The Munin master

For an overview see Architectural Fundamentals


The munin master is responsible for gathering data from munin nodes. It stores this data in RRD [1], files, and graphs them on request. It also checks whether the fetched values fell below or go over specific thresholds (warning, critical) and will send alerts if this happens and the administrator configured it to do so.

[1]RRDtool (acronym for round-robin database tool) aims to handle time-series data like network bandwidth, temperatures, CPU load, etc. The data are stored in a round-robin database (circular buffer), thus the system storage footprint remains constant over time. Source Wikipedia:


The following components are part of munin-master:

  • munin-limits is run by munin-cron. It notifies any configured contacts if a value moves between “ok”, “warn” or “crit”. Munin is commonly used in combination with Nagios, which is then configured as a contact.

Additionally munin 2.0 contains two more components:


The munin master has its primary configuration file at /etc/munin/munin.conf.

Graphing Charts