Cacti is a "complete network graphing solution" according to their website. It has also been a thorn in my side for a long time.
See what I did there? Thorn... because it's a cactus... never mind.
When Cacti is in a steady state-when I could get it to a steady state-it was good. Not great, because there was a lot of effort to get it into what I consider "steady state", but good. The rest of the time... thorny.
There are five major things that have driven me up the wall. In no particular order:
I had just lost the RAID array that hosts my ESXi data store. I didn't yet know that's what had happened, but with some investigation, some embarrassment, and a bit of swearing, I would find out that an oversight on my part three years ago would lead to this happening.