VMware ESX vs. ESXi: Overview of Key Differences 

The technological advancement of the 21st century has called for robust and easily scalable IT settings. Virtualization, a process whereby the hardware settings of a business can easily be spread over multiple smaller computers, known as virtual machines, has taken a center stage in this regard. Businesses now utilize this technology to optimize their resource management. While many companies provide this service, VMware stands out as a major player in this sector, renowned for its robust products such as VMware ESX and ESXi. Thanks to these virtualization technologies, data centers worldwide can operate with greater efficiency and scale as required.

VMware ESX and ESXi are type-1 hypervisors, operating directly on hardware without the need for an underlying operating system. As Hypervisors, they offer you the opportunity to manage multiple virtual machines on a single physical computer, optimizing resource utilization, reducing expenses, and enhancing flexibility. This blog post explores VMware ESX and its brother ESXi. It provides an overview of the key differences between VMware ESX and ESXi, shedding light on their respective advantages and applications.

What is VMware ESX?

Type-1 legacy hypervisor, VMware ESX, was first released in 2001. As its foundation, it uses a Linux-based computer operating system (COS). While VMware has advised switching to the new VMware ESXi, it didn’t stop the operation. ESX still has its use cases, especially in a legacy IT environment setup.

What is VMware ESXi?

First Released in 2007, VMware ESXi is the more modern and feature-rich hypervisor from VMware. Based on a smaller and more efficient processor, it doesn’t require a COS. This makes ESXi safer and easier to handle in a modern IT setting. Additionally, VMware ESXi has a market share of over 70%, making it the most famous hypervisor.

There are several reasons why a lot of people like VMware ESXi:

  • It is safe and trustworthy. There is less room for attack on ESXi than ESX because it doesn’t have a COS. ESXi also comes with VMware’s business support, which lets users get the most up-to-date security patches and technical help.
  • Managing it is straightforward. The web-based control interface for ESXi is user-friendly, and there are also various third-party tools available for handling ESXi.
  • ESXi is Scalable. With ESXi, you can set up and handle huge virtualization environments with tens of thousands of virtual machines.
  • Finally, ESXi is compatible with many modern hardware. A lot of different hardware manufacturers make gear that works with ESXi.

VMware ESX vs. ESXi: Table of basic differences

Feature VMware ESX VMware ESXi
Architecture Based on a Linux kernel
Bare-metal hypervisor (no separate OS)
Resource Consumption Uses some system resources for its own operation
Minimizes resource consumption for improved performance
Security Potentially vulnerable due to underlying Linux kernel
Considered more secure due to smaller footprint
Management Requires Service Console for configuration
Managed through a web interface or vCenter Server
Availability Discontinued product
Current and actively developed product

Additional Notes:

  • Functionality for both ESX and ESXi is very similar, with the key difference being architecture and management.
  • ESXi is considered the superior product due to its smaller footprint, improved security, and simplified management.
  • vSphere, a suite of virtualization products from VMware, includes ESXi. A free version of ESXi, called vSphere Hypervisor, is also available.

Key differences between VMware ESX and ESXi

Here are the fundamental distinctions between VMware ESX and ESXi:

1. Architecture

Both ESX and ESXi are type-1 hypervisors, which means they operate without the service of an OS. They just run on the hardware itself. Because of this, they are ahead of VirtualBox, VMware Workstation, and other type-2 hypervisors that run on top of an operating system. Type-1 Hypervisors excel in performance and efficiency due to their direct hardware interaction, avoiding resource sharing with an OS. Additionally, their security is enhanced as they have fewer attack vectors.

ESX architecture

The Linux-based COS serves as the foundation for ESX. As the COS, it oversees the physical hardware and serves as the ESX hypervisor’s management interface. The ESX architecture has several advantages, including:

  • ESX offers greater flexibility compared to ESXi since it permits the installation and operation of extra software on the COS.
  • Troubleshooting issues with ESX is quite easy due to the availability of a complete Linux operating system.

Despite these benefits, the ESX architecture also poses several disadvantages, including:

  • It occupies more resources than ESXi, resulting in a larger footprint.
  • ESX is less secure than ESXi due to the broader attack surface presented by the COS.
  • Managing ESX may pose greater challenges, particularly for those less familiar with Linux.

ESXi architecture

ESXi uses a modified kernel that is both smaller and more powerful. Because it doesn’t employ COS, it has better security and is less complicated to manage when compared to ESX. The ESXi architecture has several advantages, including:

  • With a smaller footprint compared to ESX, ESxi demands fewer resources.
  • Its enhanced security stems from the absence of a COS, setting it apart from ESX.
  • Particularly for those less acquainted with Linux, ESXi proves simpler to manage than ESX.

While ESXi architecture offers many benefits, it also possesses several disadvantages, including:

  • ESXi offers less flexibility than ESX, as it doesn’t support the installation and execution of additional software on its kernel.
  • Troubleshooting issues with ESXi can be more challenging due to the absence of access to a full operating system.

2. Management

Both VMware ESX and ESXi are web-based, and the management is not hard. However, they have different control interfaces.

