Making exchange 2010 highly available

I've recently upgraded to Exchange 2010 from 2003 as the first phase of an email upgrade.  In the next phase I would like to make exchange highly available to our end users.  The current exchange environment is hosted in house running on VMware.  We have a Websense email filter on the front end with one exchange server behind it that has all roles installed.  I also have a datacenter with some rackspace connected via a VPN back to our main site where I'd like to host the other exchange server.

If our primary site fails for any reason I want the end users to be able to access their emails. I know I will need to setup a database availability group but I'm not too clear on how I get from where I am to where I want to be. I'd very much appreciate an overview of the general steps I would need to take to set this up and perhaps some more detailed clarifications since this is very new to me.  Many thanks in advance for any help you could provide!
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Simon Butler (Sembee)ConsultantCommented:
First questions:
Do you have Exchange installed on Windows Enterprise edition?
Have you setup a RPC CAS Array?
If no to the first then you need to build a new Exchange server and migrate to it. Changing the version of Windows on a server with Exchange installed is not supported.
If no to the second question, then you need to configure one and then repair the profile on all clients so that they are using the RPC CAS Array address.

For full high availability you will need two servers and a load balancer. The DAG only protects the databases.

First LastAuthor Commented:
Do you have Exchange installed on Windows Enterprise edition?
Yes, I read that it was necessary for the clustering feature that the DAG will use

Have you setup a RPC CAS Array?
No, this hasn't been done and I don't know much about it other than it is a requirement.  I've reviewed a technet article about the concept and I understand its basically information stored in AD.  I can probably work through the setup of the CAS but can you elaborate on how I would repair the client profiles?  I've asked similar questions before but I never really got into the meat of how the profile repairs would work.  Thanks for the help!
Simon Butler (Sembee)ConsultantCommented:
RPC CAS Array is basically a DNS entry and a configuration change on the database. It allows the clients to access Exchange through a different name that can then be moved around, ie pointed at a load balancer or another CAS role holder.

Repairing the Outlook profile means exactly that - go in to the account configuration in Outlook and choose repair. This will force Outlook to update the server name (the CAS Array host name) instead of the actual name of the CAS role server it was using.

It is pity that while you knew about Enterprise edition for Windows, you didn't deploy the RPC CAS Array right at the start, as you would have saved yourself a lot of work.

As you have Enterprise edition of Windows on the server, all you need to do is configure another server identical to the first. Same drive arrangement etc. Then decide on the third server to be the FSW and set the required permissions. Create the DAG and add the databases to it. Then sit back and wait.
I setup six DAG's in just under an hour this afternoon.


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