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Enterprise Software Thread, Exchange DAG failover issue in Technical; Afternoon all I've finally found the time this summer to set up a DAG. The process went fairly smoothly, and ...
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    Exchange DAG failover issue

    Afternoon all

    I've finally found the time this summer to set up a DAG. The process went fairly smoothly, and now I can happily switch the active database between servers in the DAG without issue.

    The problem occurs when I shut down one member of the DAG (EXMB01). Despite the database being happily mounted on EXMB02, no outlook clients can connect, can't access any of the mailboxes via webmail (mailbox not available error). EXMB01 was originally the only mailbox server in our exchange environment. I can only resolve this issue by booting EXMB01 back up again.

    Shutting down EXMB02 when the database is mounted on EXMB01 does not cause any issues.

    The environment is as follows:

    - Four servers in total, all running exchange 2010 SP3 on windows 2008R2

    - 2 X CAS servers in a CAS array, all clients are connecting to the array and not a single server

    - All mailbox databases have their RPC client access server set to the CAS array

    - 2 X mailbox servers in a DAG

    - Arbitrary and discovery mailboxes are located within the primary staff mailbox database that has a copy

    - We do have mailboxes archiving set up, and the archive database does not have a copy as of yet. The archive database sits on EXMB01

    - Public folder databases are replicating between the two members of the DAG

    Anyone seen this before?

    Cheers
    Last edited by _Bat_; 5th August 2014 at 12:37 PM.

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    Oaktech's Avatar
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    Is there a single IP shared between both DAG boxes for connection? If there isn't, the clients might not be able to find the upright DAG.

    http://careexchange.in/how-to-create...exchange-2010/
    Last edited by Oaktech; 5th August 2014 at 12:42 PM.

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    @Oaktech is on the right track. What load balancer are you using? Windows NLB?

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    Quote Originally Posted by Oaktech View Post
    Is there a single IP shared between both DAG boxes for connection? If there isn't, the clients might not be able to find the upright DAG.

    How to create a DAG (Database Availability Group) in Exchange 2010 | CareExchange.in
    The DAG has an IP address set. If I shut one DAG member down, I can connect to the other DAG server using this IP address, regardless of which DAG member has been shut down.

    - - - Updated - - -

    Quote Originally Posted by FN-GM View Post
    @Oaktech is on the right track. What load balancer are you using? Windows NLB?
    For the CAS array? Yes

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    FN-GM's Avatar
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    Quote Originally Posted by _Bat_ View Post
    The DAG has an IP address set. If I shut one DAG member down, I can connect to the other DAG server using this IP address, regardless of which DAG member has been shut down.

    - - - Updated - - -



    For the CAS array? Yes
    Is everything set to point to that shared IP address?

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    Quote Originally Posted by FN-GM View Post
    Is everything set to point to that shared IP address?
    How do I check that? I was under the impression that the only method to link CAS servers to mailbox servers was the RPC client access server setting of the mailbox database, which is this case is pointing to the CAS array.

    Thanks

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    Afternoon all

    Turns out that the archive mailbox database not being given a second copy yet on the DAG was preventing outlook from connecting when the server it's single copy was located on (EXMB01) is shut down. Outlook won't even allow users to see their primary mailbox in this scenario, despite a copy of that database being mounted.

    The same effect is not seen if the archive mailbox is simply dismounted. EXMB01 has to be shut down.

    I have since given the archive mailbox database a second copy, so this will also failover in the event of EXMB01 going offline.

    Thanks

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