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gbksphere

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Exchange 2010 DAG possible in this this scenario

My objective is to setup DAG for my environment.  Under my environmental scenario, I wanted to ask the community to see if a simple DAG setup is possible.  Currently, our Exchange environment is fairly simple.  I'm not looking for anything fancy.  I just need the availability of the databases should one Exchange server goes down.

Scenario:

I have 2 Exchange 2010 servers running on Server 2008 R2 Enterprise.  One is located at headquarter and the other at the DR site.  Currently, each Exchange server is setup for CAS, HT, and Mailbox roles.  Both of these servers are fully functional within our environment.

Question:
Given the scenario, can I just go ahead and configure DAG on each box for passive databases (both servers)?  If one server goes down, the passive database of the failed server would be available on the other working server.  Thanks in advance for your responses.
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Simon Butler (Sembee)
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gbksphere

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Thank you for both responses. I realized shortcuts are not going to cut it.  I was already thinking about implementing a high-availability exchange environment similar to both your recommendations.  I'm now sold on the fact that this is the way to go to save future headaches.

Question:

What the best way to approach this setup in a production scenario?  Can I setup 4 new exchange servers (2 on each site) to our existing environment without messing up anything, e.g. AD schema and stuff)?

Pls confirm:
1. setup 2 new additional exchange servers on Win 2008R2 Enterprise to existing forest (for CAS Array).  
2. 1 server for CAS and HT roles;  1 server for Mailbox roles (each site)
3. Configure, configure, and configure....

Is it easier and safer to configure 4 new servers to make sure all is working?  I'm not too confident about install 1 additional server and fiddling with the existing production servers in the configuration process.  That being configuring CAS Array, setup DAG, migrate mailbox databases, and removing the mailbox roles on existing servers.  I think I'm making everything complicated.  I'm very paranoid when it comes to this stuff.  LOL. Thanks.
Microsoft are now recommending multi-role servers for most implementations, rather than splitting them out. Therefore if you have four licences available, having all four as a multi-role server with all three roles installed would be preferable
That would allow you to have an RPC CAS Array per AD site (using both servers in each site), but two different DAGs, in Active/Passive. If the link drops then both sites continue to operate and all you have to do is get the link re-established.

AD updates will not affect an existing Exchange deployment, but CAS role may, when Autodiscover becomes active.

A point to not though, if you haven't bought licences...
If you are going to use a single physical machine, rather than VM of some description, it might be worth waiting a little bit. With Windows 2012 standard you can run an Exchange 2010 DAG, that isn't possible on Windows 2008 R2 (requiring Enterprise edition). Therefore the licencing cost comes down. The only problem is that for Exchange 2010 on Windows 2012 you need Exchange 2010 SP3 which isn't expected until next year.

Simon.
I've already laid out the possible plans for you.

Regards,
Exchange_Geek