What is Microsoft Hyper-V and how does it work?

Hyper-V is a vir­tu­al­isa­tion platform from Microsoft that allows multiple virtual machines to run on a physical server. The built-in Windows hy­per­visor makes it easy for users, as they are not dependent on external—and sometimes very complex—software.

What is Hyper-V?

To vir­tu­al­ise hardware, meaning to create a hardware en­vir­on­ment that doesn’t phys­ic­ally exist in that form, you need an in­ter­me­di­ary between the physical computer and the virtual machine. This interface is called a hy­per­visor. On the physical host system, multiple virtual guest systems can be mapped this way, sharing the host’s hardware. Microsoft has created its own hy­per­visor with Hyper-V, which is included directly in the pro­fes­sion­al versions of Windows 11, 10, or Windows 8. The software is also pre-installed in Windows Server.

Hyper-V gives Windows users the ability to start their own virtual machine. In this machine, a complete hardware in­fra­struc­ture with memory, disk space, pro­cessing power, and other com­pon­ents can be vir­tu­al­ised. On this basis, a separate operating system can run, which doesn’t ne­ces­sar­ily have to be Windows. It’s popular, for instance, to run an open-source dis­tri­bu­tion of Linux in a virtual machine.

Ap­plic­a­tion areas of Hyper-V

Test en­vir­on­ments

Vir­tu­al­isa­tion tech­no­logy can be used in various scenarios. However, Hyper-V is typically used in test en­vir­on­ments. In this context, vir­tu­al­isa­tion offers two main ad­vant­ages:

1. Computer en­vir­on­ments that are otherwise in­ac­cess­ible can be rep­res­en­ted. Instead of setting up a separate PC with Linux, you can re­l­at­ively easily run the operating system in a virtual machine.

2. The virtual machine is also self-contained. So, for example, if you run software that causes a system crash, the physical device is not at risk. Only the virtual machine would need to be reset.

Private users can use Hyper-V, for example, if they want to run software that wouldn’t work with their current Windows version—either because the program requires an older version of the operating system or only supports Linux.

Es­pe­cially for software de­velopers, vir­tu­al­isa­tion with Hyper-V is a great advantage: The program created can be tested under a variety of software and hardware con­di­tions. Ad­di­tion­ally, because of the self-contained virtual machines, there’s no worry about faulty code damaging your own system.

High avail­ab­il­ity and disaster recovery

Using Hyper-V can help minimise downtime and protect business-critical systems. A key tech­no­logy is Hyper-V Replica, allowing virtual machines (VMs) to be asyn­chron­ously rep­lic­ated to a second server. In case of a server failure, the rep­lic­ated VM can be activated quickly to continue op­er­a­tions without major in­ter­rup­tions. Ad­di­tion­ally, live migration enables the transfer of running VMs between hosts without shutting them down, easing main­ten­ance and reducing downtime. For even higher avail­ab­il­ity, Hyper-V can be combined with failover clus­ter­ing, allowing virtual machines to auto­mat­ic­ally move to another node in the cluster if a host fails.

Cloud and hybrid cloud

Hyper-V also plays a central role in vir­tu­al­isa­tion within cloud and hybrid cloud en­vir­on­ments, es­pe­cially in con­nec­tion with Microsoft Azure. Companies use Hyper-V to ef­fi­ciently manage on-premises data centres while flexibly in­cor­por­at­ing cloud resources. Through in­teg­ra­tion with Azure Virtual Machines and Azure Local, IT in­fra­struc­tures can be operated and scaled both on-premises and in the cloud. Thanks to the pre­vi­ously mentioned Hyper-V Live Migration, companies can move workloads as needed. This hybrid cloud func­tion­al­ity offers flex­ib­il­ity, reduces hardware costs, and improves the scalab­il­ity of IT resources.

