[rrd-users] Re: I need help to create a specific rrd file (LONG EMAIL)

Iñaki Martínez sistema at euskal-linux.org
Mon Jun 2 12:13:19 MEST 2003

Hi Alex van den Bogaerdt!!!

 hey me again Alex.... :-)

 Well this time instead of a rapid answer with more stupid questions i have,
during this weekend, re-read your tutorial three times, again........ 

 And i think i understand better how rrdtools works.......

 I have made two formulas, one for graph width and other for calculating

 Step by step.......


 * Graph width:

 width = (time to show in seconds) / (seconds per pixe)

 Example: to show 25 hours with 4 minutes per pixel

 (25 * 60 * 60) / (4 * 60) = 375 pixels width


 * calculating rows:

                        	     minutes 1 day
    rows = (time in days) * --------------------------
                             steps * (step in minutes)

 Example: 5 years, step each minute (=60 segs), 1 steps

                         1 * 24 * 60
  row = (365 * 5 + 2) * -------------- = 2630880
                         1 * (1 * 60)



> Either use the first created RRA to generate the graph, or create an
> RRA which covers the desired time span (5 years) in the resolution you
> are going to graph it.

> It is enough to only have the 1st RRA (one time for AVG, one time for MAX)
> and use it to create all graphs.  Using extra diskspace by generating the
> other RRAs will result in less time spent while generating the graphs.

 I have one question (i hope not be stupid):

 If i create one RRA for each graph i want, making each RRA to "accommodate"
each graph and some time after i want to change the aspect of the graph,
then that RRA is worthless????



 rrdtool graph file.rrd --start now-8d --height 150 --width 461

 25 minutes per pixel

 Then instead of 25 minutes per pixel i want 30 minutes per pixel:

 rrdtool graph file.rrd --start now-1w --height 150 --width 384

 In this case the above RRA is useful or useless, in case of useless i think
then it is better only the first RRA (RRA:AVERAGE:0.5:1:2630880)

 Am i correct??????

> BTW this results in a huge database.

 OK, there is unused space.... :-)

> You should answer the question:  Do I want to trade diskspace for speed?

 OK, i want to trade diskspace for speed.......


 If all of the above is correct i will creat the following RRD file:

  rrdtool create network.rdd --step 60

 and the following graphs:

 * Hourly (show 3,5 hours)

 rrdtool graph file.png --start now-3h-30m --height 150 --width 420

 * Dayly (show 25 hours = 1 day + 1 hour)

 rrdtool graph file.png --start now-25h --height 150 --width 429

 * Weekly (show 8 days = 1 week + 1 day)

 rrdtool graph file.png --start now-8d --height 150 --width 461

 * Monthly (show 31 days = more or less 1 month)

 rrdtool graph file.png --start now-31d --height 150 --width 496

 * Yearly (show 366 days = more or less 1 year)

 rrdtool graph file.png --start now-366d --height 150 --width 462

 * 2 years (show 366 * 2 days = more or less 2 years) big graph

 rrdtool graph file.png --start now-732d --height 150 --width 924

 * 1 day in hours (show 25 hours) very big graph!!!!

 rrdtool graph file.png --start now-24h --height 150 --width 3000

 NOTE: this last graph is better shown with scroll layer :-)

 Thanks all and specially to Alex!!!!

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