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DAG in E2010

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  • DAG in E2010

    Am I right in understanding that DAG feature in Exchange 2010 is to allow up-to-date database recovery incase of corruptions?. I think this is not possible in E2K3 or E2K7 as we will be able to restore to last back up state.

    Please correct if I am wrong.

  • #2
    Re: DAG in E2010

    Yes, you're right. DAGs are used to replicate mailbox stores between up to 16 servers, either in realtime or with a configurable lag.
    Cheers,

    Daniel Petri
    Microsoft Most Valuable Professional - Active Directory Directory Services
    MCSA/E, MCTS, MCITP, MCT

    Comment


    • #3
      Re: DAG in E2010

      Thanks Daniel. Technet says it needs cluster related components, 2-nics, it creates a CNO in AD, it needs FSW(file share witness), etc which are similar to cluster setup. I am unable to understand the difference between this cluster setup and DAG

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      • #4
        Re: DAG in E2010

        Well, DAG has cluster technologies behind it. It's just that you do NOT need to manually create the cluster, and that you do NOT need to design for a cluster in advance. You can start off by having one box, install the mailbox role (actually, in Ex2010 you can also have the CAS/HUB roles on that machine). Then, when you decide it's time, you add another mailbox role server, again, without having to worry about clusters or nodes. Now, when you decide you need redundancy, you simply create the DAG and when it's done, you add the other server (up to 16 servers in a DAG). Finally, each mailbox store can be replicated to up to 15 copies, and again, this can be done when you need it, and not planned in advance.
        Cheers,

        Daniel Petri
        Microsoft Most Valuable Professional - Active Directory Directory Services
        MCSA/E, MCTS, MCITP, MCT

        Comment


        • #5
          Re: DAG in E2010

          Well, I recently tried E14 in my test environment, My hyper-v host server is running on Windows Server 2008 R2 RC and first I created a VM with R2 RC Build 7100, but later I come to know that E14 beta doesnít support on build 7100 then I used Windows Server 2008 Beta version.

          I deployed two exchange typical setup ( HUB,CAS,MBX) and one more exchange with only HUB and CAS my idea was to configure and test DAG

          Problems and issues configuring DAG in E14 beta

          1. You will not be able to configure the DAG using EMC, because there is no option to given a DAG IP using EMC. Try it but u will get FSW access denied error, or any other meaningless error.
          2. You will not be able to add the first Mailbox server in the DAG group using EMC . we have to use powershell, otherwise it will through an exception error.


          I hope this EMC issues will be taken care on the next release of E14 beta 2 or RTM.


          Apart from that DAGís are really cool, it is working very perfect. The database switch overís and fail overís ( Microsoft call it as *overís J ) are very fast, am happy that I will be able to achieve the high availability by using only two servers( itís a fact that I should use any hardware load balancer if I need a complete availability because we cannot configure both NLB and failover cluster in windows server 2008, DAGís are using same clustering technology but a striped down version and Yeh! fully automatic)


          I just want to clarify a small doubt, please guide me !

          Yes itís true that I can achieve high availability in E14 using two servers and I can install HUB , CAS along with MBX role. But we have to configure FSW as a tie breaker and Microsoft is recommending Hub transport server role, if I have only two servers where I will configure my FSW? Yes we can configure it on our ADC or any other server but that time are we loosing sum functionality? At that time can we achieve the 15 seconds * overís?

          Regards,

          Shafeer T Cheri
          MCITP. MCTS. MCSA. CCNA
          Microsoft Infrastructure Consultant
          CBS Bahrain

          Comment


          • #6
            Re: DAG in E2010

            What build are you using?
            Cheers,

            Daniel Petri
            Microsoft Most Valuable Professional - Active Directory Directory Services
            MCSA/E, MCTS, MCITP, MCT

            Comment


            • #7
              Re: DAG in E2010

              hi sir,

              I am using Windows Server 2008 Beta, build 6 series, the RC 7100 is not supported

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