Active\Active cluster how many MSDTC needs to be configured?

  • Hi

    I'm building an Active\Active cluster with two sql instances, and I have a question regarding the MSDTC.

    Do I need to configure one MSDTC per instance (Total of two MSDTC) or just one MSDTC

    Thanks

    APA

  • When you configure MSDTC it will configure both servers within the cluster.

  • Thanks,

    So I just need one MSDTC on the Active\Active cluster?

    On which cases would I need two MSDTC?

    Thanks again

  • DTC will exist on all nodes, it CAN be clustered and then the DTC will be a resource withing the resource group that SQL exists in.

    However, I have several A/A clusters and have not needed to do anything with DTC to make it work just fine.

    The exception being to allow remote access. But I didn't do anything cluster related.

    CEWII

  • Elliott Whitlow (5/10/2012)


    DTC will exist on all nodes, it CAN be clustered and then the DTC will be a resource withing the resource group that SQL exists in.

    However, I have several A/A clusters and have not needed to do anything with DTC to make it work just fine.

    The exception being to allow remote access. But I didn't do anything cluster related.

    CEWII

    Been told that MSDTC should be in its own resource group to prevent its failure from causing a SQL Server failover.

    Not sure how true as I don't have a lot of experience with SQL Server in a clustered environment. Guess that means I shouldn't consider myself a Senior DBA. Sorry wrong thread, but just thinking out loud.

  • I have never had this cause a failover, not saying it couldn't but never had it happen..

    CEWII

  • Ok, so you can leave DTC running locally as Elliott has pointed out and that's fine for some scenarios but this can affect in flight transactions though upon a failover, hence why it's best to use a clustered DTC resource.

    You can either put the clustered DTC application into the same group as the SQL server instance, this will generally force the instance to use this DTC where you have multiple DTCs within the cluster.

    You can also put the DTC into separate cluster groups\applications and use the "MSDTC tmmapping" command to map a DTC group\app to a particular clustered SQL server instance group\app.

    Check this link for mapping MSDTC.

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    "Ya can't make an omelette without breaking just a few eggs" 😉

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