[rrd-users] How to find first valid dp in rrd - repost - where are the experts?

[Tobias Oetiker]

Karl,

rrdtool does not 'know' so the best you can do is to search for it
... maybe (!!!) some clever CDEF/VDEF can be constructed to return
this result via graph:PRINT or XPORT. Otherwhise you have to fetch
the data and then analyze it in an external script ... the whole
process  will be largely disk-io-bound, hence the way you implement
this will not have a bif effect.

cheers
tobi


Today Karl Fischer wrote:

>
> Hello,
>
> since there was no answer to my last post, I'm trying again.
> Where are the experts?
>
> Is there a good way to find the first valid (not UNKN) datapoint in rrd?
>
> rrdtools first doesn't quite do what I expected.
> Instead it gives you "rrdtools last" - rrasize.
>
> Example:
>
>  --step=1
>  DS:loadavg:GAUGE:10:0:U
>  RRA:AVERAGE:0.5:1:259200     # 3 days
>  RRA:AVERAGE:0.5:10:259200    # 30 days
>  RRA:AVERAGE:0.5:60:259200    # 180 days
>  RRA:AVERAGE:0.5:600:259200   # 1800 days
>
> If I have created a rrd like this and I started to use it a week ago,
> I'm looking for a way to find out when that fist value was entered
> into the rrd. Instead of telling me the first 'valid' DP in that rrd,
> "rrdtools first file.rrd" tells me 'now - 3 days' and
> "rrdtools first file.rrd --rraindex 3" tells me 'now - 1800 days'
> What I would like to get is that point in time a week ago when I
> entered the first value.
>
> any ideas?
>
> many thanks
>
> - Karl
>
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>

-- 
Tobi Oetiker, OETIKER+PARTNER AG, Aarweg 15 CH-4600 Olten, Switzerland
http://it.oetiker.ch tobi at oetiker.ch ++41 62 775 9902 / sb: -9900