Virtualising Exchange 2010 - Database Availability Groups (DAG's)

Check out the Best Practises for Virtualising Exchange Server 2010 on Windows Server 2008 R Hyper-v : https://www.microsoft.com/downloads/en/details.aspx?FamilyID=8647c69d-6c2c-40ca-977e-18c2379b07ad

One of the most common questions I get on this topic is : Are Database Availability Groups (DAG's) supported in a virtual environment?

The answer is YES but with conditions.  To quote the guidance:

"Exchange server virtual machines, including Exchange Mailbox virtual machines that are part of a Database Availability Group (DAG), can be
combined with host-based fail-over clustering and migration technology as long as the virtual machines are configured such that they will not
save and restore state on disk when moved or taken offline."

This means the LIVE migration is supported but QUICK migration is not. Why? QUICK migration suspends the VM during migration which is could cause data loss as DAG's use log shipping to replicate the data. So how do you move a VM that is part of a DAG? Shutdown the VM OS and then move the VM. This allows the Exchange instance to gracefully stop participating in the DAG ensuring no data loss.

Check out the official post from the Exchange Team : https://blogs.technet.com/b/exchange/archive/2011/05/16/announcing-enhanced-hardware-virtualization-support-for-exchange-2010.aspx

From a design perspective, the DAG layout could be as follows: