[rrd-users] How to get calculated values in legend section
linux at thehobsons.co.uk
Tue Jan 10 11:29:00 CET 2012
Giese, Edgar wrote:
>i use nagios to collect data from a printer with
>smnp. I get the printed pages as gauge
>(10,15,25,30,80) and with the pnp I get a graph
>for the printed pages.
Does the snmp server reset the page count each
time you read this value ? If not, then you want
data type COUNTER.
Remember that no matter what you feed in,
internally RRD only deals in rates - ie
<things>/second. Also, RRD normalises and
consolidates the data - so the values you get out
will not generally match what you put in.
See http://www.vandenbogaerdt.nl/rrdtool/ and
look at the tutorial on Rates, normalizing and
>Changing to this ( wrong "Anzahl")
>$opt = "--vertical-label Anzahl -l 0 --title
>\"Gedruckte Seiten auf $hostname \" ";
>$def = "DEF:var1=$rrdfile:$DS:AVERAGE " ;
>$def .= "DEF:var1min=$rrdfile:$DS:MIN " ;
>$def .= "DEF:var1max=$rrdfile:$DS:MAX " ;
>$def .= "CDEF:var1act=var1max,var1min,- " ;
>$def .= "VDEF:varact=var1act,MAXIMUM " ;
This won't do what you want.
var1act will contain the difference between min
and max for each consolidated time point - not
the difference between the highest and lowest
over the whole time series. So lets say you
printed 15 pages for each consolidated time
period, max-min would be 15 for each data point,
and over 10 time periods you'd still only get a
max of 15 - not the 150 you might be looking for.
If you use a counter data type, then you can plot
pages/second - or multiply by 60 for pages/min,
or multiply by 3600 to get pages/hour. You can
get total pages printed by taking the average
over the period and multiplying by the period.
Eg, for total pages in a day, get the average
over the previous day (pages/second) and multiply
by 86400 (seconds/day) to get the total. Current
versions of RRD have a TOTAL function that does
this for you.
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