Exchange 2010 - DAG/Server switchover


I have exchange 2010 running on two servers. Each server has CAS, MB and HUB roles installed.

Everything is working fine, but I wanted to create a switchover procedure in the event of a problem. I'm still piecing together what I would need to do so please help me fill in the blanks.

Domain:  IP (made up of course). So the DNS record points to

Servers: ex1( and ex2 (

So let's say, ex1 goes down (or I need to take it down for maintenance). What steps do I need to do to have users connect to  ex2 to send/receive their mail. I don't need this to happen automatically, manually is fine for now. I have a test system set up that I am going to practice this one first (of course!)

Step 1:  Change the CAS server  for each DB with something like this:
Set-MailboxDatabase -id DBNAME -RpcClientAccessServer 'ex1.testmail.lcl'

Step 2: As per an article I found on technet, move the mailbox database copies to mailbox server on ex2

    In the console tree, navigate to Server Configuration > Mailbox.
    In the result pane, select the Mailbox server you want.
    In the action pane, select Switchover Server.
    In the Switchover server database copies dialog box, do one of the following:
        Accept the default setting of Automatically choose a target server (in which case, the system automatically selects the best Mailbox server for each database being switched over), and then click OK.
        Click Use the specified server as the target for switchover, click Browse to select a Mailbox server, and then click OK

Step 3: Is there a step three? What do I do about DNS records? Do I just change the physical IP address on ex2 from  to ?

Who is Participating?
Simon Butler (Sembee)ConsultantCommented:
The clients do not follow the database.
Therefore if you have all of the roles on all of the servers, when the database fails over, the clients will not follow.
To get the clients to go across as well you need a RPC CAS Array.
While a CAS array is very easy to setup (DNS entry and a modification to Exchange database configuration), getting it used by the cleints means touching every client. You have to repair the Outlook profile to get them to use the RPC CAS array address.
Then you have two options to get them to follow:
a. Change the DNS entry for the RPC CAS Array host name.
b. Use a load balancer.

Changing the CAS server on the database is NOT going to help, because the clients will not see that change. That is why you have to use the RPC CAS Array. Therefore Step 1 is useless and there is no step 3 unless you have the RPC CAS Array.

Did I mention you need an RPC CAS array?

Stelian StanNetwork AdministratorCommented:
nachtmskAuthor Commented:
Thanks Simon! I understand what you are saying.
Just for arguments sake, would it work if I changed the CAS server, moved the MB DB to the second server and changed the IP address of the second server to the IP address of the first. Not the best solution I know, but I just wanted to know if it would work.
I'm going to implement what you suggested on my testing system.
Thanks again.
Simon Butler (Sembee)ConsultantCommented:
It may work, but you would have a pretty confused domain. Remember everything is tied to DNS etc. The RPC CAS Array is how it is designed to be done.

nachtmskAuthor Commented:
Thanks again Simon. That was exactly what I needed to know.
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