[rrd-users] wrong rra used

spock collector at sappers.de
Thu Jun 26 10:34:17 CEST 2014


I am using this database to collect temperature data for a swimming pool.
I want to keep the detailed data for 36 months ("103680 * 900sec") but also
want to have a daily average temp (96 values = 24h).

# rrdtool create temp_pool.rrd --step 900 --start "20140101 00:00" \
# DS:air:GAUGE:1200:-40:50 \
# DS:flow:GAUGE:1200:-40:50 \
# DS:return:GAUGE:1200:-40:50 \
# DS:delta:COMPUTE:return,flow,- \
# DS:pump_flag:GAUGE:1200:0:1 \
# DS:heat_flag:GAUGE:1200:0:1 \
# DS:device:GAUGE:1200:0:90
# RRA:AVERAGE:0.5:1:103680 \
# RRA:MIN:0.5:96:3650 \
# RRA:MAX:0.5:96:3650 \
# RRA:AVERAGE:0.5:96:3650

When I create a graph with 
       rrdtool graph temp7d.png \
        -t "Pooltemp (Status $(date "+%d.%m.%Y %H:%M"))"  \
        -s $graph_start_7d -e $timestamp_rounded_unix \
        -w 640 -h 400 -D -a PNG -T 15\
        DEF:airmax2=temp_pool.rrd:air:MAX \
        DEF:airmin2=temp_pool.rrd:air:MIN \
        DEF:airavg2=temp_pool.rrd:air:AVERAGE \
        CDEF:airrange=airmax2,airmin2,- \
        LINE2:airmin2#00FF00:"Luft Min" \
        AREA:airrange#8dadf588::STACK \
        LINE2:airmax2#00FF00:"Luft Min" \

I get for airavg2 the datailed values - but not the daily average.
Airmin2 and airmax2 work as  expected - there is no other RRA Archive to
choose from.

Question (1)
How do I convince the tool to use the consolidated data instead of the

Question (2)
When drawing the graph, the line for max/min values are not precisely
aligned above a day. It looks like it starts about 900 secs after 0:00 each
How does rrdtool determine, which 96 values to consolidate? My data point
are stored with rounded timestamps (e.g. 13.06.2014 0:00, 0:15, 0:30, etc.)

Question (3)
The ssf factor is 0.5 for the RRAs. However, there is no min/max value for
certain days with missing data, although there are only a few values
missing. I am sure, is is not more than 50%. How can I check this.


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