[rrd-users] 3 questions

Steve Shipway s.shipway at auckland.ac.nz
Wed Oct 12 23:47:13 CEST 2011

If I understand you correctly from your diagram, you want to have a Y-axis
showing the VDEF value, and the X-axis simply has separate sources, not a


If this is the case, then you cannot do it with RRDTool alone.  In RRDtool,
the X-axis is ALWAYS time.  Your only option is to extract the VDEF data
using FETCH, and then use a separate graphing package to render this as a


If I’m wrong, and your X-Axis is intended to be time but grouped in months,
showing for a single VDEF, then you can do this by forcing your graph to
have a monthly resolution and plot that as an area with the slope option
off.  You end up with a chunky bar graph then.





Steve Shipway

ITS Unix Services Design Lead

University of Auckland, New Zealand

Floor 1, 58 Symonds Street, Auckland

Phone: +64 (0)9 3737599 ext 86487

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Email:  <mailto:s.shipway at auckland.ac.nz> s.shipway at auckland.ac.nz

P Please consider the environment before printing this e-mail 



From: rrd-users-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch
[mailto:rrd-users-bounces+s.shipway=auckland.ac.nz at lists.oetiker.ch] On
Behalf Of Shabnam Shahreza
Sent: Thursday, 13 October 2011 7:09 a.m.
To: rrd-users at lists.oetiker.ch
Subject: [rrd-users] 3 questions


Hi rrd-users;


I am new to rrdtool and have few questions:


1)      How can I draw only dots/pixels for the VDEF (MAXIMUM) values and
not *line* or dashed line?

I mean only one dot for the maximum value for start-to-end time period?

2)      And how can I compare different VDEF (MAXIMUMs) from several rrd
files in one graph and pick the MAX of them? Do I need to create a new rrd
file and extract the max from there?

3)      And how can I calculate separate VDEF (MAXIMUM) for different
start-to-end time frames in one graph, such as monthly? 



The answers can help me to draw only maximum values per month from several
sources but in one graph.

(each dot in the below example can come from a different rrd file)




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