VMware vSphere® 5.5 is the latest release of the flagship virtualization platform from VMware. VMware vSphere, known in many circles as "ESXi", for the name of the underlying hypervisor architecture, is a bare-metal hypervisor that installs directly on top of your physical server and partitions it into multiple virtual machines. Each virtual machine shares the same physical resources as the other virtual machines and they can all run at the same time. Unlike other hypervisors, all management functionality of vSphere is possible through remote management tools. There is no underlying operating system, reducing the install footprint to less than 150MB.
Improved Reliability and Security
The ESXi bare-metal hypervisor’s management functionality is in VMkernel, reducing the footprint to 150 MB. This gives it a very small attack surface for malware and over-the-network threats, improving reliability and security.
Streamlined Deployment and Configuration
With few configuration options and simple deployment and configuration, the ESXi architecture makes it easy to maintain a consistent virtual infrastructure.
Reduced Management Overhead
vSphere ESXi uses an agentless approach to hardware monitoring and system management with an API-based partner integration model. Management tasks are on remote command lines with the vSphere Command Line Interface (vCLI) and Power CLI, which uses Windows PowerShell cmdlets and scripts for automated management.
Simplified Hypervisor Patching and Updating
Fewer patches mean smaller maintenance windows and fewer scheduled maintenance windows.