The following are the main components of VMware virtualization and how they work.

VMware hypervisor

VMware virtualizes physical computers using its core hypervisor product. A hypervisor is a thin layer of software that interacts with the underlying resources of a physical computer (called the host) and allocates those resources to other operating systems (known as guests). The guest OS requests resources from the hypervisor.

The hypervisor separates each guest OS so each can run without interference from the others. Should one guest OS suffer an application crash, become unstable or become infected with malware, it won't affect the performance or operation of other operating systems running on the host.

VMware ESXi

VMware ESXi is a data-center-focused Type 1 or "bare metal" hypervisor, replacing the primary operating system that would interact with a computer's physical components. ESXi succeeded ESX, a larger hypervisor that used more of the host computer's resources. (VMware has discontinued ESX.)

Here's a comparison of VMware's ESXi with several other popular Type 1 hypervisors:

• VMware ESXi versus Hyper-V: Microsoft's Hyper-V is a hypervisor product that allows you to run multiple operating systems on the same server or client computer. Like VMware's ESXi, Hyper-V is a Type 1 hypervisor that interacts with the underlying physical computing and memory resources. Hyper-V works differently than ESXi, using partitions to manage its VMs. Hyper-V must run with the Windows OS. When activated, it installs itself alongside the Windows OS in a root partition, which gives Windows privileged access to the underlying hardware. It then runs guest operating systems in child partitions communicating with the physical hardware through the root partition. Hyper-V also ships with Windows 10 clients, competing with VMware's Workstation Pro Type 2 (hosted) hypervisors.

• VMware ESXi versus Citrix: Citrix's primary hypervisor offering is the Citrix Hypervisor (previously known as XenServer). The Citrix Hypervisor is used by personal users and small- to medium-sized businesses. In contrast, VMware ESXi is designed for small, medium and enterprise-scale companies and is not intended for personal use.

• VMware ESXi versus KVM: Both VMware ESXi and KVM are hypervisors, but KVM is part of the Linux kernel (the heart of the OS). KVM hypervisors are open source, making its code base transparent. This is a significant advantage over VMware ESX1. With KVM, you can use various open source virtualization management tools that integrate with the Linux kernel. As with many open source projects, they might need extra configuration work. You can also use Red Hat® OpenShift® Virtualization, which provides a suite of management tools for virtual servers built on KVM.

VMware is a well-established server-based hypervisor company that also sells software that virtualizes desktop operating systems. This section covers some of that desktop virtualization software and how it works.

VMware Workstation Pro and VMware Fusion Pro

VMware Workstation Pro and VMware Fusion Pro include Type 2 hypervisors. Unlike a Type 1 hypervisor, which replaces the underlying OS altogether, a Type 2 hypervisor runs as an application on the desktop OS. This capability lets desktop users run a second OS atop their primary (host) OS.

Workstation Pro is compatible with PCs running Windows and Linux operating systems. VMware also offers Fusion Pro, which is compatible with macOS systems. These products are free for personal use and paid for commercial use.

Note, VMware discontinued Workstation Player and VMware Fusion Player since starting VMware Workstation Pro and Fusion Pro.⁴

VMware Tools

VMware Tools is a collection of utilities that are essential to any Workstation Pro or Fusion Pro environment. It allows the guest OS running within the Type 2 hypervisor to work better with the host OS.

Installing VMware Tools can improve graphics performance and support shared folders between the guest and host OS. You can also drag and drop files and cut and paste between the two operating systems.

Virtual desktop integration (VDI) and VMware Horizon

Virtual desktop integration (VDI) offers centralized desktop management, letting you configure and troubleshoot desktop operating systems without remote access or onsite visits. Users can access their applications and data from any device, anywhere, without investing in expensive, high-powered client endpoint equipment. Sensitive data remains secure and never leaves the server.

VMware Horizon, VMware's suite of VDI tools, is no longer available due to Broadcom's divestment of VMware's End-User Computing (EUC) division in December 2023.

In 2024, the investment company KKR purchased the division and rebranded it to Omnissa. The Omnissa platform includes Horizon and the management platform Workspace ONE (also formerly part of the VMware portfolio).⁵

Despite simplifying the portfolio, the VMware vSphere server virtualization platform still comes in three editions: vSphere Foundation, vSphere Essentials Plus Kit and vSphere Standard. All three are available only under subscription licensing.

The VMware vSphere Foundation (VVF) is the most complete edition. Add-ons include VMware Site Recovery, NSX Advanced Load Balancer and more.

Customers looking for essential hardware consolidation or virtualization on a small number of servers can still purchase subscriptions to vSphere Essentials Plus Kit, the most basic edition, or vSphere Standard, which falls between VVF and the Essentials Plus Kit.

VMware vSphere components and technologies

Key vSphere components and technologies include the following:

VMware vCenter

The vCenter server is the management component of vSphere. It allows you to manage virtual machine deployments across a large collection of host servers. The vCenter server assigns virtual machines to hosts, allocates resources for them, monitors performance and automates workflow. This component can be used to manage user privileges based on a user's own policies.

VCenter Server has three main components:

• The vSphere Client is the platform's user interface, providing administrators browser-based access to all functions.

• The vCenter Server Database is the product's data repository. It stores data necessary for server hosts to run hypervisors and virtual machines.

• The vCenter Single Sign-On lets you access the entire vSphere infrastructure with a single login.

Using a hypervisor on a host server will maximize the use of that hardware, but most enterprise users will need more VMs than a single physical server can accommodate. That's where VMware's clustering technology comes in.

