Munin monitoring Graph Performance

Goal

Speed up munins performance by moving the generated html files and graphs to a temporary file system (tmpfs)

Intro

Munin [1] (1.x) updates its data and graphs every 5 minutes. On a system that has a lot of monitoring to perform, the time to collect the data (munin-update),  generating the graphs (munin-graph), creating the html files (munin-html) and checking the limits (munin-limits) can exceed the 5 minutes available before the next update will be performed. The consequence are gaps in the graphs.

In the log files of munin the time needed for each of the four phases is documented. This can also be visualized with the munin processing time plugin. It shows that the graphing is the phase which takes the most time to complete.
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