Home > Cloud Services - IaaS, Virtualisation, VMware > #VMware #ESXi and #ESX Architectures Compared – Understand the differences

#VMware #ESXi and #ESX Architectures Compared – Understand the differences

September 14, 2011

…Like its predecessor ESX, ESXi is a “bare-metal” hypervisor, meaning it installs directly on top of the physical server and partitions it into multiple virtual machines that can run simultaneously, sharing the physical resources of the underlying server. VMware introduced ESXi in 2007 to deliver industry-leading performance and scalability while setting a new bar for reliability, security and hypervisor management efficiency.

So how isESXi different from ESX? While both architectures use the same kernel to deliver virtualization capabilities, the ESX architecture also contains a Linux operating system (OS), called “Service Console,” that is used to perform local management tasks such as executing scripts or installing third party agents. The Service Console has been removed from ESXi, drastically reducing the hypervisor code-base footprint (less than 150MB vs. ESX’s 2GB) and completing the ongoing trend of migrating management functionality from the local command line interface to remote management tools.


VMware ESX Architecture. In the original ESX architecture, the virtualization kernel (referred to as the vmkernel) is augmented with a management partition known as the console operating system (also known as COS or service console). The primary purpose of the Console OS is to provide a management interface into the host. Various VMware management agents are deployed in the Console OS, along with other infrastructure service agents (e.g. name service, time service, logging, etc). In this architecture, many customers deploy other agents from 3rd parties to provide particular functionality, such as hardware monitoring and system management. Furthermore, individual admin users log into the Console OS to run configuration and diagnostic commands and scripts.

VMware ESXi Architecture. In the ESXi architecture, the Console OS has been removed and all of the VMware agents run directly on the vmkernel. Infrastructure services are provided natively through modules included with the vmkernel. Other authorized 3rd party modules , such as hardware drivers and hardware monitoring components, can run in vmkernel as well. Only modules that have been digitally signed by VMware are allowed on the system, creating a tightly locked-down architecture. Preventing arbitrary code from running on the ESXi host greatly improves the security of the system.

%d bloggers like this: