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Two DM's pointing at the same MDB

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  • 1.  Two DM's pointing at the same MDB

    Posted 05-26-2017 10:47 AM

    Hi,

     

    My customer is planning a contingency environment in case something happens to our production DM's, so his idea is to install a DM on another separate server and point it to the same database we currently use. Is it possible to point two DM servers at the same database? Can this imply any risks for the production environment?

     

    Thank you.



  • 2.  Re: Two DM's pointing at the same MDB
    Best Answer

    Posted 05-26-2017 01:14 PM

    No, it is not possible. During installation, the second DM would attempt to create a new Domain instance in the MDB and would fail with the message that another Domain already exists.

    Just in case this is the client's next suggestion: It is also not possible to 'clone' the first DM and have it acting as a 'cold' standby. There are objects in the DM's filesystem which are referenced by the database, and these would get out of sync with the database causing severe problems. The database and the DM filesystem MUST be kept in sync.

     

    Steve McCormick

    Services Principal Consultant, CA



  • 3.  Re: Two DM's pointing at the same MDB

    Posted 05-26-2017 04:00 PM

    Thank you very much, Stephen.

     

    I was thinking the same, but decided to ask just in case.

    I have opened a case regarding this, as the customer wishes to know if CA has any suggestions regarding contingency server configuration for the DM's. We already have a cluster configuration with failover for the MDB, but we don't have any contingency for the application servers.

     

    Thank you.



  • 4.  Re: Two DM's pointing at the same MDB

    Posted 06-02-2017 10:41 AM

    You can point it to a different instance of the same DB server but that is about all. HOWEVER, and this must be read very carefully... IF the two Domain Managers can be built on completely segregated networks with ONLY the DB Server available to both networks but accessed via different NICs; built on identical images, with identical names and HostUUIDs and both were NEVER on at the same time...then you likely could do this as it would essentially be an automated MDB move procedure or DM rebuild, but it would have to be VERY CAREFULLY maintained and could very easily result in problems.

     

    That said, there is virtually no real reason or benefit to doing this as it is not a valid DR configuration. If you lose the MDB server you have 0 DMs.

     

    The proper way to do it would be to have two 100% segregated networks, two SQL servers and two DMs built identically. Then you drop the MDB on the DR side, do a daily FULL BACKUP of the production MDB and move a copy to the DR SQL server every day which could be then used by the DM copy should the primary DM and/or DB server be lost. You can then take the Production DM and DB server offline, update DNS and put the DR DM and DB server on your production network to resume activities.

     

    Thanks,

    Joe Puccio

    Senior Engineer, Software Support