Monitoring Data - Big Data Made Easy: A Working Guide to the Complete Hadoop Toolset - page 209

Then I restart the Ganglia gmond server by using the Linux service command:
service gmond restart
I make sure that the httpd daemon is running on hc1nn; this supports the Ganglia web interface:
service httpd restart
Also, I make sure that selinux is disabled on all nodes by checking that the SELINUX value is set to the file /etc/
sysconfig/selinux. If this is not the case, then I will need to make the following change and restart my Linux servers:
[root@hc1nn ganglia]# vi /etc/sysconfig/selinux
SELINUX=disabled
Now I wait for the minimum monitoring interval of 120 seconds and attempt to access my Ganglia web interface
by using the URL http://<collector server>/ganglia/ . For example, the name of my collector server is hc1nn, with
an IP address of 192.168.1.107, making the URL http://hc1nn/ganglia/ .
At this point, I can enable Hadoop metrics collection on all Hadoop servers by editing the hadoop-metrics.
properties file in /etc/hadoop/conf.
[root@hc1r1m1 conf]# cd /etc/hadoop/conf
vi hadoop-metrics.properties
dfs.class=org.apache.hadoop.metrics.ganglia.GangliaContext
dfs.period=10
dfs.servers=localhost:8649
mapred.class=org.apache.hadoop.metrics.ganglia.GangliaContext
mapred.period=10
mapred.servers=localhost:8649
jvm.class=org.apache.hadoop.metrics.ganglia.GangliaContext
jvm.period=10
jvm.servers=localhost:8649
rpc.class=org.apache.hadoop.metrics.ganglia.GangliaContext
rpc.period=10
rpc.servers=localhost:8649
I restart the Hadoop cluster to make the changes take effect.