On Thu, Jul 30, 2009 at 10:31 AM, Brad Nicholes <bnicho...@novell.com>wrote:
> >>> On 7/29/2009 at 11:23 PM, in message
> <669f1ab30907292223t2734f551lc8d9b98201d7f...@mail.gmail.com>, Mahendra
> Kutare
> <mahendra.kut...@gmail.com> wrote:
> > Hi All,
> >
> > If I have configured gmond.conf with a udp_recv_channel with just a port
> > number will that configure ganglia gmond to listen on that particular
> port
> > any incoming data and thus making it essentially unicast communication
> > channel ?
> >
>
> Yes, specifying just a port will configure gmond's recv channel in unicast
> mode
>
> > What happens if the sending side sends data every 1 sec will that be
> > transferred immediately to gmond or it waits to collects some packets of
> > data and then delivers to gmond listening side ?
> >
> > I started sending some data from outside of gmond interface to gmond
> which
> > is configured as mentioned above to a udp_recv_channel on port 8108.
> >
> > Now even though the sending side is pushing data in every 1sec. I do not
> see
> > gmond showing in debug mode on the console that its processing Ganglia
> > message from sender side every 1 sec.
> >
> > Is it just the display part of the problem or ganglia does some
> > sophisticated processing of incoming data i.e waiting for a message size
> > before delivering it ?
> >
>
> How did you configure gmond to send data every 1 sec.? Gmond sends its
> data in collection groups and each collection group is configured with a
> send time threshold. At the very worst, the collection group will send all
> of the metric values within that group once the group's collection threshold
> has been exceeded. In addition, each metric is assigned a value threshold
> which is a percent of change differential. If any of the metrics within the
> collection group, differential change exceeds the value threshold, the
> entire group of metrics is immediately sent. So even though a collection
> group is set to collect every 1 second, that doesn't mean that the metrics
> are sent every 1 second. Also, by default the rrd files are configured by
> gmetad to store metrics at an interval of every 15 seconds. So even if the
> metrics were sent every 1 second, you will still only be seeing 15 second
> averages in the front end.
>
Thanks Brad. I am trying to do it to understand the ganglia protocol and
this helps.
Right now its fine with me even if Gmetad sees only 15 seconds average in
frontend as you described.
So as I see there are other configuration in collection groups such as -
1. collect_once and collect_every
I understand that collect_once with make some collection to be collected
only once and just send it other gmond every time_threshold.
Also, If I am not wrong If I configured collect_every = 20 and
time_threshold=90, gmond will collect every 20 sec and send every 90 sec to
other gmond.
Now the part I am not clear is if I am collecting more frequently than I am
sending does that mean we are keeping more in memory ? I mean say after
first occurance of collect in 20 sec if I am not sending it across to gmonds
am I just keeping it in memory hash ? If not, whats the behaviour ?
2. What does this configuation *cleanup_threshold* = 300 /*secs * ?
Is it cleaning stuff in memory hash ? If yes, is it happening concurrently
while gmond is trying to send data to other gmonds ? What happens if the
cleanup threshold is reached and gmond collection metric also reached
time_threshold or say if its synchronized first cleanup_threshold and next
time_threshold ?
Will it just send all NULL ?
3. Does the configuration - *max_udp_msg_len = 1472* applies to both sending
and recieving of udp packets size ?
Thanks for your responses.
Mahendra
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