https://learn.openenergymonitor.org/electricity-monitoring/ct-sensors/yhdc-sct-013-000-ct-sensor-report

rrdtool create power.rrd --step 1s DS:watts:GAUGE:1:0:6600 RRA:AVERAGE:0.5:1s:1d  # Buggy: nécessite des updates toutes les 500 ms
rrdtool create power.rrd --daemon /var/run/rrdcached.sock --step 1s DS:watts:GAUGE:1:0:6600 RRA:AVERAGE:0.5:1s:1d  # Buggy: nécessite des updates toutes les 500 ms

rrdtool create /var/lib/rrdcached/db/power.rrd \
	--step 1s \
	DS:watts:GAUGE:1s:0:10000 \
	RRA:AVERAGE:0.5:1s:1d \
	RRA:AVERAGE:0.5:1m:3d \
	RRA:AVERAGE:0.5:15m:1w \
	RRA:AVERAGE:0.5:1h:30d \
	RRA:AVERAGE:0.5:1d:3y \
	RRA:MAX:0.5:1d:3y \
	RRA:AVERAGE:0.5:1month:10y \
	RRA:MAX:0.5:1month:10y

Ceci n'est pas rafraîchi très souvent:
watch -n 0.5 rrdtool graphv - '-s' '1546280606' 'DEF:watts=/var/lib/rrdcached/db/power.rrd:watts:AVERAGE' 'VDEF:avg=watts,AVERAGE' 'VDEF:last=watts,LAST' 'PRINT:avg:%lf' 'PRINT:last:%lf'
Alors que ça si:
watch -n 0.5 rrdtool lastupdate --daemon /var/run/rrdcached.sock /var/lib/rrdcached/db/power.rrd