Test Center preview: Windows Server 2008 R2

The noisiest new feature in Windows Server 2008 R2 promises to be live virtual machine migration, as Microsoft seizes the chance to show that Hyper-V is closing the gap with VMware Infrastructure. But there are many reasons beyond server virtualization to take a close look at Windows Server 2008 R2. Important enhancements are spread across the board, ranging from IIS to networking to Terminal Services. There's even a story to be told about R2 and the upcoming Windows 7, which gains better virtual desktop integration and even secure remote access without requiring a VPN -- though the latter feature, called DirectAccess, requires the use of IPv6.

Of course, I don't want to sell the Hyper-V upgrade short (see the June 2008 review, "Microsoft's Hyper-V does the trick"). Hyper-V gains two important performance improvements, the first being that it now supports 32 logical CPUs (i.e., cores) on the physical host. Raising the CPU barrier gives large datacenters a better chance to virtualize some of their biggest CPU hogs. The second performance improvement is live VM migration, which allows you to move a virtual instance from one server to another with little to no service interruption. Users can stay connected and working while the move takes place. Although they may notice a small pause, the move will be almost completely transparent to them.

[ Windows Server 2008 is "an upgrade that IT can't refuse." See the Test Center's February 2008 review and "Secrets of Windows Server 2008." ]

Besides filling a check box in Microsoft's server virtualization marketing chart, exactly how useful is live migration? How often would you need to move a virtual instance between boxes? Well, if you're looking at a situation where the current Hyper-V host is bogged down with too many instances or the VMs are fighting over system resources, you may find yourself moving some of them to other servers. If you don't need to schedule downtime for the task, so much the better.

There are other reasons to move virtual instances. For instance, say you are experiencing minor network errors. You might want to move some of the more important virtual servers to a host on different network segment while you're working out the bugs. And of course there's always host maintenance. The physical host for these Hyper-V VMs will need periodic maintenance, which quite often means a reboot. Even when performing network maintenance on a router, it could be beneficial to move critical instances to another host. As you can see, there are several cases where moving your virtual server instance to another host could be beneficial and reduce the strain on your users and your business. I suspect this could become one of the most important features to businesses with a high number of virtual servers.