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Couple of questions about database mirroring

  • February 16, 2009 at 5:31 am

    #155277

    I have a couple of questions about database mirroring:

    1) In database mirroring the only mode that can result in automatic fall over is High availability. If you use the other modes the failover has to be forced from the principal. So if the principal server is destroyed for whatever reason and you are in either High Protection or High performance Mode, then the mirror is useless as you cannot force the fallover. Is this correct ?

    2) What are the limitations for database mirroring in the Standard edition of SQL SERVER. Am I correct in saying that high availability mode is only available in enterprise?

    3) Any changes made on the principal are committed to within minutes to the Mirror Server. So therefore if key data was deleted on the primary then this would be reflect almost instantly in the mirror. So you would have to restore the data on the primary?

  • February 16, 2009 at 5:42 am

    #944442

    Hi,

    I recommend you to check out BOL so that you can get more info there.

    Thanks

    Chandra Mohan N

    [font="Verdana"]Thanks
    Chandra Mohan[/font]

  • February 16, 2009 at 6:12 am

    #944460

    I have read through BOL for data mirroring and setup a test environment for database mirroring, however there are a number of things I am unclear on, hence my post her........

  • February 16, 2009 at 9:42 am

    #944679

    For your question #1, taken from BOL:

    To force service in a database mirroring session

    1. Connect to the mirror server.

    2. Issue the following statement:

    ALTER DATABASE SET PARTNER FORCE_SERVICE_ALLOW_DATA_LOSS

    where is the mirrored database.

    The mirror server immediately transitions to principal server, and mirroring is suspended.

    As the option states, any transactions that have not been updated from the (former) Principal are lost when you execute this command.

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  • February 16, 2009 at 9:55 am

    #944688

    Question #2, also taken from BOL:

    Database mirroring partners and witnesses are supported by SQL Server 2005 Standard SP1 and later versions, and by SQL Server 2005 Enterprise Edition SP1 and later versions. But the partners must use the same edition, and asynchronous database mirroring (high-performance mode) is supported only by SQL Server 2005 Enterprise Edition SP1 and later versions. Witnesses are also supported by SQL Server 2005 Workgroup SP1 and later versions and by SQL Server 2005 Express Edition SP1 and later versions.

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    For better assistance in answering your questions, click here[/url]

  • February 16, 2009 at 9:57 am

    #944689

    And, on question #3, depending on your setup, changes on the Principal are usually reflected almost instantly on the mirror, not within minutes, so yes, any data deleted from Principal, must be restored on Principal....

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