Hi, On 26.08.2010 11:37, Sebastian Harl wrote: > On Wed, Aug 25, 2010 at 07:49:12PM +0200, Till Dörges wrote: >> On 24.08.2010 12:44, Sebastian Harl wrote:
>>> What other real-world use-cases, other than removing spikes or undefined >>> values, are out there? Those are the only ones I've encountered so far. > >> For our particular scenario we can even limit the time window for which >> we'll accept >> an update ex post. >> >> With that particular constraint the most favorite solution right now looks >> like a >> combination of a normal RRDtool db and a MySQL db. The former works as >> always, except >> that it doesn't store updates until t_now but until t_now - t_window. >> t_window is the >> time window for which we'll accept updates ex post. All the data between >> t_now - >> t_window and t_now ends up in MySQL. If any late updates arrive putting them >> in MySQL >> shouldn't be a problem. > […] >> The downsides I can see is that an additional db adds extra complexity. And >> you have >> a bit of effort to put into transferring the data. > > That sounds like a rather special use-case to me but which adds quite > some complexity and which does not seem (on a first glance) to solve the > actual problem: modifying existing old CDPs, which would have to be done > when transferring the SQL data back to the RRD. We don't necessarily have to modify CDPs. The biggest problem for us are late updates, i.e. data with a timestamp before the last actual update. Inserting these late updates into an SQL db is easy. No math/averaging/... > As a more general solution, it might make sense to provide a feature to > replace a whole range of data in one go. That would allow to update some > CDPs with rather exact data and leave interpolation (or whatever might > be done) to one CDPs at each side of the specified time slot. Storing > that data would then be left to the user but could be supported by > RRDtool by providing means to read the data from several data-sources > (SQL db, CSV text file, …). If I understood your solution correctly that would solve our problem, too. And certainly with less hassle. Ideally one could give rrdupdate a timestamp from the past and (if feasible for the current set of RRAs) it simply exchanges the CDPs. We might have a few resources to spare, but have only experience using RRDtool - not developing it. That means I don't have a "gut feeling" of how hard this would really be. Regards -- Till -- Besuchen Sie uns auf it-sa und PITS 2010: 6. - 7.10.2010 http://www.public-it-security.de 19. - 21.10.2010 http://www.it-sa.de Dipl.-Inform. Till Dörges doer...@pre-sense.de Tel. +49 - 40 - 244 2407 - 14 Fax +49 - 40 - 244 2407 - 24 PRESENSE Technologies GmbH Sachsenstr. 5, D-20097 HH USt-IdNr.: DE263765024 Geschäftsführer/Managing Directors AG Hamburg, HRB 107844 Till Dörges Jürgen Sander Axel Theilmann _______________________________________________ rrd-developers mailing list rrd-developers@lists.oetiker.ch https://lists.oetiker.ch/cgi-bin/listinfo/rrd-developers