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  • Shane Scott ZenossMaster 1,373 posts since
    Jul 6, 2009
    Currently Being Moderated
    15. Sep 8, 2011 3:27 PM (in response to stevez)
    Re: Guage RRD Behavior

    Steve:

     

    The consolidation function needs to have one step per consolidated step/period. Can you post your RRD create?

  • Shane Scott ZenossMaster 1,373 posts since
    Jul 6, 2009
    Currently Being Moderated
    17. Sep 8, 2011 3:31 PM (in response to stevez)
    Re: Guage RRD Behavior

    Steve:

     

    Nein! You still have the Baystacks aloof? LOL

  • Shane Scott ZenossMaster 1,373 posts since
    Jul 6, 2009
    Currently Being Moderated
    18. Sep 8, 2011 3:52 PM (in response to Shane Scott)
    Re: Guage RRD Behavior

    rrdtool create newdata.rrd --step 300 \

    DS:upDown:GAUGE:0:U:U \

    RRA:AVERAGE:0.5:1:525960

     

    Is what I come up with. I'm not sure why averaged values are ending up in there.

  • Shane Scott ZenossMaster 1,373 posts since
    Jul 6, 2009
    Currently Being Moderated
    20. Sep 8, 2011 4:11 PM (in response to stevez)
    Re: Guage RRD Behavior
  • Shane Scott ZenossMaster 1,373 posts since
    Jul 6, 2009
    Currently Being Moderated
    21. Sep 8, 2011 4:19 PM (in response to Shane Scott)
    Re: Guage RRD Behavior

    Steve:

     

    Looks like a normalization issue.

     

    RRD picks the timestamps of the intervals for you using your supplied stepsize but uses its timestamps. This means that if samples are every 10 seconds and starting 6 seconds after the minute for a PDP, none of the data points will be recorded exactly as supplied them.

  • Shane Scott ZenossMaster 1,373 posts since
    Jul 6, 2009
    Currently Being Moderated
    22. Sep 8, 2011 4:31 PM (in response to Shane Scott)
    Re: Guage RRD Behavior

    Steve:

     

    "You can cause the normalisation to be a null operator by

    ensuring that you update on every step boundary - not a second early

    or late - and do no consolidation. "

     

    "Don't expect values.  Expect rates. Values are used by rrdtool to

    compute rates.  It are these rates that are normalized, consolidated

    and displayed.

     

    Depending on your counter type, and your input, rrdtool will

    'modify your values' (compute a rate from them).

     

    If you think you are dealing with values instead of rates, at some

    point in time you are going to be disappointed"

     

    Looks like it all comes down to 1:1 step per period and always updating on step/period boundaries.

  • Shane Scott ZenossMaster 1,373 posts since
    Jul 6, 2009
    Currently Being Moderated
    24. Sep 8, 2011 4:48 PM (in response to stevez)
    Re: Guage RRD Behavior

    Steve:

     

    Sorry I don't have a better answer for you.

  • Shane Scott ZenossMaster 1,373 posts since
    Jul 6, 2009
    Currently Being Moderated
    26. Sep 8, 2011 4:54 PM (in response to stevez)
    Re: Guage RRD Behavior

    Steve:

     

    Thats pretty much the case.

  • nilie Rank: Green Belt 372 posts since
    May 27, 2010
    Currently Being Moderated
    27. Sep 8, 2011 8:24 PM (in response to stevez)
    Re: Guage RRD Behavior

    From : http://oss.oetiker.ch/rrdtool/tut/rrdtutorial.en.html

     

    [quote]One important feature of RRDtool has not been explained yet: it is virtually impossible to collect data and feed it into RRDtool on exact intervals. RRDtool therefore interpolates the data, so they are stored on exact intervals. [/quote]

     

    In translation, during the ideal polling interval (T) - (T+5min) the interface status moves from 1 to 2. At T+5+delta which is the real polling moment, rrd is fed with the new value but in order to store it under T+5 time stamp, rrdtool will scale it back to something less than 2.

     

    Could it be because of this ?

  • jmp242 ZenossMaster 4,060 posts since
    Mar 7, 2007
    Currently Being Moderated
    28. Sep 9, 2011 8:22 AM (in response to stevez)
    Re: Guage RRD Behavior

    I think in this case, (depending on other factors certainly), I might consider not using zenperfsnmp to gather the data - i.e. for a binary value with 2 or 3 possible states, and/or you don't need to graph it -  don't store the values in an RRD. It's probably a hack, but when I want to check on a polled value that is a "yes/no" sort of thing, I usually use a command datasource, and store values if I need to in a file my script creates.

     

    Not to say that's a good way to do it, but maybe a bit of figuring out a correct tool for the job. I don't know all the context of what you're doing though, so this may be totally useless.

     

    Potentially for some of the community devs who are adept at writing perf daemons, maybe it would be worthwhile putting on a "nice to have" list something that's like zenperfsnmp but gives the option if storing data in (something) other than RRD for non-graphing uses.

     

    --

    James Pulver

    Information Technology Area Supervisor

    LEPP Computer Group

    Cornell University

  • Shane Scott ZenossMaster 1,373 posts since
    Jul 6, 2009
    Currently Being Moderated
    29. Sep 9, 2011 10:20 AM (in response to jmp242)
    Re: Guage RRD Behavior

    Nillie:

     

    Yes, normalization.

     

    Steve:

     

    Maybe write a daemon that uses the twisted framework to perform the snmp tasks and update statuses/create events rather than storing the data.

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