CVSup® is a software for distributing and updating collections of files accross a network. It can efficiently and accurately mirror all types of files, including sources, binaries, hard links, symbolic links, and even device nodes. In addition to being a great general-purpose mirroring tool, CVSup includes special features and optimizations specifically tailored to CVS repositories. It is being used as the preferred way to update sources within the FreeBSD, NetBSD and OpenBSD projects, and by many more projects such as PostgreSQL.
csup is a rewrite of CVSup in C.