Virtuozzo is a software application for enterprise server virtualization that allows an administrator to create virtual environments on a host computer at the operating system (OS) layer. Instead of having one physical machine run multiple operating systems simultaneously, as the virtual machine model used by VMware and Microsoft Virtual Server or XEN does, Virtuozzo approaches virtualization by running a single OS kernel as its core and exporting that core functionality to various partitions on the host. Each of the partitions effectively becomes a stand-alone entity called a virtual private server. Virtuozzo comes with a proprietary Kernel Service Abstraction Layer (KSAL) that manages access to the kernel and prevents any single VPS from bringing the entire physical server down. It also has a proprietary file system to completely isolate the partitions, a security precaution that prevents a software fault in one partition from impacting an application or data in another partition.
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