[rrd-users] rrdtool multi DS heartbeat problem

[Mike Schilli]

On Sun, 26 Apr 2009, Mike Schilli wrote:

> With multiple data sources, there seems to be a bug with rrdtool,
> causing it to ignore the heartbeat settings.

Any resolution on this issue?

-- Mike

Mike Schilli
m at perlmeister.com

>
> Here's a test case that reproduces the problem: We define a rrd with two
> data sources, each with a generous heartbeat of 57600:
>
>  rrdtool 'create' 'myrrdfile.rrd' '--start' '1240729199' \
>  '--step' '3600' 'DS:d2:GAUGE:57600:U:U' \
>  'DS:d1:GAUGE:57600:U:U' 'RRA:MAX:0.5:1:100'
>
> Then we feed in data, with separate calls for the data sources:
>
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd1' '1240729200:100'
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd2' '1240729201:100'
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd1' '1240734300:97'
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd1' '1240741440:95'
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd1' '1240750740:88'
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd1' '1240756500:86'
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd2' '1240767900:83'
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd2' '1240777140:80'
>
> Now, if you print the graph of d2, you'll notice a gap:
>
>  rrdtool 'graph' 'mygraph.png' '--vertical-label' \
>  'Graph Bug' '--end' '1240868880' '--start' '1240729200' \
>  'DEF:draw2=myrrdfile.rrd:d2:MAX' 'LINE1:draw2#0000FF:d2'
>
> Note that the data rate of d2 is compliant with the heartbeat at all
> times, but yet, rrdtool seems to miss out on some PDPs.
>
> However, if you leave d1 out of the test, hence running
>
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd2' '1240729201:100'
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd2' '1240767900:83'
>  rrdtool 'update' 'myrrdfile.rrd' '--template' 'd2' '1240777140:80'
>
> after creating the rrd, everything is okay and there's no gap in the
> graph:
>
>  rrdtool 'graph' 'mygraph.png' '--vertical-label' \
>  'Graph Bug' '--end' '1240868880' '--start' '1240729200' \
>  'DEF:draw2=myrrdfile.rrd:d2:MAX' 'LINE1:draw2#0000FF:d2'
>
> Could it be that rrdtool's heartbeat logic gets confused with multiple
> data sources?
>
> -- Mike
>
> Mike Schilli
> m at perlmeister.com
>