The hypervisor monitors and controls the creation and operation of virtual machines. This allows multiple machines with different operating systems to run on one host machine. This article will discuss the different types of hypervisors and the top hypervisor technologies.
Hypervisors are software layers that allow multiple virtual machines to be run on the same physical host. It falls under one of these two hypervisor types.
- Type 1 hypervisors
- Type 2 hypervisors
Type1 hypervisors run directly on physical hardware. They manage virtual machines as well as the hardware. Type 1 is also known as bare-metal hypervisors.
Type2 hypervisors are run on an operating system, also known as the host OS. This operating system is installed on bare hardware. This adds complexity because the guest operating systems calls must traverse through the stack of the host operating system stack before reaching the hardware.
Here is a list of free hypervisors (both type 1 and type 2) that can be used by system administrators. This will allow them to choose the best hypervisor technology for their needs and also assist in evaluating commercial hypervisors.
Top 5 Enterprise Type 1 Hypervisors
1. VMware vSphere / ESXi
VMware is the leader in Tier-1 hypervisors with its /ESXi product. It’s available in 5 commercial editions and a free edition. VMware was the first to market with innovative features like memory overcommitment and Storage vMotion. VMware used to call their free hypervisor “Free ESXi”, as ESXi Server, which is the software that is installed directly on the physical server, was previously called. VMware however calls the “suite of features” “vSphere”, which is available in different editions. Even the free hypervisor today is ” The VMware Hypervisor”.
Although the free vSphere hypervisor has a graphical interface (the vSphere client) and memory over-commitment it does not offer features such as vMotion or centralized management. Also, the free version can only support 32GB RAM per physical server. vSphere’s commercial versions include the following features:
- Memory is more important than commitment
- High availability (vSphere HA)
- Storage vMotion
- vSphere Data Protection (for recovery and backup)
- vSphere Replication
- vShield Endpoint Protection (the option of using agentless anti-virus software)
- Hot memory addition and hot plug for the CPU
- Fault tolerance (FT), for availability
- Distributed resource scheduler for VM load balancing (effectively).
- Distributed power management (DPM), which consolidates VMs and vMotion, shuts down hosts to conserve power.
- Distributed virtual switch (dvSwitch).
- Profiles of hosts
- Auto deploy
- Storage distributed resource scheduler (SDRs)
- Profile-driven storage
- Single root I/O virtualization (SR-IOV)
- Web-based management and the new vCenter virtual appliance deployment
2. Microsoft Windows Server 2012 Hyper-V (or the free Hyper-V Server 2012)
Hyper-V, XenServer (next on this list), and vSphere (next) are the top three Tier-1 hypervisors. Hyper-V frequently flips/flops between 2nd and third place with XenServer. Hyper-V was first released with Windows Server. It has been greatly improved with the addition of Windows Server. Windows Server 2012 HyperV. HyperV is available in a free edition without GUI or virtualization rights. It also comes in 4 commercial editions, Foundations (OEM only), Essentials Standard Standard, Standard, and Datacenter. Hyper-V offers the following:
- Live migration
- Migration of storage
- VM Replication (Replica).
- Dynamic memory
- Virtual switch with extended reach
- High availability
Scale up to 32 logical processors and 4TB memory. There are 2,048 virtual CPUs on each host. 64 vCPUs per VMware, 1TB memory per VMware, and 64 nodes. This will allow you to run 8000 VMs per cluster.
hypervisor virtualization rights allow you to run a limited number of Windows virtual machines without having to purchase additional licenses. Standard edition includes 2 Windows OS rights, while the datacenter has unlimited rights.
For effective management and security, consider solutions like Hyper-V backup from NAKIVO, which can safeguard your virtualized environment and ensure data protection.
