Virtualization is certainly a hot topic, and with the release of Windows Server 2008 and Microsoft's Hyper-V virtualization technology, it's only likely to get more attention. The question remains how Microsoft will support Exchange Server in this new virtual environment, and how Exchange will perform. Last week, I wrote about Microsoft's support stance for virtualizing Exchange 2007 and Exchange 2003 on current virtualization products ("Exchange Server Virtualization: Microsoft's Support," April 17, 2008). Now, let's take a look at Exchange virtualization in light of Hyper-V, which was released as an official release candidate (RC) on March 19.

Unfortunately, Microsoft hasn't publicly said much, if anything, about Exchange support for Hyper-V. This silence is somewhat understandable, given that Hyper-V isn't yet a shipping product and that feature or scope changes are possible right up to the minute it's released to manufacturing. Having said that, I think the Exchange and Hyper-V teams are missing a great opportunity to educate people about what the combination of these products will be able to do. It's obvious to everyone in the technology world that Microsoft will support Exchange on Hyper-V, so not announcing this support, or giving details about it, hardly helps Microsoft's efforts to move people to Server 2008 and Exchange 2007.

To point out one obvious example where this lack of candor is a problem, the Windows Virtualization Team Blog already has several posts about high availability and disaster recovery with Hyper-V. How will these methodologies work in conjunction with Exchange 2007's standby continuous replication (SCR) and cluster continuous replication (CCR)? Microsoft isn't saying—which makes it difficult to assess whether the move-VMs-and-restart method typical of virtualized high availability plans can be improved with Exchange's technologies. (Microsoft's silence also fails to provide any compelling reason for existing VMware customers to consider moving to Hyper-V, but that's beside the point.)

Administrators have many questions about Exchange and Hyper-V; answers to these questions would help them plan their future deployments. For many admins, an educated guess will likely provide a good enough answer. For example, if you're wondering which Exchange 2007 server roles will be officially supported, my guess is that the Unified Messaging role will have to stay on physical hardware, and that Microsoft will recommend caution when virtualizing Mailbox servers to ensure that they're properly protected and sized. Client Access and Hub Transport servers, though, seem like great candidates for virtualization. But we'll have to wait for Microsoft's official announcement to be sure.

The next reasonable question one might ask is when we'll know more about the combination of Hyper-V and Exchange? Microsoft often uses TechEd and IT Forum as platforms for making big announcements; with TechEd North America 2008 less than six weeks away, my money is on seeing some answers there.

Of course, it will be interesting to see how Hyper-V stacks up as a virtualization product against VMware. I don't claim encyclopedic knowledge, but I've been running Hyper-V with a variety of virtual workloads for a couple of months and have been very pleased with its manageability and efficiency so far. I look forward to using the final version.

One last virtualization note: One of the sessions I'm presenting at next week's Microsoft Exchange Connections 2008 conference in Orlando is on Exchange virtualization. If you're interested in the topic, come by and say hello!