Ganglia is a scalable distributed monitoring system for high-performance
computing systems such as clusters and Grids. It is based on a hierarchical
design targeted at federations of clusters. It leverages widely used
technologies such as XML for data representation, XDR for compact, portable
data transport, and RRDtool for data storage and visualization. It uses
carefully engineered data structures and algorithms to achieve very low
per-node overheads and high concurrency. The implementation is robust,
has been ported to an extensive set of operating systems and processor
architectures, and is currently in use on thousands of clusters around
the world. It has been used to link clusters across university campuses
and around the world and can scale to handle clusters with 2000 nodes.