As many know by now, Microsoft Hyper-V comes in two flavors – one as a component of Windows Server 2008 R2, the other as a separate server virtualization product. While both are technically Hyper-V, the features and use-cases vary for each version.
This short feature answers some of the most common and basic questions involving the standalone Hyper-V Server 2008 R2, with details on suggested deployment scenarios and management considerations.
OK, so first the obvious question – how does Hyper-V Server differ from Windows Server 2008 Hyper-V?
To begin, let's just clarify exactly what Hyper-V really is.
Hyper-V R2 is the most recent version of Microsoft's virtualization technology. The hypervisor component of Hyper-V is unique to the company's previous virtualization releases in that it runs directly on the physical machine's hardware and is the first software to load during the boot process. Hyper-V is also a part of the Windows Server operating system, so it can be installed as a role on Windows Server 2008 R2, after which administrators can use it to add and configure virtual machines.
On the other hand, Microsoft Hyper-V Server 2008 R2 is a completely separate, standalone product. It essentially gives you the bare-bones, core hypervisor technology without any of the features inherent to the server OS. It does, however, include most of the same capabilities you get with the server role installation of Hyper-V, such as Live Migration, host clustering and support for up to 64 logical processors.
In essence, with Hyper-V Server you get the same stripped-down version of Hyper-V that you would with the Server Core installation of Windows Server 2008 R2 – only without the operating system. Keep in mind, however, that this also means that you won't have access to Microsoft's latest failover clustering features or several other Windows Server components.
That's very confusing. Why are the names so similar?
Good question – take it up with Microsoft! Actually, the name Hyper-V Server 2008 R2 is actually pretty descriptive of what the product is. Unfortunately, that still doesn't make it any easier to keep the two straight.
I keep reading that Hyper-V is free. Is that true with both versions?
Technically, yes. Again, Hyper-V in and of itself comes with the OS. So, for example, if you purchase a Windows Server 2008 R2 Enterprise license, you get Hyper-V along with it. There is no extra charge for Hyper-V – you just install it as you would any other server role.
Similarly, Hyper-V Server is a free download, with no Windows Server license required.
So you're saying I can get Hyper-V for free by downloading the standalone server without purchasing a license for the entire Windows Server OS? There has to be more to it than that.
Of course there is. First off, each Windows Server 2008 R2 Enterprise license gives you the right to run up to four virtual instances in your environment (the Standard edition allows for one virtual instance). You do not get these rights with the Hyper-V Server, of course, so you would have to purchase a license for each virtual instance separately. In most cases, this would make it unreasonable for large enterprises to run Hyper-V Server in production without the OS.
Another cost consideration involves client access licenses, or CALs. These licenses are required to allow certain users access to the services being pushed out by the virtual servers. CALs are not required for Hyper-V Server itself, but you do need them for all of the virtual systems being hosted on the server. Once again, Windows Server 2008 R2 licenses include varying numbers of CALs depending on the edition (you get 25 CALs with the Enterprise edition, for example). Downloading the Hyper-V Server requires you to purchase each CAL separately.
OK, so then when would you want to run Hyper-V Server?
Hyper-V Server 2008 R2 is well-suited for test and development scenarios or when organizations want to consolidate on only one physical machine. As inferred above, it also makes most sense for situations where no new Windows Server 2008 licenses are required, such as the consolidation of non-Windows operating systems (e.g., Linux).
Legacy systems present another opportunity for running Hyper-V Server because it works with older systems like Windows 2000 Server or Windows Server 2003. So if for some reason you didn't want to upgrade those servers, you could still consolidate their workloads onto older hardware by implementing Hyper-V Server.
What about management? If Hyper-V Server is comparable to the Server Core installation of Windows Server 2008 R2 Hyper-V, does that mean it has to be managed from the command line?
The standalone server is just that – standalone – and it doesn't include any of the OS bells and whistles like a graphical user interface (GUI). Hyper-V Server can be configured locally from the command line, and with R2 you can actually manage virtual machines locally using Windows PowerShell. Just remember that Hyper-V Server is based on Server Core, so while R2 supports PowerShell 2.0, it is not installed or enabled by default.
The more common tactic, however, is to remotely manage Hyper-V Server via the Hyper-V Manager user interface. This is good because it gives you a comfortable GUI to work with. But, again, it's remote management on a different machine. You have a few options for this: Hyper-V Server can be managed using the Remote Server Administration Tools included with Windows Server 2008 R2 and Windows 7, or you can use Microsoft System Center Virtual Machine Manager.
No matter what, though, it's likely that the management of Hyper-V Server will be somewhat more complex, so it's up to you to decide if such challenges outweigh the cost of a full Hyper-V installation with Windows Server 2008 R2.
Note: The CodePlex website provides a free PowerShell management library for Hyper-V to help you get started.
What else has changed with the R2 version of Hyper-V Server 2008?
Well, as mentioned above, Microsoft added Live Migration to Hyper-V Server 2008 R2. This is big news for Hyper-V in general, but particularly for the standalone server, as the original release didn't even support the oft-criticized Quick Migration functionality.
A lot of support changes have been made as well. For example, Hyper-V Server 2008 R2 supports up to 384 virtual machines, or as many as can be run on the maximum supported 1 TB of physical memory. This is twice as many virtual machines that were supported by the version one release. It also supports up to eight physical processors per physical machine and four virtual processors per virtual machine.
Also, just like with the latest Windows Server OS, Hyper-V Server 2008 R2 is x64 only.
Still have more questions about Hyper-V Server 2008 R2? There's plenty more to learn. Check out Microsoft's Hyper-V Server product page for a more in-depth FAQ on deployment specifications and requirements.
For more information on Microsoft Hyper-V and server virtualization in general, visit SearchServerVirtualization.com.
This was first published in May 2010