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As I understand it, when you enable Hyper-V role in Server 2008 and above, it will actually virtualize Server OS itself to run on top of Hyper-V.

Source:

When I enable the Hyper-V role on Win 10 Pro, does the same thing happen?

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defcon
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1 Answers1

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In both cases (server and non-server Windows versions) hyper-v is installed as a type 1 hypervisor in between the hardware and the host OS; so in that sense the Host OS is converted to a virtual machine.

There are differences in implementation between server and non-server versions however:

Differences between Hyper-V on Windows and Hyper-V on Windows Server

There are some features that work differently in Hyper-V on Windows than they do in Hyper-V running on Windows Server.

The memory management model is different for Hyper-V on Windows. On a server, Hyper-V memory is managed with the assumption that only the virtual machines are running on the server. In Hyper-V on Windows, memory is managed with the expectation that most client machines are running software on host in addition to running virtual machines. For example, a developer might be running Visual Studio as well as several virtual machines on the same computer.

Hyper-V features available in Windows Server only

There are some features included in Hyper-V on Windows Server that are not included in Hyper-V on Windows. These include:

Virtualizing GPUs using RemoteFX
Live migration of virtual machines from one host to another
Hyper-V Replica
Virtual Fiber Channel
SR-IOV networking
Shared .VHDX

Limitations

Using virtualization does have limitations. Features or applications that depend on specific hardware will not work well in a virtual machine. For example, games or applications that require processing with GPUs might not work well. Also, applications relying on sub-10ms timers such as live music mixing applications or high precision times could have issues running in a virtual machine.

In addition, if you have Hyper-V enabled, those latency-sensitive, high-precision applications may also have issues running in the host. This is because with virtualization enabled, the host OS also runs on top of the Hyper-V virtualization layer, just as guest operating systems do. However, unlike guests, the host OS is special in that it has direct access to all the hardware, which means that applications with special hardware requirements can still run without issues in the host OS.

Argonauts
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  • They are referring to a server configuration typically running only virtual machines (clients) without a user session on the host OS. They are stating that as the assumption on which their memory usage model differences between server and windows are based. That's really a side note in the context of your question. In either OS version the host OS is a 'special' client of the hypervisor, with full HW access, but still running on top of the virtualization layer. – Argonauts Aug 22 '16 at 00:28
  • "In both cases (server and non-server Windows versions) hyper-v is installed as a type 1 hypervisor in between the hardware and the host OS" Are you sure about this? I looked for a way to detect if Windows is running virtualized and found this - 'wmic baseboard get manufacturer,product', this should show Microsoft as the oem when running as guest. I enabled the Hyper-V role on my Windows 10 Pro pc, and this command still shows Dell as before. Also I've read that Hyper-V doesn't passthru SMART data as it uses its own disk driver, but that is not happening either. I have raw disk access. – defcon Aug 22 '16 at 01:08
  • Also do you have a source which says that even on Win 10 enabling Hyper-V virtualizes the OS? I'll be very happy if that indeed is the case. – defcon Aug 22 '16 at 01:11
  • In the link I provided (and the quoted excerpt from it) it explicitly states that. It's from MS... – Argonauts Aug 22 '16 at 01:13
  • Sorry if I missed it, but the msdn link only talks about the differences and specifically the memory management, which you quoted here. I don't see anything related to 'in both cases its installed as a type 1 hypervisor and host OS is converted to a VM'. – defcon Aug 22 '16 at 01:45