Database Mirroring - High Safety Mode RRS feed

  • Question

  • Hello!

    I'm reading about database mirroring in High Safety Mode (Synchronous with no witness). I'm a little confused about what happens if the mirror server disappears.

    From Books Online
    "If the mirror server instance goes down, the principal server instance is unaffected and runs exposed (that is without mirroring the data)."

    I was to the course [Upgrading your Database Administration Skills to SQL Server 2005] and the course material does not say the same."Scenario: Synchronous mirroring without a witness server. If the mirror server becomes unavailable, the principal server will take the database offline. This action attempts to maximize the protection of the database and ensure the integrity of its contents"
    I've made tests that shows that Books Online is right,
    but I would like to know if this is a behaviour that has changed.

    I also would like to know if it's possible to run in a more secure mode,
    where exposed operations is not allowed.

    Best regards

    Ola Hallengren

    Sunday, October 1, 2006 11:57 AM

All replies



    Thank you for finding this issue in our training materials. The principal is not taken offline when the mirror or witness is unavailable since this would decrease the availability of the principal database otherwise. There is no formal option to take the principal offline if the mirroring state is not synchronized, however you can customize the installation and use an event to take this action if the state changes from synchroned. Keep in mind that intermittent network outages could cause the principal to be taken offline if you make this alteration. Also you will need to decide how you want to handle bringing the database back online.




    Matt Hollingsworth

    Sr. Program Manager

    Microsoft SQL Server

    Wednesday, October 11, 2006 3:56 PM