Cloud Parts

Microsoft Hyper-V

Microsoft’s type-1 hypervisor, built into Windows Server and Windows 10 and 11 Pro and Enterprise: a thin hypervisor under a Windows root partition, which also underpins Azure’s hypervisor and Windows features like VBS, WSL 2 and Windows Sandbox.

What it is
Hypervisors
Used for
Virtual machines
Type
Commercial product
Made by
Microsoft
License
Proprietary
Facts checked
11 October 2026
Website

What it is

Turning on Hyper-V slides the Microsoft hypervisor underneath Windows. The hypervisor’s main job is to create isolated partitions. The Windows install you started from becomes the root (or parent) partition: it runs the virtualization management stack and the device drivers, and it is the only partition with direct access to physical memory and devices. Each VM is a child partition, created through the hypercall API, that sees only virtual devices. Its requests travel over VMBus, a channel between partitions: a Virtualization Service Consumer (VSC) driver in the guest talks to a Virtualization Service Provider (VSP) in the root. These synthetic, “enlightened” devices for storage, networking, graphics and input skip hardware emulation, but the guest needs drivers that know about VMBus. Integration services provide them, plus heartbeat, shutdown, time sync and data exchange services; for Linux, these drivers (Linux Integration Services) are part of the kernel. Microsoft’s own 2009 slides call this a microkernel hypervisor with no device drivers, in contrast to monolithic hypervisors that carry their own driver model.

Generation 1 VMs emulate an older PC with BIOS, IDE disks and a legacy network card. Generation 2 VMs, added in Windows Server 2012 R2, use UEFI with Secure Boot on by default, boot from SCSI .vhdx disks up to 64 TB or over the network with the synthetic adapter, and drop the floppy and legacy devices. A VM’s generation can’t be changed after it is created. On Windows Server, live migration moves running VMs between hosts without perceived downtime, with or without shared storage, and Failover Clustering restarts a failed node’s VMs on another node. Hyper-V Replica keeps an asynchronous copy of a VM at another site, sending changes every 30 seconds, 5 minutes or 15 minutes. Nested virtualization runs Hyper-V inside a Hyper-V VM.

The same hypervisor sits under much of Windows and Azure. Virtualization-based security (VBS) uses it to create an isolated environment that hosts features like memory integrity. WSL 2 runs a real Linux kernel in a lightweight utility VM. Windows Sandbox runs a separate, throwaway kernel. Windows containers started with --isolation=hyperv each run inside a highly optimized VM with their own kernel. Microsoft says “the Azure hypervisor system is based on Windows Hyper-V.” Hyper-V needs a 64-bit CPU with hardware virtualization and SLAT and isn’t available on Windows Home. Windows Server 2025 (November 2024, the current long-term release) supports up to 4 PB of memory and 2,048 logical processors per host, GPU partitioning and clusters outside Active Directory. The free standalone Hyper-V Server ended with the 2019 version: Microsoft said it would no longer offer the product, and its extended support ends in January 2029.

Why teams pick it

  • No separate hypervisor license: it ships with Windows Server and Windows Pro and Enterprise, and Windows Server Datacenter includes rights to unlimited Windows Server VMs
  • Drivers live in the Windows root partition, so it reuses Windows’ own hardware drivers, and it is managed with familiar tools: PowerShell, Hyper-V Manager, Windows Admin Center and System Center Virtual Machine Manager
  • Enterprise features in the box: live migration with or without shared storage, Failover Clustering, Hyper-V Replica with a 30-second interval, nested virtualization and GPU partitioning
  • Guests are well supported: Linux has its Hyper-V drivers upstream in the kernel, and generation 2 VMs boot with UEFI and Secure Boot

Watch out for

  • No free standalone edition any more: Hyper-V Server 2019 was the last, with mainstream support ended in January 2024, so new hosts need a Windows Server or Windows Pro/Enterprise license
  • Everything runs through the root partition, a full Windows Server or Windows 10 or 11 Pro or Enterprise install that holds the management stack and every device driver (Windows Home can’t run Hyper-V)
  • Other hypervisors on the same PC suffer: Microsoft warns that VMware Workstation or VirtualBox VMs might not start or might run unreliably while the Hyper-V hypervisor is running
  • A VM’s generation is fixed at creation, and Linux distributions on older kernels may lack the latest Hyper-V driver fixes

