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Backup Exec ignoring Oracle RMAN Compression?

Created: 14 Jul 2013 | 2 comments

Backup Exec 2012 running on W2K8R2

Oracle databases running on Linux.

Using Backup Agent to run backup jobs of Oracle database - to disk on Backup Exec W2K8 server.

 

We're trying to reduce the size of Backup Exec (BE) backup files.  The backups, having been written to disk, or then copied across a 10Mb WAN link using robocopy.

The bulk of our BE backup are Oracle databases, and so I'm concentrating on these database backups.  I'm familar with Oracle and RMAN, I can run local RMAN backups on the Linux servers with or without RMAN compression, by settting CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COMPRESSED BACKUPSET;   Running with RMAN compression reduces the size of the rman backup files by about 70%.

Now, back in BE:

Even though I've set the Oracle databases to use RMAN compression for all database backups, BE seems to ignore this setting.

Backing up the same Oracle database in BE - with or without RMAN compression set at the RMAN device level, makes no difference to the resultant BE backup files. Looking at the BE Job Log shows the same volume of data having been backed up, and no indication of rman compression having been used.

So, it would seem Backup Exec ignores the RMAN devices settings, and uses it's own compression. In this case, 'Software compression' has been used by Backup Exec.

 

Any thoughts?

TIA

 

Operating Systems:

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sidd3009's picture

This is how I understand it:

RMAN compression would include compressing the backups in a format of either 'zlib' or 'bzip2'. Although Backup Exec depends on RMAN for performing a backup of Oracle Database, it has its own set of predefined commands which it triggers via RMAN. These commands do not have 'COMPRESSION' added to it as Backup Exec would not be able to verify the contents of the above mentioned formats once the backup operation completes(compressed using RMAN; verify the compressed data using RMAN would not work). 

Moreover, I am assuming that compression(as a feature) would need an additional license from Oracle. 

Based on the situation that is mentioned(getting a compression ratio of 70%) as a workaround, a backup could be performed of the .zlib or .bzip2 files(as a flat file). Once the restore of the flat files is done, you would have to refer to RMAN to perform further restore. Backup Exec would not be responsible for restoring Oracle. 

Note: For Oracle Backup jobs, Backup Exec does provide the following backup methods: 

Full - Back up selections.
This method is the equivalent of the Oracle RMAN Incremental: Level 0 backup. Select this method to perform a full backup of Oracle selections.
 
Differential - Back up changes since last full.
This method is the equivalent of the Oracle RMAN Cumulative Incremental: Level 1 backup. Select this method to back up all database changes since the last full backup. A full backup is performed of all archived redo logs since log files are never partially backed up.
 
Incremental - Back up changes since last full or incremental.
This method is the equivalent of the Oracle RMAN Incremental: Level 1 backup. Select this method to back up all database changes since the last full or incremental backup. A full backup is performed of all archived redo logs since log files are never partially backed up.

Please refer to the following link to get more details on it:  http://www.symantec.com/business/support/index?page=content&id=HOWTO24305#v19824858

Regards,

Siddhant Saini
Advanced Technical Support Engineer, Symantec Corporation 
www.symantec.com

MusSeth's picture

can we use DBA initiated job in this scenario