VMware shares resources between hosts by grouping them into a cluster and treating them as a single machine. You can then use VMware's clustering technology to pool hardware resources between the hypervisors running on each host in the cluster. When adding a VM to a cluster, you can give it access to these pooled resources. There may be many clusters in a VMware-powered enterprise.

VMware allows you to create and manage clusters within its vSphere environment. A cluster supports many vSphere features, including workload balancing, high availability and fault-tolerant resilience.

VMware clustering gives you access to several VMware functions to make your virtual infrastructure run smoothly and reliably.

VMware High Availability (HA)

VMware vSphere's High Availability (HA) lets you switch virtual machines between physical hosts if the underlying hardware fails. It monitors the cluster and if it detects a hardware failure, it restarts its VMs on alternative hosts.

VMware Fault Tolerance

While vSphere HA provides rapid recovery from outages, you can still expect downtime while it moves and restarts a VM. If you need more protection for mission-critical applications, vSphere fault tolerance offers higher availability. It promises no loss of data, transactions or connections.

VSphere Fault Tolerance works by running a primary and secondary VM on separate cluster hosts and ensuring they are identical at all times. If either of their hosts fails, the remaining host continues operating, and vSphere Fault Tolerance creates a new secondary VM, reestablishing redundancy. VSphere automates the whole process.

VMware Distributed Resource Scheduling (DRS)

If you allow many VMs to run unmanaged across your host machines, problems arise. Some VMs will be more demanding on CPU and memory resources than others. This can create unbalanced workloads, with hosts handling more than their share of work while others sit idle. VMware Distributed Resource Scheduling (DRS) solves that problem by balancing VMware workloads between ESXi hypervisors.

DRS, a feature of vSphere Foundation, works within a cluster of ESXi hosts sharing resources. It monitors host CPU and RAM usage and moves the VMs between them to avoid overworked and underused hosts. You can set these allocation policies to reallocate resources aggressively or rebalance them less often.

VMware made a name for itself by virtualizing servers and desktop operating systems. In 2012, it announced plans to virtualize and automate everything in the data center in a concept called the software-defined data center (SDDC).

The software-defined data center (SDDC) extends virtualization from compute to storage and networking resources, providing a single software toolset to manage those virtualized resources. It results from years of evolution in server virtualization.

VMware's SDDC elements include the following.

VMware NSX

VMware NSX is a network virtualization product that enables you to define and control your IT network logically in software. You can consolidate network functions such as switching, routing, traffic load balancing and firewalls into hypervisors running on x86 computers. You can manage these functions together from a single screen rather than manually configuring different hardware across different interfaces, and you can also apply software-based policies to automate network functions. The network component of VMware's SDDC brings the same virtualization benefits to networking, software and computing functions.

The product supports hybrid cloud environments, including your on-premises data center, public cloud and private cloud settings. This makes it easier for your network to support cloud-native apps that rely on container environments and microservices.

VMware vSAN

VMware vSan is part of VMware's storage virtualization solution. It creates a software interface between VMs and physical storage devices. This software—part of the ESXi hypervisor—represents physical storage devices as a single pool of shared storage accessible by machines in the same cluster.

Using VMware vSAN, your VMs can use storage on any computer in a cluster rather than relying only on a single computer, which might run out of storage. This avoids wasting a physical computer's storage if the VMs running on that computer don't use it. VMs running on other hosts can also use its storage. 

VSAN integrates with vSphere to create a storage pool for management tasks, such as high availability, workload migration and workload balancing. Custom policies give you complete control over how vSphere uses shared storage.

VMware Cloud

VMware offers several cloud infrastructure products and services under the banner VMware Cloud. This includes ecosystem partnerships to deliver VMware infrastructure on any cloud. Partnerships include IBM Cloud® for VMware Solutions, Azure VM Solution and Google Cloud VMware Engine.

The previously mentioned VMware Cloud Foundation (VCF) falls under the VMware Cloud category. This integrated software suite supports hybrid cloud operations. It also includes a range of software-defined services for computing, storage, networking and security.

VCF is available as a service from a variety of cloud service providers. You can deploy it in a private cloud environment via vSANReadyNode, a validated server configuration provided by an original equipment manufacturer (OEM) working with VMware.  VCF supports containerized workloads on a single platform, enables artificial intelligence/machine learning (AI/ML) workloads, integrated data services capabilities and more.

VMware HCX

VMware HCX is software that helps companies use a mixture of computing environments. This gives IT teams the functionality they want at the right cost and enables them to keep more sensitive data on their own computers. The challenge is getting these VMs to work together across these different environments.

HCX is VMware's answer to managing hybrid cloud complexity. It is a software as a service (SaaS) offering that lets you manage multiple vSphere instances across different environments, from on-premises data centers to hosted cloud environments.

Formerly called Hybrid Cloud Extension and NSX Hybrid Connect, HCX abstracts your vSphere environment so that the VMs it manages appear to have the same IP address no matter where they run. HCX uses an optimized wide-area network (WAN) connection to extend on-premise applications to the cloud without reconfiguration. This allows you to call on extra computing power from the cloud to maintain the performance of on-premise applications when computing demand exceeds on-premise physical resources.

You can often see this situation occur in retail. A spike in e-commerce demand might use up all your data center resources. You can keep the orders flowing and avoid frustrated customers by calling on computing resources in the cloud.

HCX lets you replicate your data to a cloud-based vSphere instance for disaster recovery. If your on-premises infrastructure becomes unavailable, you can switch to a standby server or system without reconfiguring IP addresses.