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

[Karl Fischer]

Tobias Oetiker wrote:
> 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

thanks Tobi.
At least I know now that searching for it is the only way -
this is what I have done so far but I found it to be expensive ...

- Karl


> 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