RRDtool data inconsistency -

i using rrdtool graph status of pump on raspberry pi. must doing configuration wrong, since values close inputting, not exact.

the pin status should either 1 or 0.

<!-- 2014-03-10 10:24:00 cdt / 1394465040 --> <row><v>nan</v></row> <!-- 2014-03-10 10:25:00 cdt / 1394465100 --> <row><v>nan</v></row> <!-- 2014-03-10 10:26:00 cdt / 1394465160 --> <row><v>1.0000000000e+00</v></row> <!-- 2014-03-10 10:27:00 cdt / 1394465220 --> <row><v>2.3711630000e-01</v></row> <!-- 2014-03-10 10:28:00 cdt / 1394465280 --> <row><v>9.8168226667e-01</v></row> <!-- 2014-03-10 10:29:00 cdt / 1394465340 --> <row><v>1.6624716667e-02</v></row> <!-- 2014-03-10 10:30:00 cdt / 1394465400 --> <row><v>9.8544061667e-01</v></row> <!-- 2014-03-10 10:31:00 cdt / 1394465460 --> <row><v>2.9590616667e-02</v></row> <!-- 2014-03-10 10:32:00 cdt / 1394465520 --> <row><v>9.7204963333e-01</v></row> <!-- 2014-03-10 10:33:00 cdt / 1394465580 --> <row><v>2.6263616667e-02</v></row> <!-- 2014-03-10 10:34:00 cdt / 1394465640 --> <row><v>9.7533411667e-01</v></row> <!-- 2014-03-10 10:35:00 cdt / 1394465700 --> <row><v>2.3075633333e-02</v></row> <!-- 2014-03-10 10:36:00 cdt / 1394465760 --> <row><v>9.7849575000e-01</v></row> <!-- 2014-03-10 10:37:00 cdt / 1394465820 --> <row><v>1.9948233333e-02</v></row> <!-- 2014-03-10 10:38:00 cdt / 1394465880 --> <row><v>9.8158333333e-01</v></row> <!-- 2014-03-10 10:39:00 cdt / 1394465940 --> <row><v>1.6888216667e-02</v></row> <!-- 2014-03-10 10:40:00 cdt / 1394466000 --> <row><v>9.2141166667e-01</v></row> <!-- 2014-03-10 10:41:00 cdt / 1394466060 --> <row><v>5.2411610000e-01</v></row> <!-- 2014-03-10 10:42:00 cdt / 1394466120 --> <row><v>5.2411610000e-01</v></row> <!-- 2014-03-10 10:43:00 cdt / 1394466180 --> <row><v>9.6672030000e-01</v></row> <!-- 2014-03-10 10:44:00 cdt / 1394466240 --> <row><v>5.0939110833e-01</v></row> <!-- 2014-03-10 10:45:00 cdt / 1394466300 --> <row><v>5.0939110833e-01</v></row> <!-- 2014-03-10 10:46:00 cdt / 1394466360 --> <row><v>4.9845539167e-01</v></row> <!-- 2014-03-10 10:47:00 cdt / 1394466420 --> <row><v>4.9845539167e-01</v></row> <!-- 2014-03-10 10:48:00 cdt / 1394466480 --> <row><v>9.9399037500e-01</v></row> <!-- 2014-03-10 10:49:00 cdt / 1394466540 --> <row><v>9.9399037500e-01</v></row> <!-- 2014-03-10 10:50:00 cdt / 1394466600 --> <row><v>2.6977033333e-02</v></row> <!-- 2014-03-10 10:51:00 cdt / 1394466660 --> <row><v>9.7898348333e-01</v></row> <!-- 2014-03-10 10:52:00 cdt / 1394466720 --> <row><v>9.7898348333e-01</v></row>

create_db.sh #!/bin/bash rrdtool create pinstats.rrd \ --step 60 \ ds:pump:gauge:600:0:1 \ rra:max:0.5:1:2016

update.sh

#!/bin/sh a=0 while [ "$a" == 0 ]; echo "pump ondate" /home/pi/on.sh /home/pi/graph.sh pump=1 rrdtool update pinstats.rrd n:$pump sleep 60 echo "pump offdate" /home/pi/off.sh /home/pi/graph.sh pump=0 rrdtool update pinstats.rrd n:$pump sleep 120 done

you being affected data normalisation.

this adjust values according linear approximation in order make time point lie on interval boundary. ie, if interval 5min, updated value @ 12:00, 12:05, 12:10 ... etc

this makes sense if graphing large number rate; overall averages still work out , data @ regular intervals. however, if using gauge data type small integers becomes problematic.

in order avoid this, have update on interval boundary rather using n time point.

try shell code:

interval=60 timestamp=`date +%s` num_intervals=`expr $timestamp / $interval` adjusted_time=`expr $num_intervals '*' $interval` rrdtool update pistats.rrd $adjusted_time:1 sleep $interval adjusted_time=`expr $adjusted_time + $interval` rrdtool update pistats.rrd $adjusted_time:0 

this code ensures update times on interval boundary, , hence no data normalisation performed (actually, becomes null operation).

for more details, see alex van den bogaerdt's excellent tutorial here.