The virtualization layer plays a crucial role in hyper-convergence, yet its presence is invisible. That doesn't diminish the role of other hyper-converged infrastructure components, but an effective system strives to keep the focus on virtual machines.
The virtualization layer in an HCI system consists of a hypervisor and multiple VMs that deliver the underlying hardware as logical services. Without that layer, an HCI implementation would be nothing more than a pile of hardware.
In theory, the physical layer can be made up of any assortment of specialized or commodity hardware. The virtualization layer handles the complexities of managing and interfacing with the various components.
Virtualizing the physical components helps IT administrators better use resources, while increasing flexibility and scalability. Virtualization also simplifies resource management and allocation. Most virtualization software comes with a full set of administrative tools, as well as mechanisms for ensuring fault tolerance and high availability.
VMware vSphere, for example, offers a suite of server virtualization products that are commonly used in hyper-converged systems. The vSphere suite includes the ESXi hypervisor, vSAN software-defined storage, vCenter Server management tools and various other components for controlling the VMs and delivering pooled resources.
The virtual machine
By managing the resources via the virtualization layer, the VMs and the workloads they support become the central players in the hyper-converged system, with resources distributed among them as needed. In this sense, all HCI components have one primary role: to support the VMs and ensure that they can deliver the necessary resources to the targeted workloads.
Because the VM takes center stage in the HCI model, it also becomes the basic management block for delivering services and applying administrative and security policies. The IT team can manage storage and process resources without expertise in the underlying products or technologies, via the virtualization layer.
Of course, depending on how the IT admin implements the HCI system, some expertise is still required to set up the system and keep it running, but ensuring that the VMs can support the specified workloads is the focus of the day-to-day management.
The VM-centric approach also makes it easier to implement processes such as replication, backups, load balancing and quality of service. A centralized portal carries out most management tasks, and admins can also monitor the VMs through the portal to ensure optimal performance and safeguard resources.
The VM also has another advantage. Because it is essentially a file (or integrated set of files), admins can easily move it from one host to the next, even if the hosts reside in different data centers. Admins can also automate migrations to better accommodate fluctuating workloads, peak usage periods or maintenance schedules. In addition, the VM's portable nature makes it easier to clone, back up or create snapshots.