Alternatives

What all hypervisors have in common →
Cloud HypervisorOpen sourceA Rust virtual machine monitor for modern cloud VMs on KVM or Microsoft’s hypervisor: virtio devices only, plus hotplug, VFIO passthrough, live migration, snapshots and Windows guests.KVM (Kernel-based Virtual Machine)Open sourceThe hypervisor built into the Linux kernel: it runs guest code directly on the CPU through `/dev/kvm`, and leaves device emulation to a user-space program such as QEMU or Firecracker.libvirtOpen sourceA stable API, daemon and `virsh` command line for managing virtual machines, storage and networks, with drivers for QEMU/KVM, Xen, LXC, Cloud Hypervisor, VMware ESX, Hyper-V and more.Oracle VirtualBoxOpen sourceOracle’s free, open-source desktop hypervisor: a type-2 hypervisor that runs VMs as an application on Windows, macOS, Linux and Solaris, scriptable with `VBoxManage` and the default provider for Vagrant.Proxmox Virtual EnvironmentOpen sourceA Debian-based server platform from Vienna that runs KVM virtual machines and LXC containers, with clustering, high availability, Ceph and ZFS storage, backups and a web interface in one free ISO.QEMUOpen sourceThe open-source machine emulator and virtualizer: it emulates whole computers in software, or runs them at native speed on a hypervisor such as KVM, and supplies the virtual devices either way.VMware ESXiCommercialVMware’s bare-metal hypervisor (called ESX again since VCF 9), whose own kernel runs VMs directly on servers while vCenter adds vMotion, HA, DRS and vSAN; since Broadcom bought VMware in 2023 it is sold only as per-core subscriptions.Xen Project hypervisorOpen sourceThe open-source type-1 hypervisor from Cambridge that ran the first Amazon EC2 instances: a small microkernel-style core that boots first, with drivers and management in a privileged VM called dom0.

How it fits with other technologies

Create and start a generation 2 VM with the Hyper-V PowerShell module (from Microsoft Learn; not run here) · text

# Elevated PowerShell on Windows Server 2025
Install-WindowsFeature -Name Hyper-V -IncludeManagementTools -Restart
# On Windows 11 Pro or Enterprise instead:
#   Enable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V -All

New-VM -Name "VM01" -Generation 2 -MemoryStartupBytes 1GB `
  -NewVHDPath D:\vhd\base.vhdx -NewVHDSizeBytes 40GB
Set-VMProcessor -VMName VM01 -Count 2
Add-VMDvdDrive -VMName VM01 -Path D:\ISOs\disc1.iso
Set-VMFirmware -VMName VM01 -FirstBootDevice (Get-VMDvdDrive -VMName VM01)

# Optional, while the VM is off: let it run its own Hyper-V (nested virtualization)
Set-VMProcessor -VMName VM01 -ExposeVirtualizationExtensions $true

Start-VM -Name VM01
Get-VM -Name VM01

Generation 1 or generation 2?#

From Microsoft’s guidance on choosing a VM generation. Microsoft recommends generation 2 unless the guest or the boot method needs generation 1.

Generation 1Generation 2
FirmwareLegacy BIOSUEFI, with Secure Boot on by default
Boot diskIDE controller: .vhd, .iso or a physical CD/DVDVirtual SCSI: .vhdx up to 64 TB with online resize, or .iso
Network bootPXE through the legacy (emulated) network adapterPXE over IPv4 and IPv6 through the synthetic adapter
Other devicesFloppy and DMA controllers, UART for COM ports, i8042 keyboard controllerNo floppy; optional UART for debugging; software-based input, with less emulation and a smaller attack surface
Available sinceThe first Hyper-V (2008)Windows Server 2012 R2 (2013)
  • A VM’s generation can’t be changed after it’s created. Since Windows Server 2025, Hyper-V Manager’s wizard picks generation 2 by default.

