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  1. #1
    Join Date
    Jun 2008
    Posts
    5

    Unanswered: backing up using rman before a check point

    hi,
    My database is operating in archivelog mode. If i create a table. and backup the database before the checkpoint ie before log switch and archiving of the redo logs when the data is still not written to datafile, will my backup have the table that i created. I tried the following and got the below result.

    My database is in archive log
    At 10:00 AM i created a table t1. then took a incremental level 0 backup.
    Then at 10:01 i created a table t2. then took a incremental level 1 backup.
    then at 10:02 i created a table t3. then took a incremental level 2 backup.
    I think the check point did not occurtill now

    Then i deleted all my controlfiles, redolog files, datafiles except archived redologs

    Aborted the instance.
    Started in nomount mode. Restore the control file incremental level 0 backup.
    started in mount. Restored and recoverd all the datafile from level 0 backup.

    opened the database using reset logs. the table t1 was there in the database.

    Then through rman i reseted the database to previous incarnation.
    followd the steps as similar as above to recover till level 1. when i opened the database i did not get the table t1.

    i again reseted the database incarnation. This time i restored and recoverd the database till level 2.. the latest one. But i did not get the table t1 and t2 that i created after level 0 backup. Can any one please help me out wat i missed here. Still i have a doubt whether the table that i created got lost as it was neither written to archived redo logs nor datafiles

  2. #2
    Join Date
    Jun 2003
    Location
    West Palm Beach, FL
    Posts
    2,713

    Talking reset logs

    Quote Originally Posted by dineshb4u
    ...
    opened the database using reset logs. the table t1 was there in the database.
    ...
    Once you open the database "reset logs" the redo logs are initialized and all information there is lost.

    That is why you need to "archive" the logs before backup.

    .
    The person who says it can't be done should not interrupt the person doing it. -- Chinese proverb

  3. #3
    Join Date
    Jun 2008
    Posts
    5

    wont the rman automatically record the changes

    Thanks for ur answer. But my doubt is that the rman should record all the commited changes when we take the backup even if it is not in datafiles (still in redo logs). Because the SCN for the transaction is already there in the control file. So if i restore the database to a time in past or do a restore until the last scn, i will be losing some committed data that was there in the redo log(active current, at the time of backing the database).

  4. #4
    Join Date
    Jun 2008
    Posts
    5
    Then does that mean that even though i archive my redologs, and follow proper backing up policy, my data will be lost if (through some means) my online redo logs are lost.

  5. #5
    Join Date
    Jun 2003
    Location
    West Palm Beach, FL
    Posts
    2,713

    Talking Database reset logs

    If you do PIT recovery and open the database resetlogs, the redo logs are re-initialized and the previous logs lost.

    If you reset database to previous incarnation you can only recover up to whatever logs are in the database plus any previous archive logs you may have, but no longer is there any data in the redo logs.
    The person who says it can't be done should not interrupt the person doing it. -- Chinese proverb

  6. #6
    Join Date
    Jul 2003
    Posts
    2,296
    Quote Originally Posted by dineshb4u
    Then does that mean that even though i archive my redologs, and follow proper backing up policy, my data will be lost if (through some means) my online redo logs are lost.
    Your idea of "proper backup policy" is the main driving force here.
    If you cannot afford to lose any data then you archive off all redo
    before your backups.

    Just to get you more paranoid:
    How often do your normal archivelogs get generated?
    With a disaster you are more than likely going to lose all data/changes
    after your last archive log. If an archivelog gets generated once every 3 hours
    then you will most likely lose 3 hours of changes if you have a disaster.
    - The_Duck
    you can lead someone to something but they will never learn anything ...

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