Michael Flores Feliz VMware ESXi is a bare-metal hypervisor software installed on servers that can use the physical hardware to create one or more virtual machines (VMs). It is an operating system-independent hypervisor based on the VMkernal operating system that interfaces with agents that run on top of it.
This article walks you through what is VMware ESXi, how it works, and some basic benefits and tasks performed using ESXi.
What is VMware ESXi?
VMware ESXi is a type-1 hypervisor, meaning its installation is not on an operating system but instead integrates OS components within itself.
The name ESXi comes from VMware’s original hypervisor software: ESX, which stood for Elastic Sky X.
ESXi is an integrated version (Elastic Sky X Integrated). It allows you to use the total capacity of your hardware, efficiently dividing resources in virtualized environments for small or large-scale deployment.
With ESXi, you can allocate CPU, memory, disk space, and network adapters based on the demands of your deployment.
Why did VMware transition from ESX to ESXi?
VMware transitioned to ESXi to reduce complexity and potential vulnerabilities. Originally, ESX included a Linux-based Service Console for management. ESXi eliminated the Service Console altogether. Since vSphere 5.0 (2011), ESXi has become the default and only hypervisor VMware supports.
How does VMware ESXi work?
VMware ESXi provides a robust virtualization layer between the hardware and the OS. Since it is standalone, no OS is necessary on the hardware before installation. Once installed, you will be able to manage and monitor your host.
VMware ESXi partitions the server into multiple secure and movable VMs running side by side on the same hardware. Each VM is a complete system, isolated one from another by the virtual layer. This isolation prevents one failed VM from affecting another.
The bare metal architecture gives VMware ESXi control over server resources allocated to each virtual machine and provides near-native VM performance and enterprise-level scalability.
In addition, VMware ESXi offers built-in features to deliver improved service levels to software applications than static physical environments.
Top features of VMware ESXi
Application size
VMware ESXi is 150Mb in size, one of the smallest hypervisors. Due to the size of the application, ESXi minimally uses RAM without affecting the input and output (I/O) of the boot device.
Installation speed
VMware ESXi is installable straight from a USB device. Usually, ESXi takes about 5-7 minutes to install, which includes a variety of ways to install the OS and can even be used from an SD card. Also, importing a virtual machine into ESXi is a click away.
Ease of use
VMware ESXi can be easily remotely managed for your convenience. Administrators use a secure connection and the command line interface on their local device or from another location.
Security
Encrypted data on VMware ESXi is on by default and makes decryption harder, adding additional security. This secure environment includes a detailed logging system for troubleshooting to locate and fix issues. In addition, the Tasks and Events tab in vSphere provides the ability to audit security and easily find changes made.
Easy scalability
VMware ESXi has limits of 64 CPU cores and up to 6TB of RAM, which is considered to be a high limitation. However, starting with lower resources and adding them as your needs change is possible depending on your needs.
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VMware ESXi requirements
VMware ESXi requires a physical computer or server with at minimum 4 GB of RAM, 2 CPUs, and 32 GB of storage. For more flexibility, you can start with 8 GB of RAM, 2 CPU cores, and 128 GB storage.
A RAID 1 storage configuration is recommended to mitigate drive failure and data loss. You must also turn on hardware virtualization in your system basic input/output system (BIOS) for ESXi to function correctly.
Each VM contains the following:
- BIOS or UEFI
- Processors (vCPUs)
- Memory (RAM)
- Storage (virtual machine disk)
- Networking (virtual network interfaces)
After creating a VM, an OS and software applications can be installed and run like any computing device.
ESXi versions and licensing
Since its early days, VMware ESXi has evolved significantly—from a hypervisor with a full Linux-based management layer to an enterprise-ready virtualization platform. Each version has introduced key improvements, shaping how businesses virtualize workloads.
Here’s a quick look at major ESXi versions over the years:
| Version | Release year | Key features |
|---|---|---|
| ESXi 8.x | 2022 | Latest ESXi version. Support for DPUs, AI/ML workloads, vSphere Distributed Services Engine |
| ESXi 7.x | 2020 | Kubernetes support, DRS enhancements, vSphere Lifecycle Manager |
| ESXi 6.5 / 6.7 | 2016–2018 | Improved web client, VM encryption, Secure Boot |
| ESXi 5.x | 2011 | Full transition from ESX to ESXi; no service console |
| ESXi 4.x | 2009 | First widespread adoption of ESXi architecture |
| ESX 3.x | 2006 | The original hypervisor. Included Linux-based service console |
There are free and paid versions of ESXi. The free version offers a basic hypervisor, but it does not include vCenter, vMotion, or high availability. The paid license includes access to features the free version lacks, along with automated resource balancing, live migration, and enhanced infrastructure management.
Free licenses can be obtained by creating a free account on VMware Customer Connect. After an evaluation period, you’ll need to apply for a free license key. The service will continue to be free unless you choose to upgrade.
Paid licenses are purchased through VMware or authorized resellers.
Top business benefits of VMware ESXi
Easy, cost-effective deployment and management
Since VMware ESXi is a minimal application for creating virtual machines, deployment is easy and fast to set up. It uses bare-metal or dedicated physical resources, making workloads easy to manage. Sharing physical resources among several VMs increases hardware utilization while decreasing costs.
Once you have the hardware and ESXi all set up, the only additional investment needed is future hardware upgrades.
Create test and production environments
VMware ESXi offers easy over-allocation of server resources. You can create servers to test new updates for compatibility and tweak them, allowing more resource usage. Production servers exist alongside test servers to host the completed project. Each server instance is separate, allowing for a more private test environment.
Common tasks in VMware ESXi
Scaling infrastructure
One of the most common tasks in VMware ESXi is scaling the environment, which is simple to do as your business grows. Scaling allows you to expand your CPU, RAM, and storage to handle more resource-intensive workloads. Each upscale on hardware requires a reboot to ensure settings reallocate correctly.
Setting up alarms for resource overloading
VMware ESXi allows the creation or editing of alarms in the Monitor tab of the interface for any alerts you’d like to receive. For example, the system performs specific health checks for virtual machines. You can add and edit them with a few clicks and see the alarm definitions.
The interface also provides a notification history for anyone needing to troubleshoot. However, it is worth noting that you are not allowed to edit the default alarms preset in ESXi.
Assigning roles to users in your company/business
The administrator configuring VMware ESXi has the most control as the root controls ESXi and the server’s hardware. Each VM should have permissions and user roles assigned to perform specific tasks.
Users will have assigned roles associated with what they need to view, check, or troubleshoot. Certain users do not require root privileges as misuse can cause catastrophic damage to the virtual machines if not done correctly.
Now you know the meaning of ESXi
This article answers the question, what is VMware ESXi? It is a powerful tool that allows you to control your infrastructure and maximize performance. Whether you use a single server setup or a cluster of servers, VMware ESXi enables the ability to harness the power of the hardware to its full potential.
Liquid Web offers unmanaged dedicated servers for advanced users looking to set up ESXi servers. However, not everyone is required to know what VMware ESXi is. For those seeking a managed environment, choose Liquid Web’s VMware private cloud, managed by the Most Helpful Humans in Hosting.
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