[Xymon] graphing problem

[Phil Crooker]

First, many thanks for everyone's help, I really appreciate it and it saves me a lot of time.
 
Now, I followed Michael's directions, and the data was recorded in the rrd files. But no graphs. So, I then changed the DEF entries in graphs.cfg from GAUGE to AVERAGE as per Wim Nelis's advice and voila - they are there! I think I will change the colour scheme, though....  ;-)
 
Many, many thanks, all, this is excellent.
 
regards, Phil

>>> 

The problem is most certainly that your data is coming in at 10 minute intervals.  The RRD files are created to have a step of 300 seconds and a heartbeat of 600 seconds.  This means that rrd expects a new data point every 300 seconds (5 minutes) and if it doesn't get a new data point withing 600 seconds (10 minutes) it considers the data junk and disregards it.  Typically, this is set to be double the step, so if you miss one, its okay, but if you miss 2 it returns NaN (Not a Number), there is nothing to stop you from going larger.  Since your data is coming in every 10 minutes, it is in violation of your heartbeat and the data is being ignored.

I have asked around before and didn't get a solid answer as to if there is a better way to do it, but I have worked out a way to fix this.  If there is a better way, please let me know!

There are two places you need to tweak, first is in xymonserver.cfg.  You need to fully define your NCV value for that RRD.
You have: 
NCV_internet="google:GAUGE,businessspectator:GAUGE,bloomberg:GAUGE"

When an rrd file is created it is in the following format:
dataSourceName:dataSourceType:heartbeat:min_value:max_value

So, your NCV value should be fully defined as:
NCV_internet="google:GAUGE:1200:0:U,businessspectator:GAUGE:1200:0:U,bloomberg:GAUGE:1200:0:U

This will create your 3 datasets, all of type GAUGE with a 1200 (double your 10 minute test) with a 0 for a minimum expected value and an "U"nlimited maximum value.

Next, you need to set your rrddefinition.cfg to set the "step" to override the default 300 second value.  Since your script runs every 10 minutes, it should be 600.  To do this, put a "-s" parameter in your rrddefinition
[internet]
    -s 600
    RRA:AVERAGE:0.5:1:576

One thing to note, while you can change the heartbeat on the fly, the step is permanent.  Once the file is created, changing your rrddefinition.cfg won't change the RRD file.  As long as you are still in development, every time you make a change, just delete the rrd file and let xymon create a new one, it will set the step you have defined in rrddefinition.cfg.  If you aren't in development and do not want to loose the data you currently have, the only option I know you have is to export the rrd using "rrdtool dump" to an XML file, manually edit the STEP of that file, then do an "rrdtool restore" to convert that XML back into an rrd.  

Here is a link to the rrd man page, its a good read.
http://oss.oetiker.ch/rrdtool/doc/rrdgraph.en.html
Michael Beatty
On 04/16/2013 09:48 PM, Phil Crooker wrote:


I'm a graphing newbie and can't get the graph to work. Could anyone please help? This is to measure internet latency, the test is called "internet". This is running over four hosts, so we should be getting four sets of graphs. The rrd file is created, but I just see NaN values, no data is being recorded. 
 
many thanks, Phil
 
I've got the following data coming in from an ext script every 10 mintues:
 
google : 0.15
businessspectator : 1.28
bloomberg : 0.05
-------------------------------------
 
I set this up as a gauge graph. Here is one of the entries:
 
	    <ds>
			    <name> google </name>
			    <type> GAUGE </type>
			    <minimal_heartbeat> 600 </minimal_heartbeat>
			    <min> NaN </min>
			    <max> NaN </max>
 
			    <!-- PDP Status -->
			    <last_ds> U </last_ds>
			    <value> 0.0000000000e+00 </value>
			    <unknown_sec> 172 </unknown_sec>
	    </ds>
 
----------------------------------------------------
Here are the config files.
 
 
in xymonserver.cfg:
 
I added this to the GRAPHS string: internet=ncv
 
and put in this line after that 
 
NCV_internet="google:GAUGE,businessspectator:GAUGE,bloomberg:GAUGE"
 
-------------------------------------
 
graphs.cfg:
 
[internet]
	    TITLE Internet Latency
	    YAXIS Seconds
	    DEF:google=internet.rrd:google:GAUGE
	    DEF:businessspectator=internet.rrd:businessspectator:GAUGE
	    DEF:bloomberg=internet.rrd:bloomberg:GAUGE
	    LINE2:google#00CCCC:Inode cache
	    LINE2:businessspectator#FF0000:Dentry cache
	    LINE2:bloomberg#00FF00:In 
	    COMMENT:Time to load home page in seconds.\n


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