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3 Replies Latest reply: Nov 26, 2012 11:45 AM by efierro RSS

Question Regarding RMAN Incremental Level 0

976258 Newbie
Currently Being Moderated
Hi to all,

I am looking through the benefits of running different types of backups. One of which is the Incremental strategy.

If I run a nightly Incremental 0 and not subsequent incremental level 1 backups would that mean the the incremental level 0 would essentially backup all the changes since the database creation over and over, behaving in such a way as a full database backup.

The reason I ask is.

I have a incremental level 0 backup ran nightly but the incremental changes are small in comparison to the size of the database. For example the size of the database used space is 500GB and the size of the compressed incremental level 0 is only 60GB, even taking into consideration compression this seems very small.

Appreciate all who reply.
  • 1. Re: Question Regarding RMAN Incremental Level 0
    mseberg Guru
    Currently Being Moderated
    Hello;

    Do you have many empty blocks inside your 500GB database? 60GB seems very small to me also.

    Can you post your backup script?

    By running a level 0 you have the option of running a true incremental backup ( level 1 ) at any time. If you just run a backup RMAN will not be able to distinguish which blocks needed to be backed up during an incremental backup. So its not a bad idea. But I would worry something is wrong if my backup was so small.

    rc_rman_backup_job_details should provide details of the correct size.



    RMAN Backup Compression

    Compression can be set as follows :
    RMAN> CONFIGURE COMPRESSION ALGORITHM ‘HIGH’;
    
    RMAN> CONFIGURE COMPRESSION ALGORITHM ‘MEDIUM’;
    
    RMAN> CONFIGURE COMPRESSION ALGORITHM ‘LOW’;
    
    RMAN> CONFIGURE COMPRESSION ALGORITHM ‘BASIC’;
    I would expect compression ratios to be 5.0 at the very best. Since yours are sky high you probably have an issue. You ratio appears to be around 8.3


    Best Regards

    mseberg

    Edited by: mseberg on Nov 26, 2012 11:15 AM
  • 2. Re: Question Regarding RMAN Incremental Level 0
    nnarimanov Newbie
    Currently Being Moderated
    I advice you to take Inc 0 backups on every Monday, all other days take Inc 1. Also enable block_change_tracking, it's amazing thing.
  • 3. Re: Question Regarding RMAN Incremental Level 0
    efierro Newbie
    Currently Being Moderated
    You can consider incremental level 0 as a full backup with option to run incremental backups later. If you are not getting any errors during the rman backup then the 60G size should be correct and you are probably calculating the size of your database wrong, taking into account probably allocated empty data files or empty segments.

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