SmartOS is an open-source UNIX-like operating system based on illumos, a community fork of OpenSolaris. It features four technologies - ZFS (a combined file system and logical volume manager), DTrace (a dynamic tracing framework for troubleshooting kernel and application problems), Zones (a lightweight virtualisation solution) and KVM (a full virtualisation solution for running a variety of guest operating systems, including Linux, Windows, BSD and Plan9). SmartOS is designed to be particularly suitable for building clouds and generating appliances.

~~Dsitrowatch