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I'm using a javascript library to visualize rrdtool data and using rrdtool xport to retreive the data from the rrd files.

Today I noticed the following: When viewing the data from now-1day: there is a datapoint of 100
but when viewing the data from now-31day, the datapoint of 100 is nowhere to be seen...

How can I make sure I get all datapoints within the specified time when using xport?
I'm using --step 10, but it didn't make a difference. No matter what --step I set it doesn't get used. I read this is because it is ignored if it's less than 1 pixel, so what's the suggested solution to this problem?

Additional info:
I'm using Collectdtool with default RRDtool plugin options: http://collectd.org/documentation/manpages/collectd.conf.5.shtml#plugin_rrdtool

Edit: Seems its the essence of RRDtool to have several archives for one month, one day, one year etc, so it makes sense that I can't get every single datapoint for the archive for one month?

Sam Stoelinga
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1 Answers1

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The number of data points also depends on the available data ... so if your high-resolution RRA only covers 30 days (for example) you would get data from a lower resolution RRA once you request data for more than 30 days.

Tobi Oetiker
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  • Thanks, for this clear explanation after doing some more research I was going in that direction. But it may help some people wondering the same. I think the problem for me was, that the lower resoluation did not have the latest datapoint yet. I'm using the MAX but it didnt show the correct MAX yet, because it wasn't calculated in the lower resolution RRA. You made a great tool BTW!! Thanks – Sam Stoelinga Jun 28 '12 at 01:34
  • I double checked it, but even when there is a high resolution RRA available it still will always return me only about 300-400 datapoints, even though there are more datapoints available? How can I get all datapoints available between a specific time range? from the highest resolution rra – Sam Stoelinga Jul 02 '12 at 09:37
  • if you want really everything you could use rrdtool dump :-) or rrdtool info and then specify the boundaries accordingly. Note that the 1.4.x rrdtool series does only consider the start time in selecting an RRA and not the end time as all rras will contain as good an end time coverage as possible anyway ... – Tobi Oetiker Jul 04 '12 at 13:37