As announced in the PDC, the virtual machine role feature was added to Azure with the primary goal to move existing applications to the cloud. This allows us to upload our own VHD with the Operating System on it (Windows 2008 R2 Enterprise). This machine could have your application pre-packaged and installed. After doing this, you are now able to spin up multiple instances of that machine.
As stated in most discussions,
“MSDTC is not enabled on the cloud machines. There’s no workaround. But, in the cloud environment, there’s indeed no need to use MSDTC. The load balance is done automatically. In SQL Azure, when you use a normal BEGIN_TRANSACTION statement, the transaction may automatically be distributed, or it may not, depends on what the load balancer thinks best suits the operation.”
What this means?
◦BizTalk Server relies heavily on SQL Server and uses MSDTC to keep transactional state across databases and with the adapters.
◦SQL Azure does not support distributed transactions and also introduces more latency to the database queries.
So….
◦It won’t be possible to build a multi-machine BizTalk Server Group through the VM role.
