Microsoft had promised to deliver a road map for how to run its database and messaging platform on Hyper-V at both TechEd in June and its Worldwide Partner Conference in July.
The applications can run on Hyper-V today, but customers really need a support statement from Microsoft with details, experts say.
Customers are interested in virtualizing Exchange Server, but there has always been the supportability question, said Richard Luckett, president of SYSTMS of NY Inc., an integrator. "We've been virtualizing [Exchange Server] for various reasons, for education and as a proving ground," he said. "Everyone realizes it's possible, but it all comes down to supportability."
IT managers hold back from virtualizing I/O-intensive applications because the performance cannot be guaranteed as it can with an application using dedicated hardware.
One technical barrier has been disk performance.
"[VMware's] ESX has a complex driver model that lets the virtual machines talk to the hardware," Luckett said. "Microsoft has a simplified driver model that is run by the virtual machine, and it has a few options to let drivers talk to the hardware. That will enhance performance from a disk I/O perspective."
It's likely the Exchange and SQL Server experts will recommend that IT shops use dedicated hardware for dedicated roles. For example, Exchange Server has a mailbox role and it will probably be a best practice to run that role from a dedicated server; other roles, such as transport or client-access servers, might be good candidates to be virtualized.
"If someone doesn't want to buy five different servers to take advantage of a role-based architecture, they can virtualize some of it," Luckett said.
In June at TechEd, Microsoft did issue some guidance regarding the use of Exchange Server with Hyper-V. It said it would support guests running Exchange Server 2007 SP1 on Windows Server 2008. It would only support fixed disks and not dynamic disks, and storage should be on spindles that are separate from the guest operating system VHD physical storage.
Also, storage must be SCSI passthrough with a preference of SCSI passthrough for queues, databases and log files. All Exchange Server roles, other than unified messaging, will be supported. Finally, Microsoft said there would be a limit on VHD size of 2,040 GB.