[rrd-users] Is is possible to get short term average directly in RRD tool ?
di07s at yahoo.fr
Sun May 2 10:34:21 MEST 2004
Is is possible to get short term average directly in RRD tool ?
I'm using the RRD Tool through the frontend JFF NMS application.
I would like to have in my graph a curve which represent a "short term value" of a RRD Data Source.
By "short term value" I want to have a curve for which each point is computed from the "20 last minutes" of the RRD Data Source,
For example if we have 5 minutes between (t-1) and (t) ==> 20 minutes represent 5 intervals of time
Data Source Value v(t-7) v(t-6) v(t-5) v(t-4) v(t-3) v(t-2) v(t-1) v(t)
Short Term value Nan Nan Nan Nan A B C D
With A=average of v(t-7), v(t-6) , v(t-5) , v(t-4) , v(t-3)
B=average of v(t-6), v(t-5) , v(t-4) , v(t-3), v(t-2)
C=average of v(t-5), v(t-4) , v(t-3) , v(t-2), v(t-1)
I have imagine a way, but it doesn't not optimize the resource of my computer, so I'm wondering this question because may be there is a more simple way to do it.
In JFF NMS a data is appended to the RRD data base at each collect.
So the way I have imagined is in pseudo code :
1) Collect data and put in "Data Source 1" ---> RRD 1 (So there is already a RRD file writing operation)
2) Do RRDTOOL fetch "average" on "Data Source 1" with -start=-1200 (which represents 20 minutes from current time)(a RRD file reading operation)
3) Register result of previous "rrdtool" into another RRD 2 (So there is a RRD file writing operation)
4) After to display the graph I can display curves for both the "current metric" (from RRD1) and for the "short terme average" (from RRD2)
(So there are reading of 2 RRD files)
But may be it is possible to avoid the 2 last operations (2 and 3) by doing some computations directly in the "rdtool graph".
Has anybody an idea ?
Thanks a lot for any suggestion.
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