I'm looking to move from a single Exchange 2013server to multi server for HA, i.e. multiple database servers and client access servers. What the best way to migrate? I would like to keep the existing single server as a client access server. I'll be using a hardware load balancer for the client access servers.  Existing 2013 Exchange server has Windows 2012 Datacenter installed.

Can just make a new database sever and create a DAG then create a new client access server then configure the load balancer?

Thanks for any input on how to migrate from a single server to multiple server for additional HA.

 

What OS are the new servers going to have?  Are they going to be Server 2012 R1 or Server 2012 R2?

If they are going to be server 2012R2, then you need to stand up the new servers, configure the dag, create new databases, test of course :), and then start moving users over to the new environment.

If it was me, and I had the resources, I would go with multirole servers (unless other org requirements dictate otherwise).  This was I can isolate the new and the old environment and not impact users.  

You can use Windows 2012 Standard instead of Datacenter if that saves you some money.

Keep the DAG simple:

http://blogs.technet.com/b/exchange/archive/2014/04/21/the-preferred-architecture.aspx

Yes, server 2012 R2. I don't want to get ride of the first server, just scale out for HA. Can I setup another server with client access and database role, then create a third server with just database role for a lag copy? This way I'll have two servers with client and database roles and one server with a lag copy of the database. A hardware load balancer would be used for the client access servers. Don't I need enterprise or data enter version of windows to make a dag?

Does standard support clustering for the dag?

If you want to keep the original server in the mix as part of the DAG, then you will need to deploy Exchange on Windows Server 2012 R1 since the Failover cluster pieces are only supported to run with the same OS version (Server 2012 R1 -> Server 2012 R1 and Server 2012r2 -> Server 2012R2).

If you plan on using R2, then I might consider migrating everything over to the 2012R2 DAG, remove Exchange (VIA Add/Remove Programs) and rebuild it running Server 2012 R2 and use that as your 3rd DAG member.

starting with server 2012 MSFT changed the license requirements to allow you to install the clustering components on Standard Editions of Windows.

Does standard support clustering for the dag?

Yes. and 3 copies is not enough to justify a lagged copy. I would recommend 4 copies in that case. 3 HA copies, 1 lagged.

Is there any benefit to using Server 2012 R2 vs Server 2012 R1? The single server is currently Server 2012 R1.  Can I do an in place upgrade from 2012 R1 to R2 without messing up Exchange?

Here's my thoughts so far:

1. Make 3 additional 2012 R1 servers

2. On 2 of the servers install additional Exchange servers with mailbox database roles (it appears each new mailbox server comes with a database which I'll delete).

3. On the last new server, install CAS role

4. Create DAG with all 3 servers with database role

5. Add production database copies to DAG

6. Configure load balancer for CAS load balancing

Thoughts?  Is the production database on the single server available while a copy is being made to the new mailbox database servers? Also, I thought I read some where to move mailboxes to DAG, but I don't see why if I can just add copies of the existing database to the DAG group.

 

R2 has a lot of fixes and is superior IMO and is a better option going forward, but its not the end of the world if you stick with 2012 RTM

You cant upgrade the O/S with Exchange installed however. You can only apply SPs and fixes to the O/S.

You should install multirole servers. Each Server should be a CAS/MBX role server, then add all the servers to the load balancer for the Client Access.

Once you add the servers to a DAG, you can replicate that original database, no need to move mailboxes if you decide to go that route.

I think this may make the most sense if I have a hardware load balancer to help cut down on # of servers to manage.

Thanks!

Had one more question, after I setup my servers with CAS and mailbox roles, what should I do if I have a CAS/Mailbox server fail before I get the load balancer installed?  Just update the mail record to point to a different CAS?  Not sure if Outlook will try to connect to a specific server to get the mailbox, but I believe this has changed?