model state. It still uses the old configuration like port. When such mismatch occurs then the role is marked with the “Outdated Configuration” and for synchronization we have to restart that role. 

Question-43: What is Cloudera Express and Cloudera Enterprise?

Answer: Cloudera Express has the free version of Cloudera Manager, while Cloudera Enterprise does not have free Cloudera Manager, you can have 60 days trial version for that. And after that you need a license to use full featured Cloudera Manager.

Question-44: What do you mean that Cloudera Manager maintains the separate configuration for both Server and Client?

Answer: Service instance started by Cloudera Manager does not read configuration from the default location like /etc/hadoop/conf. If you are not using Cloudera Manager then both the Server-side daemon process and client running on the same host would read configuration on the same location e.g. /etc/hadoop/conf 

Without Cloudera Manager

With Cloudera Manager

However, Cloudera Manager distinguishes the Server and Client configurations. Client read the configuration from the default location as mentioned above while server-side Role instance read configuration from a private per-process directory under /var/run/Cloudera -scm-agent/process/ This helps in not exposing sensitive information to the client like Passwords. 

Question-45: With Cloudera Manager can you use init script to start and stop services?

Answer: No, Cloudera Manager does not use init scripts for the daemons it manages. Cloudera Manager uses the open source tool called “supervisord”, that starts processes, which takes care of redirecting log files, notifying of process failures, setting the effective user id of the calling process.