3. Xen / Citrix XenServer
Xen is a type-1 bare-metal hypervisor. Citrix uses Xen for its commercial XenServer, just as Red Hat Enterprise Virtualization uses KVM. Citrix purchased XenSource, Inc. in 2007, which supported Xen. Today, the Xen open-source projects and community are available at Xen.org. Today’s XenServer, a commercial tier-1 hypervisor from Citrix, is available in four editions. Citrix also branded other proprietary solutions such as XenApp or XenDesktop under the Xen name, confusingly. XenServer features include:
- Conversion tools
- Integration System Center Virtual Machine Administrator
- Snapshot and revert
- XenCenter Management console (even in the free version)
- Live migration (even in the Free Edition)
- Live storage migration
- Virtual switch distributed
- High availability
- Power management
- Memory optimization
- Monitoring and alerting
4. Red Hat Enterprise Virtualization (RHEV)
Red Hat Enterprise Virtualization This commercial implementation of the KVM Type-1 hypervisor is available. Red Hat Enterprise Virtualization SPICE Protocol (Virtual Desktop Server Manager) and VDSM. RHEL Central management server that is web-based. RHEV supports the following advanced features
- Network bonding, VLAN, and 10GB
- Live migration, policy-based workload balance, high availability and power saving, cluster maintenance image management, templating thin-provisioning, and event monitoring
- Hosts can support up to 160 cores, 2 TB RAM, and up to 160 vCPUs. Guests can support 64 vCPUs, up to 512GB RAM, and up to 64 vCPUs
- Self Service user portal
- Monitoring and reporting, historical trending, monitoring, monitoring, reporting, monitoring
Open-source KVM The Kernel-Based Virtual Machine (or Kernel-Based Virtual Machine), is a Linux-based hypervisor that can be used to add Linux-based operating systems such as Ubuntu, SUSE, and Red Hat Enterprise Linux. It is compatible with most Linux operating systems, Solaris and Windows. KVM is a standard feature on most hypervisors. Many also offer Red Hat’s management tools. Virtual hypervisor Machine Manager.
Top 5 Enterprise Type 2 Hypervisors
Xvisor is a Type2 monolithic, open-source hypervisor that aims to provide lightweight, portable and flexible virtualization options. It supports both ARM and X86 CPU architectures. The main difference between Xvisor and other hypervisor software is that it is entirely monolithic. This means that it only uses one software to access hardware, virtualize CPUs, and emulate guest IOs.
KVM and Xen are partially based on monolithic micro-kernels. KVM and partially monolithic hypervisors such as KVM are extensions to general-purpose monolithic OSSs (such as hypervisor Linux), which allow hosting physical access and enable CPU virtualization within the kernel. Guest IO emulation is provided by an application running inside the user space (such as Qemu). Micro-kernel hypervisors, which are usually lightweight micro-kernels, provide basic host hardware access as well as kernel virtualization. The rest depend on managing guests (such as Xen Dom0).
Also read: Top 5 Web Hosting Technology Trends in 2021
2. Oracle VirtualBox
Oracle VirtualBox is a Type2 hypervisor, which can be used on Linux hypervisor, Windows, and Solaris hosts. It can be used on any 32-bit or 64-bit host. Because it needs a hypervisor operating system already installed, it is called a hosted hypervisor. VirtualBox’s best feature is the ease with which virtual machines can easily be imported and exported via OVF (Open Virtualization Format). You can even import OVFs from different virtualization software.
3. VMware Workstation Player
VMware Workstation Player is a Type2 desktop virtualization tool that makes it easy to test and run operating systems on a virtual machine running Windows, Linux, or both. Its easy-to-use interface makes it an ideal tool for delivering a virtual desktop to employees, contractors, and customers. It is available for download from this
Lguest is a lightweight hypervisor built into the Linux kernel. Lguest’s core is the driver module (named “lg”) available in Linux kernel 2.6.23 or higher. Lguest offers para-virtualized solutions for Linux. During initialization, the lg driver module allocates memory. It maps to the kernel’s address space. A small hypervisor is also loaded into this area. It also offers a virtualized I/O system. It doesn’t have all the features that other hypervisors offer, but it is an option for those who need to test and develop the kernel boot.
5. LinuX Containers (LXC)/Docker
LinuX Containers is an operating system-level virtualisation technique that allows multiple Linux systems to be run on one control host (LXC). This virtual environment does not contain a machine but rather a virtual environment with its own CPU, memory, and block I/O. It makes use of the Linux kernels’ cgroups functionality to provide isolated namespaces for running isolated applications. Containers have the advantage that they don’t require a full-fledged guest OS such as virtual machines. For more information on containers.
Linux-VServer can be used to virtualize OS levels. It is a soft partitioning technology that relies on security contexts. It creates virtual private server (VPS), which run on one physical server and share hardware resources. Each VPS is assigned a root password and a database account to ensure it is isolated from other virtual servers. To learn more and download the Linux-VServer website, please refer to this link.