[rrd-users] GAUGE stored values

Simon Hobson linux at thehobsons.co.uk
Thu Aug 19 08:53:09 CEST 2010

Marc MERLIN wrote:

>  > > See 'Can't I turn off data smoothing for GAUGE?' thread that I 
>started just
>>  > a few days earlier :)
>>  >
>>  > Marc
>>  The doc says that there isn't any (see my second post).
>If it does say that, it is likely wrong then.

It is wrong, or more correctly, it is misleading in the wrong context.

>  > Perhaps the answer is to add a new data type which is explicitly
>>  recorded "as is" (maybe call it RAW).
>that, or DATA like I proposed (i.e. we pretty much said the same thing

The problem is that without **significantly** changing the data 
model, it is not possible to store arbitrary data at arbitrary times 
without normalisation. The data model simply does not deal with 
timestamped data, all data is normalised into regularly sized 'bins'.

IFF you feed in data on each step boundary (not a second early, not a 
second late, and don't miss any), then normalisation is a null 
operator and what you feed in will be what's stored (after conversion 
to a floating point). But you obviously can't do consolidation 
without breaking that.

See http://www.vandenbogaerdt.nl/rrdtool/
In particular, see the tutorial on "Rates, normalizing and consolidating"
for an explanation of what rrd tool does.

Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
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