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Database Mirroring Scenarios RRS feed

  • Question

  • Hi Everyone,

    I am doing some test for database mirroring. I come with come with these two scenarios i unable to test out.

    1) The principal database server disks full. In these case is the database mirroring failover will happen?

    2) The principal database server and mirror database server disk full. In these case what will happen to database mirroring?

    Saturday, January 18, 2014 12:53 PM

Answers

  • Hello,

    1. I dont think in this failover will happen but your application will fail.Failover will not happen because Database is not affected and network is also online .You should not worry about failover here but to create extra space.Since network is up logs will keep on moving from principal to mirror and mirror will keep on replaying it.But moment disk on which data file reside fills it wont be able to grow application will crash.If disk on which log file resides get filled no more logs will be generated this will again affect application and mirroring will be in suspended state.

    2.I have not  seen this scenario but if it happens no failover will occur but every thing will crash.


    Please mark this reply as the answer or vote as helpful, as appropriate, to make it useful for other readers


    • Edited by Shanky_621MVP Monday, January 20, 2014 9:59 AM
    • Marked as answer by tracycai Monday, January 27, 2014 1:43 AM
    Saturday, January 18, 2014 3:20 PM
  • Hi,

    No. Database mirroring endpoints use Transmission Control Protocol (TCP) to send and receive messages between the server instances participating database mirroring sessions. Automatic failover will occur if the principal server has lost communication with the rest of the database mirroring configuration, while the mirror and witness retain quorum. If all server instances lose communication, however, and the witness and the mirror server later regain communication, automatic failover does not occur.

    See ‘Conditions required for an Automatic failover’ section in the below link:

    http://technet.microsoft.com/en-us/library/ms189590(v=sql.105).aspx

    Additional information:

    Possible Failures During Database Mirroring
    http://technet.microsoft.com/en-us/library/ms190913(v=sql.105).aspx

    Thanks.


    Tracy Cai
    TechNet Community Support


    • Edited by tracycai Monday, January 20, 2014 9:46 AM
    • Marked as answer by tracycai Monday, January 27, 2014 1:43 AM
    Monday, January 20, 2014 9:41 AM

All replies

  • Hello,

    1. I dont think in this failover will happen but your application will fail.Failover will not happen because Database is not affected and network is also online .You should not worry about failover here but to create extra space.Since network is up logs will keep on moving from principal to mirror and mirror will keep on replaying it.But moment disk on which data file reside fills it wont be able to grow application will crash.If disk on which log file resides get filled no more logs will be generated this will again affect application and mirroring will be in suspended state.

    2.I have not  seen this scenario but if it happens no failover will occur but every thing will crash.


    Please mark this reply as the answer or vote as helpful, as appropriate, to make it useful for other readers


    • Edited by Shanky_621MVP Monday, January 20, 2014 9:59 AM
    • Marked as answer by tracycai Monday, January 27, 2014 1:43 AM
    Saturday, January 18, 2014 3:20 PM
  • Hi,

    No. Database mirroring endpoints use Transmission Control Protocol (TCP) to send and receive messages between the server instances participating database mirroring sessions. Automatic failover will occur if the principal server has lost communication with the rest of the database mirroring configuration, while the mirror and witness retain quorum. If all server instances lose communication, however, and the witness and the mirror server later regain communication, automatic failover does not occur.

    See ‘Conditions required for an Automatic failover’ section in the below link:

    http://technet.microsoft.com/en-us/library/ms189590(v=sql.105).aspx

    Additional information:

    Possible Failures During Database Mirroring
    http://technet.microsoft.com/en-us/library/ms190913(v=sql.105).aspx

    Thanks.


    Tracy Cai
    TechNet Community Support


    • Edited by tracycai Monday, January 20, 2014 9:46 AM
    • Marked as answer by tracycai Monday, January 27, 2014 1:43 AM
    Monday, January 20, 2014 9:41 AM