VMware ESX Server
VMware ESX Server uses a stripped-down proprietary kernel (derived from work done on Stanford University's SimOS) that replaces the Linux kernel after hardware initialization. The Service Console (also known as "COS" or as "vmnix") for ESX Server 2.x derives from a modified version of Red Hat Linux 7.2. (The Service Console for ESX Server 3.x derived from a modified version of Red Hat Enterprise Linux 3.) In general, this Service Console acts as a boot-loader for the vmkernel and provides management interfaces (CLI, webpage MUI, Remote Console). This VMware ESX hypervisor virtualization approach provides lower overhead and better control and granularity for allocating resources (cpu time, disk bandwidth, network bandwidth, memory utilization) to virtual machines. It also increases security, thus positioning VMware ESX as an enterprise-grade product.