Version 3 (modified by oetiker, 14 years ago) (diff)


RRDtool Frequently asked Questions with Answers


Peaks get smaller the larger the graph resolution gets

Q: I notice that the graph of day (--end now --start end-86400) is accurate but my other graphs are not looks like they are decreasing, say in the day graph u see it gets to 30000 point on the Y-axis but in the week (--end now --start end-604800) its not passing the 25000 point and in month (--end now --start end-2419200) its not passing the 23000 and year (--end now --start end-29030400) its not passing the 15000 point

A: If you are graphing an AVERAGE RRA then the data shown in the graph will be consolidated using the same method in order to fit the graph. In a high resolution graph, each pixel may represent 5 minutes worth of data. In this graph you would see a 5 minute transfer rate of 120 as a 1 pixel wide peak of 120. In a graph where 1 pixel represents 1 hour worth of data, the same incident would show up as a 1 pixel wide peak of 10.


RRDtool does not return what I put in

Q: I created an rrd file and then used rrdtool update to input a few values. I then used rrdtool fetch to get them back out. The values that come out of rrdtool are sort of similar to what I put in, but they do not match exactly.

A: ?

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