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5 Replies Latest reply: Aug 16, 2013 4:02 AM by cardel RSS

Different full backup size of identical databases

cardel Newbie
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Hello,

I am on Oracle 10GR2.

I have 1 database instance with size approximately 50GB. Today I created second instance with RMAN duplication process from the first instance. So now I have two similar DB instances with same size 50GB.

What is strange to me is size of FULL LEVEL0 backups of these databases.

Backup size of original database has approximately 22 GB, backup size of second (duplicated) instance has 7GB.

 

Can you explain me why? Or what should I do with original database to have same small backup size.

 

Executed RMAN command for backup is: BACKUP INCREMENTAL LEVEL 0 DATABASE PLUS ARCHIVELOG;

 

Thank you

  • 1. Re: Different full backup size of identical databases
    DK2010 Guru
    Currently Being Moderated

    Hi,

     

    Did you use until time for duplication, what is the current size of your source(first) and second database.

    use the dba_segments for  getting the size.

     

    HTH

  • 2. Re: Different full backup size of identical databases
    Hemant K Chitale Oracle ACE
    Currently Being Moderated

    Do a SHOW ALL  in RMAN connected to each database and compare the output.

    Check the Backup script for each database.

     

    See if you have COMPRESSED BACKUPSET configured in the second database ?

     

     

    Hemant K Chitale

  • 3. Re: Different full backup size of identical databases
    cardel Newbie
    Currently Being Moderated

    select sum(bytes)/1024/1024/1024 GB from dba_segments;

     

    This select gives me 6,79 GB in both instances.

     

    I did not used UNTIL TIME for duplication.

     

    RMAN settings is same for both instances and I don't use any compression

     

    RMAN configuration parameters are:

    CONFIGURE RETENTION POLICY TO REDUNDANCY 1; # default

    CONFIGURE BACKUP OPTIMIZATION OFF; # default

    CONFIGURE DEFAULT DEVICE TYPE TO DISK; # default

    CONFIGURE CONTROLFILE AUTOBACKUP ON;

    CONFIGURE CONTROLFILE AUTOBACKUP FORMAT FOR DEVICE TYPE DISK TO '%F'; # default

    CONFIGURE DEVICE TYPE DISK PARALLELISM 1 BACKUP TYPE TO BACKUPSET; # default

    CONFIGURE DATAFILE BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

    CONFIGURE ARCHIVELOG BACKUP COPIES FOR DEVICE TYPE DISK TO 1; # default

    CONFIGURE MAXSETSIZE TO UNLIMITED; # default

    CONFIGURE ENCRYPTION FOR DATABASE OFF; # default

    CONFIGURE ENCRYPTION ALGORITHM 'AES128'; # default

    CONFIGURE ARCHIVELOG DELETION POLICY TO NONE; # default

  • 4. Re: Different full backup size of identical databases
    DK2010 Guru
    Currently Being Moderated

    Hi,

     

    How did you check the Difference in Backup Size, from OS Utility ?

    Check the size from RMAN Command  list backup;

     

    RMAN Only take the Backup of used Block, so segment size with ~7G backup size won't be 22G.

     

    HTH

  • 5. Re: Different full backup size of identical databases
    cardel Newbie
    Currently Being Moderated

    I have deleted all old backups and archivelogs. Configure compression on new backups and run new full LEVEL 0 backup plus archivelog.

    I don't know why, but now, both backups has same size ~1GB.

     

    Thank you for some tips

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