Microsoft Hyper-V
When we discuss Windows virtualization, Microsoft’s native HyperVisor, called Hyper-V (formerly codenamed “Viridian”), may outrank all other virtualization software. Initially, the Hyper-V beta version was shipped with several Windows Server 2008 editions. Later on, its stable version was released as a part of Windows Updates.
You can create virtual machines in a Hyper-V server that can be accessed remotely through Remote Desktop. Microsoft Hyper-V is available in two variants: Stand-alone Hyper-V Server and Bare Metal HyperVisor.
Bare Metal HyperVisor runs with very a minimal set of Windows Server components to optimize the virtualization environment. This dedicated virtual environment eliminates common Windows Server components, such as DNS server, IIS web server, programming components, Microsoft FTP server, DHCP server, Active Directory and many more.
One major benefit of the Stand-alone Hyper-V Server is you will reduce attack surfaces by omitting unwanted components from the platform. Since there is no services-listening on ports, you can block unwanted ports in Firewall, thus reducing the chances of becoming a target.
Microsoft has made available stand-alone versions of Hyper-V through a downloadable DVD ISO image file at no cost. However, it should not be assumed that since it is an absolutely free HyperVisor, it comes with restricted features. On the contrary, this free HyperVisor supports all of the same enterprise feature sets of a Windows 2012 Server with the Hyper-V role enabled.
More importantly, you may find very little or no patches on Patch Tuesday. For instance, say Microsoft has lately found vulnerability in IIS services and releases a critical patch that requires reboot. You wouldn’t have to worry about it, since it is not applicable to bare metal HyperVisors. As a result, your VPS customers will have significantly less downtime.
As an alternative, Windows Server 2012/2008 host with Hyper-V role installed is used to manage Hyper-V Server 2012/2008 through a management console, namely Hyper-V Manager. The administrator can accomplish their management and configuration tasks through remote desktop to host. Through Hyper-V Manager, virtual machine management can be carried out, allowing much easier point-and-click configuration and monitoring of the Hyper-V Server.
VirtualBox
VirtualBox is a cross-platform open source virtualization software under the GNU General Public License. VirtualBox can be installed in your existing Intel or AMD-based systems in your choice of operating system. You are allowed to create cross-platform virtual machines in your existing hardware. Thus, it extends the capabilities of your existing computer so it can handle multiple operating systems simultaneously.
With VirtualBox, users can enjoy Windows and Linux machines on their Mac system alongside existing software. There is no limit on the number of virtual machines you can create; the only practical limits are disk space and memory.
VirtualBox is a free, simple, yet powerful virtualization software. You can utilize its features everywhere, from small desktop machines to Enterprises like datacenters – even in Cloud environments. VirtualBox treats each virtual machine and its virtual hard disks as a “container” that can be frozen, woken up, copied and backed up, as well as allows migration between hosts.
Now, imagine a situation where your virtual machine has started misbehaving after installing some software or due to some malfunctioning. Nothing to worry about – thanks to a VirtualBox feature called snapshots, you can save the particular state of a virtual machine and at a later time then resume to its previous state. Within a few mouse clicks, you can easily restore your virtual machine from the previous snapshot.
The great thing about this feature is that you are allowed to create any number of snapshots. In fact, if you have ended up with a number of snapshots, you can reclaim disk space by deleting any unwanted snapshots.
VirtualBox is sometimes referred to as a hosted Hypervisor, since it requires an existing operating system to be installed. It runs on almost all 32-bit and 64-bit host operating systems. In many cases, VirtualBox does not need any processor features that demand the latest hardware. Unlike other virtualization solutions, you can use VirtualBox even on your older Home PC where other enterprise-class hardware is not compatible.
VirtualBox allows guest machines to access files from host machines with the help of a feature called Shared Folders. You can attach and access any USB devices to your virtual machines without installing device-specific drivers on the host system. Additionally, VirtualBox Remote Desktop Extension (VRDE) supports the Remote Desktop Protocol (RDP) originally built into Microsoft Windows, with special additions for full client USB support.
With such a large list of features and some unique capacity, VirtualBox can be considered a great choice for wanting to create your own virtual environment.
Infrastructure consolidation: Virtualization can significantly reduce hardware and electricity costs. Most of the time, computers today only use a fraction of their potential power and run with low average system loads. A lot of hardware resources, as well as electricity, is thereby wasted. So, instead of running many physical computers that are only partially used, one can pack many virtual machines onto a few powerful hosts and balance the loads between them.
Xen
The Xen HyperVisor is claimed to be the only open source type-1 HyperVisor, also known as bare metal HyperVisor, as it does not require any operating system to be installed upon. As a HyperVisor, Xen enables host machines to run many guest operating system instances or several different operating systems in parallel on a single machine.
Xen has a wide application base for different commercial and open source applications; for example, server and desktop virtualization, Infrastructure as a Service (IaaS), and security applications, to list a few. Lately, the Xen Project HyperVisor is also engaged in powering the largest clouds today.
Xen HyperVisor is said to be most flexible and secure due to its small memory footprint and interface (as small as 1MB) and has succeeded in keeping its memory footprint and interface overhead to that low only because of its Microkernel design.
HyperVisor loads itself exactly after exiting the bootloader. A number of virtual machines (be it domain or guest) run on top of the Xen HyperVisor. A special domain, called Domain 0, contains the drivers for all the devices in the system, as well as a control stack to manage virtual machine creation, destruction, and configuration.
The Xen HyperVisor is an absolute thin software layer that operates at the hardware level and handles CPU, memory, as well as interrupts of the created virtual machines. The HyperVisor itself has no knowledge of I/O functions such as networking and storage. Virtual machines run in completely isolated virtualized environments, each running their own operating systems and applications. Guest VMs are isolated from the hardware in a way that they don’t hold privilege to access hardware or I/O functionality.
The Control Domain (or Domain 0) has virtual machine privileges that can access the hardware directly. It can also handle all access to the system’s I/O functions and interacts with the other VMs. The Xen HyperVisors are not workable without Domain 0, which is the first VM started by the system.
XenServer is a proven enterprise-class virtualization platform that delivers all of the critical features needed for the implementation of any server and datacenter virtualization.
