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Microsoft changes tune on Exchange 2010 VMware HA support

Microsoft will finally support Exchange 2010 DAG failover with VMware High Availability. The company announced the new Exchange 2010 VMware support policy at TechEd.

ATLANTA -- Microsoft Corp. has reversed course and will now support the use of VMware High Availability with database availability groups in Exchange Server 2010 Service Pack 1.

There is no technical change to DAGs.

Jim Lucey, Microsoft product manager

Previously, Microsoft had said it wouldn’t support VMware High Availability (HA) or other hypervisor-based, third-party failover tools because they could make it more expensive and complex to run Exchange. But users all along doubted there were any technical issues that would make it risky to run VMware HA with Exchange database availability groups (DAGs).

“At this point, application vendors will get so much resistance from their customers if they take the position of not supporting their product running on a virtual platform,” said Shannon Snowden, manager of delivery services at New Age Technologies in Louisville, Ky., in an email. “They eventually have to change their stance.  That includes Microsoft.”

New Exchange 2010 DAG failover support policy
Microsoft issued its new support statement Monday during the TechEd North America conference.

“Combining Exchange 2010 high availability solutions (database availability groups (DAGs)) with hypervisor-based clustering, high availability, or migration solutions that will move or automatically failover mailbox servers that are members of a DAG between clustered root servers, is now supported,” Kevin Allison, an Exchange general manager, wrote on The Exchange Team Blog.

The blog post doesn’t mention VMware HA by name, but in an interview, senior technical product manager Jim Lucey confirmed that the new support will include this product. The blog post also cites “improvements … made in Exchange Server 2010 SP1” and “more comprehensive testing of Exchange 2010 in a virtualized environment” as reasons for the new support policy.

But Lucey said in this case, quality-assurance testing was the difference-maker.

“There is no technical change to DAGs with regard to live migration and HA,” he said. “We did testing with Service Pack 1 and so made that the basis of support.”

Microsoft will support its own products, and if the cause of the support issue is a third-party tool, Microsoft will either engage that vendor directly, or in the case of a competitor such as VMware, engage the Technical Support Alliance Network to coordinate support.

Matthew Liebowitz, a solutions architect for Manhattan solutions provider Kraft and Kennedy, Inc., said he was “thrilled” to see the updated policy. But he cautioned that users should make sure deployments are configured correctly.

“I never saw much technical merit to the restriction against using VMware HA in combination with DAGs, but I have seen issues with DAGs and vMotion and [Distributed Resource Scheduler],” he said.

Exchange 2010 VMware HA support: A long time coming
Despite the new policy, Microsoft still argues that DAGs make tools such as VMware HA redundant because they are aware of both application and hardware failures.

The spat over support began last fall, when, VMware issued a white paper (PDF) explaining how its HA feature can be used alongside Exchange 2010's DAGs for application high availability and disaster recovery. The Microsoft Exchange Team took umbrage, calling VMware's guidance "reckless” and saying that it "puts Exchange customers at risk."

The conflict continued into March, when VMware returned fire with an architecture design proposal that claimed to eliminate the need for DAGs. The back and forth between the two vendors drew plenty of attention from the virtualization community, much of which was critical of Microsoft.

Lucey acknowledged that this criticism prompted further testing of Exchange 2010 DAGs with third-party HA and live-migration tools.

“As more customers move toward virtualization, we’re going to adapt to the trend,” he said. “From an Exchange perspective, we saw customers demanding [this support] and said, ‘Let’s do the testing.’”

Beth Pariseau is a senior news writer for Write to her at

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