rrdtool create node-1.rrd --start `date +%s` --step=300 \
DS:getattr:COUNTER:600:0:U \
DS:access:COUNTER:600:0:U \
DS:read:COUNTER:600:0:U \
DS:write:COUNTER:600:0:U \
RRA:AVERAGE:0.5:1:2016 \
RRA:AVERAGE:0.5:288:31 \
RRA:AVERAGE:0.5:2016:52
RRA1: 604800
RRA2: 2678400
RRA3: 31449600
---------------
34732800 seconds = 402 days.
So, theoretically I should be able to get the oldest data point by taking `date +%s` - 34732800.
But, that seems not to be the case, as demonstrated here:
testserver~$ rrdtool fetch node-1.rrd AVERAGE --start $(echo "`date +%s` - 34732800" | bc) \
| head -3; rrdtool fetch node-1.rrd AVERAGE | tail -1
timestamp getattr access read write
1140048000: nan nan nan nan
1175106600: nan nan nan nan