It Is Time to Upgrade to vSphere 5 and Migrate from ESX to ESXi!
VMware vSphere 5.0 has finally arrived and includes several new unique features – such as Storage DRS and Autodeploy – that deliver unprecedented value to VMware customers. Unlike prior versions, vSphere 5 supports only the ESXi hypervisor architecture, the only thin purpose-built hypervisor that does not depend on a general purpose operating system. In order to benefit from the unique capabilities and features of vSphere 5 and ESXi 5, VMware recommends that customers:
Learn About ESXi — VMware’s Most Advanced Hypervisor Architecture
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.
Deploy ESXi — VMware’s Most Advanced Hypervisor Architecture
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.
ESXi and ESX Architectures Compared
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.
Benefits of VMware ESXi Hypervisor Architecture
The hypervisor architecture of VMware vSphere plays a critical role in the management of the virtual infrastructure. The introduction of the bare-metal ESX architecture in 2001 significantly enhanced performance and reliability, which in turn allowed customers to extend the benefits of virtualization to their mission-critical applications. Once again, the introduction of the ESXi architecture represents a similar leap forward in reliability and virtualization management. Less than 5% of the size of ESX, VMware ESXi runs independently of an operating system and improves hypervisor management in the areas of security, deployment and configuration, and ongoing administration.
Improve Reliability and Security. The older architecture of VMware ESX relies on a Linux-based console operating system (OS) for serviceability and agent-based partner integration. In the new, operating-system independent ESXi architecture, the approximately 2 GB console OS has been removed and the necessary management functionality has been implemented directly in the core kernel. Eliminating the console OS drastically reduces the codebase size of ESXi to approximately 100 MB improving security and reliability by removing the security vulnerabilities associated with a general purpose operating system.
Streamline Deployment and Configuration. ESXi has far fewer configuration items than ESX, greatly simplifying deployment and configuration and making it easier to maintain consistency.
Reduce Management Overhead. The API-based partner integration model of ESXi eliminates the need to install and manage third party management agents. You can automate routine tasks by leveraging remote command line scripting environments such as vCLI or PowerCLI.
Simplify Hypervisor Patching and Updating. Due to its smaller size and fewer components, ESXi requires far fewer patches than ESX, shortening service windows and reducing security vulnerabilities. Over its lifetime, ESXi 3.5 required approximately 10 times fewer patches than ESX 3.5
Reference Link: http://www.vmware.com/products/vsphere/esxi-and-esx/overview.html
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