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
relies on a multicast-based listen/announce protocol to monitor the
state within clusters and uses a tree of point-to-point connections
among representative cluster nodes to federate clusters and aggregate
their state. It leverages widely-used technologies such as XML for data
representation, XDR for compact, portable data transport, and RRDtool
for data storage and visualization.