Plotting a large gauge when value slowly changes over time

[amiliv]

I need to plot a value of a gauge that is in thousands, or sometimes hundreds of thousands range (depending on the device). The value of the gague doesn't change much over time, sometimes the change will be 10 units over an hour, sometimes it will be 100 or so units over an hour.

I'm currently using autoscaling with --alt-autoscale option (so both lower and upper bounds are adjusted). However, the problem is, if I use rigid boundaries (--rigid), there is no Y grid, so by just looking at the graph you can't tell what range of values it shows. If I don't use --rigid, than some of the graphs just show flat lines, because range between grid lines is too large.

For example, when not using --rigid option, I get one Y grid line at 320,000, and another one at 321,000. If my data for last 24 hours is let say in 320,566-320,589 range, I simply get more or less flat line on the graph with absolutely no details.

I know that I could try defining a function that would substract some value to "normalize" the gauge to some normal lower range (for example, by substracting 300,000 it would start plotting nicely since grid lines would be at 32,5k and 32,6k). However, I'd like to have something more generic. As I said, some of devices return values in thousand's range, some return it in hundreds of thousands range, so simply substracting an constant value wouldn't work. And I'd need to update the amout being substracted from time to time, so not really managable option either.

Given the example above, is it possible to generate graph that will autoscale like using --rigid does, but still shows some grid lines with values (for the example above, a grid lines at 320,500 and 320,600 would be perfectly fine)? They don't need to be metric, I just want to see what is the range of data shown on the graph. I see that rrdtool has --alt-y-grid option which looks promising from what I've read in manual page, but it seems cacti doesn't utilize it.

Thanks for any and all help

[gandalf]

As there is no real progress on this item (and personally, I can't help), I suggest that you post it on the rrdtool-users mailing list at http://www.rrdtool.org cause its mainly a rrdgraph formatting item. It would be nice to hear of a solution if any
Reinhard

[amiliv]

Actually, the solution is to use --alt-y-grid option. I've changed lib/rrd.php to always include this option on all of my graphs, and it works nicely now.

Would be nice if this was added as an checkbox to graph templates. Or if graph templates included a field where admin could pass custom options to rrdgraph.

[gandalf]

Ok, alt-y-grid support should not be a problem. But this would have to wait until next release. You may want to post a Feature Request for this
Reinhard