rrdtool: Use Consulidation-Function MIN, exclude NaN Values

Question

i have an archive which contains the minimum duration times of messages going through an enterprise service bus.

During night-time or on weekends it is possible, that there are no messages, so the minimum duration time is NULL. Because of this, i write NaN into my rrd-db.

If i now want to consolidate an archive with the MINIMUM-Function over 6 hours, i get a problem if in this 6 hours there is a NaN-Value. Because then the whole 6-hours timeframe will be saved as NaN.

Is there any option to use a MINIMUM-Function, which ignores NaN-Values?

(Replacing NaN-Values with 0 would distort my graphs and is therefore not a good solution.)

Any help is very appreciated. Thank you in advance for participating!

Answer 1

i found the solution by myself. I haven't looked exactly enough at the documentation. To ignore NaN / Unknown values, you have to use the xff (xfiles factor). With a xff of 0.99, the NaN values will be ignored by the consolidation function.

http://oss.oetiker.ch/rrdtool/doc/rrdcreate.en.html

RRA:AVERAGE | MIN | MAX | LAST:xff:steps:rows

xff The xfiles factor defines what part of a consolidation interval may be made up from UNKNOWN data while the consolidated value is still regarded as known. It is given as the ratio of allowed UNKNOWN PDPs to the number of PDPs in the interval. Thus, it ranges from 0 to 1 (exclusive).