[rrd-users] problem with lost of data, file size always the same!

Nuno Pereira nunopereira at interacesso.pt
Fri Oct 3 13:40:12 CEST 2008

> -----Mensagem original-----
> De: rrd-users-bounces at lists.oetiker.ch [mailto:rrd-users-
> bounces at lists.oetiker.ch] Em nome de Francesco Andreozzi
> Enviada: sexta-feira, 3 de Outubro de 2008 12:08
> Para: rrd-users at lists.oetiker.ch
> Assunto: [rrd-users] problem with lost of data, file size always the
> same!
> Hi all, this is my first post and i hope to be clear :D
This is a case where a FTFM would be apropriate
(http://oss.oetiker.ch/rrdtool/doc/rrdcreate.en.html), but let's try to
figure a few things out.

> i have start to using rrd because seems to be really nice stuff....
> i create a lot of rrd to collect data from a specific device ...
> i create an rrd with the command like this
> rrdtool create <RRDNAME.rrd> --start <my-date> \
>          DS:<my-obj>:GAUGE:<my-time>0:U \
>          RRA:MIN:0.5:12:1440 \
>          RRA:MAX:0.5:12:1440 \
>          RRA:AVERAGE:0.5:1:1440
> the collection seems to be good except i'm lost some data!!!...

If I'm not wrong, you have just created an RRD which hás just one sample,
that is a GAUGE, and you collect 1440 points of the MIN and MAX value of
each 12 samples. Each sample, you store the sample AVERAGE (which would be
the same to put there a MAX and MIN, as you have only one value to average).
Clarify one thing: give us na example of what you put in <my-time> in the
line " DS:<my-obj>:GAUGE:<my-time>0:U \". You missed a semicolon there,
between <my-time> (heartbeat) and the 0 (minimal accpetable variable).

> if i do a rrdtool dump I can see min and max value from the starting
> time, but avarage no, the first values are lost every 5 minutes, when
> i do the rrdtool update!
You have 4 sections (or 2, with the last divided in 3). Check out the end of
the file, or whatch the ouput of "rrdtool info", as you'll see there an

> the file size is always the same and it doesn't increase!
That happens with all the RRDs that aren't resized.

> when i'm creating graph i really want to use avarage values! but on
> this way i think i will gona lost all this information!
Only if you are putting samples with a step that is lower than step (300 in
your case, which is default), and in this case you could put a smaller step,
if you need. Or if you don't update the RRD with samples in a period bigger
than heartbeat (your <my-time>).

> Ciao
> Francesco
Nuno Pereira

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