"Between Microsoft Virtual Server and [VMware] ESX, there's no comparison," said Chris Wolf, an independent consultant and author of Virtualization: From the Desktop to the Enterprise. "Bells and whistles-wise, ESX is still miles ahead of Virtual Server," he said.
Over the course of his presentation, Wolf listed several areas where Microsoft has to work to bring Virtual Server up to snuff. For example, whereas VMware supports full access to the storage area network (SAN) within each virtual machine (VM), Microsoft Virtual Server guests access the SAN through a mount point or drive letter on the host operating system. Accessing the SAN this way adds latency, Wolf claims.
Wolf also called out the latency of the two platforms' virtual disk implementations – the .vmdk file for VMware, and .vhd for Microsoft Virtual Server. VMware published tests that showed ESX Server latency at 13% when running with virtual (rather than physical) disks. Tests performed by the Australian consulting firm Capitalhead benchmarked Microsoft Virtual Server virtual hard drive latency at 28%.
Among Microsoft Virtual Servers' other shortcomings that Wolf listed were slightly higher memory requirements per VM and a less mature physical-to-virtual (P2V) migration facility.
Nevertheless, said Wolf, a large number of IT shops are investigating Microsoft's offering. "They are buying in to the future that Microsoft is promising."
Microsoft, for its part, was on hand to defend itself as one of the seminar's sponsors. Peter J. Meister, group product manager for Microsoft's global virtualization technical team, acknowledged that "there are workloads where we don't [virtualize] well," but emphasized the company's commitment to developing the platform. "We're investing a large amount of our R&D budgets to getting this right because it's a platform change," he said.
Management of virtual environments is a prime focus area for Microsoft, Meister said. As part of the company's Dynamic Systems Initiative, the group is working to support Volume Shadow Copy Service (VSS) on MVS, as well as failover and fail-back via virtual iSCSI LUN adapters. Integration within Microsoft SMS and Microsoft Operations Manager (MOM), meanwhile, will allow IT managers to "take advantage of an environment that they already know," said Meister, rather than have to go with a "rip and strip" management stack from a third party.
An arduous path ahead for IT managers
Whatever virtualization path you choose to go down, brace yourself, warned another presenter, Bernard Golden, CEO of the IT strategy firm Navica Inc. "Virtualization is a journey, not a project," he said.
For example, many people that start to play with virtualization start out by using local disk drives for storage, Golden said. "That's not an ideal solution, so you start to drive toward virtualizing your storage – that's the journey part."
Virtualization will also force its practitioners into hardware and capacity planning – two disciplines that many IT managers may have abandoned long ago. "Let's face it, underutilized systems reduce administrative burden," Golden said. "It's much easier to admin a server that has way more power than it can actually use."
But highly utilized virtual environments present what Golden called "a moving bottleneck – new things become the choke point."
Ultimately, dealing with this complexity may require hiring new staff or getting additional training, he said. "You're going to have to get people that are better at analyzing problems."