Ar­chi­tec­ture of Microsoft Hyper-V

With Hyper-V, one or more virtual machines can be hosted on x64 versions of Windows, each con­tain­ing a fully con­figured operating system. These guest systems are treated as par­ti­tions. This term is familiar from disk par­ti­tion­ing, and vir­tu­al­isa­tion via Hyper-V works similarly. Each virtual machine is an isolated unit alongside the parent partition, which is the actual operating system.

The in­di­vidu­al par­ti­tions or guest systems are or­ches­trated by the hy­per­visor. Through an interface (the Hypercall API) in the host system, the sub­or­din­ate par­ti­tions can be created and managed. However, isolation always remains intact. Guest systems are allocated virtual hardware resources but can never access the host’s physical hardware. To request hardware resources, sub­or­din­ate par­ti­tions use the VMBus. This is a channel that enables com­mu­nic­a­tion between the par­ti­tions. Guest systems can request resources from the host and the­or­et­ic­ally also have the cap­ab­il­ity to com­mu­nic­ate with one another.

Services run on the par­ti­tions that process the requests and responses running over the VMBus. The host system runs the Vir­tu­al­iz­a­tion Service Provider (VSP), and the sub­or­din­ate par­ti­tions run the Vir­tu­al­iz­a­tion Service Clients (VSC).

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Dif­fer­ences between Hyper-V and other vir­tu­al­isa­tion tech­niques

Unlike all other vir­tu­al­isa­tion solution providers, Hyper-V has the advantage of being closely in­teg­rated with Windows. Users of the Microsoft operating system for PCs or servers can benefit from this good in­teg­ra­tion. Hyper-V is also a Type 1 hy­per­visor, which only a few other solutions offer. This means Hyper-V runs directly on the system’s hardware. When comparing Type 1 and Type 2 hy­per­visors, the central dif­fer­ence is that the latter always has to go through the host’s operating system to provide resources.

Ad­vant­ages

For Windows users, a very clear advantage is the close in­teg­ra­tion with the operating system. This can also have budgetary benefits, as Hyper-V is often included for free with Windows. In terms of func­tion­al­ity, Hyper-V competes well with its rivals. Regarding per­form­ance, users don’t have to com­prom­ise with Hyper-V (as long as they work only with Windows as the guest system). Since man­age­ment is re­l­at­ively simple, beginners can also benefit from vir­tu­al­isa­tion.

Dis­ad­vant­ages

While Hyper-V works very well with Windows, the software reaches its limits with other operating systems. For one, Hyper-V is not designed to run on other systems, and the potential guest systems are very limited. Outside of Windows, only a few selected Linux dis­tri­bu­tions can run in a virtual machine. For example, those wanting to use macOS as a guest system must choose a competing product. It’s also been noted that when running multiple Linux guest systems, sig­ni­fic­ant per­form­ance losses should be expected.

Al­tern­at­ives to Hyper-V

Those looking for al­tern­at­ives to Hyper-V have several powerful vir­tu­al­isa­tion solutions to choose from.

• VMware: One of the best-known is VMware vSphere, widely used in corporate en­vir­on­ments due to its stability and high scalab­il­ity. For smaller busi­nesses, VMware Work­sta­tion and VMware Fusion are suitable, user-friendly, and com­pat­ible with many operating systems.
• Vir­tu­al­Box: Vir­tu­al­Box is a free open-source software from Oracle, par­tic­u­larly suitable for testing purposes and smaller vir­tu­al­isa­tion projects, and available for both Windows and macOS.
• Proxmox: Proxmox VE is an open-source al­tern­at­ive for server vir­tu­al­isa­tion. Both KVM (Kernel-based Virtual Machine) and LXC con­tain­ers are supported.
• KVM / QEMU: QEMU is a vir­tu­al­isa­tion solution in­teg­rated into Linux. It provides a flexible and high-per­form­ance al­tern­at­ive, though it often requires more manual con­fig­ur­a­tion.
• Parallels Desktop: For macOS users, Parallels Desktop is one of the best solutions as it is spe­cific­ally optimised for Apple devices.