Ensure that the host's hostname is configured properly.
Ensure that port 7182 is accessible on the Cloudera Manager Server (check firewall rules).
Ensure that ports 9000 and 9001 are free on the host being added.
Check agent logs in /var/log/cloudera-scm-agent/ on the host being added (some of the logs can be found in the installation details).
修改/etc/sysconfig/network中的hostname
然後再修改/etc/hosts
參考
http://www.rackspace.com/knowledge_center/article/centos-hostname-change