If your exchange servers are joined to a DAG (i.e a 2-way DAG), do you need 2x exchange server enterprise liscences or just one?

Do you have any official MS documentation that confirms the rules on this for evidence?

Hi

You need a license for all members in the DAG. In Exchange 2010 a server does not become passive/active like in previous versions. It's the mailbox database that is active or passive. A DAG can contain a server running both active and passive mailbox databases. Because of this Microsoft build their licensing around "all servers in a DAG must have a server license regardless if they have all mailbox databases passive or not". 

This also depends on how many databases you will be hosting on each node.

1.  Every server that will be running Exchange, needs an OS license.  Since they need clustering, you will need Server 2008 R2 Enterprise or Server 2012 Standard.

2.  Every instance of Exchange needs an Exchange server license.  Standard allows you to run up to 5 DBs and Enterprise allows you to run up to 100 per server (See Here)

3.  Every user will need an Exchange User CAL either Standard or Enterprise depending on the features needed.  See the above link for this as well.

Hope this helps.

Jason

Hi,

The suggestions mentioned above are pretty helpful. Every physical or virtual server that you install Exchange Server 2010 onto requires a Server License. It doesnt matter whether the server is being used for redundancy purposes or not, you must have a license to install Exchange Server.

Here is an article which can help you to understand Exchange licensing for your reference.

Licensing 101: Exchange Server 2010 http://blogs.technet.com/b/haroldwong/archive/2011/02/25/licensing-101-exchange-server-2010.aspx

Hope this helps.

Best regards,
B