Mirroring

  • Admingod

    SSCertifiable

    Points: 5340

    I have database mirroring configured from Server A(principal) to Server C(mirror). However, i am thinking to do another DB mirroring from Server B(Principal). Is it okay to configure mirroring from Server B(Principal) to Server C(mirror)? Since there is already mirroring configured from Server A to Server C. it doesn't look like good practice, but is there any issues you can think of?
    So it would be something like
    Principal databases 
    Server A(X database),
    Server B (Y database) 

    Mirror databases
    Server C  (X database and Y Database)

  • yelouati

    SSC Enthusiast

    Points: 108

    Yes, it is technically feasible. It seems as if you are setting up D/R or consolidating databases. As long as Server C has enough resources it is more than OK.

  • Admingod

    SSCertifiable

    Points: 5340

    Thanks. However, the principal database would be part of N way SQL Server cluster. I have question what is the difference between two node cluster and N-Way cluster? Also, when failover happens will that have any impact on mirroring?

  • yelouati

    SSC Enthusiast

    Points: 108

    N Way has many meanings. What are you trying to accomplish? 

    With DB mirroring, or ALWAYSON too, when you failover a database (Mirroring) or an availability group (set of databases) , if done correctly, clients are pushed to the replica. So the server A database goes to C, or if you failover Server B's database it goes to server C. If you want both on server C then fail both of them over.

    Be mindful of logins and jobs...

  • Admingod

    SSCertifiable

    Points: 5340

    Thanks! I am familiar with fail over for DR. However, the principal database will be on 2 node cluster. What happens when the failover happened on Principal server side, like active node becomes passive and passive node becomes active, would that cause any issues with Mirroring side?

  • crow1969

    SSCrazy

    Points: 2730

    From what I remember of doing mirroring (it is a deprecated feature, these days), is that the mirroring will pick up just fine after a failover.  A failover is really no different from a restart of the service in any terms that mirroring cares about.  That said, you do have to make sure that both nodes have the proper firewall rules enabled, and the network can route between the mirror server, and the primary server's node.

  • Admingod

    SSCertifiable

    Points: 5340

    Thanks again. I agree with you about mirroring deprecated feature. However, lot of applications are not really supporting for AG group setup until SQL 2016.

  • Admingod

    SSCertifiable

    Points: 5340

    Can you setup mirroring from SQL 2012 to SQL Server 2014? Primary on SQL 2012 and mirror on SQL 2014. Is that possible?

  • yelouati

    SSC Enthusiast

    Points: 108

    As long as the secondary is the same or higher version. This is how I upgrade servers side by side

  • Admingod

    SSCertifiable

    Points: 5340

    Thanks! So you saying i can configure mirroring from SQL 2012(primary) to SQL 2014 or SQL 2016(mirrored database)? Also, another question does SQL 2012 can be installed on Windows 2016 server?

  • Admingod

    SSCertifiable

    Points: 5340

    So you saying configuring mirroring secondary as higher version is possible. Will there be any setup issues or any other issues noticed?

  • andreas.kreuzberg

    SSCertifiable

    Points: 5977

    Hi,

    if your synchronized is a higher version of sql server, be sure, if you ever failover to the newer sql server, you never can back to the lower version. This is a "one way migration".

    Kind regards,

    Andreas

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