Ganglia is a monitoring tool for high performance computing systems such as private clouds, public clouds, clusters, and grids. The Ganglia system contains: 1) two unique daemons, 2) a PHP-based Web front-end, and 3) other small programs. Gmond, a multi threaded daemon, runs on each node to monitor changes in the host state, announce applicable changes, listen to the state of all Ganglia nodes via a unicast or multicast channel based on installation, and respond to requests. At regular intervals, Ganglia Meta Daemon polls a collection of data sources, parses the XML, saves all metrics to round-robin databases and exports the aggregated XML. The Ganglia Web front-end is written in PHP and uses graphs generated by gmetad, and provides the collected information like CPU utilisation for the past day, week, month, or year.
Multicast mode is the default setting in Ganglia installation and is the simplest to set up, providing redundancy. Public Cloud Environments such as Amazon's AWS EC2 do not support multicast, so unicast mode installation is the only set-up option available. Eucalyptus is an open source product for building AWS compatible private clouds; its open source version does not provide built-in monitoring but that can be achieved with Ganglia.
The Eucalyptus source package includes scripts that can be used with third party tools such as Ganglia to enable Eucalyptus