[xymon] Aggregation of data from multiple machines in to a single graph

Henrik Størner henrik at hswn.dk
Tue Nov 9 18:34:11 CET 2010

In <11707_1289309067_4CD94B8B_11707_20800_1_1F7B01020EC4D04DA17703634B9E888E0A01CFF4 at ULPGCTMVMAI003.EU.COLT> "Ward, Martin" <Martin.Ward at colt.net> writes:

>I have a number of mail servers and I have tailored the Xymon client config=
> on each server to return the number of emails in the deferred mail queue. =
>What I would like is to have a single graph that displays all these values =
>together (in the same way that it displays graph for all the different disk=
>s on a single server).  I know that the graphs can be created as I run an e=
>xternal command to generate the graphs and display them in a web page outsi=
>de of Xymon. It would be nice to be able to have a configuration item for a=
> given Xymon page and data value such that it creates an RRD graph for ever=
>y server on that page which has that data value in its RRD file.

Presumably, you have a graph definition for your single-host graph. Guess
it looks somewhat like the "swap" graph:

	TITLE Swap Utilization
	YAXIS % Used
	LINE2:p#0000FF:% Swap used

Now, if you look at the graph definitions, you'll see that there is an
"swap-multi" graph also. This is almost identical, except it uses an
"FNPATTERN" definition:

	TITLE Multi-host Swap Utilization
	FNPATTERN memory.swap.rrd
	YAXIS % Used
	DEF:p at RRDIDX@=@RRDFN@:realmempct:AVERAGE

The "multi" definition is used whenever there is more than one host names in the
"hostname" parameter for the hobbitgraph.sh CGI script. This is used by the
"Metrics report", whose web form template is in the ~xymon/server/web/hostgraphs_form
file. Try defining a "mailq-multi" graph in hobbitgraphs.cfg and then referencing 
this via the hostgraphs-form - it should give you a way of at least getting a 
graph showing the mail-queue for your servers.

Unfortunately, error messages are difficult to capture when you're working on this.
One common pitfall is to include a server in the list which hasn't got the data
for the graph - this just gives you a blank webpage, no error. Try beginning with
a multi-graph of just one host - when that works, adding more hosts should work OK.


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