ESXi

ESXi is a bare-metal Type-1 hypervisor developed by VMware. It is part of the VMware vSphere virtualization platform and is installed directly on server hardware to host multiple virtual machines. ESXi runs the VMkernel, a purpose-built control plane, and does not require a general-purpose host operating system.

Historically, ESXi evolved from the earlier ESX product, which included a service console. ESXi eliminates the service console and uses a smaller footprint, improving reliability and manageability. As a result, it is commonly deployed on data center servers to consolidate workloads and improve resource utilization.

Key features and components include rapid VM provisioning, live migration via vMotion, high availability (HA), and distributed resource scheduling (DRS). For storage, ESXi supports the VMFS filesystem and, in conjunction with vSAN or external storage, provides flexible datastores for virtual disks. Management is typically performed through VMware vCenter Server with the vSphere Client, which enables centralized management of multiple ESXi hosts and virtual machines. Standalone ESXi can run without vCenter, but lacks centralized orchestration and some advanced features.

Hardware compatibility is ensured by the VMware Compatibility Guide, which lists supported servers, CPUs, I/O devices, and drivers. Licensing ranges from a free version (with limited management capabilities) to paid editions that unlock the full feature set, including HA, DRS, FT, and advanced storage options.

ESXi is widely used for data center virtualization, test and development environments, and disaster recovery setups, offering robust isolation, performance, and scalability for running diverse operating systems as virtual machines.