On Sun, Aug 17, 2008 at 12:41:25PM -0400, Ofer Inbar wrote: > Carlo Marcelo Arenas Belon <[EMAIL PROTECTED]> wrote: > > then it means it is not receiving any of the messages sent (it is deaf). > > Oh! It took me a while to figure out what you meant, but I think I > got it: does gmond communicate with *itself* using multicast?
yes (short answer, longer answer and explanation below) there are 2 personalities for gmond. the first of those personalities is as an agent that collects metrics and sends them somewhere (by default every other gmond in the same cluster that are using the same multicast address). for this personality to work (if using multicast), you have to be listening to multicast packets AND sending multicast packets (by default UDP packets in port 8649), so if you only have 1 sole gmond then it uses the network to update its own status as you said. you can also configure gmond (for example using unicast) to send all its metrics to another gmond which is collecting all metrics from your cluster (a gmond collector, and so it will never know its own host status. a gmond collector (the second of gmond's personalities) is the one that will know all metrics from all hosts that he has been told about and MUST listen in tcp port 8649, so you can query it to dump the status of the cluster. by default gmond will be configured to act as both personalities and that is why you can usually poke its port 8649 with netcat and get a dump of all the metrics he has collected, which usually include its own metrics. Carlo ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Ganglia-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/ganglia-general
