[rrd-users] y-axis repeated label and scale problem

Martin Muc mmuc at new-sense.com
Wed Jul 23 18:10:49 CEST 2014


I'm having problem with the y-axis labelling and scale.  I do not want 
the data shown with the y-axis going all the way down to 0 V, so most of 
the time the autoscaling works fine.

My data within this 1 h timeframe ranges only between about 26.6 and 
27.6 V (if I look at the last 1 hour only from my 2 hour graph I can see 
what the data and correct labels are).

But in the 1 h graph, the automatic y-axis labelling puts dark grid 
lines and two labels for "27" on both of the horizontal grid lines 
representing 27.0 and 27.4 and nothing else is labelled.  It puts light 
grid lines at the other 0.2 divisions.  Actually in the screen shot I've 
captured a few minutes later, it put 27 label at the 27.0 grid line, and 
a 28 label at the 27.8 grid line (and made it dark). Similar issue to 
the duplicate 27s I saw that started me trying to reproduce and document 
this.  My graphing options are as follows, using the .cgi:

                         --imginfo '<img src="../../_s/base5500/%s" 
alt="main voltage | 1 hour graph" />'
                         --start -75min --end -15min
                         --title "base station main voltage - 1 hour graph"
                         --vertical-label "main voltage, V"
                         --width 1600 --height 400
                         --border 0
                         --color BACK#E0E0E0 --color SHADEA#000000 
--color SHADEB#000000 --color GRID#E0E0E0 --color MGRID#C0C0C0
                         --font DEFAULT:12:Verdana --font TITLE:16:Times
MINUTE:1:MINUTE:5:MINUTE:10:0:"%Y-%m-%d %H:%M UTC"
                         --units-exponent 0
                         --grid-dash 1:0
                         --font DEFAULT:10:Verdana --font TITLE:16:Times
                         LINE:volt#0000FF:"main voltage">

I've also tried it removing alt-y-grid, that is bad in a different way 
(shows seven duplicate labels "27" for every 0.1 division up to 27.4 and 
five duplicate labels "28" for 27.5 up to 27.9)

Or removing alt-autoscale, that is bad in another different way (shows 
data range from 25 to 30 so real data is compressed in middle)

Is there something I'm doing wrong?  It seems like a bug in alt-autoscale.

I've also found some online references to --left-axis-format but it 
doesn't work in my version (the .cgi returns no image with this option 
added).  Is this only available after a certain version?  I have rrdtool 
1.4.7 on an Ubuntu 14.04 LTS machine.

I can put samples online if it helps, what pasting site do people suggest?



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