What is Hyper-V? Microsoft's hypervisor explained, with the commands to use it

Short answer: Hyper-V is Microsoft’s hypervisor — the software that lets one physical computer run several isolated virtual machines, each with its own operating system. It is built into Windows Server and into the Pro, Enterprise and Education editions of Windows 10 and 11, and it is a type 1 hypervisor: it runs directly on the hardware, and even the Windows you log into runs on top of it, in a privileged partition of its own.

Hyper-V first shipped as a role of Windows Server 2008, in June 2008. It runs Windows, Linux and FreeBSD guests, and the same technology sits underneath Azure, Windows Sandbox, WSL 2 and Windows’ virtualization-based security. Below: how it is put together, what you need to enable it, the commands to build a first VM, and what to know before you try to run it on a rented server.

How does Hyper-V work?

Hyper-V isolates operating systems in partitions. When the role is enabled, the hypervisor loads first at boot and the Windows installation you were using becomes the root (or parent) partition. Every virtual machine is a child partition.

• The hypervisor owns the CPU and memory: it schedules virtual processors, handles interrupts and gives each partition its own private address space. It needs hardware virtualisation — Intel VT-x or AMD-V — and second-level address translation (SLAT), which Windows Server 2016 and later require.
• The root partition runs the management stack (the Virtual Machine Management Service and one worker process per VM) and is the only partition with direct access to physical devices. Storage and network drivers live here.
• Child partitions see virtual devices. Their I/O requests travel over the VMBus, a channel between partitions, from a client driver in the guest (VSC) to a provider in the root (VSP). Guests with these drivers — current Windows, and Linux with the in-kernel hv_* modules — are called “enlightened” and skip slow hardware emulation.

That is why Hyper-V is type 1 even though you install it from inside Windows: once it is on, Windows no longer runs on the bare hardware. It is also why VMware Workstation and VirtualBox used to stop working when Hyper-V was enabled — they wanted the same processor features. Current versions of both can run on top of Microsoft’s hypervisor platform, with some loss of speed.

Which Windows editions include Hyper-V?

Client Hyper-V needs a 64-bit CPU with SLAT, hardware virtualisation enabled in the firmware and at least 4 GB of RAM. Server Hyper-V adds what client Hyper-V lacks: failover clustering, live migration between hosts, Hyper-V Replica for disaster recovery and shielded VMs.

How do you enable Hyper-V?

Run PowerShell as Administrator. On Windows Server:

Install-WindowsFeature -Name Hyper-V -IncludeManagementTools -Restart
# after the reboot
Get-WindowsFeature Hyper-V

On Windows 10 or 11 Pro, Enterprise or Education:

Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V -All
# or with DISM
DISM /Online /Enable-Feature /All /FeatureName:Microsoft-Hyper-V

Both need a restart. To see whether a hypervisor is already running, look at the last lines of systeminfo: “A hypervisor has been detected” means one is active, Hyper-V or another vendor’s underneath you.

How do you create a virtual machine in Hyper-V?

Hyper-V Manager has a wizard; PowerShell is quicker to repeat. First a virtual switch, then the VM:

# an External switch bridges VMs onto the physical network
New-VMSwitch -Name "External" -NetAdapterName "Ethernet" -AllowManagementOS $true

New-VM -Name "debian01" -Generation 2 -MemoryStartupBytes 4GB `
  -NewVHDPath "D:\VMs\debian01.vhdx" -NewVHDSizeBytes 60GB -SwitchName "External"
Set-VMProcessor -VMName "debian01" -Count 2
Add-VMDvdDrive -VMName "debian01" -Path "D:\ISO\debian-13-amd64-netinst.iso"
Set-VMFirmware -VMName "debian01" -FirstBootDevice (Get-VMDvdDrive -VMName "debian01")
# Linux on generation 2 with Secure Boot needs the UEFI CA template
Set-VMFirmware -VMName "debian01" -SecureBootTemplate MicrosoftUEFICertificateAuthority
Start-VM -Name "debian01"

Three choices in there matter later:

• Generation. Generation 2 VMs boot UEFI with Secure Boot, boot from virtual SCSI and support boot disks up to 64 TB. Generation 1 emulates a legacy BIOS with IDE and exists for old guests and old VHD images. The generation cannot be changed after creation, so pick 2 unless the guest needs 1.
• Switch type. External connects VMs to the physical network, Internal to the host and each other, Private only to each other. Windows 10 and 11 also add a NAT-ed “Default Switch”.
• Disk format. VHDX is the current format (up to 64 TB, resizable while a generation 2 VM runs); VHD is the old one, limited to 2,040 GB.

Checkpoints are Hyper-V’s snapshots. The default “production” checkpoints use backup technology inside the guest (VSS on Windows, a file-system freeze on Linux) so the saved state is consistent; standard checkpoints also capture memory. Neither is a backup: they live on the same disk as the VM.

How does Hyper-V compare with KVM, VMware and VirtualBox?

Hyper-V and KVM are both type 1 and perform alike for most workloads; the choice usually follows the rest of the stack. Windows administrators get Hyper-V with the licence and manage it with the tools they know. Hosting providers mostly run KVM: it is part of Linux, free, and scriptable through libvirt.

Can you run Hyper-V on a VPS?

Only if the VPS itself can run a hypervisor. Hyper-V needs VT-x or AMD-V, and inside a virtual machine those exist only when the host passes them through — nested virtualisation. Microsoft supports nesting Hyper-V inside Hyper-V (enable it per VM with Set-VMProcessor -VMName NAME -ExposeVirtualizationExtensions $true while the VM is off) but states that Hyper-V on another vendor’s virtualisation is not tested and not supported.

On a KVM-based VPS, which is what most hosting is, the Hyper-V role may refuse to install, install but fail to start VMs, or run slowly, depending on how the host is configured. Nested setups also lose features: a VM running Hyper-V inside cannot have its memory changed while running. For a lab, that can be fine; for production Hyper-V, use hardware where Hyper-V is the only hypervisor.

Hyper-V and VMHeaven

Every VMHeaven VPS line — Standard KVM, Hi-CPU KVM and the others — is a KVM virtual machine, and a Windows VPS runs Windows Server as a KVM guest, which suits anything that is not itself a hypervisor. To run Hyper-V as it is meant to be run, on the hardware, rent a dedicated server: a single-tenant machine with no hypervisor of ours in the way, so Windows Server with the Hyper-V role can run directly on the hardware. The difference between the two is laid out in VPS vs dedicated server.

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