There are currently two Microsoft HyperVisor products:
Hyper-V Server 2008 R2
http://www.microsoft.com/hyper-v-server/en/us/default.aspx
Server 2008 R2 Hyper-V Role
http://www.microsoft.com/windowsserver2008/en/us/hyperv-main.aspx
Question - Is there a functional difference between the two, regarding hypervisor performance or features?
If not, what possible reason is there to use the Hyper-V Role instead of the standalone hypervisor? There are clear advantages in having a smaller footprint and attack surface from the standalone hypervisor.
It seems like Hyper-V role gets much more media spotlight and documentation as opposed to the standalone hypervisor.
If you're using Server 2008 R2 Hyper-V Role, can you share why you chose to do this rather than Hyper-V Server?
With Hypervisor perfomance and features, there isn't a difference, they will both do exactly the same thing without limitation. When you install the full Server product, you incur the overhead that the OS requires. You are able to use all other roles available in the edition you've installed, each one adding impact to each other as they are added.
I have one in each scenario. The Hyper-V Server was a lower spec'd machine, and I wanted to squeeze everything out of it for VMs.
The Server 2008 R2 w/ Hyper-V is a development server with a ton of memory and disk space, and I wanted full GUI control direct from the console.
Yes, this is why you will instally Heyper-V ROLE on top of a.... Server CORE, not a full server. Same attack surface. Hyper-V server is basically jsut packed up for different licensing.
it cmoes with mor RAM support than Standard. Plus, when running Linux hosts you ahve zero licensing costs. Hyper-V server thus is in R2 the "better" hypervisor due to flexibility, but the pracitcal enefit is close to zero normally. Mainteannce is NOT a difference.
besides the theoretical performance benefits of hyper-v server, there is an important licensing consideration.
with server 2008 r2 datacenter plus the hyper-v role, you can host an unlimited number of server 2008 r2 standard guests without needing licenses for the guests. in other words, the licenses for the standard guests is included in the license for the datacenter host.
with hyper-v server, there are no guest licenses included.