Thanks to Michael Pietroforte
One of Hyper-V Server’s advantages is that its footprint is smaller than that of Windows Server 2008 R2 plus Hyper-V R2. Its biggest plus of course is that it is free. However, in considering this, you have to take into account that it doesn’t include any Windows licenses for guests. Windows Server 2008 R2 Standard includes one Windows Server guest license, Windows Server 2008 R2 Enterprise includes four Windows guest licenses, and the Datacenter edition allows you to install an unlimited number of Windows Server guests.
A downside might be its lack of graphical interface, such as Hyper-V Manager. You have to manage Hyper-V Server through a command line-like interface. You can, however, also control Hyper-V Server R2 remotely with Hyper-V Manager and Virtual Machine Manager R2.
Another disadvantage of Hyper-V Server R2 is that you can’t install additional server roles on it, although, I think, in most cases it doesn’t make sense to use a Hyper-V machine for other purposes, anyway. Furthermore, Hyper-V Server R2 doesn’t support application fail-over in a clustered environment. It does, however, support full server failover (High Availability).
Hyper-V Server R2’s new features
Except for the first, the new features of Hyper-V Server R2 listed here also apply to Hyper-V:
- Boot from flash: Useful for OEMs who want to ship servers with Hyper-V Server (not possible with Hyper-V R2)
- Live Migration: Move running VMs from one Hyper-V physical host to another without any disruption (works also between Hyper-V and Hyper-V Server: watch the demo video at end of the post).
- High Availability: VMs that go down will automatically restart on another node.
- Processor Compatibility for Live Migration: Allows you to move a virtual machine up and down multiple processor generations from the same vendor. Does not, however, allow you to move a VM from an Intel host to a AMD machine or vice versa.
- Dynamic Storage: Hot add/remove virtual storage while the VM is running, without downtime.
- Physical Processor support: Supports up to 8 CPUs (Hyper-V Server V1 supports 4)
- Logical Processor support: Supports up to 64 logical processors (Hyper-V Server V1 supports 16)
- Virtual Machine Memory support: Supports up to 1TB (Hyper-V Server V1 supports 32GB)
- Management options: System Center Virtual Machine Manager R2 (Hyper-V Server supports SCVMM), Hyper-V Manager
- 10 Gb/E Ready
- Improved processor and networking performance (I haven’t seen benchmarks yet, though.)