For a basic understanding on ganglia more general information, do look at Installing and configuring Ganglia on CentOS 5.4

Part I: To install ganglia on CentOS 5.8 on the Cluster Head Node, do the followings:

1. Make sure you have the RPM Repositories installed. For more information, see Useful Repositories for CentOS 5
2. Make sure installed the libdbi-0.8.1-2.1.x86_64.rpm for CentOS 5.9 be installed on the CentOS 5.8. Apparently, there is no conflict or dependency issues. See RPM Resource libdbi.so.0()(64bit)

   # wget 
   ftp://rpmfind.net/linux/centos/5.9/os/x86_64/CentOS/libdbi-0.8.1-2.1.x86_64.rpm

   # rpm -ivh libdbi-0.8.1-2.1.x86_64.rpm

3. Install PHP 5.4. See Installing PHP 5.4 on CentOS 5
4. Install the Ganglia Components

   # yum install rrdtool ganglia ganglia-gmetad ganglia-gmond ganglia-web httpd

5. By default, Ganglia uses multi-cast or UDP to pass information. I refer to use UDP as I can have better control
6. Assuming 192.168.1.5 is our head node and port number 8649. Edit /etc/ganglia/gmond.conf and start the gmond service.

   cluster {
   name = "My Cluster"
   owner = "kittycool"
   latlong = "unspecified"
   url = "unspecified"
   }
   udp_send_channel {
   host = 192.168.1.5
   port = 8649
   ttl = 1
   }
   udp_recv_channel {
   port = 8649
   }

7. Configure the service level startup-up and start the service for gmond

   chkconfig --levels 235 gmond on
   service gmond start

8. Configure the /etc/ganglia/gmetad.conf to define the datasource

   Data_source "my cluster" 192.168.1.5:8649

9. Configure the service level startup-up and start the service for gmetad

   chkconfig --levels 235 gmetad on
   service gmetad start

10. Configure the service level startup-up and start the service for httpd

    chkconfig --levels 235 httpd on
    service httpd start

Part II: To install on the Compute Nodes, I’m assuming the Compute Node are on private network and does not have access to the internet. Only the Head Node has access to internet. I’m also assuming there is no routing from the compute nodes via the head node for internet access

1. Read the following blog  Using yum to download the rpm package that have already been installed.
2. Copy the rpm to all the compute nodes
3. Install the package on each compute nodes*

   yum install ganglia-gmond

4. Configure the service startup for each compute nodes*

   chkconfig --levels 235 gmond on

5. Copy the gmond /etc/ganglia/gmond.conf configuration file from head node to the compute node.

For more information, do look at

1. Installing and configuring Ganglia on CentOS 5.4