2 distinct y-axis in one graph?

[alexs77]

Hello!

I'd like to plot 2 curves in a graph. But those 2 curves should NOT share the same y-axis.

Eg. I'd like to plot the CPU Usage (idle) values of "ucd 00 CPU Solaris (enhanced)" which are always in the range 0-100 (because it's a percentage value) - and it's typcially in the higher range of 90-100. And in the same graph, I'd like to show eg. the 5 minutes load average from "ucd 01 Load Average", which is (on my systems) typically in the range 0-2.

If I'd plot those two curves on the same graph, then there'd be a (more or less) flat line at about 1 for the load and another flat line at 90-100 for CPU usage. That wouldn't tell much.

Now, if it were possible to have distinct y-axis for both graphs, then I could set y1 to 90-100 and y2 to 0-2 and see more.

Can this be done with Cacti? Oh, and if it were possible to have y1 be logarithmic and y2 not, then that would be even better!

BTW: That was just an example so that everybody should be able understand it with "publically available" values. In reality, y1 would still be CPU usage with 0-100 (%) but y2 would be some self derived value showing "application performance", measured in 1000-10000 (and best be shown in log.).

Thanks a lot,
Alexander

[BSOD2600]

Can this be done with Cacti? Oh, and if it were possible to have y1 be logarithmic and y2 not, then that would be even better!

The real question is if RRDTOOL can do this -- since this is what cacti uses to create/store the graphs.

Find how to accomplish this in the rrdtool manual/mailing list and then you can file a feature request.

[alexs77]

Hi.

In the RRDgraph manual, I found:

[--right-axis scale:shift] [--right-axis-label label]

A second axis will be drawn to the right of the graph. It is tied to the left axis via the scale and shift parameters. You can also define a label for the right axis.

[--right-axis-format format-string]

By default the format of the axis lables gets determined automatically. If you want todo this your self, use this option with the same %lf arguments you know from the PRING and GPRINT commands.

So it should be possible. I haven't checked yet, but I'd assume that this would conflict with auto scaling.

But given that there's only ONE upper-limit and lower-limit option, I'm confused on how to set the left y-axis to eg. 0..100 and the right y-axis to 1000..10000.

Any ideas?

Thanks a lot,
Alexander

[BSOD2600]

Appears its a recent new feature, 1.2.29, I believe. Wouldn't hurt to create the feature request in Cacti (if its not already requested) though. www.cacti.net/bugs.php

Per Tobias Oetiker,

you have todo the scaling of the graphs yourself, using CDEF. So if
one line is in the 100 thousands, then you do a CDEF:b=a,1000,/ and
draw b ... along with setting the scaling factor for the right axis
to 0.001

[TheWitness]

Yes, please log this feature. I have waited on it for long enough. Might as well have it in Cacti.

TheWitness

[rony]

I vote yes.... But... Oh man, what a pain to do version checking for....

[gandalf]

I vote yes.... But... Oh man, what a pain to do version checking for....

Yep. Well said. "unfortunately", some 1.3.x stuff was backported to 1.2.x. And now, 1.4 is on the run.
Unfortunately, the 2nd y-axis refers to the first one. From my point of understanding, this makes things more complicated ...
Reinhard

[transisco]

Yes, this would be very useful. I'd vote for it also. Version checking would be a a bit harder but it's a matter of running "rrdtool" and parsing it's output. Perhaps to make things easier for the folks who really want this feature, could you integrate in a custom rrdtool flags field?

[gandalf]

Yes, this would be very useful. I'd vote for it also. Version checking would be a a bit harder but it's a matter of running "rrdtool" and parsing it's output.

Bah, that's easy.
But can you imagine the table for all current rrdtool options, parameters and stuff having a separate column for each release? That will be about 30 columns! And do you know a single place where to find the information, which exact parameter was introduced an which exact rrdtool release?
If anyone provides me with that table, I will implement it in the next cacti main release!

Perhaps to make things easier for the folks who really want this feature, could you integrate in a custom rrdtool flags field?

That was indeed suggested from time to time. Until now, we refrain from doing so because this may break compatibilty between cacti versions (and perhaps between rrdtool versions).
Having the table as a start would allow for easier integration of new features.
Reinhard

[Lobz]

Is there any way at all to do this while using cacti?

[gandalf]

Not yet. This feature is already part of 088, but this version is pre-alpha
R.

[classen]

is this feature in 0.8.8a ?

Thanks

[gandalf]

No, postponed to 089 which is currently under development.
R.