RMAN - "Full" backup versus "Incremental level=0"
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Thread: RMAN - "Full" backup versus "Incremental level=0"

  1. #1
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    RMAN - "Full" backup versus "Incremental level=0"

    I'm a little confused with RMAN terminology. Can someone help me out here.

    1) In what scenario would a DBA initiate a "Full" backup versus doing an "full incremental level 0" backup? I don't see why a DBA would ever kick off the former. Might as well do a "level 0" instead everytime, right?

    2) Below are the definitions of "Full" and "Incremental" backups from the TRM. Now what is a "Whole" database backup (referred to in the below 'Note')?! Per my understanding - full, whole, and incremental only backup used data blocks in the datafiles.
    Thanks, Anand

    Here are the definitions from the TRM.

    Backup Type : Definition
    1) Full :
    A backup that is not incremental. A full backup includes all used data blocks in the datafiles. Full backups of control files and archived logs always include all blocks in the files.

    Note: A full backup is different from a whole database backup, which is a backup of all datafiles and the current control file.


    2) Incremental
    A backup of datafiles that includes only the blocks that have changed since a previous incremental backup. Incremental backups require a full or incremental level 0 backup to serve as a basis.

  2. #2
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    Re: RMAN - "Full" backup versus "Incremental level=0"

    Originally posted by Axr2
    1) In what scenario would a DBA initiate a "Full" backup versus doing an "full incremental level 0" backup? I don't see why a DBA would ever kick off the former. Might as well do a "level 0" instead everytime, right?

    Functionally they are the same thing. However, if you are implementing an incremental backup strategy, a "Full" backup can't be used as a baseline.


    2) Below are the definitions of "Full" and "Incremental" backups from the TRM. Now what is a "Whole" database backup (referred to in the below 'Note')?! Per my understanding - full, whole, and incremental only backup used data blocks in the datafiles.

    Kinda yes, kinda no. RMAN backs up blocks that have been used regardless of whether they are empty or not. RMAN won't backup blocks that have never been used.

    Not familiar with what the difference between a Whole backup and a Full backup are.
    Jeff Hunter
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  3. #3
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    Might as well do a "level 0" instead everytime, right?
    I presume that much more info has to be stored in the catalog for a "level 0" backup, so that subsequently changed blocks can be identified at "level 1". Is that right?

  4. #4
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    The following is a very good feature of 10g for those of you who take increemental backups:

    alter database enable block change tracking
    using file '/u03/oradata1/bct_01.dbf';
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  5. #5
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    Originally posted by julian
    The following is a very good feature of 10g for those of you who take increemental backups:

    alter database enable block change tracking
    using file '/u03/oradata1/bct_01.dbf';
    OK, and what's that do?
    Jeff Hunter
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  6. #6
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    Originally posted by marist89
    OK, and what's that do?
    Oracle will not have to put every single block into memory to check if it has been changed or not.
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  7. #7
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    Just an update to an old thread. Found a satisfactory answer to my initial question -

    "1) In what scenario would a DBA initiate a "Full" backup versus doing an "full incremental level 0" backup? I don't see why a DBA would ever kick off the former. Might as well do a "level 0" instead everytime, right?"

    Block media recovery (in 9i) is not possible via an Incremental backup (whatever level). You must have a Full RMAN backup.

    Now that's a good enough reason for me to incorporate one Full backup on my systems every month.
    Last edited by Axr2; 05-14-2004 at 04:54 PM.

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