[rrd-users] trigger an alert?

Sven Ulland sveniu at opera.com
Wed May 9 17:29:47 CEST 2007

John Conner wrote:
> Hmmm, I installed a new rrdtool and enabled aberrant detection, but 
> seems there is nothing new on the generated graphic, no upper/lower 
> boundary, no tick mark.
> Does it means rrdtool needs to reach the limit of the 5 days "length" 
> (RRA:HWPREDICT:1440: 0.1:0.0035:288 ) to begin to generate upper/lower 
> boundary and alert?

Yes, you have to wait for one seasonal period before the HWPREDICT
value is visible, and two periods before the deviation bars are there.

This is a major hurdle when trying to tune the values, since it takes
days and even ways to try out new values every time. That is why you
probably want to make some scripts that can quickly regenerate graphs.
There's something called hw-reapply that can do this for you, but I
haven't tried it, and I don't know if it shows immediate results:

What I do is to log all 'rrdtool update' commands to a file, so I
can easily run this file to repopulate the RRD files. Then I can tune
the HW values when creating the RRD, run the backlog, and see graphs

Also, I'd rather use a 1 day (or 7 days) season. A five day season
could have problems with deviations in week-ends. Depends on your
traffic patterns, of course.


> On 5/4/07, *John Conner* < bs7799 at gmail.com <mailto:bs7799 at gmail.com>> 
> wrote:
>     Hey Sven , thank you very much for you detailed information, I spent
>     a few hours going thought some documents about aberrant yesterday
>     and feel better now.
>     My current rrdtool is at version 1.0.49, which even does not support
>     "updatev" argument, so I am not sure what the different between
>     "update" and "updatev" will be,  will install rrdtool-1.2.19 today
>     and do some test.
>     Thanks again!
>     Joh
>     On 5/3/07, *Sven Ulland* < sveniu at opera.com
>     <mailto:sveniu at opera.com>> wrote:
>         Next, to actually have it report aberrant behaviour in real-time,
>         as opposed to post-mortem, you'll need a wrapper script to run
>         'rrdtool updatev' and parse the output. There are probably fancy
>         bindings in perl for this, or some other graceful way of doing it.
>         My way is a quick python script that parses the output looking for
>         'FAILURES', and then determining if the corresponding value is
>         greater than 0.0.
>         Well, that's pretty much it. Good luck!
>         Sven
>         > >     I use the aberrant behaviour detection in rrdtool and I find
>         > >     it quite handy. To detect problems, i use the 'rrdtool
>         updatev'
>         > >     command, which will output FAILURE=1.0 (different syntax), if
>         > >     it detects failures. FAILURE=0.0 if not. In other words,
>         I parse
>         > >     the output of the command, and trigger alerts based on
>         it. You
>         > >     should probably implement a wrapper around the
>         parsing/alarming,
>         > >     so that you won't get flooded with mails/SMS messages
>         every five
>         > >     minutes while a deviation is happening.
>         > >
>         > >     Sven

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