It's time to virtualize Microsoft Exchange (but not with Hyper-V)

Hyper-V missing critical disaster recovery feature

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Microsoft isn't accustomed to being in second place in any market, but that's the situation it has had to accept as it challenges VMware for supremacy in the x86 virtualization world.

Microsoft has undoubtedly made significant progress in the last couple of years, bolstering its virtualization and management capabilities with Hyper-V and System Center Virtual Machine Manager. Microsoft thinks it offers enterprises everything they need to virtualize mission-critical workloads, but not everyone agrees.

Microsoft's 2010 software presents "most complicated lock-in decision in years"

At the Burton Group Catalyst conference this week, analysts told an audience of IT pros that they should be virtualizing Microsoft Exchange - but not with Hyper-V. The recommendation isn't likely to sit well with Microsoft, whose officials have already disputed the Burton Group's claim that Hyper-V is not enterprise-ready. But the analysts are standing firm.

VMware and Citrix are the only two virtualization vendors that meet every one of the Burton Group's criteria for running enterprise workloads. The analyst firm has more than two dozen requirements, and Microsoft has steadily been meeting more and more of them, including the ability to perform live migration of virtual machines across physical servers.

But there is still one feature missing in the area of disaster recovery. Hyper-V does not let IT pros assign priority status specifying which virtual machines get restored first in the wake of a hardware failure.

"The most critical workloads should restart first following a physical server outage, and the Hyper-V R2 platform has no way to prioritize VM restarts," explains Burton Group analyst Bill Pray.

Many customers have decided they can live with this limitation, and expect Microsoft to fix it eventually, and so have gone ahead and virtualized Exchange with Hyper-V anyway. But Burton Group analysts recommend that only VMware and Citrix be used for Exchange and other mission-critical apps.

This is becoming a more important issue, because new features in Exchange 2010, as well as advances in hypervisors and hardware, make virtualization more viable and cost-effective. Exchange 2010 does a better job handling I/O performance, making it possible for customers to virtualize without sacrificing speed, and even letting them make do with cheap storage systems.

"One of the things we did as a big investment in the latest version of Exchange is to move to an environment where you don't need high-end storage for the underlying storage subsystem," says Mike Neil, general manager of Microsoft's server virtualization and Windows Server division.

In the past, Exchange performance on virtual servers "drove some customers crazy," Pray said. The high I/O performance required by email still makes it important to "supersize the server," he notes. But IT should now consider virtualization of Exchange the default option, he said.

"Now the technology is in place," he said. "You should be moving your Exchange server to virtualized environments to get those benefits."

The question of which hypervisor to use remains a source of dispute between Burton Group and Microsoft.

Although Hyper-V doesn't include the exact disaster recovery feature the Burton Group considers necessary, Windows Server 2008 R2's failover clustering has settings that "address some of the scenarios that assignable restart priority addresses," a Microsoft spokesman says.

For example, Microsoft's "VM Auto Start" setting lets customers decide which VMs will automatically restart after failures and which will not. Secondly, a "persistent nodes" feature "will attempt to place a VM back on the node that it last ran on and if not feasible place the VM on other nodes."

Neil said he was surprised the Burton Group recommended against using Hyper-V, and argued that the higher price of VMware's products are not justified by the VMware feature set, especially after the various improvements made to Hyper-V.

Microsoft did not say when it will add the one "missing" feature, but Microsoft customers seem to be confident that the functionality will be added sooner or later.  

"That feature has not stopped our clients from deploying the product," said Burton Group analyst Chris Wolf.

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