[rrd-users] Changing the start and end times for daily (step=86400) consolidation?

mmclure manuel at mclure.org
Mon Jun 27 21:06:49 CEST 2016

Is there any way to specify that daily consolidation should occur between
times that are not midnight UTC?

I have the following rrd definition:

rrdtool create /var/lib/weather/weather.rrd \
        --start 1466838000 \
        --step 300 \
        DS:temperature:GAUGE:1200:-40:158 \
        DS:humidity:GAUGE:1200:0:100 \
        DS:windspeed:GAUGE:1200:0:128 \
        DS:rain:DERIVE:1200:0:U \
        RRA:AVERAGE:0.5:1:2880 \
        RRA:AVERAGE:0.5:12:700 \
        RRA:AVERAGE:0.5:288:2000 \
        RRA:MAX:0.5:1:2880 \
        RRA:MAX:0.5:12:700 \
        RRA:MAX:0.5:288:2000 \
        RRA:MIN:0.5:1:2880 \
        RRA:MIN:0.5:12:700 \

The 1466838000 used as the start time corresponds to June 26, 2016 00:00:00
Pacific Daylight Time since I thought that the consolidation interval might
be dependent on the start time of the RRD.

I have a chart where I want to display the temperature for the week, as well
as the high and low for each day:

rrdtool graph ${PNGDIR}/temp1w.png \
        --title="1 Week Temperature" \
        --upper-limit=120 --lower-limit=0 \
        --end now --start end-1w --width 600 --height 200 \
        DEF:temperature=${RRD}:temperature:AVERAGE \
        DEF:temperaturemax=${RRD}:temperature:MAX:step=86400 \
        DEF:temperaturemin=${RRD}:temperature:MIN:step=86400 \
        LINE:temperature#0000FF:"Temperature" \
        LINE:temperaturemax#FF0000:"Max Temperature" \
        LINE:temperaturemin#00FF00:"Min Temperature"

The problem is that the Max Temperature and Min Temperature lines go from
5:00PM to 5:00PM PDT (midnight to midnight UTC) instead of from midnight to
midnight PDT. I'd like to be able to set an offset for the consolidation so
that it consolidates from, say 7:00AM to 7:00AM UTC (midnight to midnight
PDT, 11:00PM to 11:00PM PST).

I understand that I can't just request "consolidate in local time" since
Daylight Saving would cause a discontinuity twice a year, but a fixed offset
would be good enough. As it is now, the day's high can occur after 5:00PM
and get pushed into the next day's consolidation.

Anything I'm missing as far as configuration options that might provide the
functionality I'm looking for?


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