The Extended root file server consists of a file server called xrootd and a cluster management server called cmsd.

The xrootd server was developed for the root analysis framework to serve root files. However, the server is agnostic to file types and provides POSIX-like access to any type of file.

The cmsd server is the next generation version of the olbd server, originally developed to cluster and load balance Objectivity/DB AMS database servers. It provides enhanced capability along with lower latency and increased throughput.