Munin

Monitoring our systems, networks and server’s performance and activity is one of the duller aspects of administration, and often something that is overlooked until there is a problem. Fortunately, there are many tools that can be used to monitor our system resources with differing levels of complexity and difficulty to configure. One of the simpler tools for getting the details for all the above can be simply derived from the monitoring tools called “Munin”, which is considered as one of the most flexible network resource monitoring systems available for UNIX and UNIX-like operating systems including Linux, FreeBSD, NetBSD, Solaris.

Munin is an open source and free software in which it helps in monitoring the networks, systems and other infrastructure software application systems. It is designed to be very plug and play. Mainly it offers monitoring and alerting services for servers, switches, applications, services, etc.

Note: In Norse mythology, Hugin and Munin are the ravens of the god-king Odin. They flew all over Midgard for him, seeing and remembering, and later telling him. Munin means memory in old Norse.

Jimmy Olsen was the founder of Munin application based on the RRD tool which helps in creating the graphical representation which can be accessible over a web interface by Tobi Oetiker. However, all other monitoring tools are somewhat not maintained properly with the development side and also with the compatibility part. whereas, Munin is considered as a stable tool and is maintained with proper updation.

Munin presents all of the pieces of information with a graphical representation. By using this tool we can get information about the systems through a web interface. It is written in Perl and emphasis is on plug and play capabilities. About 500 monitoring plugins are currently available. It is intended to make it easy to determine “what’s different today” when a performance problem happens and to provide visibility into capacity and utilization of resources.

Requirements to install Munin

– A reasonable Perl5, both on the server and nodes
– RRD with perl support
– Perl modules for server: Time::HiRes, Storable, Digest::MD5, HTML::Template, Text::Balanced
– Perl modules for node: Net::Server
– Perl modules for plugins: Depends on the plugins you want to use, but probably none.
– Gnu Make

Munin has a master/node architecture in which the master connects to all the nodes at regular intervals and asks them for data. It then stores the data in RRD files, and (if needed) updates the graphs. One of the main goals has been the ease of creating new plugins (graphs).

Architectural Fundamentals

 

 

Running Munin

  • Munin master

In order to run the Munin master, we need the below constraints :
– A reasonable perl 5 (Version 5.10 or newer)
– All the perl modules used when building Munin
– A web server (optional)

  • Munin node

The Munin node is lighter on the requirements, and need only the following perl modules:

– Net::Server
– Net::Server::Fork
– Time::HiRes
– Net::SNMP (Optional)

The Munin plugins run by the node have their own needs. Many plugins need libraries or utilities related to what they monitor.

Munin monitoring tools generally display the below list of breakdowns.
1) Inode usage in percent
2) Disk throughput per device

3) Network
Firewall Throughput
eth0 Traffic

4) Processes
Fork rate
Number of threads
CPU Usage

5) System
Available entropy
Inode table usage
Load average

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