vSphereESXi

VMware vSphere ESXi is a bare-metal hypervisor that forms the core of VMware’s vSphere virtualization platform. It runs directly on server hardware, without a general-purpose operating system, and enables multiple virtual machines to share CPUs, memory, storage, and networking resources in an isolated manner.

Architecturally, ESXi is a type-1 hypervisor built around the VMkernel, a purpose-built kernel that manages virtualization tasks such as CPU scheduling, memory management, I/O virtualization, and networking. It uses datastores, including VMFS, NFS, and VMware vSAN, to store virtual disks and configuration files. ESXi supports a wide range of guest operating systems and works with hardware validated by VMware’s Hardware Compatibility List.

Management and licensing: In production, ESXi hosts are typically managed by VMware vCenter Server, which provides centralized lifecycle management, vMotion live migration, High Availability, and Distributed Resource Scheduling. Many advanced features require vCenter and appropriate licensing. VMware also offers a free standalone edition with basic management capabilities but limited features.

Key features and use cases: Core capabilities include secure isolation of virtual machines, live migration of running VMs across hosts (vMotion), storage migration (Storage vMotion), and high availability through clustering when managed by vCenter. Additional capabilities such as Fault Tolerance, DRS, and advanced automation become available with vCenter and proper licensing. ESXi supports a broad ecosystem of management tools, APIs, and automation options for data-center and edge deployments.

History and evolution: ESXi originated in the mid-2000s as part of VMware’s ESX lineage and was rebranded and evolved into the ESXi product line. It has seen major releases through the 6.x, 7.x, and 8.x series, expanding scalability, security, and integration with cloud and automation workflows.