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July 22, 2004
OpenNMS .I.
Unfortunately I won't be telling my life story in this column :) So my sincere apologies to the technically declined!
Entries in this category will keep track if my onms progress. I've never dealt with any sort of nms system before so this is a good start to reflect and learn. Also, if the onms faq site didn't help much, you might get some answers here.
Anyway I had an interesting problem to fix today. While checking out the cpu utilization graph for a winxp workstation I was polling from, I noticed that it hadn't been updated for the past 12 hours! Now, how could that have happened when none of the xml config files were screwed around with? Sensibly, I did a rrdtool dump on the said winxp node and came up with NaN (not a number) values. Which meant 2 things:
1. The snmp agent on the winxp node somehow altered it's own mib. (Don't know how this is possible, I have yet to view the default set, if any. If anyone knows where I can find mibs in winxp do let me know. Previously installed snmp informant, just in case, but a snmpwalk on one if its oid (object id) didn't fetch anything!)
2. cpuPercentBusy oid was wrongly specified in the datacollection.xml file. (Very unlikely, since polling did graph results after the last alteration)
With these two possibilities in mind, one could tell that not a single value was polled because of an unknown or a non integer value from the cpuPercentBusy oid, hence the NaN values and the empty graph!
So, how was this fixed? With the knowledge that an invalid oid could as well have been the cause, I compared two snmpwalk dumps on the said oid which I did the day before, and a newer one this morning. Which resulted in this:
old dump
HOST-RESOURCES-MIB::hrProcessorLoad.1 = INTEGER: 99
new dump
HOST-RESOURCES-MIB::hrProcessorLoad.2 = INTEGER: 99
How was it possible that the instance changed from 1 to 2 is something i'm trying to figure out. AFAIK the snmp agent on winxp has static mib values, which shouldn't contribute to this problem.
So, a quick change of the instance value from "1" to "2" in the datacollection-config.xml file fixed it:
mibObj oid=".1.3.6.1.2.1.25.3.3.1.2" instance="2" alias="cpuPercentBusy" type="integer"
Restart and wallah, no more NaN!
Posted by kahjin at July 22, 2004 06:33 PM
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