Steps and heartbeats.

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Steps and heartbeats.

tintin
This post was updated on .
Hello Folks,

I understand that this topic has been posted before - but my understanding wasn't perfectly clear after reading those posts. Also I read the tutorials on the website and also those those by Alex - but I still have a doubt as to how these parameters relate / work with one another. I apologize for the double posting but I only do so in the interest of clarity. I hope other newbies like me benefit from this post.

I have created the following rrd database:

rrdtool create test.rrd --start 1314270000 --step 300 --no-overwrite DS:no-signal-3-steps:GAUGE:1800:U:U RRA:AVERAGE:0:1:15

I then carry out the following updates:

rrdtool update test.rrd 1314270300:1
rrdtool update test.rrd 1314270600:2
rrdtool update test.rrd 1314270900:3
rrdtool update test.rrd 1314271200:4
rrdtool update test.rrd 1314272100:7
rrdtool update test.rrd 1314272400:10
rrdtool update test.rrd 1314274800:5

I then do a fetch:

rrdtool fetch test.rrd AVERAGE

I expected to get the value of 5 at 1314274800 but I get NaN. I understand that RRDTool does the following before it stores values: Rates, Normalization, Consolidation. In this case my DS is a GAUGE so it is a rate - no conversion is required here. I am normalizing stuff every 300 seconds (step is 300) beginning from the start time of 1314270000. I then have a CF of AVERAGE that is averaging 1 value. So in this case, I am not really averaging anything.

Can you please elaborate as to why it is so?

I appreciate your time on the matter.

Much obliged,

- Tintin
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Re: Steps and heartbeats.

Alex van den Bogaerdt-5

> but I still have a doubt as to
> how these parameters relate / work with one another.

They don't.

> I have created the following rrd database:

> rrdtool create test.rrd --start 1314270000 --step 300 --no-overwrite
> DS:no-signal-3-steps:GAUGE:1800:U:U RRA:AVERAGE:0:1:15
[...]
> rrdtool update test.rrd 1314272400:10
> rrdtool update test.rrd 1314274800:5

update at times 1314272400 and 1314274800. The difference is 2400 seconds.
That is more than the heartbeat, thus is the rate unknown between
1314272400 and 1314274800. Now this unknown goes into normalization and
consolidation. All parameters like X-Files Factor, step, steps play a role
only after heartbeat did its work.

HTH
Alex

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Re: Steps and heartbeats.

tintin
This post was updated on .

Hi Alex,

Yes that was helpful.

Many thanks for your time on the matter.

Regards,
- Tintin