Where Windows and Azure use the hypervisor#

Hyper-V the role is the part you manage, but the same Microsoft hypervisor runs underneath these features.

Virtualization-based security

Windows 10 and 11

Uses hardware virtualization and the Windows hypervisor to create an isolated environment that assumes the kernel can be compromised, and hosts features such as memory integrity (HVCI) in it.

WSL 2

Linux on Windows

Runs a Linux kernel inside a lightweight utility VM; Linux distributions run as isolated containers inside that managed VM.

Windows Sandbox

disposable desktop

A throwaway Windows desktop that relies on the Microsoft hypervisor to run a separate kernel, discarded when you close it.

Hyper-V isolated containers

`--isolation=hyperv`

Each Windows container runs in a highly optimized VM with its own kernel. It is the default for Windows containers on Windows 10 Pro and Enterprise.

Azure

cloud

Microsoft says the Azure hypervisor system is based on Windows Hyper-V, with a privileged root partition running the host OS and guest partitions for customer VMs.

See it in a real stack

No architecture uses Microsoft Hyper-V yet. Drop it into the playground and wire it up yourself.Open playground →
Where it came from2003–2024

Microsoft entered virtualization by buying Connectix’s virtual machine products, Virtual PC and Virtual Server, in February 2003. They were hosted products that ran on top of Windows. For servers Microsoft then built its own hypervisor: Hyper-V shipped with Windows Server 2008 and was released to manufacturing on June 26, 2008. Microsoft’s announcement called it “microkernelized” and contrasted it with “monolithic” solutions such as VMware ESX.

The design kept the hypervisor thin and reused Windows: drivers and the virtualization stack run in the root partition, so Hyper-V supported whatever hardware Windows supported. Later Windows Server releases filled in the data center features: live migration in Windows Server 2008 R2, Hyper-V Replica in Windows Server 2012 and generation 2 VMs with UEFI in Windows Server 2012 R2. The same hypervisor became the base of Azure’s hosts and, on the desktop, of features such as WSL 2, Windows Sandbox and virtualization-based security.

Microsoft also offered a free download, Hyper-V Server. It stopped after Hyper-V Server 2019, which Microsoft said was the last version of the free product. Hyper-V remains a role in Windows Server, and Windows Server 2025 raised its limits to 4 PB of memory and 2,048 logical processors per host.

Why it’s built this way

A microkernel hypervisor with drivers in the root partition
Microsoft’s architecture slides list the goals: a very thin, highly reliable hypervisor with no device drivers or third-party code, reusing the large base of existing Windows drivers instead.
Synthetic devices over VMBus instead of emulation
Enlightened I/O for storage, networking, graphics and input bypasses device emulation, which is more efficient but needs guests with Hyper-V drivers, hence integration services and the Hyper-V drivers in the Linux kernel.
Shipping it inside Windows
Hyper-V arrived as a role of Windows Server 2008, so anyone with Windows Server could run VMs without buying a separate hypervisor, and Datacenter licenses include unlimited Windows Server VMs.
A second, UEFI-only VM generation
Generation 2 dropped emulated legacy hardware for synthetic devices, UEFI and Secure Boot; generation 1 stayed for guests that still need BIOS and IDE.

Timeline

  1. 2003

    Microsoft acquires Connectix’s Virtual PC and Virtual Server (Feb 19)

  2. 2008

    Hyper-V released to manufacturing for Windows Server 2008 (June 26)

  3. 2009

    Windows Server 2008 R2 adds live migration (Oct 22)

  4. 2012

    Windows Server 2012 adds Hyper-V Replica (Oct 30)

  5. 2013

    Windows Server 2012 R2 adds generation 2 (UEFI) VMs

  6. 2018

    Hyper-V Server 2019, the last free standalone edition (Nov 13)

  7. 2024

    Windows Server 2025: 4 PB and 2,048 logical processors per host, generation 2 by default (Nov 1)

Sources27 · facts checked 11 October 2026

Improve this page on GitHub