[rrd-developers] rrdcached: info command: cacheable?

Tobias Oetiker tobi at oetiker.ch
Wed Feb 2 23:58:17 CET 2011

Hi Steve,

I think this should be cached in mrtg/routers2 ... since rrdtool
info should realy return 'the real thing' ... so if there was
support for this in rrdcached then the option would have to be for


Today Steve Shipway wrote:

> I'm coding up a quick change to rrd_daemon.c to make it cache the results of rrd_info calls for a predetermined period.  This means that any calls to rrdc_info (IE, rrdtool info over rrdcached) would be cached, speeding up retrieval at the cost of items such as 'last_update' and '*.value', '*.cur_row' etc being out of date.  Probably there would need to be an option to info to allow bypassing of the cache?
> The motivation for this is that MRTG makes a substantial number of these calls (as does Routers2 and others) but are only interested in the structure of the RRD, not the current values.  By caching it would speed up access and minimise disk IO.
> Thoughts, anyone?  I have yet to see how much actual difference it would make...
> Steve
> ________________________________
> Steve Shipway
> ITS Unix Services Design Lead
> University of Auckland, New Zealand
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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

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