Ceilometer can integrate the ganglia to monitor the resources

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.

Ganglia is a mature open source monitoring project, has a good support metrix and performance. Ceilometer can integrate the ganglia to enhance its support metrix.

And also Ganglia is used widely to monitor the resources. This proposal is used to integrate the original environment monitored by Ganglia to OpenStack environment easily.