[rrd-users] Trouble with graph and CDEF

[dani goma]

Hello,



I have trouble creating a graph based on points that are not time
equidistant. I want to create a "garbage collector" graph that appears every
"x" unit of time, "x" being a time variable.



I am trying to create a rrd database with points every 30 seconds; at the
moment the "gc" appears, a rrd update will amend the values with the
consumed memory and 30 seconds later with the memory that is consumed after
getting free.



Here you have an example:



09:00:00 - 1500Mb  (carry out gc process)

09:00:30 - 1100Mb

09:01:00 –  No value

09:01:30 - No value

09:02:00 - No value

09:02:30 - 1450Mb (carry out gc process)

09:03:00 - 1100Mb

09:03:30 - No value

09:04:00 - 1390Mb (carry out gc process)

09:04:30 - 1200Mb



The particualr problem I have is with these "no values" because of the fact
that the "rrd" automatically fills in these spaces with the last value
included. The BBDD looks this way.* *



09:00:00 - 1500Mb  (carry out gc process)

09:00:30 - 1100Mb

09:01:00 - 1450Mb

09:01:30 - 1450Mb

09:02:00 - 1450Mb

09:02:30 - 1450Mb (carry out gc process)

09:03:00 - 1100Mb

09:03:30 - 1390Mb

09:04:00 - 1390Mb (carry out gc process)

09:04:30 - 1200Mb





So when the graph is created, this is the way it looks:



http://www.gamacomplementos.com/dani.png



And this is not real, becasue the memory is progressively being consumed. I
would like to create a graph where the real points are direclty joined
together, so that it looks this way:



http://www.gamacomplementos.com/grafica_gc.jpg



Do you think you could help me with this?



I was thinking of  introducing a very low frequency time so that the values
are considered az zero and so instead of autocompleting themselves they
remain as NAN; than I was thinking of treating it with a CDEF function, but
I am not really sure about this.



Many thanks,
Dani
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