Which component is crucial for running virtual machines on ESXi?

The VMkernel is the core component of the ESXi hypervisor that is essential for running virtual machines. It is responsible for managing the hardware resources and providing the necessary environment for virtual machines to execute their workloads. The VMkernel interacts directly with the physical hardware, scheduling CPU and memory resources, managing I/O operations, and facilitating communication between virtual machines and the host system.

In a virtualized environment, the VMkernel acts as an intermediary that abstracts the physical resources, allowing multiple virtual machines to share the underlying hardware while maintaining isolation and performance. It handles critical tasks such as memory management, process scheduling, and device drivers for networking and storage.

Other components, while important for managing and orchestrating virtual machines, do not play the same foundational role as the VMkernel. For instance, the VMware Client is primarily a management interface for users but does not run virtual machines itself. Resource Pools are used for organizing and allocating resources among virtual machines but are not directly involved in their execution. The vCenter Server provides centralized management for the virtual environment but relies on the VMkernel to operate the virtual machines on the ESXi hosts. Thus, the essential role attributed to the VMkernel makes it the key component for running virtual machines in this context.