I have 3 machines. One of them collects ganglia data for all 3 of them. When I reboot this "collector" server, both gmetad and ganglia-monitor are started from the /etc/rc3.d, and I can see in tcpdump that the other 2 servers send the monitoring data every 15 seconds, however only the "collector" server's data show up in the web GUI.
The only way I can get the other servers show up in the graphs again is: stop ganglia-monitor on the remote servers, wait 'till the servers show up as "offline", then start ganglia-monitor on the remote again.
I'm pretty sure this should work out of the box, any idea what can be wrong?