Chapter 21. Debugging

Table of Contents
Check Cacti Log File
Check Basic Data Gathering
Check cacti's poller
Check MySQL updating
Check rrd file updating
Check rrd file ownership
Check rrd file numbers
Check rrdtool graph statement
RPM Installation?
Not NaN, but 0 (zero) values?

Cacti users sometimes complain about NaN's in their graphs. Unfortunately, there are several reasons for this result. The following is a step-by-step procedure recommended for debugging.

Check Cacti Log File

Please have a look at your cacti log file. Usually, you'll find it at <path_cacti>/log/cacti.log. Else see Settings, Paths. Check for this kind of error:

CACTID: Host[...] DS[....] WARNING: SNMP timeout detected [500 ms], ignoring host '........'

For "reasonable" timeouts, this may be related to a snmpbulkwalk issue. To change this, see Settings, Poller and lower the value for The Maximum SNMP OID's Per SNMP Get Request. Start at a value of 2 and increase it again, if the poller starts working. (1 or less disables snmpbulkwalk) Some agent's don't have the horsepower to deliver that many OID's at a time. Therefore, we can reduce the number for those older/underpowered devices.