Cacti debugging

The saga of the UPS continues. Yesterday I got the SNMP card set up and working. I also found this Cacti template, which promised lots of pretty graphs. But there were a few bumps along the way.

First, Cacti was convinced that the UPS was down. Actually, it took me a while to figure this out because the logs didn't say anything abou this host at all. Eventually I tracked it down to Cacti using SNMP queries to see if it was up; turns out that this machine doesn't like being queried at the OID 0.1, and just doesn't respond. Changing the upness-detecting algorithm (heh) to TCP ping did the trick nicely.

Next, the graphs for the UPS were still not being produced, even though the RRDs were now being updated. I got the debug info for a graph and ran the rrdtool command by hand. The RRD does not contain an RRA matching the chosen CF was the response.

This thread showed a lot of people having the same problem. Since some of these problems were fixed by an upgrade, I did so; there were a few CentOS updates waiting for that machine anyhow. That made it worse: no graphs were being shown now. rrdtool said that there were no fonts present, so maybe fontconfig was out of order. Installing dejavu-lgc-fonts did the trick nicely, and I got my graphs back.

Well, all except the UPS ones I was after in the first place. I was still getting the error about not containing the chosen CF. Well, when all else fails keep reading the forum, right?

The rrdtool command used the LAST function; this was the culprit. If I ran s/LAST/AVERAGE/g on the command, it worked a treat. Thus, one option would have been to edit the template. However, I decided on an alternate approach, suggested in the forum: I removed the UPS RRDs, went to Data Sources -> RRAs in the Console menu, selected each RRA in turn and added LAST to the consolidation function.

Finally! Whee! Except for one: the graph of voltage vs input frequency. I still don't know what this means to me, but I wasn't about to give up now.

Again, rrdtool provided the error: "For a logarithmic yaxis you must specify a lower limit > 0". Bug reports to the rescue: Console -> Graph Templates -> Voltage/Freq, and set Lower Limit to 0.1.

All that and I'm still the only one looking at these graphs. Man, I should frame them.