antiX
antiX is a fast, lightweight and easy-to-install Linux live CD distribution based on Debian's "Stable" branch for x86 compatible systems. antiX offers users the "antiX Magic" in an environment suitable for old computers.
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SmartOS
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), KVM and bhyve (two full virtualisation solutions for running a variety of guest operating systems, including Linux, Windows, BSD and Plan9).