  • ESX management: The management of ESX is via the VMware Service Console. The Service Console is a Linux-based operating system with a web-based interface for managing the ESX hypervisor. You can access the ESX Service Console through a web browser or a secure shell (SSH) client.
  • ESXi management: The management of ESXi is through the VMware Direct Console User Interface (DCUI). The DCUI is a text-based management interface. It is accessible via a serial console or a remote KVM (Keyboard, Video, and Mouse) over an IP connection. Even though the ESXi DCUI doesn’t have as many features as the ESX Service Console, it’s still good enough to manage most ESXi setups.

ESXi’s management interface has several advantages over ESX’s management interface, including:

  • It is more user-friendly and easier to navigate.
  • It is easier to use remotely.
  • It is more secure because it does not have a full Linux operating system.

3. Features

VMware ESX and ESXi both provide a plethora of functions, including:

  • Support for multiple virtual machines: With ESX and ESXi, you can set up and control multiple virtual machines on the same physical computer. This can help you make better use of your resources, cut costs, and be more flexible.
  • Resource pooling: Using ESX and ESXi, you can combine the resources of several physical computers into a single pool. In this way, you can allocate virtual machine resources whenever they need them.
  • Live migration: You can live-migrate virtual machines from one physical server to another without downtime when using ESX and ESXi. This can help with upkeep, load balancing, and disaster recovery.
  • High availability: Clustering and vMotion are two high-availability tools that come with ESX and ESXi. With clustering, you can connect several ESX or ESXi machines into a single group. Moving virtual machines between hosts in a cluster without any downtime is possible with vMotion, a live migration tool.
  • Fault tolerance: ESX and ESXi provide fault tolerance capabilities through features like VMware Fault Tolerance (FT). FT establishes and upholds a duplicate virtual machine alongside the primary one. In the event of a primary virtual machine failure, the secondary virtual machine seamlessly takes over without any downtime.

In addition to these fundamental capabilities, ESX and ESXi encompass a range of additional features, including:

  • Robust management tools: These include the VMware vSphere Client and the VMware vSphere Web Client for effective administration.
  • Storage versatility: They accommodate various storage types, encompassing local, SAN, and NAS storage.
  • Security enhancements: ESX and ESXi incorporate a suite of security features, including role-based access control (RBAC), network isolation, and encryption.
  • Network adaptability: Support is provided for multiple network types like Ethernet, Fibre Channel, and InfiniBand.

However, ESXi offers some additional features, such as ESXi Stateless Caching, ESXi Direct Connect.

ESXi Stateless Caching: ESXi Stateless Caching enables the caching of frequently accessed data on local storage devices, leading to enhanced performance and reduced strain on the SAN.

ESXi Direct Connect: ESXi Direct Connect enables the direct connection of ESXi hosts to storage devices, bypassing the need for a Storage Area Network (SAN). This can lead to enhanced performance and cost savings. Overall, VMware ESXi offers a user-friendly and secure management interface with a robust feature set, surpassing VMware ESX. ESXi also includes extra features such as ESXi Direct Connect and ESXi Stateless Caching.

Which features are most important?

The significance of features will hinge on your specific requirements. When it comes to virtualizing your computers, it’s essential to locate a hypervisor that offers features like high availability, live migration, and fault tolerance. Ensure that the hypervisor you choose lets you set up and manage virtual desktops and has security and remote access features.

Use Cases for VMware ESX and ESXi

There are several use cases for VMware ESX and ESXi. This includes:

Server consolidation: With ESX and ESXi, you can turn multiple underpowered physical servers into a few super-efficient virtual ones. You can cut down on hardware costs and energy usage by doing this.

Desktop virtualization: To enable workstation virtualization, you can utilize ESX or ESXi. This approach allows employees to access their workstations remotely from anywhere.

Application development and testing: For the purpose of developing and testing software, you can use ESX and ESXi to construct and control sandbox environments. This can assist you in enhancing your software’s quality and lessen the likelihood of production downtime.

Disaster recovery: Making backup plans via ESX and ESXi possible before a disaster happens. This can assist in reducing downtime and minimizing disruptions to your business in case of a disaster.

Which one to choose?

VMware suggests that users should switch from ESX to ESXi. ESXi is the more up-to-date and feature-packed server. But ESX might still be a good choice for some businesses with old hardware or specific needs. Here are some factors to consider when choosing between ESX and ESXi:

  • How old is your infrastructure? ESXi doesn’t work on all hardware, so you might need to use ESX if your hardware is old.
  • Also, Do you have a specific requirement? You might need to use ESX if you have special needs, like running extra software on the hypervisor.
  • Finally, what is your budget? While ESXi has a higher licensing cost compared to ESX, it can lead to savings in hardware and energy expenses over time.

Final Thought

Virtualization, particularly through VMware’s ESX and ESXi, has revolutionized modern IT infrastructure, enabling businesses to operate more efficiently and flexibly.

ESX, though a legacy hypervisor, still holds relevance in legacy setups. Due to its contemporary design, strengthened security measures, and extensive feature package, ESXi has become the favored option for the majority of users. Its appeal lies in its reliability, scalability, and ability to work with a wide range of hardware configurations.

Ultimately, the choice between ESX and ESXi depends on factors like infrastructure age, specific requirements, and budget constraints, where consulting VMware or certified partners can provide valuable guidance.

text written by:

Grzegorz Pytel, Presales Engineer at Storware