Unknown health for all hosts, and "Internal error while querying the Host Monitor"

On Friday, June 28, 2013 11:25:50 AM UTC-7, Hao Huang wrote:
All nodes show unknown health, and I can't see any status for any roles
due to error "Internal error while querying the Host Monitor".
How to fix this? I'm pretty new to CDH and Hadoop, so I don't know which
log I should show.

my /etc/hosts file for all nodes are

127.0.0.1 localhost
10.0.0.1 node1
10.0.0.2 node2
10.0.0.3 node3
10.0.0.4 node4
10.0.0.5 node5