5 Replies Latest reply: Aug 16, 2013 6:02 AM by cardel RSS

    Different full backup size of identical databases

    cardel

      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

          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

            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

              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

                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

                  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