Multiplexing Control & Red0
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Thread: Multiplexing Control & Red0

  1. #1
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    Multiplexing Control & Red0

    I had a query. Since "Data Guard" can protect high availability of media failure, is "Multiplexing" of Redo and Control files still a need?


    I mean if Data Guard is setup, do we need to have even Multiplexing of Control and Redo? Please clarify.

  2. #2
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    Even if data guard protects your data, I'd still multiplex the control file and the redo logs. It's better to be safe than sorry... (multiplexing was invented for easy recovery)
    An expert is one who knows more and more about less and less until he knows absolutely everything about nothing.

  3. #3
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    Thanks for the reply; but frankly speaking, the Q hasn't been answered. The Q is - given that Data Guard is in place, is there any advantage in having Multiplexing? The answer is binary (YES or NO). And if Yes, why? Is it just for Double Security besides the Data Guard, or is it something it can do which the Data Guard may not be able to do?
    Last edited by Vipassana; 04-13-2004 at 05:59 AM.

  4. #4
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    Originally posted by Vipassana
    The answer is binary (YES or NO). And if Yes, why?
    If the answer is binary, there is no need for a "Why", right (the answer is rhetorical)?

    Multiplexing your control files and redo files is not required in a normal database, therefore it wouldn't be required in a DG configuration.

    However, with a dataguard solution, you have a possibility of missing a small number of transactions that might have been logged in your redo logs, but haven't been archvied yet. Even if it has been archived, the archive might not have gotten over to the standby database yet. Is this an acceptable loss to you?
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  5. #5
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    Hmmm, lets expound on this..
    master server. no multiplexing
    2 redo logs
    1 control file
    scenario 1
    check point occurs.. (why is irrelevant)
    BOOM! ORA-01578: ORACLE data block corrupted (file # 347, block # 13591)
    it just so happens that your redo log resides on the same disk that just blew up or maybe your control file.

    scenario 2
    cd /oradata/prod_database/
    rm *.log
    oops!
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  6. #6
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    Originally posted by marist89
    If the answer is binary, there is no need for a "Why", right (the answer is rhetorical)?

    Multiplexing your control files and redo files is not required in a normal database, therefore it wouldn't be required in a DG configuration.

    However, with a dataguard solution, you have a possibility of missing a small number of transactions that might have been logged in your redo logs, but haven't been archvied yet. Even if it has been archived, the archive might not have gotten over to the standby database yet. Is this an acceptable loss to you?
    This answered my doubts. Many thanks.

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