Installing CAS role Exchange 2010

Posted on 2011-10-03
Medium Priority
Last Modified: 2012-08-14
I'm in the process of installing Exchange 2010 into an Exchange 2003 FE/BE environment.  For budgetary purposes and to make best use of the existing new hardware I am planning to install the CAS, HT and MBX roles on both new servers.  I am also planning to setup a CAS array and a DAG, except I will not load balance the CAS array due to Microsoft limitations and no external hardware load balancer.  With that said, I need clarification on the naming convention of the DAG, CAS array and Internet facing name space.  

If I want the OWA name to be mail.domainname.com, do I use this same name for the CAS array and/or DAG name?  

When prompted for the Internet facing name during the CAS install, will I input the same name during the installation on both CAS servers or is this going to throw an error?  If I am not load balancing, I'm confused how both servers can have the same OWA address/configuration?
Question by:wpstech
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Author Comment

ID: 36905596
i should add that I was planning to setup a DAG so that each of the (2) Ex 2010 servers would each have 2 active DB's and hold the 2 passive DB's of each other
LVL 11

Expert Comment

ID: 36906358
there won't be a cas array because that would require a third server or nlb device, so you will need two different internet facing fqdn's.  One for each cas server, that is if both cas servers will be internet facing.

Accepted Solution

sumit_arora earned 900 total points
ID: 36908620
i think you are confused with DAG namespace and CAS array name space.

1. DAG name space is just for dag specific only, outlook, activesync and any other client application is not bothered with it. you can have DAG name wht ever you want, but make sure its diffrent from CAS array if you opted to have it.

2. Cas array name space is very import now as it is used in outlook and any other client which connect to exchage server. there is an attribute named as rpcclientaccessserver which is actually on database only. if you run this command ( Get-MailboxDatabase <DB name> | fl RpcClientAccessserver) you will see you first CAS server name in it.

 x named CAS server will connect that particular databse to provide clients connectivty and in outlook in server name (where we do check name)  you will see CAS array or cas server name.

Now important thing. if you want to keep same name space for CAS array and external URL you can have it, but in your enviorment i dont see NLB device as we have all roles running on both servers and we will have DAG too.
reason- Windows NLB and Cluster service use few same files as both are windows components. but if you have hardware NLB then u can use CAS array.  

You cannt use same name space for both CAS server with out CAS array.
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Author Comment

ID: 36909498
I've read many references online to an option where DAG and CAS array can both be configured/deployed on a 2 server Exchange 2010 environment w/ all 3 roles installed on both servers, while this configuration must sacrifice load balancing it still offers HA.  

My plan was to create a CAS array, point the DB's on both servers to the CAS array, and create a DNS record that points the CAS array to ExServer1.  I realize that this doesnt offer load balancing, which at this point is fine.  If ExServer1 ever fails all I have to do is update the DNS record to point the CAS array to ExServer2.  

So...based on this scenario, when I begin the installation on the servers once I do the install on the 1st server should I then go ahead and create the CAS array and the DAG before installing Ex2010 on the second server, or will that even matter?  Am I going to be prompted for the "internet facing name" during the installation of CAS on the second server?  If so, is it going to let me use the same name that I used on the first installation of CAS?

Lastly, does the DAG get a FQDN?  If so, do I need to use the same or different name for the CAS?  Does it matter?

Here are a few links i've referenced:


I'd really like to hear from an expert whose deployed this same 2 server scenario.  

Author Comment

ID: 36909702
Update:  I've also read references to creating a CAS array and pointing the CAS array name to the DAG IP in DNS, rather than pointing it directly to a physical server such as ExServer1.  

Which of these options is the proper/correct option for deploying a CAS and DAG on a 2 server setup w/out load balancing?  

Please advise.

Author Comment

ID: 36911707

Assisted Solution

sumit_arora earned 900 total points
ID: 36915401
1. To create CAS array you need to have 2 CAS servers. So fisrt go ahead and install 2 CAS/HUB server role if you dont want to change the RPCClientaccess attribute later. But if you have installed all roles at the same time on both server its just a matter of few commands using which you can change it.

2. You need to specify DAG name not FQDN, its diffrent from CAS array name.
     Get-DatabaseAvailabilityGroup DAG1 -Status | fl  
This example displays the list of servers in a DAG named DAG1. It also displays real-time status information for DAG1. In addition, several properties of the DAG, such as the file share witness directory and share configuration information are also displayed

So DAG name will just be used as identity to find whats the status like in exchange 2007 we use

3.Yes you will get a prompt for internet facing server when u will install 2nd exchange CAS server, you can use the same name space too.  

Please follow these articles which can help you to deploy DAG and some info too

Must read article and you can follow it in your deployment

Author Comment

ID: 36916819
the question still remains...if deploying CAS array w/ no load balancing and DAG on same boxes, do I point the CAS to the DAG IP or to the IP of one of the CAS servers?  See questions and related articles above.  I've read references to doing it both ways.

Assisted Solution

sumit_arora earned 900 total points
ID: 36923277
Yes. it should go to the IP of the CAS server.

Author Closing Comment

ID: 36926554
still wasnt a clear answer to the question.

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