It's hard to argue with free--unless you need more than server virtualization basics.
Windows-only shops looking to do a little virtualization on the cheap need look no further than Microsoft's Hyper-V and the freebie Hyper-V Server 2008 standalone host. However, our tests showed that customers with even mildly complex virtualization requirements should run Hyper-V on top of Enterprise or Datacenter editions of Windows Server 2008 and manage guest virtual machines by adding System Center Virtual Machine Manager--which brings on licensing costs.
As for non-Windows environments, Microsoft's claim that Hyper-V is capable of mixed operating system virtualization is technically accurate, but the latest version of Novell's SUSE Enterprise is the only flavor of Linux supported across the Hyper-V range.
This leaves Red Hat, Debian, and other Linux variants to run on other hosts, such as Xen, KVM, and VMware. Linux-heavy organizations that aren't using SUSE Enterprise should bypass Hyper-V in favor of VMware ESX, Citrix XenServer 5.0, or another alternative.
The elephant in the room is Hyper-V's lack of live migration support; VMware and Citrix allow a running virtual machine to shift from host to host with no production outage. But despite early promises to the contrary, Hyper-V doesn't allow live migration.
If these issues don't apply to you, Hyper-V has a couple of selling points beyond the price tag. Windows guest virtual machine performance was more than satisfactory on both our trimmed-down Hyper-V Server 2008 test setup and our "fat OS" installation of Hyper-V on Windows Server 2008 Enterprise.
Microsoft also offers a sensible license model that simplifies management for midsize and larger companies using Windows Server 2008 Datacenter. Datacenter removes Windows guest VM licensing compliance headaches by permitting one physical server (the VM host) and unlimited guest OS instances under the same umbrella license. Citrix and VMware, in contrast, can't offer blanket licensing for Microsoft guests. Windows Server 2008 Enterprise versions allow for a host server plus four VM licenses.
At the other end of the spectrum, a Server 2008 Standard Edition license includes the host plus one guest; additional guests must each get their own license codes. And although Hyper-V Server is free, organizations are responsible for individual licenses for all hosted Windows virtual machines.
>Hyper-V is best for virtualization novices in small shops or Windows-only environments
> It's hard to argue with free, but overall, Hyper-V feels like a "me-too" product, released so Microsoft would have a modern virtualization offering on the market
> Rival products cost more, but you don't have to spend extra to get broad Linux support and live migration
We had no setup or installation issues adding Hyper-V services to our new or existing Windows Server 2008 hosts. Hyper-V Server 2008 ran well on our virtualization-aware chipsets from Intel and AMD, although each server in our test environment required a base installation of Windows Server 2008 and attendant updates prior to revving up Hyper-V.
Hyper-V proved to be a worthy host on our test setup, a four-host Windows 2008 cluster accessing a shared EqualLogic iSCSI SAN. We had to install Microsoft's System Center Virtual Machine Manager (SC-VMM) 2008 to match the management tool functionality in other host platforms in this Rolling Review. With Hyper-V essentially free, the $869 SC-VMM unlimited license or $505 five-host license are relative bargains for Microsoft customers.
Tapping SC-VMM's "intelligent placement," Hyper-V does a capable job of allocating new virtual machines to physical servers, comparable to XenCenter's virtual machine placement.
SC-VMM's physical-to-virtual conversions virtualized existing Windows servers without a hitch in our tests. Physical-to-virtual conversions of XP, Windows 2003, and newer Microsoft operating systems utilize Volume Shadow Copy Service. Like XenConvert or VMware Converter, SC-VMM physical-to-virtual migrations can grab a snapshot of a running production machine.
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