On Mon, Feb 11, 2008 at 02:04:14PM -0800, Ben Rockwood wrote: > > I previously had believed that each node > needed to be aware of every other node in some fashion and my > configurations were absolutely out of control.
no, if you are using the default configuration (which uses multicast) and your cluster has all nodes in the same VLAN (the usual setup for HPC) then all gmond will know about the others because they are all by default configured to use the same multicast IP and so they are all listening to the updates that are send by any of the nodes. but this is an artifact of that configuration and not a requisite for gmond to work. > I would really appreciate it if you could help educate me a bit on why > this works. Based on observation it would seem that gmond's send out to > the udp_send_channel some form of update which the "collector" gmond > then stores in memory for later requests. Is this roughly correct? yes, gmond main purpose in life is to schedule metric collection on each node and then report them. the list of metrics and the frequency is scheduled internally based on the information in the configuration. a secondary function of gmond is to collect all metrics and give an XML representation of the cluster (which is what the collector is doing in your configuration), the gmetad polls that periodically and stores it so that trends can be observed. > My > mistake had been in believing that gmond's were entirely passive and > only returned data when explicitly requested. there used to be some really cool papers in the homepage describing why gmond is instead active so that it can scale horizontally the scheduled for all metrics and it was designed to have a minimum impact in CPU utilization in the nodes and a very efficient in memory representation. Carlo ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Ganglia-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/ganglia-general
