Is TREND rrdtool function taken into account

[Didier]

Hi,

I'd like to know if the TREND rrdtool function is taken into account into the last release of cacti. If not how can I intergrate it ?

A description of this function can be seen at

http://people.ee.ethz.ch/~oetiker/webto ... pn.en.html (search for TREND keyword)

CDEF:result=x,delay,TREND


where delay is in second
x is a variable
result will be at each time t an avareage of x between [t-delay] and [t]

This function allows to display a trend and have a baseline in the graph to make comparison easier to the current value and what we should have. I think it will be very useful.

Thanks

Didier

[scavenger67]

Have a trendling line will be very good to anticipate bottleneck..
hope this new function will be added in the next release !

[Grand Master Wierdo]

I implemented this by adding a CDEF into Cacti. This can then be applied on a graph item against a data source in a graph.

See attached

[fmangeant]

Hi

thanks for the CDEF. Could you post an example of a graph with trend ?

Thanks in advance.

[Grand Master Wierdo]

I originally created the CDEF as an academic exercise, but I have quickly knocked up a graph to show it in action. In addition, this uses a '30 Min moving average bits negative' CDEF which is the same as the one above, just with -1 & * added as extra steps, to make the cdef

cdef=CURRENT_DATA_SOURCE,1800,TREND,8,*,-1,*

Enjoy

[egarnel]

Awesome cdef! simple & easy to implement


custom interface graph template with the cdef
It worked for me, your mileage may vary

Running Cacti 0.8.6e patched with 0.8.6.f patches

| CentOS 3.5 | mysql-3.23.58-1 |php-4.3.2-23.ent | httpd-2.0.46-44.ent.centos.2|

[disorganizer]

the trending function works great, just one question:
is it possible to turn off the 30min average (or change it to another base) on the non-daily graphs?

as it uses a roaming average of 30 mins, beginning from the weekly graphs that graph is identical to the original graph anyways. so changing this to for example a 3hrs roaming average for weekly would be perfect, but turning it completely off for those would also fit.
tnx

[egarnel]

Sure, the 1800 in the CDEf refers to 30 minutes. 1800/60 = 30. Plug in what ever seconds value you want. 3 hours - 10800 seconds

cdef=CURRENT_DATA_SOURCE,10800,TREND,8,*,-1,*

not sure what it would look like. It would be interesting to have a template with 30 minutes, 60 minutes, 4 hour, & 24 hour averages. Something to do when I have more time

[disorganizer]

interesting. but how do i define that the daily graph cacti displays per default uses the 30minutes, the weekly graph uses the <whatever> minutes..... ?

another interesting point i check when i have time:
i would like to use a rra with 5 minute data, storing this data for 2 months, showing a one month graph.
now afaik in that graph the roaming 30 minute average should show the right values in a monthly overview.
the interesting point would be (if diskspace doesnt matter) to turn off the rrd accumulation feature and just have a rra with only one thing in it: 5 minute values, for 1,5 years of data ;-)

also we should be aware that rrd_maximum must obviously be automatically set to ifspeed/8, as cacti does not set this correctly. so the %-calculations do indeed go wrong by a factor of 10 on my gigabit interfaces *g*

[newbie1]

I am trying to implement a moving average in cacti, but am getting an error. I'm using cdef=CURRENT_DATA_SOURCE,1800,TREND.

Item Item Value
Item #1 Special Data Source: CURRENT_DATA_SOURCE
Item #2 Custom String: 1800
Item #3 Custom String: TREND

The error I get is:
ERROR: invalid rpn expression 'b,1800,TREND'.

Do I need something else to get cacti to recognize the trend function?

Thanks in advance!

[scavenger67]

What version of rrdtool you have ?
as i know you need at least 1.2 to have TREND feature.

[gandalf]

the interesting point would be (if diskspace doesnt matter) to turn off the rrd accumulation feature and just have a rra with only one thing in it: 5 minute values, for 1,5 years of data

You'll find my tutorial for doing so at http://forums.cacti.net/viewtopic.php?t=9605. But I don't think that this is a good solution. I'm going to compile some howto, similar to http://forums.cacti.net/viewtopic.php?t=9383. It will show you the MAX values for consolidated data, so you'll have an idea about the spreading of values, even if consolidation is done
Reinhard

[gandalf]

Sure, the 1800 in the CDEf refers to 30 minutes. 1800/60 = 30. Plug in what ever seconds value you want. 3 hours - 10800 seconds

cdef=CURRENT_DATA_SOURCE,10800,TREND,8,*,-1,*

not sure what it would look like. It would be interesting to have a template with 30 minutes, 60 minutes, 4 hour, & 24 hour averages. Something to do when I have more time

Would it be a solution, if the CDEF could access the timespan for the actual graph to be displayed? Like the one in the RRA definitions at "Data Sources" -> "RRAs"? Then, the calculation for the TREND interval could refer to this timespan?
Of course, this must be filled in dynamically, cause you may have different timespans if you select special intervals (or even use zooming). But I don't know, if RRDTOOL provides some kind of "special variable" for start/end time of the graph. In this case, it would be nice to have these "special values" as variables in cacti.
Reinhard

[gandalf]

Found a starting point at http://people.ee.ethz.ch/~oetiker/webto ... ph.en.html. It says

LAST, FIRST
Return the last/first value including its time. The time for FIRST is actually the start of the corresponding interval, whereas LAST returns the end of the corresponding interval.

Example: VDEF:first=mydata,FIRST

So it should be possible to get FIRST and LAST timestamp of the current graph. But it seems, there's a nice CDEF ahead ...
Reinhard