VMware vSphere is a software suite which helps you to provide a virtualization solution to Your Infrastructure. You can provide complete virtualized Infrastructure solution with this product and this is not the only solution which you can use to build your virtualized Infrastructure. Basically the base component of any virtualized environment is known as a Hypervisor. Hypervisor is the bridge between virtualized environment and the actual hardware. In VMware we call this hypervisor as “ESXi”.
Previously this hypervisor named as ESX (Elastic Sky X) and the vmkernel is the virtualization kernel which is managed by a console operating system which is also called as Service console. The main purpose of this service console is provide a management interface to the ESX host and manage the agents. This is a linux based service console and this has been replaced by a very thin vmkernal in the ESXi version.
VMware has developed a very thin vmkernal and they named their hypervisor as ESXi (Elastic Sky X Integrated). All the VMware management and monitoring agents can be managed by this developed vmkernal and it helped to improve the VMware capabilities. ESXi is ultra-thin architecture which is highly reliable and its small code-base allows it to be more secure with less codes to patch. ESXi use Direct Console User Interface which is known as DCUI to perform all the management tasks associated with vSphere.
ESXi is a type 1 hypervisor – There are two types of hypervisors: type 1 hypervisor and type 2 hypervisors. ESXi is a type 1 hypervisor which is directly installed on the hardware also call it as native or bare-metal hypervisors. Hypervisors which are installed on operating systems such as VMware player, Oracle Virtual Box, Microsoft Virtual PC,etc are normally called as type 2 hypervisors or hosted hypervisors.