misconcept in backup mode
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Thread: misconcept in backup mode

  1. #1
    Join Date
    Jan 2007
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    231

    misconcept in backup mode

    Does backup mode stops writing into datafile?and increase in log file generation relates to this concept.

    Explanations pls Thanks.

  2. #2
    Join Date
    Aug 2007
    Location
    Cyberjaya,kuala lumpur
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    Hi

    When you place a tablespace in backup mode, the Oracle instance notes that a backup is being performed and internally compensates for it. As you know, it is impossible to make an authentic copy of a database file that is being written to. On receipt of the command to begin the backup, however, Oracle ceases to make direct changes to the database file. It uses a complex combination of rollback segments, buffers, redo logs, and archive logs to store the data until the end backup command is received and the database files are brought back in sync.
    Gopu

  3. #3
    Join Date
    Sep 2002
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    England
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    Quote Originally Posted by gopu_g
    When you place a tablespace in backup mode, the Oracle instance notes that a backup is being performed and internally compensates for it. As you know, it is impossible to make an authentic copy of a database file that is being written to. On receipt of the command to begin the backup, however, Oracle ceases to make direct changes to the database file. It uses a complex combination of rollback segments, buffers, redo logs, and archive logs to store the data until the end backup command is received and the database files are brought back in sync.
    Gopu
    err not true, the datafile DO get written to, that is so horribly wrong.

    All that happens is that the datafile headers get frozen.

    Stop writing rubbish

  4. #4
    Join Date
    Jan 2007
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    got a thread

    http://www.speakeasy.org/~jwilton/or...ot-backup.html

    but can't find exact thread from metalink and Reason for Increase in redo log generation during bkup can't find exact thread.

  5. #5
    Join Date
    Jun 2000
    Location
    Madrid, Spain
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    Quote Originally Posted by gopu_g
    When you place a tablespace in backup mode, the Oracle instance notes that a backup is being performed and internally compensates for it. As you know, it is impossible to make an authentic copy of a database file that is being written to. On receipt of the command to begin the backup, however, Oracle ceases to make direct changes to the database file. It uses a complex combination of rollback segments, buffers, redo logs, and archive logs to store the data until the end backup command is received and the database files are brought back in sync.
    Gopu
    what have you smoked...?!

  6. #6
    Join Date
    Jan 2008
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    Hampshire, UK
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    And would someone care to explain the dangers of fogetting to take the tablespace out of backup mode after the data file copy has been performed?...

  7. #7
    Join Date
    Sep 2002
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    England
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    extra redo log generation

    believe restarting a database with a tablespace in backup mode will cause problems

  8. #8
    Join Date
    Dec 2007
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    55
    but can't find exact thread from metalink and Reason for Increase in redo log generation during bkup can't find exact thread.
    It applies all the changes in the block at once to the redologs instead of individual changes when not in backup mode.

  9. #9
    Join Date
    Jan 2007
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    231
    Dave., can u explain me briefly on extra redo log generation.

  10. #10
    Join Date
    Apr 2003
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    Pune,Maharashtra. India.
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    Rgds
    Parag

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