[smokeping-users] Storing high time resolution results over longer periods

[Chris Wilson]

Hi Luigi,

On Tue, 4 Dec 2012, Luigi Corsello wrote:

> I am using a step of 60 seconds in my smokeping setup, had all RRDs 
> regenerated to get the graphs I need to see:
>
> However all graphs of my benchmarks are captured in batches one or more days 
> later (up to 4-5 months in corner cases). But taking a graph just one days 
> later all details are gone! (for good, I fear):
>
> One Hour fping graph - yesterday - ALL DETAIL GONE!

Yes. That is the point of rrdtool, to make it easy to automatically 
aggregate old results, which drops the resolution. The raw data is 
discarded once it's been incorporated into the aggregates.

> If the detail is really lost, this is a bit of a disaster forcing to 
> repeat an all bunch of measurements that were already done and then 
> immediately capture the graphs. Can anyone confirm most details of my 
> history are gone?

Yes, because:

> # consfn mrhb steps total
>
> AVERAGE  0.5   1  1008

You only store 1008 results at full detail (step 1). That's 1008 minutes 
if you use step = 60.

> AVERAGE  0.5  12  4320

And 4320 results are stored at one data point per 12 steps (12 minutes 
in your config). That means that the last 4320*12 minutes are stored 
averaged over 12 minutes (and the minimum and maximum over each 12 minute 
period).

If you really want to store full resolution data for 6 months, you need a 
line that has type average, step 1, and length 60*24*(365/2) = 262800 
minutes (365/2 days):

AVERAGE 0.5 1 262800

You may not find much use for the other detail levels in this case, so you 
might want to delete them.

Cheers, Chris.
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