Monitoring Data - Big Data Made Easy: A Working Guide to the Complete Hadoop Toolset - page 210

Potential Errors
Potential Ganglia errors can relate to the web server configuration, permissions, access, and Ganglia servers that
might be down. Here are some common error messages and some possible solutions.
For example, if you encounter an error like this on the Ganglia web page:
Not Found
The requested URL /ganglia was not found on this server.
Apache/2.2.15 (CentOS) Server at 192.168.1.107 Port 80
the solution is to edit the Ganglia web configuration file /etc/httpd/conf.d/ganglia.conf and change the Deny line to an
Allow line. The # character comments out a line so that the httpd web server will ignore that line:
#Deny from all
Allow from all
Then you can restart the httpd service on the server hc1nn by using the Linux service command as the Linux
root user:
service httpd restart
Displayed on the Ganglia web user interface, an error like the following implies that the SELINUX option needs to
be disabled on the cluster:
There was an error collecting ganglia data (127.0.0.1:8652): fsockopen error: Permission denied
This means that Ganglia is not compatable with the option enabled. You edit the file /etc/sysconfig/selinux and
set the SELINUX option to the value disabled . You will need to do this as the Linux root user account and restart each
server afterwards. If you're in doubt, consult a systems administrator; otherwise, use the following command:
[root@hc1nn ganglia]# vi /etc/sysconfig/selinux
SELINUX=disabled
If an error like this occurs in the /var/log/messages file:
Aug 16 17:12:52 hc1nn /usr/sbin/gmetad[4575]: Please make sure that /var/lib/ganglia/rrds is owned
by ganglia
then the directory mentioned, /var/lib/ganglia/rrds, is not owned by the Linux ganglia user account. Check the
ownership of the directory by using the Linux ls long listing and it will show that it is owned by “nobody.” You can
reset ownership recursively using the Linux chmod -R command:
[root@hc1nn log]# ls -ld /var/lib/ganglia/rrds
drwxrwxrwx. 4 nobody root 4096 Aug 16 15:06 /var/lib/ganglia/rrds
[root@hc1nn log]# chown -R ganglia /var/lib/ganglia/rrds
Next, you restart the Ganglia servers on the data collector server hc1nn:
service gmetad restart
service gmond restart