adminHYPERVISOR
A hypervisor is a virtual machine monitor (VMM) that abstracts physical hardware (CPU, RAM, storage, network etc.) and presents virtualized resources to multiple isolated guest operating systems simultaneously.
There are two main types of hypervisor and they are; bare metal and hosted hypervisor.
Bare metal hypervisor runs directly on hardware with no host operating system. It is characterized by maximum performance and security in its operations. Examples include, VMware ESXi, Microsoft hyper-V, Xen, IBMz/VM etc.
Hosted hypervisor runs on an app on top of a host operating system. It is easy to use but it is characterized by lower performance in its operation. Examples include virtual box, VMware work station, parallel desktop, QEMU etc.
The advantages of hypervisors are; they allow the running of multiple virtual machines (VM) on one physical machine, drastically reducing hardware costs and energy consumption. Each virtual machine (VM) is sandboxed such that a crash or breach in one does not affect others. Virtual machines (VMs) are portable across physical hosts. It can migrate or clone entire environments easily. It captures virtual machine (VM) state at any point and can also roll back instantly after a failed update or attack. It dynamically allocates CPU, RAM and storage to virtual machines (VMs) based on demand. It can spin up new virtual machines in seconds rather than provisioning new physical servers. It replicates and restores virtual machines to remote sites with minimum downtime.
The disadvantages of hypervisors are; virtualization adds some latency especially for input/output intensive workloads. Managing virtual networks, storage and clusters requires specialized skills. Enterprise hypervisors (VMware VSphere) carry significant licensing fees. If the hypervisor host fails, all virtual machines on it will go down together. Vulnerability in the hypervisor itself (VM escape) can compromise all the guest virtual machines simultaneously. Virtual machines share physical resources, a noisy neighbor can degrade performance for others.
Hypervisors find applications in the following; cloud platforms such as AWS, AZURE and Google cloud are built entirely on hypervisors serving millions of customer’s virtual machines. Enterprise data centers to consolidate workloads, virtual desktop infrastructure (VDI) and internet IT services. Development and testing, to test operating systems versions. Security and research, for malware analysis in isolated sandboxes and penetration testing labs. Telecom/NFV for virtualizing network functions like firewalls and load balancers or commodity hardware. Education, for delivering lab environments to students without physical hardware. Virtual machines replicates and automates fail over for business continuity.
The future of hypervisors is based on the advances and development of the following technologies; ultra-lightweight hypervisors like AWS firecracker boot in milliseconds with tiny memory footprints, bridging the gap between containers and virtual machines. Emerging technologies like AMD SEV and Intel TDX encrypts virtual machines even from the hypervisor itself, critical for regulated industries. In the future hypervisors would expand beyond X86 data centers into cars, industrial systems and IoT devices. AI/GPU virtualization will enhance sharing GPUs and AI accelerators across virtual machines (NVIDIA VGPU, MIG) as machine learning (ML) workloads dominate infrastructure. Tools like kata containers give containers VM-level isolation, blurring the boundary between the two technologies. Also in the future, stripped down single purpose virtual machines with no unnecessary operating system components may be faster, smaller and far more secure.
SOURCES:
- The practice of virtualization by Michael Jang.
- Mastering KVM virtualization by Vedran Dakic, Humble Devas Chirammat, Prasad Mukhedkar, Anil Vettathu.
- Modern operating systems by Andrew S. Tanenbaum and Herbert Bos.
- Computer organization and architecture by William Stallings.
- Cloud computing: concepts, technology and architecture by Thomas Erl, Ricardo Puttini and Zaigham Mahmood.
