ccah-500 第34题 you want to change a configuration parameter so that it affects all six DataNodes

34.What two processes must you do if you are running a Hadoop cluster with a single NameNode and six DataNodes, and you want to change a configuration parameter so that it affects all six DataNodes.(Choose two)

A. You must modify the configuration files on the NameNode only. DataNodes read their configuration from the master nodes

B. You must modify the configuration files on each of the six dataNodes machines

C. You don't need to restart any daemon, as they will pick up changes automatically

D. You must restart the NameNode daemon to apply the changes to the cluster

E. You must restart all six DatNode daemon to apply the changes to the cluster

Answer: B,E

 

reference:

http://www.cloudera.com/documentation/archive/manager/4-x/4-8-2/Cloudera-Manager-Managing-Clusters/cmmc_mod_configs.html

Restarting Services and Instances after Configuration Changes

If you change the configuration settings after you start a service or instance, you may need to restart the service or instance to have the configuration settings become active. If you need to restart, a message is displayed
at the top of the Configuration tab when you save your changes.

  Note: If you change configuration settings at the service level that affect a particular role only (such as all DataNodes
but not the NameNodes), you can restart only that role; you do not need to restart the entire service. If you changed the configuration for a particular instance only (such as one of four DataNodes), you may need to restart only that instance.