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VMware ESXi

By Alexander S. Gillis

What is VMware ESXi?

VMware ESXi, also called VMware ESXi Server, is a bare-metal hypervisor developed by VMware for vSphere. ESXi is one of the primary components in the VMware infrastructure software suite.

ESXi is a Type 1 hypervisor, meaning it runs directly on system hardware without the need for an OS. Type 1 hypervisors are also referred to as bare-metal hypervisors because they run directly on hardware. Hypervisors help run multiple VMs efficiently on a physical server.

ESXi is targeted at enterprises, small organizations and individuals. ESXi's VMkernel interfaces directly with VMware agents and approved third-party modules. Administrators can configure VMware ESXi using a vSphere client and update it with the Lifecycle Manager plug in. ESXi is installed directly on a local disk in the host machine. When a VMkernel receives a resource request, the kernel sends the request to the host's physical hardware. New VMs can be created in ESXi 7.0 as well.

Key features of VMware ESXi

As a component of vSphere, VMware ESXi supports the following key features:

Admins can manage ESXi using remote tools instead of a command-line interface. ESXi also has a lightweight architecture and a small codebase, which helps make the installation process quick and reduces its attack surface.

ESX and ESXi versions

Before ESXi, VMware offered the ESX hypervisor, which consisted of more parts, such as the console OS and firewall. VMware released ESXi after VMware ESX version 4.1 in 2010. Only ESXi has continued support, and ESXi 7.0 is the most current version.

ESXi hosts are licensed based on vSphere licenses, and each vSphere license has a specific capacity for licensing multiple physical CPUs on ESXi hosts. With vSphere 7.0, a CPU license covers one CPU with up to 32 cores. CPUs with more than 32 cores need additional CPU licenses.

Versions of ESXi are then separated based on the number of CPUs, cores per CPU and CPU licenses as follows.

To license an ESXi host, users must select a vSphere license with the capacity to handle the number of physical CPUs; the license must also support all the features used by the host.

A stripped-down free version of ESXi -- VMware vSphere Hypervisor -- offers fewer features. Although it can't communicate with vCenter Server, it virtualizes servers with options like thin provisioning. The paid version of ESXi includes live migration of machines, automatic load balancing, and pooling of storage and compute resources across multiple hosts.

The vSphere Lifecycle Manager is typically used to apply patches to ESXi 7.0 hosts.

ESXi benefits and drawbacks

ESXi offers the following advantages:

Unfortunately, ESXi does have the following downsides:

ESXi requirements and setup

Because it's lightweight, ESXi 7.0 requires minimal hardware resources. Specifically, ESXi 7.0 requires a host machine with a minimum of two CPU cores, a 64-bit x86 processor and at least 4 gigabytes to 8 GB of RAM. to run VMs. Admins can find a full list of the required resources for ESXi 7.0 under "Hardware and System Resources" in VMware's ESXi Installation and Setup Guide.

ESXi is installed directly on a local hard disk in the host machine. It can be installed with the purchase of a vSphere license or as a more limited version for free. The free version can be downloaded using the following steps:

  1. Visit the vSphere Hypervisor 7.0 Download Center.
  2. Log in or create an account.
  3. Click on Register and register ESXi.
  4. Download the VMware vSphere Hypervisor 7.0 binaries.
  5. Install ESXi to the intended hardware.
  6. Log in with the Embedded Host Client.
  7. Navigate to Manage > Licensing.
  8. Click Assign License and enter the assigned license key.

ESXi pricing

Because ESXi hosts are licensed based on vSphere licenses, ESXi pricing depends on the vSphere license chosen. Each license includes ESXi, and its cost depends on the support option chosen -- one or three years. These licenses include the following:

VMware ESXi and vSphere

VMware vSphere acts as a suite of VMware's server virtualization products, which includes ESXi. ESXi is the exclusive hypervisor for VMware vSphere licenses. Admins can use a vSphere host as a foundation for a private cloud environment.

VMware products included in vSphere encompass software such as VMware vCenter Server, vSphere Web Client, vSphere Client, vSphere Distributed Switch, vSphere HA and VMware Virtual Symmetric Multi-Processing.

VMware ESXi vs. XenServer vs. Hyper-V

Citrix XenServer is an open source server virtualization platform comparable to ESXi that's based on the Xen hypervisor. Xen is also a Type 1 hypervisor; however, it's aimed at consumers. XenServer can host, deploy and manage server desktop and cloud VMs.

Features in XenServer include live VM migration, health checks and performance reporting alerts. Xen is included in the Linux kernel.

By comparison, Microsoft Hyper-V is a native Type 1 hypervisor. It runs multiple OSes as VMs on Windows and each VM runs on virtual hardware. Hyper-V is designed to integrate with other Microsoft products and offers Shielded VM updates, support for persistent memory, updates to Shielded VMs and ReFS deduplication.

Learn about the new features in vSphere 7.0 and the improvements made in ESXi.

02 Aug 2022

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