Hi Simon and David, thank you for your hints! I actually found some missing update values - that means not every second a new set of values.
Now I intent to tune the heartbeat value to 5 instead of 2, and step size of 1 remaining constant... So missing 1, 2 or 3 measures will not generate an *unknown* value in the RRD. Do you think that is the right way? Thank you and BR Peter Simon Hobson schrieb: > Peter A. Menzel <[email protected]> wrote: > > Here is the setup script: >> >> rrdtool create AgroFire.rrd --step 1 \ >> DS:KesselTemp:GAUGE:2:U:U \ >> ... >> RRA:AVERAGE:0.5:1:864000 \ > Can you be certain that you provide an update *every* second ? > You have a step size of 1, and a heartbeat value of 2. That means that > you can only have data 2 seconds old before it is considered unknown. > What isn't clear is which side of the point the decision is taken as > the manual says : > heartbeat defines the maximum number of seconds > that may pass between >> two updates of this data source before the value of the data source is >> assumed to be *UNKNOWN*. > Eg, if you miss an update at time t=1 having done one at time t=0, does > the value become unknown at time t=2 or *after* time t=2. The difference > is that if you miss just one update, then in the former condition, when > you come to do the update at time t=2, the data from time t=0 to time > t=2 will be marked as unknown; but if it's the latter then the data > wouldn't become unknown unless you also miss an update at time t=2. > > So firstly I would be checking to see that you are reliably doing an > update every second and not creating a few unknown values. You might > consider increasing the heartbeat value. > > You have specified an xff value of 0.5, so you would regard a > consolidation as unknown if 50% of the source values are unknown. Since > missing one update could be marking 2 seconds worth (ie 2 primary steps) > as unknown, then missing an average of one update every 4 seconds would > result in missing consolidated data. > > _______________________________________________ > rrd-users mailing list > [email protected] > https://lists.oetiker.ch/cgi-bin/listinfo/rrd-users >
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