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  1. #1
    Join Date
    May 2004
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    Singapore
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    Unanswered: Decrease Redo log Size Procedure

    Hi All,

    I use oracle 9i V9.2 running on aix 5L V.5.2
    How to deduct the redo size (default=100Mb) ?
    Pls ask me step by step procedure.
    Thanks for advance

    regards
    chalie

  2. #2
    Join Date
    Feb 2004
    Location
    Dublin, Ireland
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    212
    I guess this example is so clear and will help you:

    -- Make sure the redo log to be dropped is not the current log

    SELECT group#, bytes, status FROM v$log;

    GROUP# BYTES STATUS
    ---------- ---------- ----------------
    1 1048576 INACTIVE
    2 1048576 CURRENT
    3 1048576 INACTIVE

    -- And where are the current logfile members?

    SELECT * FROM v$logfile;

    GROUP# STATUS MEMBER
    ---------- ------- ----------------------------------------
    1 D:\ORACLE\ORADATA\ORA816\REDO01.LOG
    2 D:\ORACLE\ORADATA\ORA816\REDO02.LOG
    3 D:\ORACLE\ORADATA\ORA816\REDO03.LOG

    -- Lets re-create group 1 (since its not active).
    -- First, drop the existing group.

    ALTER DATABASE DROP LOGFILE GROUP 1;

    -- Note, since we are making the log file bigger, we will
    -- need to drop the original.

    Host del D:\ORACLE\ORADATA\ORA816\REDO01.LOG
    -- or delete it on operating system level

    -- Now, re-create logfile group 1 as 20MB logfile.

    ALTER DATABASE ADD LOGFILE GROUP 1 ('d:\oracle\oradata\ora816\redo01a.log') SIZE 20M;

  3. #3
    Join Date
    Jun 2004
    Location
    Liverpool, NY USA
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    2,509
    Just curious, Why do you want to decrease the size of your redo logs. by changing from 100meg to 20meg you will increase the number of archive logs generated by a factor of 5 (same amount of space though) and will increase the frequency of log switches. And what are you really saving, a couble of 100 meg.
    Bill
    You do not need a parachute to skydive. You only need a parachute to skydive twice.

  4. #4
    Join Date
    Feb 2004
    Location
    Dublin, Ireland
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    212
    read again both articles...
    first one ask how to change redo log size
    second one is just an example how to do this

  5. #5
    Join Date
    Apr 2003
    Location
    Greenville, SC (USA)
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    1,155
    I'm not sure if he wants to find out the size of the redos
    select group#,bytes from v$log;

    or to reduce the size ... in which case, post 2 has that info...

  6. #6
    Join Date
    May 2004
    Location
    Singapore
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    Decrease Redo log Size Procedure

    Thank's All,

    My transaction database is small so the redo log will generate in arount 5 hours. I don't want to more lose data. In this chase, i want reduce log become 20 Mb and my assume, the log will be generate every 1 hour.

    Regards,
    chalie

  7. #7
    Join Date
    Jun 2004
    Location
    Liverpool, NY USA
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    You have a small concept problem. Just because you don't have an archive log generated, doesn't mean that you are not protected against data loss. An archve is just a copy of a used redo log that is flushed to disk and then reused. If you have to recover, your database will user Archive logs and the current redo logs.
    Bill
    You do not need a parachute to skydive. You only need a parachute to skydive twice.

  8. #8
    Join Date
    May 2004
    Location
    Singapore
    Posts
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    Decrease Redo log Size Procedure

    thank's for your respone, my database already archive mode. Another reason why I want to reduce redo log size is the archive log on the Production server will transfer to my DRC server (distance : +/- 60 km) from production server and bandwidth around 128 kbps.

    Now, I've idea to zip the file before transfer to DRC site, so i ignore to reduce redo size.

    regards
    chalie

  9. #9
    Join Date
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    Where the Surf Meets the Turf @Del Mar, CA
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    Provided Answers: 1
    Which is smaller five redo logfiles at 100MB each or 25 redo logfiles at 20MB each?
    The amount of data which gets transfered to the DR site will be the SAME regardless of the actual size of the redo logfiles themselves!
    Either you'll have fewer larger files or more smaller files so it does NOT matter what is the size of the redo logfiles.
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