Exchange 2010 Install to co-exist with Exchange 2003

Posted on 2011-04-26
Last Modified: 2012-05-11
I need to know the correct order to install 2 - 2010 CAS, 2-2010 HT, and 2-2010 Mbx servers to co-exist in a Exchange 2003 Organiztion.

I know you should install the CAS server first then the HT and then the Mailbox.  But since I'm installing 6- 2010 Exchange  servers I need to know the correct order.

I plan to create a CAS Array from the two CAS servers.  I'm installing 1-CAS, 1-HT, 1- Mbx on one VMWare Host and the other 3 servers on another VMWare Host.
Question by:JimmyRiverside
    LVL 31

    Accepted Solution

    You can create the CAS array with only 1 server in it and then add the other CAS later. The important thing is to try and create the CAS array before you install the mailbox server so it can be used straight away by the mailbox databases and you don't have to go back and edit them later.

    The order is as you know already CA, HT, MB. It's up to you if you want to install 1 of each role to begin with or install 2 of each role at a time.
    LVL 6

    Expert Comment

    by:Vipin Vasudevan

    Please find the order for having Exchange 2010 in an Exchange 2003 organization.. (please refer this link for more on coexistance (

    1.      Bring the Exchange organization to Exchange Native Mode.
    2.      Upgrade all Exchange 2003 Servers to Exchange Server 2003 Service Pack 2.
    3.      Bring the AD forest and domains to Windows Server 2003 Functional (or higher) levels.
    4.      Upgrade at least one Global Catalog domain controller in each AD Site that will house Exchange Server to Windows Server 2003 SP2 or greater.
    5.      Prepare a Windows Server 2008 (RTM or R2) x64 edition server for the first Exchange 2010 server.
    6.      Install the AD LDIFDE tools on the new Exchange 2010 server (to upgrade the schema).
    7.      Install any necessary prerequisites (WWW for CAS server role).
    8.      Run setup on the Exchange 2010 server, upgrade the schema, and prepare the forest and domains. (Setup runs all in one step or separate at the command line.)
    9.      Install CAS server role servers and configure per 2010 design. Validate functionality.
    10.      Transfer OWA, ActiveSync, and Outlook Anywhere traffic to new CAS servers.
    11.      Install Hub Transport role and configure per 2010 design.
    12.      Transfer inbound and outbound mail traffic to the HT servers.
    13.      Install Mailbox servers and configure Databases (DAG if needed).
    14.      Create public folder replicas on Exchange 2010 servers using pfmigrate.wsf script, AddReplicatoPFRecursive.ps1,or Exchange 2010 Public Folder tool.
    LVL 24

    Expert Comment

    The order is as you have said, CAS, HUB and Mailbox.

    As mentioned above, do create a CAS array if possible before the mailbox role installation. Not a show stopper, it will save you an additional step. That's all.

    Author Closing Comment

    Thanks great answer.

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