Welcome back for another episode of the ABC's of NSM.  What's NSM you say?  We'll go with Network and System Management, but you could throw Security in there as well.  We'll work our way through the alphabet over the next several weeks looking at tools and concepts along the way for all the administrators out there.  By the way, you can thank Joe for the format & Don for the title (I couldn't for the life of me come up with one.)

Today's letter G is for Ganglia.  Ganglia is an open-source monitoring system specifically designed to meet the needs of distributed systems.  The platform is hierarchical, allowing for central systems to reach out to a handful of collection points instead of every node where an agent is installed.  Ganglia's main components are:

• gmond -- The Ganglia monitoring daemon.  This is installed on every node you wish to monitor and has four main responsibilities: monitor changes in host state, announce relevant changes, listen to the state of all other Ganglia nodes, and answer requests for the cluster state.
• gmetad -- The Ganglia meta daemon collects data from other gmetad or directly from gmond sources and stores the info in indexed rrd files.
• The Ganglia PHP Web Frontend.

Details on the Ganglia architecture (pictured below) and a deeper dive into monitoring distributed systems are available in this paper on Parallel Computing.