Hrm, I guess when I have created an rrd file for GAUGE data, and later want to switch to DERIVE, I'm mostly on my own? At least I couldn't find anything useful in a short time of searching...
Ah well, just deleted the rrd files, it's only been a couple days of data anyway.
Oh. And also I'll have to rethink the whole thing and probably split it off into two different graphs since what I really have is one GAUGE value and three that are DERIVEd, separated by a couple orders of magnitude.
@smallsees Yeah, that's pretty much what I assumed I'd have to do, and it didn't seem worth it.