DAG is not supported by MS in a virtual environment using an option such as vmotion, HA or DRS. and they have a lot of other little surprises for you - if you want to virtualise Exchange 2010.
See the following url - click on the hardware virtualisation option.
VMware have a section on there web site on exchange - see below.
Thanks for the reply,
Its ok, but, If, Exchange setup is not a part of HA and DRS in VMware. We use only Virtual machine in our VMware infra. Then let me know any issue occur.
We segregate the Exchange setup.
If the exchange servers are going to be VMs then i would look at the vmware document on virtualising exchange 2010 and go down that route rather than look to use DAGs.
They are now
I came to the same conclusions so asked this question of my rep recently, and they said
"I’ve confirmed with the engineering team that Microsoft DAG's are fully supported on VMFS, the difference between a DAG and a Microsoft Failover Cluster is that the DAG replicates between the exchange nodes without the need of a shared Quorum our Resources"