DragonFly is an operating system and environment originally based on FreeBSD. DragonFly branched from FreeBSD in 2003 in order to develop a radically different approach to concurrency, SMP, and most other kernel subsystems.
DragonFly belongs to the same class of operating system as BSD and Linux and is based on the same UNIX ideals and APIs. DragonFly gives the BSD base an opportunity to grow in an entirely different direction from the one taken in the FreeBSD, NetBSD, and OpenBSD series. From 2003 to early 2007 the DragonFly BSD project focused on rewriting most of the major kernel subsystems in order to support the second phase of the project. This involved a great deal of work in nearly every subsystem, particularly the filsystem APIs and kernel core. During all of this they have managed to keep the system up-to-date with regards to the third party applications and base system utilities that are needed to make any system usable in production. They have also adopted the PkgSrc system for management of all non-base-system third-party applications in order to pool their resources with other BSD projects using the system.
The second phase of the project is beginning now. The ultimate goal of DragonFly BSD is to provide generic clustering support natively in the kernel. This involves the creation of a sophisticated cache management framework for filesystem namespaces, file spaces, and VM spaces, which allows heavily interactive programs to run across multiple machines with cache coherency fully guarenteed in all respects. This also involves being able to chop up resources, including the cpu by way of a controlled VM context, for safe assignment to unsecured third-party clusters over the internet.