[rrd-users] dump/fetch do not show lastupdate value

Simon Hobson linux at thehobsons.co.uk
Wed Nov 6 11:20:54 CET 2013

Konstantin wrote:
> I have noticed that rrdtool dump/fetch commands sometimes populate values as NaN even
> if I have written updates several times to rrd (with different timestamps).

> "lastupdate" command shows that value was successfully written, but whats preventing it from being displayed?
> Please note, that I put single values into rrd few times a day, but the resolution is 600 seconds. So most of the
> values will be NaN, but why I get NaN for periods with updated values?

Just because an update has been written does not mean that a "bucket" has been filled with data. it will need several updates, including one after the end of a bucket before that bucket will have any data - and even then, whether it does or doesn't have a value will depend on your heartbeat setting, "fudge factor", and the freqency of updates.

The data you give doesn't give any clue at all about what previous updates you've done. What I suggest you do is put together a set of updates which demonstrate the problem, then someone might be able to spot the problem.

Also, have a look at Alex's tutorials athttp://www.vandenbogaerdt.nl/rrdtool/, in particularRates, normalizing and consolidating

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