[rrd-developers] rrdcached support for --template

Tobias Oetiker tobi at oetiker.ch
Wed Jan 5 10:43:00 CET 2011

Hi Eric,

I will look a bit more closely at to code to see what can be done
without going for the big rewrite ... I think template is doable
... the piece de resistance is updatev which requires quite
fundamental changes to the whole infrastructure ...


Yesterday Eric Schoeller wrote:

> Steve and Tobi,
> Thanks for your replies. I was certainly excited to initially read about rrdcached, and I was disappointed
> to find out that my application (Cacti) utilizes a feature of rrdtool that is not supported (yet). I don't
> know enough about rrdtool/rrdcached to fully understand the negative performance implications of supporting
> '--template'. My goal was to implement rrdcached and observe any performance improvements of our
> application/hardware. One thought is that it might help evenly distribute I/O load.  As my application
> footprint grows I'd also be investigating the network socket option to offload work to additional hardware.
> I don't have the time or the experience with C to implement this myself, and if I did you'd probably reject
> the patch anyway :) We also have a team of student employees who may be up to the task, but I would be more
> comfortable with having a software engineer already familiar with rrdtool working on such a feature. Our
> institution has been using rrdtool for quite some time now. We've never paid a dime for anything that
> utilizes rrdtool (well, other than hardware and FTE dollars) and I believe it would be possible to
> contribute to the effort now that we value it so highly. If someone could give me an idea of how many hours
> this would take along with an hourly rate (or just an overall cost) I can investigate this further.
> Thanks!
> Eric Schoeller
> University of Colorado, Boulder
> Information Technology Services
> Steve Shipway wrote:
> The trunk version of rrdtool has support for rrdinfo via rrdcached; so theoretically, this could be used to
>  retrieve the structure so that --template could be supported by rrdupdate via rrdcached.  However it would
> n't vbe a 5min job.  Also, it would necessitate several more actions by rrdtool/rrdcached which would proba
> bly negate any benefits of using rrdcached (other than being able to work over the network) so might not be
>  worth the effort.
> Steve
> Steve Shipway
> University of Auckland ITS
> UNIX Systems Design Lead
> s.shipway at auckland.ac.nz
> Ph: +64 9 373 7599 ext 86487
> ________________________________________
> From: rrd-developers-bounces+steve=steveshipway.org at lists.oetiker.ch [rrd-developers-bounces+steve=steveshi
> pway.org at lists.oetiker.ch] on behalf of Tobias Oetiker [tobi at oetiker.ch]
> Yesterday Eric Schoeller wrote:
> Is there a plan to enable rrdcached support for 'rrdtool update
> --template ...', and if so what is the approximate time frame? Apologies
> in advance if the feature has already been added and I've missed it.
> I don't know of anyone working towards this at present ... the
> problem with supporting --template is that it requires knowledge
> about the structure of the rrd file which rrdcached does not have
> by design ... there are ideas on how to change this (it would also
> enable updatev) but the changes would be quite extensive ...

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

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